Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / serial / ioc4_serial.c

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2003-2006 Silicon Graphics, Inc.  All Rights Reserved.
 */


/*
 * This file contains a module version of the ioc4 serial driver. This
 * includes all the support functions needed (support functions, etc.)
 * and the serial driver itself.
 */
#include <linux/errno.h>
#include <linux/tty.h>
#include <linux/serial.h>
#include <linux/serialP.h>
#include <linux/circ_buf.h>
#include <linux/serial_reg.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/ioc4.h>
#include <linux/serial_core.h>

/*
 * interesting things about the ioc4
 */

#define IOC4_NUM_SERIAL_PORTS   4       /* max ports per card */
#define IOC4_NUM_CARDS          8       /* max cards per partition */

#define GET_SIO_IR(_n)  (_n == 0) ? (IOC4_SIO_IR_S0) : \
                                (_n == 1) ? (IOC4_SIO_IR_S1) : \
                                (_n == 2) ? (IOC4_SIO_IR_S2) : \
                                (IOC4_SIO_IR_S3)

#define GET_OTHER_IR(_n)  (_n == 0) ? (IOC4_OTHER_IR_S0_MEMERR) : \
                                (_n == 1) ? (IOC4_OTHER_IR_S1_MEMERR) : \
                                (_n == 2) ? (IOC4_OTHER_IR_S2_MEMERR) : \
                                (IOC4_OTHER_IR_S3_MEMERR)


/*
 * All IOC4 registers are 32 bits wide.
 */

/*
 * PCI Memory Space Map
 */
#define IOC4_PCI_ERR_ADDR_L     0x000   /* Low Error Address */
#define IOC4_PCI_ERR_ADDR_VLD           (0x1 << 0)
#define IOC4_PCI_ERR_ADDR_MST_ID_MSK    (0xf << 1)
#define IOC4_PCI_ERR_ADDR_MST_NUM_MSK   (0xe << 1)
#define IOC4_PCI_ERR_ADDR_MST_TYP_MSK   (0x1 << 1)
#define IOC4_PCI_ERR_ADDR_MUL_ERR       (0x1 << 5)
#define IOC4_PCI_ERR_ADDR_ADDR_MSK      (0x3ffffff << 6)

/* Interrupt types */
#define IOC4_SIO_INTR_TYPE      0
#define IOC4_OTHER_INTR_TYPE    1
#define IOC4_NUM_INTR_TYPES     2

/* Bitmasks for IOC4_SIO_IR, IOC4_SIO_IEC, and IOC4_SIO_IES  */
#define IOC4_SIO_IR_S0_TX_MT       0x00000001   /* Serial port 0 TX empty */
#define IOC4_SIO_IR_S0_RX_FULL     0x00000002   /* Port 0 RX buf full */
#define IOC4_SIO_IR_S0_RX_HIGH     0x00000004   /* Port 0 RX hiwat */
#define IOC4_SIO_IR_S0_RX_TIMER    0x00000008   /* Port 0 RX timeout */
#define IOC4_SIO_IR_S0_DELTA_DCD   0x00000010   /* Port 0 delta DCD */
#define IOC4_SIO_IR_S0_DELTA_CTS   0x00000020   /* Port 0 delta CTS */
#define IOC4_SIO_IR_S0_INT         0x00000040   /* Port 0 pass-thru intr */
#define IOC4_SIO_IR_S0_TX_EXPLICIT 0x00000080   /* Port 0 explicit TX thru */
#define IOC4_SIO_IR_S1_TX_MT       0x00000100   /* Serial port 1 */
#define IOC4_SIO_IR_S1_RX_FULL     0x00000200   /* */
#define IOC4_SIO_IR_S1_RX_HIGH     0x00000400   /* */
#define IOC4_SIO_IR_S1_RX_TIMER    0x00000800   /* */
#define IOC4_SIO_IR_S1_DELTA_DCD   0x00001000   /* */
#define IOC4_SIO_IR_S1_DELTA_CTS   0x00002000   /* */
#define IOC4_SIO_IR_S1_INT         0x00004000   /* */
#define IOC4_SIO_IR_S1_TX_EXPLICIT 0x00008000   /* */
#define IOC4_SIO_IR_S2_TX_MT       0x00010000   /* Serial port 2 */
#define IOC4_SIO_IR_S2_RX_FULL     0x00020000   /* */
#define IOC4_SIO_IR_S2_RX_HIGH     0x00040000   /* */
#define IOC4_SIO_IR_S2_RX_TIMER    0x00080000   /* */
#define IOC4_SIO_IR_S2_DELTA_DCD   0x00100000   /* */
#define IOC4_SIO_IR_S2_DELTA_CTS   0x00200000   /* */
#define IOC4_SIO_IR_S2_INT         0x00400000   /* */
#define IOC4_SIO_IR_S2_TX_EXPLICIT 0x00800000   /* */
#define IOC4_SIO_IR_S3_TX_MT       0x01000000   /* Serial port 3 */
#define IOC4_SIO_IR_S3_RX_FULL     0x02000000   /* */
#define IOC4_SIO_IR_S3_RX_HIGH     0x04000000   /* */
#define IOC4_SIO_IR_S3_RX_TIMER    0x08000000   /* */
#define IOC4_SIO_IR_S3_DELTA_DCD   0x10000000   /* */
#define IOC4_SIO_IR_S3_DELTA_CTS   0x20000000   /* */
#define IOC4_SIO_IR_S3_INT         0x40000000   /* */
#define IOC4_SIO_IR_S3_TX_EXPLICIT 0x80000000   /* */

/* Per device interrupt masks */
#define IOC4_SIO_IR_S0          (IOC4_SIO_IR_S0_TX_MT | \
                                 IOC4_SIO_IR_S0_RX_FULL | \
                                 IOC4_SIO_IR_S0_RX_HIGH | \
                                 IOC4_SIO_IR_S0_RX_TIMER | \
                                 IOC4_SIO_IR_S0_DELTA_DCD | \
                                 IOC4_SIO_IR_S0_DELTA_CTS | \
                                 IOC4_SIO_IR_S0_INT | \
                                 IOC4_SIO_IR_S0_TX_EXPLICIT)
#define IOC4_SIO_IR_S1          (IOC4_SIO_IR_S1_TX_MT | \
                                 IOC4_SIO_IR_S1_RX_FULL | \
                                 IOC4_SIO_IR_S1_RX_HIGH | \
                                 IOC4_SIO_IR_S1_RX_TIMER | \
                                 IOC4_SIO_IR_S1_DELTA_DCD | \
                                 IOC4_SIO_IR_S1_DELTA_CTS | \
                                 IOC4_SIO_IR_S1_INT | \
                                 IOC4_SIO_IR_S1_TX_EXPLICIT)
#define IOC4_SIO_IR_S2          (IOC4_SIO_IR_S2_TX_MT | \
                                 IOC4_SIO_IR_S2_RX_FULL | \
                                 IOC4_SIO_IR_S2_RX_HIGH | \
                                 IOC4_SIO_IR_S2_RX_TIMER | \
                                 IOC4_SIO_IR_S2_DELTA_DCD | \
                                 IOC4_SIO_IR_S2_DELTA_CTS | \
                                 IOC4_SIO_IR_S2_INT | \
                                 IOC4_SIO_IR_S2_TX_EXPLICIT)
#define IOC4_SIO_IR_S3          (IOC4_SIO_IR_S3_TX_MT | \
                                 IOC4_SIO_IR_S3_RX_FULL | \
                                 IOC4_SIO_IR_S3_RX_HIGH | \
                                 IOC4_SIO_IR_S3_RX_TIMER | \
                                 IOC4_SIO_IR_S3_DELTA_DCD | \
                                 IOC4_SIO_IR_S3_DELTA_CTS | \
                                 IOC4_SIO_IR_S3_INT | \
                                 IOC4_SIO_IR_S3_TX_EXPLICIT)

/* Bitmasks for IOC4_OTHER_IR, IOC4_OTHER_IEC, and IOC4_OTHER_IES  */
#define IOC4_OTHER_IR_ATA_INT           0x00000001  /* ATAPI intr pass-thru */
#define IOC4_OTHER_IR_ATA_MEMERR        0x00000002  /* ATAPI DMA PCI error */
#define IOC4_OTHER_IR_S0_MEMERR         0x00000004  /* Port 0 PCI error */
#define IOC4_OTHER_IR_S1_MEMERR         0x00000008  /* Port 1 PCI error */
#define IOC4_OTHER_IR_S2_MEMERR         0x00000010  /* Port 2 PCI error */
#define IOC4_OTHER_IR_S3_MEMERR         0x00000020  /* Port 3 PCI error */
#define IOC4_OTHER_IR_KBD_INT           0x00000040  /* Keyboard/mouse */
#define IOC4_OTHER_IR_RESERVED          0x007fff80  /* Reserved */
#define IOC4_OTHER_IR_RT_INT            0x00800000  /* INT_OUT section output */
#define IOC4_OTHER_IR_GEN_INT           0xff000000  /* Generic pins */

#define IOC4_OTHER_IR_SER_MEMERR (IOC4_OTHER_IR_S0_MEMERR | IOC4_OTHER_IR_S1_MEMERR | \
                                  IOC4_OTHER_IR_S2_MEMERR | IOC4_OTHER_IR_S3_MEMERR)

/* Bitmasks for IOC4_SIO_CR */
#define IOC4_SIO_CR_CMD_PULSE_SHIFT              0  /* byte bus strobe shift */
#define IOC4_SIO_CR_ARB_DIAG_TX0        0x00000000
#define IOC4_SIO_CR_ARB_DIAG_RX0        0x00000010
#define IOC4_SIO_CR_ARB_DIAG_TX1        0x00000020
#define IOC4_SIO_CR_ARB_DIAG_RX1        0x00000030
#define IOC4_SIO_CR_ARB_DIAG_TX2        0x00000040
#define IOC4_SIO_CR_ARB_DIAG_RX2        0x00000050
#define IOC4_SIO_CR_ARB_DIAG_TX3        0x00000060
#define IOC4_SIO_CR_ARB_DIAG_RX3        0x00000070
#define IOC4_SIO_CR_SIO_DIAG_IDLE       0x00000080  /* 0 -> active request among
                                                           serial ports (ro) */
/* Defs for some of the generic I/O pins */
#define IOC4_GPCR_UART0_MODESEL    0x10 /* Pin is output to port 0
                                                   mode sel */
#define IOC4_GPCR_UART1_MODESEL    0x20 /* Pin is output to port 1
                                                   mode sel */
#define IOC4_GPCR_UART2_MODESEL    0x40 /* Pin is output to port 2
                                                   mode sel */
#define IOC4_GPCR_UART3_MODESEL    0x80 /* Pin is output to port 3
                                                   mode sel */

#define IOC4_GPPR_UART0_MODESEL_PIN   4 /* GIO pin controlling
                                           uart 0 mode select */
#define IOC4_GPPR_UART1_MODESEL_PIN   5 /* GIO pin controlling
                                           uart 1 mode select */
#define IOC4_GPPR_UART2_MODESEL_PIN   6 /* GIO pin controlling
                                           uart 2 mode select */
#define IOC4_GPPR_UART3_MODESEL_PIN   7 /* GIO pin controlling
                                           uart 3 mode select */

/* Bitmasks for serial RX status byte */
#define IOC4_RXSB_OVERRUN       0x01    /* Char(s) lost */
#define IOC4_RXSB_PAR_ERR       0x02    /* Parity error */
#define IOC4_RXSB_FRAME_ERR     0x04    /* Framing error */
#define IOC4_RXSB_BREAK         0x08    /* Break character */
#define IOC4_RXSB_CTS           0x10    /* State of CTS */
#define IOC4_RXSB_DCD           0x20    /* State of DCD */
#define IOC4_RXSB_MODEM_VALID   0x40    /* DCD, CTS, and OVERRUN are valid */
#define IOC4_RXSB_DATA_VALID    0x80    /* Data byte, FRAME_ERR PAR_ERR
                                         * & BREAK valid */

/* Bitmasks for serial TX control byte */
#define IOC4_TXCB_INT_WHEN_DONE 0x20    /* Interrupt after this byte is sent */
#define IOC4_TXCB_INVALID       0x00    /* Byte is invalid */
#define IOC4_TXCB_VALID         0x40    /* Byte is valid */
#define IOC4_TXCB_MCR           0x80    /* Data<7:0> to modem control reg */
#define IOC4_TXCB_DELAY         0xc0    /* Delay data<7:0> mSec */

/* Bitmasks for IOC4_SBBR_L */
#define IOC4_SBBR_L_SIZE        0x00000001  /* 0 == 1KB rings, 1 == 4KB rings */

/* Bitmasks for IOC4_SSCR_<3:0> */
#define IOC4_SSCR_RX_THRESHOLD  0x000001ff  /* Hiwater mark */
#define IOC4_SSCR_TX_TIMER_BUSY 0x00010000  /* TX timer in progress */
#define IOC4_SSCR_HFC_EN        0x00020000  /* Hardware flow control enabled */
#define IOC4_SSCR_RX_RING_DCD   0x00040000  /* Post RX record on delta-DCD */
#define IOC4_SSCR_RX_RING_CTS   0x00080000  /* Post RX record on delta-CTS */
#define IOC4_SSCR_DIAG          0x00200000  /* Bypass clock divider for sim */
#define IOC4_SSCR_RX_DRAIN      0x08000000  /* Drain RX buffer to memory */
#define IOC4_SSCR_DMA_EN        0x10000000  /* Enable ring buffer DMA */
#define IOC4_SSCR_DMA_PAUSE     0x20000000  /* Pause DMA */
#define IOC4_SSCR_PAUSE_STATE   0x40000000  /* Sets when PAUSE takes effect */
#define IOC4_SSCR_RESET         0x80000000  /* Reset DMA channels */

/* All producer/comsumer pointers are the same bitfield */
#define IOC4_PROD_CONS_PTR_4K   0x00000ff8      /* For 4K buffers */
#define IOC4_PROD_CONS_PTR_1K   0x000003f8      /* For 1K buffers */
#define IOC4_PROD_CONS_PTR_OFF           3

/* Bitmasks for IOC4_SRCIR_<3:0> */
#define IOC4_SRCIR_ARM          0x80000000      /* Arm RX timer */

/* Bitmasks for IOC4_SHADOW_<3:0> */
#define IOC4_SHADOW_DR   0x00000001     /* Data ready */
#define IOC4_SHADOW_OE   0x00000002     /* Overrun error */
#define IOC4_SHADOW_PE   0x00000004     /* Parity error */
#define IOC4_SHADOW_FE   0x00000008     /* Framing error */
#define IOC4_SHADOW_BI   0x00000010     /* Break interrupt */
#define IOC4_SHADOW_THRE 0x00000020     /* Xmit holding register empty */
#define IOC4_SHADOW_TEMT 0x00000040     /* Xmit shift register empty */
#define IOC4_SHADOW_RFCE 0x00000080     /* Char in RX fifo has an error */
#define IOC4_SHADOW_DCTS 0x00010000     /* Delta clear to send */
#define IOC4_SHADOW_DDCD 0x00080000     /* Delta data carrier detect */
#define IOC4_SHADOW_CTS  0x00100000     /* Clear to send */
#define IOC4_SHADOW_DCD  0x00800000     /* Data carrier detect */
#define IOC4_SHADOW_DTR  0x01000000     /* Data terminal ready */
#define IOC4_SHADOW_RTS  0x02000000     /* Request to send */
#define IOC4_SHADOW_OUT1 0x04000000     /* 16550 OUT1 bit */
#define IOC4_SHADOW_OUT2 0x08000000     /* 16550 OUT2 bit */
#define IOC4_SHADOW_LOOP 0x10000000     /* Loopback enabled */

/* Bitmasks for IOC4_SRTR_<3:0> */
#define IOC4_SRTR_CNT           0x00000fff      /* Reload value for RX timer */
#define IOC4_SRTR_CNT_VAL       0x0fff0000      /* Current value of RX timer */
#define IOC4_SRTR_CNT_VAL_SHIFT         16
#define IOC4_SRTR_HZ                 16000      /* SRTR clock frequency */

/* Serial port register map used for DMA and PIO serial I/O */
struct ioc4_serialregs {
        uint32_t sscr;
        uint32_t stpir;
        uint32_t stcir;
        uint32_t srpir;
        uint32_t srcir;
        uint32_t srtr;
        uint32_t shadow;
};

/* IOC4 UART register map */
struct ioc4_uartregs {
        char i4u_lcr;
        union {
                char iir;       /* read only */
                char fcr;       /* write only */
        } u3;
        union {
                char ier;       /* DLAB == 0 */
                char dlm;       /* DLAB == 1 */
        } u2;
        union {
                char rbr;       /* read only, DLAB == 0 */
                char thr;       /* write only, DLAB == 0 */
                char dll;       /* DLAB == 1 */
        } u1;
        char i4u_scr;
        char i4u_msr;
        char i4u_lsr;
        char i4u_mcr;
};

/* short names */
#define i4u_dll u1.dll
#define i4u_ier u2.ier
#define i4u_dlm u2.dlm
#define i4u_fcr u3.fcr

/* Serial port registers used for DMA serial I/O */
struct ioc4_serial {
        uint32_t sbbr01_l;
        uint32_t sbbr01_h;
        uint32_t sbbr23_l;
        uint32_t sbbr23_h;

        struct ioc4_serialregs port_0;
        struct ioc4_serialregs port_1;
        struct ioc4_serialregs port_2;
        struct ioc4_serialregs port_3;
        struct ioc4_uartregs uart_0;
        struct ioc4_uartregs uart_1;
        struct ioc4_uartregs uart_2;
        struct ioc4_uartregs uart_3;
} ioc4_serial;

/* UART clock speed */
#define IOC4_SER_XIN_CLK_66     66666667
#define IOC4_SER_XIN_CLK_33     33333333

#define IOC4_W_IES              0
#define IOC4_W_IEC              1

typedef void ioc4_intr_func_f(void *, uint32_t);
typedef ioc4_intr_func_f *ioc4_intr_func_t;

static unsigned int Num_of_ioc4_cards;

/* defining this will get you LOTS of great debug info */
//#define DEBUG_INTERRUPTS
#define DPRINT_CONFIG(_x...)    ;
//#define DPRINT_CONFIG(_x...)  printk _x

/* number of characters left in xmit buffer before we ask for more */
#define WAKEUP_CHARS    256

/* number of characters we want to transmit to the lower level at a time */
#define IOC4_MAX_CHARS  256
#define IOC4_FIFO_CHARS 255

/* Device name we're using */
#define DEVICE_NAME_RS232  "ttyIOC"
#define DEVICE_NAME_RS422  "ttyAIOC"
#define DEVICE_MAJOR       204
#define DEVICE_MINOR_RS232 50
#define DEVICE_MINOR_RS422 84


/* register offsets */
#define IOC4_SERIAL_OFFSET      0x300

/* flags for next_char_state */
#define NCS_BREAK       0x1
#define NCS_PARITY      0x2
#define NCS_FRAMING     0x4
#define NCS_OVERRUN     0x8

/* cause we need SOME parameters ... */
#define MIN_BAUD_SUPPORTED      1200
#define MAX_BAUD_SUPPORTED      115200

/* protocol types supported */
#define PROTO_RS232     3
#define PROTO_RS422     7

/* Notification types */
#define N_DATA_READY    0x01
#define N_OUTPUT_LOWAT  0x02
#define N_BREAK         0x04
#define N_PARITY_ERROR  0x08
#define N_FRAMING_ERROR 0x10
#define N_OVERRUN_ERROR 0x20
#define N_DDCD          0x40
#define N_DCTS          0x80

#define N_ALL_INPUT     (N_DATA_READY | N_BREAK |                       \
                         N_PARITY_ERROR | N_FRAMING_ERROR |             \
                         N_OVERRUN_ERROR | N_DDCD | N_DCTS)

#define N_ALL_OUTPUT    N_OUTPUT_LOWAT

#define N_ALL_ERRORS    (N_PARITY_ERROR | N_FRAMING_ERROR | N_OVERRUN_ERROR)

#define N_ALL           (N_DATA_READY | N_OUTPUT_LOWAT | N_BREAK |      \
                         N_PARITY_ERROR | N_FRAMING_ERROR |             \
                         N_OVERRUN_ERROR | N_DDCD | N_DCTS)

#define SER_DIVISOR(_x, clk)            (((clk) + (_x) * 8) / ((_x) * 16))
#define DIVISOR_TO_BAUD(div, clk)       ((clk) / 16 / (div))

/* Some masks */
#define LCR_MASK_BITS_CHAR      (UART_LCR_WLEN5 | UART_LCR_WLEN6 \
                                        | UART_LCR_WLEN7 | UART_LCR_WLEN8)
#define LCR_MASK_STOP_BITS      (UART_LCR_STOP)

#define PENDING(_p)     (readl(&(_p)->ip_mem->sio_ir.raw) & _p->ip_ienb)
#define READ_SIO_IR(_p) readl(&(_p)->ip_mem->sio_ir.raw)

/* Default to 4k buffers */
#ifdef IOC4_1K_BUFFERS
#define RING_BUF_SIZE 1024
#define IOC4_BUF_SIZE_BIT 0
#define PROD_CONS_MASK IOC4_PROD_CONS_PTR_1K
#else
#define RING_BUF_SIZE 4096
#define IOC4_BUF_SIZE_BIT IOC4_SBBR_L_SIZE
#define PROD_CONS_MASK IOC4_PROD_CONS_PTR_4K
#endif

#define TOTAL_RING_BUF_SIZE (RING_BUF_SIZE * 4)

/*
 * This is the entry saved by the driver - one per card
 */

#define UART_PORT_MIN           0
#define UART_PORT_RS232         UART_PORT_MIN
#define UART_PORT_RS422         1
#define UART_PORT_COUNT         2       /* one for each mode */

struct ioc4_control {
        int ic_irq;
        struct {
                /* uart ports are allocated here - 1 for rs232, 1 for rs422 */
                struct uart_port icp_uart_port[UART_PORT_COUNT];
                /* Handy reference material */
                struct ioc4_port *icp_port;
        } ic_port[IOC4_NUM_SERIAL_PORTS];
        struct ioc4_soft *ic_soft;
};

/*
 * per-IOC4 data structure
 */
#define MAX_IOC4_INTR_ENTS      (8 * sizeof(uint32_t))
struct ioc4_soft {
        struct ioc4_misc_regs __iomem *is_ioc4_misc_addr;
        struct ioc4_serial __iomem *is_ioc4_serial_addr;

        /* Each interrupt type has an entry in the array */
        struct ioc4_intr_type {

                /*
                 * Each in-use entry in this array contains at least
                 * one nonzero bit in sd_bits; no two entries in this
                 * array have overlapping sd_bits values.
                 */
                struct ioc4_intr_info {
                        uint32_t sd_bits;
                        ioc4_intr_func_f *sd_intr;
                        void *sd_info;
                } is_intr_info[MAX_IOC4_INTR_ENTS];

                /* Number of entries active in the above array */
                atomic_t is_num_intrs;
        } is_intr_type[IOC4_NUM_INTR_TYPES];

        /* is_ir_lock must be held while
         * modifying sio_ie values, so
         * we can be sure that sio_ie is
         * not changing when we read it
         * along with sio_ir.
         */
        spinlock_t is_ir_lock;  /* SIO_IE[SC] mod lock */
};

/* Local port info for each IOC4 serial ports */
struct ioc4_port {
        struct uart_port *ip_port;      /* current active port ptr */
        /* Ptrs for all ports */
        struct uart_port *ip_all_ports[UART_PORT_COUNT];
        /* Back ptrs for this port */
        struct ioc4_control *ip_control;
        struct pci_dev *ip_pdev;
        struct ioc4_soft *ip_ioc4_soft;

        /* pci mem addresses */
        struct ioc4_misc_regs __iomem *ip_mem;
        struct ioc4_serial __iomem *ip_serial;
        struct ioc4_serialregs __iomem *ip_serial_regs;
        struct ioc4_uartregs __iomem *ip_uart_regs;

        /* Ring buffer page for this port */
        dma_addr_t ip_dma_ringbuf;
        /* vaddr of ring buffer */
        struct ring_buffer *ip_cpu_ringbuf;

        /* Rings for this port */
        struct ring *ip_inring;
        struct ring *ip_outring;

        /* Hook to port specific values */
        struct hooks *ip_hooks;

        spinlock_t ip_lock;

        /* Various rx/tx parameters */
        int ip_baud;
        int ip_tx_lowat;
        int ip_rx_timeout;

        /* Copy of notification bits */
        int ip_notify;

        /* Shadow copies of various registers so we don't need to PIO
         * read them constantly
         */
        uint32_t ip_ienb;       /* Enabled interrupts */
        uint32_t ip_sscr;
        uint32_t ip_tx_prod;
        uint32_t ip_rx_cons;
        int ip_pci_bus_speed;
        unsigned char ip_flags;
};

/* tx low water mark.  We need to notify the driver whenever tx is getting
 * close to empty so it can refill the tx buffer and keep things going.
 * Let's assume that if we interrupt 1 ms before the tx goes idle, we'll
 * have no trouble getting in more chars in time (I certainly hope so).
 */
#define TX_LOWAT_LATENCY      1000
#define TX_LOWAT_HZ          (1000000 / TX_LOWAT_LATENCY)
#define TX_LOWAT_CHARS(baud) (baud / 10 / TX_LOWAT_HZ)

/* Flags per port */
#define INPUT_HIGH      0x01
#define DCD_ON          0x02
#define LOWAT_WRITTEN   0x04
#define READ_ABORTED    0x08
#define PORT_ACTIVE     0x10
#define PORT_INACTIVE   0       /* This is the value when "off" */


/* Since each port has different register offsets and bitmasks
 * for everything, we'll store those that we need in tables so we
 * don't have to be constantly checking the port we are dealing with.
 */
struct hooks {
        uint32_t intr_delta_dcd;
        uint32_t intr_delta_cts;
        uint32_t intr_tx_mt;
        uint32_t intr_rx_timer;
        uint32_t intr_rx_high;
        uint32_t intr_tx_explicit;
        uint32_t intr_dma_error;
        uint32_t intr_clear;
        uint32_t intr_all;
        int rs422_select_pin;
};

static struct hooks hooks_array[IOC4_NUM_SERIAL_PORTS] = {
        /* Values for port 0 */
        {
         IOC4_SIO_IR_S0_DELTA_DCD, IOC4_SIO_IR_S0_DELTA_CTS,
         IOC4_SIO_IR_S0_TX_MT, IOC4_SIO_IR_S0_RX_TIMER,
         IOC4_SIO_IR_S0_RX_HIGH, IOC4_SIO_IR_S0_TX_EXPLICIT,
         IOC4_OTHER_IR_S0_MEMERR,
         (IOC4_SIO_IR_S0_TX_MT | IOC4_SIO_IR_S0_RX_FULL |
          IOC4_SIO_IR_S0_RX_HIGH | IOC4_SIO_IR_S0_RX_TIMER |
          IOC4_SIO_IR_S0_DELTA_DCD | IOC4_SIO_IR_S0_DELTA_CTS |
          IOC4_SIO_IR_S0_INT | IOC4_SIO_IR_S0_TX_EXPLICIT),
         IOC4_SIO_IR_S0, IOC4_GPPR_UART0_MODESEL_PIN,
         },

        /* Values for port 1 */
        {
         IOC4_SIO_IR_S1_DELTA_DCD, IOC4_SIO_IR_S1_DELTA_CTS,
         IOC4_SIO_IR_S1_TX_MT, IOC4_SIO_IR_S1_RX_TIMER,
         IOC4_SIO_IR_S1_RX_HIGH, IOC4_SIO_IR_S1_TX_EXPLICIT,
         IOC4_OTHER_IR_S1_MEMERR,
         (IOC4_SIO_IR_S1_TX_MT | IOC4_SIO_IR_S1_RX_FULL |
          IOC4_SIO_IR_S1_RX_HIGH | IOC4_SIO_IR_S1_RX_TIMER |
          IOC4_SIO_IR_S1_DELTA_DCD | IOC4_SIO_IR_S1_DELTA_CTS |
          IOC4_SIO_IR_S1_INT | IOC4_SIO_IR_S1_TX_EXPLICIT),
         IOC4_SIO_IR_S1, IOC4_GPPR_UART1_MODESEL_PIN,
         },

        /* Values for port 2 */
        {
         IOC4_SIO_IR_S2_DELTA_DCD, IOC4_SIO_IR_S2_DELTA_CTS,
         IOC4_SIO_IR_S2_TX_MT, IOC4_SIO_IR_S2_RX_TIMER,
         IOC4_SIO_IR_S2_RX_HIGH, IOC4_SIO_IR_S2_TX_EXPLICIT,
         IOC4_OTHER_IR_S2_MEMERR,
         (IOC4_SIO_IR_S2_TX_MT | IOC4_SIO_IR_S2_RX_FULL |
          IOC4_SIO_IR_S2_RX_HIGH | IOC4_SIO_IR_S2_RX_TIMER |
          IOC4_SIO_IR_S2_DELTA_DCD | IOC4_SIO_IR_S2_DELTA_CTS |
          IOC4_SIO_IR_S2_INT | IOC4_SIO_IR_S2_TX_EXPLICIT),
         IOC4_SIO_IR_S2, IOC4_GPPR_UART2_MODESEL_PIN,
         },

        /* Values for port 3 */
        {
         IOC4_SIO_IR_S3_DELTA_DCD, IOC4_SIO_IR_S3_DELTA_CTS,
         IOC4_SIO_IR_S3_TX_MT, IOC4_SIO_IR_S3_RX_TIMER,
         IOC4_SIO_IR_S3_RX_HIGH, IOC4_SIO_IR_S3_TX_EXPLICIT,
         IOC4_OTHER_IR_S3_MEMERR,
         (IOC4_SIO_IR_S3_TX_MT | IOC4_SIO_IR_S3_RX_FULL |
          IOC4_SIO_IR_S3_RX_HIGH | IOC4_SIO_IR_S3_RX_TIMER |
          IOC4_SIO_IR_S3_DELTA_DCD | IOC4_SIO_IR_S3_DELTA_CTS |
          IOC4_SIO_IR_S3_INT | IOC4_SIO_IR_S3_TX_EXPLICIT),
         IOC4_SIO_IR_S3, IOC4_GPPR_UART3_MODESEL_PIN,
         }
};

/* A ring buffer entry */
struct ring_entry {
        union {
                struct {
                        uint32_t alldata;
                        uint32_t allsc;
                } all;
                struct {
                        char data[4];   /* data bytes */
                        char sc[4];     /* status/control */
                } s;
        } u;
};

/* Test the valid bits in any of the 4 sc chars using "allsc" member */
#define RING_ANY_VALID \
        ((uint32_t)(IOC4_RXSB_MODEM_VALID | IOC4_RXSB_DATA_VALID) * 0x01010101)

#define ring_sc     u.s.sc
#define ring_data   u.s.data
#define ring_allsc  u.all.allsc

/* Number of entries per ring buffer. */
#define ENTRIES_PER_RING (RING_BUF_SIZE / (int) sizeof(struct ring_entry))

/* An individual ring */
struct ring {
        struct ring_entry entries[ENTRIES_PER_RING];
};

/* The whole enchilada */
struct ring_buffer {
        struct ring TX_0_OR_2;
        struct ring RX_0_OR_2;
        struct ring TX_1_OR_3;
        struct ring RX_1_OR_3;
};

/* Get a ring from a port struct */
#define RING(_p, _wh)   &(((struct ring_buffer *)((_p)->ip_cpu_ringbuf))->_wh)

/* Infinite loop detection.
 */
#define MAXITER 10000000

/* Prototypes */
static void receive_chars(struct uart_port *);
static void handle_intr(void *arg, uint32_t sio_ir);

/*
 * port_is_active - determines if this port is currently active
 * @port: ptr to soft struct for this port
 * @uart_port: uart port to test for
 */
static inline int port_is_active(struct ioc4_port *port,
                struct uart_port *uart_port)
{
        if (port) {
                if ((port->ip_flags & PORT_ACTIVE)
                                        && (port->ip_port == uart_port))
                        return 1;
        }
        return 0;
}


/**
 * write_ireg - write the interrupt regs
 * @ioc4_soft: ptr to soft struct for this port
 * @val: value to write
 * @which: which register
 * @type: which ireg set
 */
static inline void
write_ireg(struct ioc4_soft *ioc4_soft, uint32_t val, int which, int type)
{
        struct ioc4_misc_regs __iomem *mem = ioc4_soft->is_ioc4_misc_addr;
        unsigned long flags;

        spin_lock_irqsave(&ioc4_soft->is_ir_lock, flags);

        switch (type) {
        case IOC4_SIO_INTR_TYPE:
                switch (which) {
                case IOC4_W_IES:
                        writel(val, &mem->sio_ies.raw);
                        break;

                case IOC4_W_IEC:
                        writel(val, &mem->sio_iec.raw);
                        break;
                }
                break;

        case IOC4_OTHER_INTR_TYPE:
                switch (which) {
                case IOC4_W_IES:
                        writel(val, &mem->other_ies.raw);
                        break;

                case IOC4_W_IEC:
                        writel(val, &mem->other_iec.raw);
                        break;
                }
                break;

        default:
                break;
        }
        spin_unlock_irqrestore(&ioc4_soft->is_ir_lock, flags);
}

/**
 * set_baud - Baud rate setting code
 * @port: port to set
 * @baud: baud rate to use
 */
static int set_baud(struct ioc4_port *port, int baud)
{
        int actual_baud;
        int diff;
        int lcr;
        unsigned short divisor;
        struct ioc4_uartregs __iomem *uart;

        divisor = SER_DIVISOR(baud, port->ip_pci_bus_speed);
        if (!divisor)
                return 1;
        actual_baud = DIVISOR_TO_BAUD(divisor, port->ip_pci_bus_speed);

        diff = actual_baud - baud;
        if (diff < 0)
                diff = -diff;

        /* If we're within 1%, we've found a match */
        if (diff * 100 > actual_baud)
                return 1;

        uart = port->ip_uart_regs;
        lcr = readb(&uart->i4u_lcr);
        writeb(lcr | UART_LCR_DLAB, &uart->i4u_lcr);
        writeb((unsigned char)divisor, &uart->i4u_dll);
        writeb((unsigned char)(divisor >> 8), &uart->i4u_dlm);
        writeb(lcr, &uart->i4u_lcr);
        return 0;
}


/**
 * get_ioc4_port - given a uart port, return the control structure
 * @port: uart port
 * @set: set this port as current
 */
static struct ioc4_port *get_ioc4_port(struct uart_port *the_port, int set)
{
        struct ioc4_driver_data *idd = dev_get_drvdata(the_port->dev);
        struct ioc4_control *control = idd->idd_serial_data;
        struct ioc4_port *port;
        int port_num, port_type;

        if (control) {
                for ( port_num = 0; port_num < IOC4_NUM_SERIAL_PORTS;
                                                        port_num++ ) {
                        port = control->ic_port[port_num].icp_port;
                        if (!port)
                                continue;
                        for (port_type = UART_PORT_MIN;
                                                port_type < UART_PORT_COUNT;
                                                port_type++) {
                                if (the_port == port->ip_all_ports
                                                        [port_type]) {
                                        /* set local copy */
                                        if (set) {
                                                port->ip_port = the_port;
                                        }
                                        return port;
                                }
                        }
                }
        }
        return NULL;
}

/* The IOC4 hardware provides no atomic way to determine if interrupts
 * are pending since two reads are required to do so.  The handler must
 * read the SIO_IR and the SIO_IES, and take the logical and of the
 * two.  When this value is zero, all interrupts have been serviced and
 * the handler may return.
 *
 * This has the unfortunate "hole" that, if some other CPU or
 * some other thread or some higher level interrupt manages to
 * modify SIO_IE between our reads of SIO_IR and SIO_IE, we may
 * think we have observed SIO_IR&SIO_IE==0 when in fact this
 * condition never really occurred.
 *
 * To solve this, we use a simple spinlock that must be held
 * whenever modifying SIO_IE; holding this lock while observing
 * both SIO_IR and SIO_IE guarantees that we do not falsely
 * conclude that no enabled interrupts are pending.
 */

static inline uint32_t
pending_intrs(struct ioc4_soft *soft, int type)
{
        struct ioc4_misc_regs __iomem *mem = soft->is_ioc4_misc_addr;
        unsigned long flag;
        uint32_t intrs = 0;

        BUG_ON(!((type == IOC4_SIO_INTR_TYPE)
               || (type == IOC4_OTHER_INTR_TYPE)));

        spin_lock_irqsave(&soft->is_ir_lock, flag);

        switch (type) {
        case IOC4_SIO_INTR_TYPE:
                intrs = readl(&mem->sio_ir.raw) & readl(&mem->sio_ies.raw);
                break;

        case IOC4_OTHER_INTR_TYPE:
                intrs = readl(&mem->other_ir.raw) & readl(&mem->other_ies.raw);

                /* Don't process any ATA interrupte */
                intrs &= ~(IOC4_OTHER_IR_ATA_INT | IOC4_OTHER_IR_ATA_MEMERR);
                break;

        default:
                break;
        }
        spin_unlock_irqrestore(&soft->is_ir_lock, flag);
        return intrs;
}

/**
 * port_init - Initialize the sio and ioc4 hardware for a given port
 *                      called per port from attach...
 * @port: port to initialize
 */
static int inline port_init(struct ioc4_port *port)
{
        uint32_t sio_cr;
        struct hooks *hooks = port->ip_hooks;
        struct ioc4_uartregs __iomem *uart;

        /* Idle the IOC4 serial interface */
        writel(IOC4_SSCR_RESET, &port->ip_serial_regs->sscr);

        /* Wait until any pending bus activity for this port has ceased */
        do
                sio_cr = readl(&port->ip_mem->sio_cr.raw);
        while (!(sio_cr & IOC4_SIO_CR_SIO_DIAG_IDLE));

        /* Finish reset sequence */
        writel(0, &port->ip_serial_regs->sscr);

        /* Once RESET is done, reload cached tx_prod and rx_cons values
         * and set rings to empty by making prod == cons
         */
        port->ip_tx_prod = readl(&port->ip_serial_regs->stcir) & PROD_CONS_MASK;
        writel(port->ip_tx_prod, &port->ip_serial_regs->stpir);
        port->ip_rx_cons = readl(&port->ip_serial_regs->srpir) & PROD_CONS_MASK;
        writel(port->ip_rx_cons | IOC4_SRCIR_ARM, &port->ip_serial_regs->srcir);

        /* Disable interrupts for this 16550 */
        uart = port->ip_uart_regs;
        writeb(0, &uart->i4u_lcr);
        writeb(0, &uart->i4u_ier);

        /* Set the default baud */
        set_baud(port, port->ip_baud);

        /* Set line control to 8 bits no parity */
        writeb(UART_LCR_WLEN8 | 0, &uart->i4u_lcr);
                                        /* UART_LCR_STOP == 1 stop */

        /* Enable the FIFOs */
        writeb(UART_FCR_ENABLE_FIFO, &uart->i4u_fcr);
        /* then reset 16550 FIFOs */
        writeb(UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT,
                        &uart->i4u_fcr);

        /* Clear modem control register */
        writeb(0, &uart->i4u_mcr);

        /* Clear deltas in modem status register */
        readb(&uart->i4u_msr);

        /* Only do this once per port pair */
        if (port->ip_hooks == &hooks_array[0]
                            || port->ip_hooks == &hooks_array[2]) {
                unsigned long ring_pci_addr;
                uint32_t __iomem *sbbr_l;
                uint32_t __iomem *sbbr_h;

                if (port->ip_hooks == &hooks_array[0]) {
                        sbbr_l = &port->ip_serial->sbbr01_l;
                        sbbr_h = &port->ip_serial->sbbr01_h;
                } else {
                        sbbr_l = &port->ip_serial->sbbr23_l;
                        sbbr_h = &port->ip_serial->sbbr23_h;
                }

                ring_pci_addr = (unsigned long __iomem)port->ip_dma_ringbuf;
                DPRINT_CONFIG(("%s: ring_pci_addr 0x%lx\n",
                                        __func__, ring_pci_addr));

                writel((unsigned int)((uint64_t)ring_pci_addr >> 32), sbbr_h);
                writel((unsigned int)ring_pci_addr | IOC4_BUF_SIZE_BIT, sbbr_l);
        }

        /* Set the receive timeout value to 10 msec */
        writel(IOC4_SRTR_HZ / 100, &port->ip_serial_regs->srtr);

        /* Set rx threshold, enable DMA */
        /* Set high water mark at 3/4 of full ring */
        port->ip_sscr = (ENTRIES_PER_RING * 3 / 4);
        writel(port->ip_sscr, &port->ip_serial_regs->sscr);

        /* Disable and clear all serial related interrupt bits */
        write_ireg(port->ip_ioc4_soft, hooks->intr_clear,
                       IOC4_W_IEC, IOC4_SIO_INTR_TYPE);
        port->ip_ienb &= ~hooks->intr_clear;
        writel(hooks->intr_clear, &port->ip_mem->sio_ir.raw);
        return 0;
}

/**
 * handle_dma_error_intr - service any pending DMA error interrupts for the
 *                      given port - 2nd level called via sd_intr
 * @arg: handler arg
 * @other_ir: ioc4regs
 */
static void handle_dma_error_intr(void *arg, uint32_t other_ir)
{
        struct ioc4_port *port = (struct ioc4_port *)arg;
        struct hooks *hooks = port->ip_hooks;
        unsigned long flags;

        spin_lock_irqsave(&port->ip_lock, flags);

        /* ACK the interrupt */
        writel(hooks->intr_dma_error, &port->ip_mem->other_ir.raw);

        if (readl(&port->ip_mem->pci_err_addr_l.raw) & IOC4_PCI_ERR_ADDR_VLD) {
                printk(KERN_ERR
                        "PCI error address is 0x%lx, "
                                "master is serial port %c %s\n",
                     (((uint64_t)readl(&port->ip_mem->pci_err_addr_h)
                                                         << 32)
                                | readl(&port->ip_mem->pci_err_addr_l.raw))
                                        & IOC4_PCI_ERR_ADDR_ADDR_MSK, '1' +
                     ((char)(readl(&port->ip_mem->pci_err_addr_l.raw) &
                             IOC4_PCI_ERR_ADDR_MST_NUM_MSK) >> 1),
                     (readl(&port->ip_mem->pci_err_addr_l.raw)
                                & IOC4_PCI_ERR_ADDR_MST_TYP_MSK)
                                ? "RX" : "TX");

                if (readl(&port->ip_mem->pci_err_addr_l.raw)
                                                & IOC4_PCI_ERR_ADDR_MUL_ERR) {
                        printk(KERN_ERR
                                "Multiple errors occurred\n");
                }
        }
        spin_unlock_irqrestore(&port->ip_lock, flags);

        /* Re-enable DMA error interrupts */
        write_ireg(port->ip_ioc4_soft, hooks->intr_dma_error, IOC4_W_IES,
                                                IOC4_OTHER_INTR_TYPE);
}

/**
 * intr_connect - interrupt connect function
 * @soft: soft struct for this card
 * @type: interrupt type
 * @intrbits: bit pattern to set
 * @intr: handler function
 * @info: handler arg
 */
static void
intr_connect(struct ioc4_soft *soft, int type,
                  uint32_t intrbits, ioc4_intr_func_f * intr, void *info)
{
        int i;
        struct ioc4_intr_info *intr_ptr;

        BUG_ON(!((type == IOC4_SIO_INTR_TYPE)
               || (type == IOC4_OTHER_INTR_TYPE)));

        i = atomic_inc(&soft-> is_intr_type[type].is_num_intrs) - 1;
        BUG_ON(!(i < MAX_IOC4_INTR_ENTS || (printk("i %d\n", i), 0)));

        /* Save off the lower level interrupt handler */
        intr_ptr = &soft->is_intr_type[type].is_intr_info[i];
        intr_ptr->sd_bits = intrbits;
        intr_ptr->sd_intr = intr;
        intr_ptr->sd_info = info;
}

/**
 * ioc4_intr - Top level IOC4 interrupt handler.
 * @irq: irq value
 * @arg: handler arg
 */

static irqreturn_t ioc4_intr(int irq, void *arg)
{
        struct ioc4_soft *soft;
        uint32_t this_ir, this_mir;
        int xx, num_intrs = 0;
        int intr_type;
        int handled = 0;
        struct ioc4_intr_info *intr_info;

        soft = arg;
        for (intr_type = 0; intr_type < IOC4_NUM_INTR_TYPES; intr_type++) {
                num_intrs = (int)atomic_read(
                                &soft->is_intr_type[intr_type].is_num_intrs);

                this_mir = this_ir = pending_intrs(soft, intr_type);

                /* Farm out the interrupt to the various drivers depending on
                 * which interrupt bits are set.
                 */
                for (xx = 0; xx < num_intrs; xx++) {
                        intr_info = &soft->is_intr_type[intr_type].is_intr_info[xx];
                        if ((this_mir = this_ir & intr_info->sd_bits)) {
                                /* Disable owned interrupts, call handler */
                                handled++;
                                write_ireg(soft, intr_info->sd_bits, IOC4_W_IEC,
                                                                intr_type);
                                intr_info->sd_intr(intr_info->sd_info, this_mir);
                                this_ir &= ~this_mir;
                        }
                }
        }
#ifdef DEBUG_INTERRUPTS
        {
                struct ioc4_misc_regs __iomem *mem = soft->is_ioc4_misc_addr;
                unsigned long flag;

                spin_lock_irqsave(&soft->is_ir_lock, flag);
                printk ("%s : %d : mem 0x%p sio_ir 0x%x sio_ies 0x%x "
                                "other_ir 0x%x other_ies 0x%x mask 0x%x\n",
                     __func__, __LINE__,
                     (void *)mem, readl(&mem->sio_ir.raw),
                     readl(&mem->sio_ies.raw),
                     readl(&mem->other_ir.raw),
                     readl(&mem->other_ies.raw),
                     IOC4_OTHER_IR_ATA_INT | IOC4_OTHER_IR_ATA_MEMERR);
                spin_unlock_irqrestore(&soft->is_ir_lock, flag);
        }
#endif
        return handled ? IRQ_HANDLED : IRQ_NONE;
}

/**
 * ioc4_attach_local - Device initialization.
 *                      Called at *_attach() time for each
 *                      IOC4 with serial ports in the system.
 * @idd: Master module data for this IOC4
 */
static int inline ioc4_attach_local(struct ioc4_driver_data *idd)
{
        struct ioc4_port *port;
        struct ioc4_port *ports[IOC4_NUM_SERIAL_PORTS];
        int port_number;
        uint16_t ioc4_revid_min = 62;
        uint16_t ioc4_revid;
        struct pci_dev *pdev = idd->idd_pdev;
        struct ioc4_control* control = idd->idd_serial_data;
        struct ioc4_soft *soft = control->ic_soft;
        void __iomem *ioc4_misc = idd->idd_misc_regs;
        void __iomem *ioc4_serial = soft->is_ioc4_serial_addr;

        /* IOC4 firmware must be at least rev 62 */
        pci_read_config_word(pdev, PCI_COMMAND_SPECIAL, &ioc4_revid);

        printk(KERN_INFO "IOC4 firmware revision %d\n", ioc4_revid);
        if (ioc4_revid < ioc4_revid_min) {
                printk(KERN_WARNING
                    "IOC4 serial not supported on firmware rev %d, "
                                "please upgrade to rev %d or higher\n",
                                ioc4_revid, ioc4_revid_min);
                return -EPERM;
        }
        BUG_ON(ioc4_misc == NULL);
        BUG_ON(ioc4_serial == NULL);

        /* Create port structures for each port */
        for (port_number = 0; port_number < IOC4_NUM_SERIAL_PORTS;
                                                        port_number++) {
                port = kzalloc(sizeof(struct ioc4_port), GFP_KERNEL);
                if (!port) {
                        printk(KERN_WARNING
                                "IOC4 serial memory not available for port\n");
                        return -ENOMEM;
                }
                spin_lock_init(&port->ip_lock);

                /* we need to remember the previous ones, to point back to
                 * them farther down - setting up the ring buffers.
                 */
                ports[port_number] = port;

                /* Allocate buffers and jumpstart the hardware.  */
                control->ic_port[port_number].icp_port = port;
                port->ip_ioc4_soft = soft;
                port->ip_pdev = pdev;
                port->ip_ienb = 0;
                /* Use baud rate calculations based on detected PCI
                 * bus speed.  Simply test whether the PCI clock is
                 * running closer to 66MHz or 33MHz.
                 */
                if (idd->count_period/IOC4_EXTINT_COUNT_DIVISOR < 20) {
                        port->ip_pci_bus_speed = IOC4_SER_XIN_CLK_66;
                } else {
                        port->ip_pci_bus_speed = IOC4_SER_XIN_CLK_33;
                }
                port->ip_baud = 9600;
                port->ip_control = control;
                port->ip_mem = ioc4_misc;
                port->ip_serial = ioc4_serial;

                /* point to the right hook */
                port->ip_hooks = &hooks_array[port_number];

                /* Get direct hooks to the serial regs and uart regs
                 * for this port
                 */
                switch (port_number) {
                case 0:
                        port->ip_serial_regs = &(port->ip_serial->port_0);
                        port->ip_uart_regs = &(port->ip_serial->uart_0);
                        break;
                case 1:
                        port->ip_serial_regs = &(port->ip_serial->port_1);
                        port->ip_uart_regs = &(port->ip_serial->uart_1);
                        break;
                case 2:
                        port->ip_serial_regs = &(port->ip_serial->port_2);
                        port->ip_uart_regs = &(port->ip_serial->uart_2);
                        break;
                default:
                case 3:
                        port->ip_serial_regs = &(port->ip_serial->port_3);
                        port->ip_uart_regs = &(port->ip_serial->uart_3);
                        break;
                }

                /* ring buffers are 1 to a pair of ports */
                if (port_number && (port_number & 1)) {
                        /* odd use the evens buffer */
                        port->ip_dma_ringbuf =
                                        ports[port_number - 1]->ip_dma_ringbuf;
                        port->ip_cpu_ringbuf =
                                        ports[port_number - 1]->ip_cpu_ringbuf;
                        port->ip_inring = RING(port, RX_1_OR_3);
                        port->ip_outring = RING(port, TX_1_OR_3);

                } else {
                        if (port->ip_dma_ringbuf == 0) {
                                port->ip_cpu_ringbuf = pci_alloc_consistent
                                        (pdev, TOTAL_RING_BUF_SIZE,
                                        &port->ip_dma_ringbuf);

                        }
                        BUG_ON(!((((int64_t)port->ip_dma_ringbuf) &
                                (TOTAL_RING_BUF_SIZE - 1)) == 0));
                        DPRINT_CONFIG(("%s : ip_cpu_ringbuf 0x%p "
                                                "ip_dma_ringbuf 0x%p\n",
                                        __func__,
                                        (void *)port->ip_cpu_ringbuf,
                                        (void *)port->ip_dma_ringbuf));
                        port->ip_inring = RING(port, RX_0_OR_2);
                        port->ip_outring = RING(port, TX_0_OR_2);
                }
                DPRINT_CONFIG(("%s : port %d [addr 0x%p] control 0x%p",
                                __func__,
                                port_number, (void *)port, (void *)control));
                DPRINT_CONFIG((" ip_serial_regs 0x%p ip_uart_regs 0x%p\n",
                                (void *)port->ip_serial_regs,
                                (void *)port->ip_uart_regs));

                /* Initialize the hardware for IOC4 */
                port_init(port);

                DPRINT_CONFIG(("%s: port_number %d port 0x%p inring 0x%p "
                                                "outring 0x%p\n",
                                __func__,
                                port_number, (void *)port,
                                (void *)port->ip_inring,
                                (void *)port->ip_outring));

                /* Attach interrupt handlers */
                intr_connect(soft, IOC4_SIO_INTR_TYPE,
                                GET_SIO_IR(port_number),
                                handle_intr, port);

                intr_connect(soft, IOC4_OTHER_INTR_TYPE,
                                GET_OTHER_IR(port_number),
                                handle_dma_error_intr, port);
        }
        return 0;
}

/**
 * enable_intrs - enable interrupts
 * @port: port to enable
 * @mask: mask to use
 */
static void enable_intrs(struct ioc4_port *port, uint32_t mask)
{
        struct hooks *hooks = port->ip_hooks;

        if ((port->ip_ienb & mask) != mask) {
                write_ireg(port->ip_ioc4_soft, mask, IOC4_W_IES,
                                                IOC4_SIO_INTR_TYPE);
                port->ip_ienb |= mask;
        }

        if (port->ip_ienb)
                write_ireg(port->ip_ioc4_soft, hooks->intr_dma_error,
                                IOC4_W_IES, IOC4_OTHER_INTR_TYPE);
}

/**
 * local_open - local open a port
 * @port: port to open
 */
static inline int local_open(struct ioc4_port *port)
{
        int spiniter = 0;

        port->ip_flags = PORT_ACTIVE;

        /* Pause the DMA interface if necessary */
        if (port->ip_sscr & IOC4_SSCR_DMA_EN) {
                writel(port->ip_sscr | IOC4_SSCR_DMA_PAUSE,
                        &port->ip_serial_regs->sscr);
                while((readl(&port->ip_serial_regs-> sscr)
                                & IOC4_SSCR_PAUSE_STATE) == 0) {
                        spiniter++;
                        if (spiniter > MAXITER) {
                                port->ip_flags = PORT_INACTIVE;
                                return -1;
                        }
                }
        }

        /* Reset the input fifo.  If the uart received chars while the port
         * was closed and DMA is not enabled, the uart may have a bunch of
         * chars hanging around in its rx fifo which will not be discarded
         * by rclr in the upper layer. We must get rid of them here.
         */
        writeb(UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR,
                                &port->ip_uart_regs->i4u_fcr);

        writeb(UART_LCR_WLEN8, &port->ip_uart_regs->i4u_lcr);
                                        /* UART_LCR_STOP == 1 stop */

        /* Re-enable DMA, set default threshold to intr whenever there is
         * data available.
         */
        port->ip_sscr &= ~IOC4_SSCR_RX_THRESHOLD;
        port->ip_sscr |= 1;     /* default threshold */

        /* Plug in the new sscr.  This implicitly clears the DMA_PAUSE
         * flag if it was set above
         */
        writel(port->ip_sscr, &port->ip_serial_regs->sscr);
        port->ip_tx_lowat = 1;
        return 0;
}

/**
 * set_rx_timeout - Set rx timeout and threshold values.
 * @port: port to use
 * @timeout: timeout value in ticks
 */
static inline int set_rx_timeout(struct ioc4_port *port, int timeout)
{
        int threshold;

        port->ip_rx_timeout = timeout;

        /* Timeout is in ticks.  Let's figure out how many chars we
         * can receive at the current baud rate in that interval
         * and set the rx threshold to that amount.  There are 4 chars
         * per ring entry, so we'll divide the number of chars that will
         * arrive in timeout by 4.
         * So .... timeout * baud / 10 / HZ / 4, with HZ = 100.
         */
        threshold = timeout * port->ip_baud / 4000;
        if (threshold == 0)
                threshold = 1;  /* otherwise we'll intr all the time! */

        if ((unsigned)threshold > (unsigned)IOC4_SSCR_RX_THRESHOLD)
                return 1;

        port->ip_sscr &= ~IOC4_SSCR_RX_THRESHOLD;
        port->ip_sscr |= threshold;

        writel(port->ip_sscr, &port->ip_serial_regs->sscr);

        /* Now set the rx timeout to the given value
         * again timeout * IOC4_SRTR_HZ / HZ
         */
        timeout = timeout * IOC4_SRTR_HZ / 100;
        if (timeout > IOC4_SRTR_CNT)
                timeout = IOC4_SRTR_CNT;

        writel(timeout, &port->ip_serial_regs->srtr);
        return 0;
}

/**
 * config_port - config the hardware
 * @port: port to config
 * @baud: baud rate for the port
 * @byte_size: data size
 * @stop_bits: number of stop bits
 * @parenb: parity enable ?
 * @parodd: odd parity ?
 */
static inline int
config_port(struct ioc4_port *port,
            int baud, int byte_size, int stop_bits, int parenb, int parodd)
{
        char lcr, sizebits;
        int spiniter = 0;

        DPRINT_CONFIG(("%s: baud %d byte_size %d stop %d parenb %d parodd %d\n",
                __func__, baud, byte_size, stop_bits, parenb, parodd));

        if (set_baud(port, baud))
                return 1;

        switch (byte_size) {
        case 5:
                sizebits = UART_LCR_WLEN5;
                break;
        case 6:
                sizebits = UART_LCR_WLEN6;
                break;
        case 7:
                sizebits = UART_LCR_WLEN7;
                break;
        case 8:
                sizebits = UART_LCR_WLEN8;
                break;
        default:
                return 1;
        }

        /* Pause the DMA interface if necessary */
        if (port->ip_sscr & IOC4_SSCR_DMA_EN) {
                writel(port->ip_sscr | IOC4_SSCR_DMA_PAUSE,
                        &port->ip_serial_regs->sscr);
                while((readl(&port->ip_serial_regs->sscr)
                                                & IOC4_SSCR_PAUSE_STATE) == 0) {
                        spiniter++;
                        if (spiniter > MAXITER)
                                return -1;
                }
        }

        /* Clear relevant fields in lcr */
        lcr = readb(&port->ip_uart_regs->i4u_lcr);
        lcr &= ~(LCR_MASK_BITS_CHAR | UART_LCR_EPAR |
                 UART_LCR_PARITY | LCR_MASK_STOP_BITS);

        /* Set byte size in lcr */
        lcr |= sizebits;

        /* Set parity */
        if (parenb) {
                lcr |= UART_LCR_PARITY;
                if (!parodd)
                        lcr |= UART_LCR_EPAR;
        }

        /* Set stop bits */
        if (stop_bits)
                lcr |= UART_LCR_STOP /* 2 stop bits */ ;

        writeb(lcr, &port->ip_uart_regs->i4u_lcr);

        /* Re-enable the DMA interface if necessary */
        if (port->ip_sscr & IOC4_SSCR_DMA_EN) {
                writel(port->ip_sscr, &port->ip_serial_regs->sscr);
        }
        port->ip_baud = baud;

        /* When we get within this number of ring entries of filling the
         * entire ring on tx, place an EXPLICIT intr to generate a lowat
         * notification when output has drained.
         */
        port->ip_tx_lowat = (TX_LOWAT_CHARS(baud) + 3) / 4;
        if (port->ip_tx_lowat == 0)
                port->ip_tx_lowat = 1;

        set_rx_timeout(port, 2);

        return 0;
}

/**
 * do_write - Write bytes to the port.  Returns the number of bytes
 *                      actually written. Called from transmit_chars
 * @port: port to use
 * @buf: the stuff to write
 * @len: how many bytes in 'buf'
 */
static inline int do_write(struct ioc4_port *port, char *buf, int len)
{
        int prod_ptr, cons_ptr, total = 0;
        struct ring *outring;
        struct ring_entry *entry;
        struct hooks *hooks = port->ip_hooks;

        BUG_ON(!(len >= 0));

        prod_ptr = port->ip_tx_prod;
        cons_ptr = readl(&port->ip_serial_regs->stcir) & PROD_CONS_MASK;
        outring = port->ip_outring;

        /* Maintain a 1-entry red-zone.  The ring buffer is full when
         * (cons - prod) % ring_size is 1.  Rather than do this subtraction
         * in the body of the loop, I'll do it now.
         */
        cons_ptr = (cons_ptr - (int)sizeof(struct ring_entry)) & PROD_CONS_MASK;

        /* Stuff the bytes into the output */
        while ((prod_ptr != cons_ptr) && (len > 0)) {
                int xx;

                /* Get 4 bytes (one ring entry) at a time */
                entry = (struct ring_entry *)((caddr_t) outring + prod_ptr);

                /* Invalidate all entries */
                entry->ring_allsc = 0;

                /* Copy in some bytes */
                for (xx = 0; (xx < 4) && (len > 0); xx++) {
                        entry->ring_data[xx] = *buf++;
                        entry->ring_sc[xx] = IOC4_TXCB_VALID;
                        len--;
                        total++;
                }

                /* If we are within some small threshold of filling up the
                 * entire ring buffer, we must place an EXPLICIT intr here
                 * to generate a lowat interrupt in case we subsequently
                 * really do fill up the ring and the caller goes to sleep.
                 * No need to place more than one though.
                 */
                if (!(port->ip_flags & LOWAT_WRITTEN) &&
                        ((cons_ptr - prod_ptr) & PROD_CONS_MASK)
                                <= port->ip_tx_lowat
                                        * (int)sizeof(struct ring_entry)) {
                        port->ip_flags |= LOWAT_WRITTEN;
                        entry->ring_sc[0] |= IOC4_TXCB_INT_WHEN_DONE;
                }

                /* Go on to next entry */
                prod_ptr += sizeof(struct ring_entry);
                prod_ptr &= PROD_CONS_MASK;
        }

        /* If we sent something, start DMA if necessary */
        if (total > 0 && !(port->ip_sscr & IOC4_SSCR_DMA_EN)) {
                port->ip_sscr |= IOC4_SSCR_DMA_EN;
                writel(port->ip_sscr, &port->ip_serial_regs->sscr);
        }

        /* Store the new producer pointer.  If tx is disabled, we stuff the
         * data into the ring buffer, but we don't actually start tx.
         */
        if (!uart_tx_stopped(port->ip_port)) {
                writel(prod_ptr, &port->ip_serial_regs->stpir);

                /* If we are now transmitting, enable tx_mt interrupt so we
                 * can disable DMA if necessary when the tx finishes.
                 */
                if (total > 0)
                        enable_intrs(port, hooks->intr_tx_mt);
        }
        port->ip_tx_prod = prod_ptr;
        return total;
}

/**
 * disable_intrs - disable interrupts
 * @port: port to enable
 * @mask: mask to use
 */
static void disable_intrs(struct ioc4_port *port, uint32_t mask)
{
        struct hooks *hooks = port->ip_hooks;

        if (port->ip_ienb & mask) {
                write_ireg(port->ip_ioc4_soft, mask, IOC4_W_IEC,
                                        IOC4_SIO_INTR_TYPE);
                port->ip_ienb &= ~mask;
        }

        if (!port->ip_ienb)
                write_ireg(port->ip_ioc4_soft, hooks->intr_dma_error,
                                IOC4_W_IEC, IOC4_OTHER_INTR_TYPE);
}

/**
 * set_notification - Modify event notification
 * @port: port to use
 * @mask: events mask
 * @set_on: set ?
 */
static int set_notification(struct ioc4_port *port, int mask, int set_on)
{
        struct hooks *hooks = port->ip_hooks;
        uint32_t intrbits, sscrbits;

        BUG_ON(!mask);

        intrbits = sscrbits = 0;

        if (mask & N_DATA_READY)
                intrbits |= (hooks->intr_rx_timer | hooks->intr_rx_high);
        if (mask & N_OUTPUT_LOWAT)
                intrbits |= hooks->intr_tx_explicit;
        if (mask & N_DDCD) {
                intrbits |= hooks->intr_delta_dcd;
                sscrbits |= IOC4_SSCR_RX_RING_DCD;
        }
        if (mask & N_DCTS)
                intrbits |= hooks->intr_delta_cts;

        if (set_on) {
                enable_intrs(port, intrbits);
                port->ip_notify |= mask;
                port->ip_sscr |= sscrbits;
        } else {
                disable_intrs(port, intrbits);
                port->ip_notify &= ~mask;
                port->ip_sscr &= ~sscrbits;
        }

        /* We require DMA if either DATA_READY or DDCD notification is
         * currently requested. If neither of these is requested and
         * there is currently no tx in progress, DMA may be disabled.
         */
        if (port->ip_notify & (N_DATA_READY | N_DDCD))
                port->ip_sscr |= IOC4_SSCR_DMA_EN;
        else if (!(port->ip_ienb & hooks->intr_tx_mt))
                port->ip_sscr &= ~IOC4_SSCR_DMA_EN;

        writel(port->ip_sscr, &port->ip_serial_regs->sscr);
        return 0;
}

/**
 * set_mcr - set the master control reg
 * @the_port: port to use
 * @mask1: mcr mask
 * @mask2: shadow mask
 */
static inline int set_mcr(struct uart_port *the_port,
                int mask1, int mask2)
{
        struct ioc4_port *port = get_ioc4_port(the_port, 0);
        uint32_t shadow;
        int spiniter = 0;
        char mcr;

        if (!port)
                return -1;

        /* Pause the DMA interface if necessary */
        if (port->ip_sscr & IOC4_SSCR_DMA_EN) {
                writel(port->ip_sscr | IOC4_SSCR_DMA_PAUSE,
                        &port->ip_serial_regs->sscr);
                while ((readl(&port->ip_serial_regs->sscr)
                                        & IOC4_SSCR_PAUSE_STATE) == 0) {
                        spiniter++;
                        if (spiniter > MAXITER)
                                return -1;
                }
        }
        shadow = readl(&port->ip_serial_regs->shadow);
        mcr = (shadow & 0xff000000) >> 24;

        /* Set new value */
        mcr |= mask1;
        shadow |= mask2;

        writeb(mcr, &port->ip_uart_regs->i4u_mcr);
        writel(shadow, &port->ip_serial_regs->shadow);

        /* Re-enable the DMA interface if necessary */
        if (port->ip_sscr & IOC4_SSCR_DMA_EN) {
                writel(port->ip_sscr, &port->ip_serial_regs->sscr);
        }
        return 0;
}

/**
 * ioc4_set_proto - set the protocol for the port
 * @port: port to use
 * @proto: protocol to use
 */
static int ioc4_set_proto(struct ioc4_port *port, int proto)
{
        struct hooks *hooks = port->ip_hooks;

        switch (proto) {
        case PROTO_RS232:
                /* Clear the appropriate GIO pin */
                writel(0, (&port->ip_mem->gppr[hooks->rs422_select_pin].raw));
                break;

        case PROTO_RS422:
                /* Set the appropriate GIO pin */
                writel(1, (&port->ip_mem->gppr[hooks->rs422_select_pin].raw));
                break;

        default:
                return 1;
        }
        return 0;
}

/**
 * transmit_chars - upper level write, called with ip_lock
 * @the_port: port to write
 */
static void transmit_chars(struct uart_port *the_port)
{
        int xmit_count, tail, head;
        int result;
        char *start;
        struct tty_struct *tty;
        struct ioc4_port *port = get_ioc4_port(the_port, 0);
        struct uart_info *info;

        if (!the_port)
                return;
        if (!port)
                return;

        info = the_port->info;
        tty = info->port.tty;

        if (uart_circ_empty(&info->xmit) || uart_tx_stopped(the_port)) {
                /* Nothing to do or hw stopped */
                set_notification(port, N_ALL_OUTPUT, 0);
                return;
        }

        head = info->xmit.head;
        tail = info->xmit.tail;
        start = (char *)&info->xmit.buf[tail];

        /* write out all the data or until the end of the buffer */
        xmit_count = (head < tail) ? (UART_XMIT_SIZE - tail) : (head - tail);
        if (xmit_count > 0) {
                result = do_write(port, start, xmit_count);
                if (result > 0) {
                        /* booking */
                        xmit_count -= result;
                        the_port->icount.tx += result;
                        /* advance the pointers */
                        tail += result;
                        tail &= UART_XMIT_SIZE - 1;
                        info->xmit.tail = tail;
                        start = (char *)&info->xmit.buf[tail];
                }
        }
        if (uart_circ_chars_pending(&info->xmit) < WAKEUP_CHARS)
                uart_write_wakeup(the_port);

        if (uart_circ_empty(&info->xmit)) {
                set_notification(port, N_OUTPUT_LOWAT, 0);
        } else {
                set_notification(port, N_OUTPUT_LOWAT, 1);
        }
}

/**
 * ioc4_change_speed - change the speed of the port
 * @the_port: port to change
 * @new_termios: new termios settings
 * @old_termios: old termios settings
 */
static void
ioc4_change_speed(struct uart_port *the_port,
                  struct ktermios *new_termios, struct ktermios *old_termios)
{
        struct ioc4_port *port = get_ioc4_port(the_port, 0);
        int baud, bits;
        unsigned cflag;
        int new_parity = 0, new_parity_enable = 0, new_stop = 0, new_data = 8;
        struct uart_info *info = the_port->info;

        cflag = new_termios->c_cflag;

        switch (cflag & CSIZE) {
        case CS5:
                new_data = 5;
                bits = 7;
                break;
        case CS6:
                new_data = 6;
                bits = 8;
                break;
        case CS7:
                new_data = 7;
                bits = 9;
                break;
        case CS8:
                new_data = 8;
                bits = 10;
                break;
        default:
                /* cuz we always need a default ... */
                new_data = 5;
                bits = 7;
                break;
        }
        if (cflag & CSTOPB) {
                bits++;
                new_stop = 1;
        }
        if (cflag & PARENB) {
                bits++;
                new_parity_enable = 1;
                if (cflag & PARODD)
                        new_parity = 1;
        }
        baud = uart_get_baud_rate(the_port, new_termios, old_termios,
                                MIN_BAUD_SUPPORTED, MAX_BAUD_SUPPORTED);
        DPRINT_CONFIG(("%s: returned baud %d\n", __func__, baud));

        /* default is 9600 */
        if (!baud)
                baud = 9600;

        if (!the_port->fifosize)
                the_port->fifosize = IOC4_FIFO_CHARS;
        the_port->timeout = ((the_port->fifosize * HZ * bits) / (baud / 10));
        the_port->timeout += HZ / 50;   /* Add .02 seconds of slop */

        the_port->ignore_status_mask = N_ALL_INPUT;

        info->port.tty->low_latency = 1;

        if (I_IGNPAR(info->port.tty))
                the_port->ignore_status_mask &= ~(N_PARITY_ERROR
                                                | N_FRAMING_ERROR);
        if (I_IGNBRK(info->port.tty)) {
                the_port->ignore_status_mask &= ~N_BREAK;
                if (I_IGNPAR(info->port.tty))
                        the_port->ignore_status_mask &= ~N_OVERRUN_ERROR;
        }
        if (!(cflag & CREAD)) {
                /* ignore everything */
                the_port->ignore_status_mask &= ~N_DATA_READY;
        }

        if (cflag & CRTSCTS) {
                port->ip_sscr |= IOC4_SSCR_HFC_EN;
        }
        else {
                port->ip_sscr &= ~IOC4_SSCR_HFC_EN;
        }
        writel(port->ip_sscr, &port->ip_serial_regs->sscr);

        /* Set the configuration and proper notification call */
        DPRINT_CONFIG(("%s : port 0x%p cflag 0%o "
                "config_port(baud %d data %d stop %d p enable %d parity %d),"
                " notification 0x%x\n",
             __func__, (void *)port, cflag, baud, new_data, new_stop,
             new_parity_enable, new_parity, the_port->ignore_status_mask));

        if ((config_port(port, baud,            /* baud */
                         new_data,              /* byte size */
                         new_stop,              /* stop bits */
                         new_parity_enable,     /* set parity */
                         new_parity)) >= 0) {   /* parity 1==odd */
                set_notification(port, the_port->ignore_status_mask, 1);
        }
}

/**
 * ic4_startup_local - Start up the serial port - returns >= 0 if no errors
 * @the_port: Port to operate on
 */
static inline int ic4_startup_local(struct uart_port *the_port)
{
        struct ioc4_port *port;
        struct uart_info *info;

        if (!the_port)
                return -1;

        port = get_ioc4_port(the_port, 0);
        if (!port)
                return -1;

        info = the_port->info;

        local_open(port);

        /* set the protocol - mapbase has the port type */
        ioc4_set_proto(port, the_port->mapbase);

        /* set the speed of the serial port */
        ioc4_change_speed(the_port, info->port.tty->termios,
                          (struct ktermios *)0);

        return 0;
}

/*
 * ioc4_cb_output_lowat - called when the output low water mark is hit
 * @the_port: port to output
 */
static void ioc4_cb_output_lowat(struct uart_port *the_port)
{
        unsigned long pflags;

        /* ip_lock is set on the call here */
        if (the_port) {
                spin_lock_irqsave(&the_port->lock, pflags);
                transmit_chars(the_port);
                spin_unlock_irqrestore(&the_port->lock, pflags);
        }
}

/**
 * handle_intr - service any interrupts for the given port - 2nd level
 *                      called via sd_intr
 * @arg: handler arg
 * @sio_ir: ioc4regs
 */
static void handle_intr(void *arg, uint32_t sio_ir)
{
        struct ioc4_port *port = (struct ioc4_port *)arg;
        struct hooks *hooks = port->ip_hooks;
        unsigned int rx_high_rd_aborted = 0;
        unsigned long flags;
        struct uart_port *the_port;
        int loop_counter;

        /* Possible race condition here: The tx_mt interrupt bit may be
         * cleared without the intervention of the interrupt handler,
         * e.g. by a write.  If the top level interrupt handler reads a
         * tx_mt, then some other processor does a write, starting up
         * output, then we come in here, see the tx_mt and stop DMA, the
         * output started by the other processor will hang.  Thus we can
         * only rely on tx_mt being legitimate if it is read while the
         * port lock is held.  Therefore this bit must be ignored in the
         * passed in interrupt mask which was read by the top level
         * interrupt handler since the port lock was not held at the time
         * it was read.  We can only rely on this bit being accurate if it
         * is read while the port lock is held.  So we'll clear it for now,
         * and reload it later once we have the port lock.
         */
        sio_ir &= ~(hooks->intr_tx_mt);

        spin_lock_irqsave(&port->ip_lock, flags);

        loop_counter = MAXITER; /* to avoid hangs */

        do {
                uint32_t shadow;

                if ( loop_counter-- <= 0 ) {
                        printk(KERN_WARNING "IOC4 serial: "
                                        "possible hang condition/"
                                        "port stuck on interrupt.\n");
                        break;
                }

                /* Handle a DCD change */
                if (sio_ir & hooks->intr_delta_dcd) {
                        /* ACK the interrupt */
                        writel(hooks->intr_delta_dcd,
                                &port->ip_mem->sio_ir.raw);

                        shadow = readl(&port->ip_serial_regs->shadow);

                        if ((port->ip_notify & N_DDCD)
                                        && (shadow & IOC4_SHADOW_DCD)
                                        && (port->ip_port)) {
                                the_port = port->ip_port;
                                the_port->icount.dcd = 1;
                                wake_up_interruptible
                                            (&the_port-> info->delta_msr_wait);
                        } else if ((port->ip_notify & N_DDCD)
                                        && !(shadow & IOC4_SHADOW_DCD)) {
                                /* Flag delta DCD/no DCD */
                                port->ip_flags |= DCD_ON;
                        }
                }

                /* Handle a CTS change */
                if (sio_ir & hooks->intr_delta_cts) {
                        /* ACK the interrupt */
                        writel(hooks->intr_delta_cts,
                                        &port->ip_mem->sio_ir.raw);

                        shadow = readl(&port->ip_serial_regs->shadow);

                        if ((port->ip_notify & N_DCTS)
                                        && (port->ip_port)) {
                                the_port = port->ip_port;
                                the_port->icount.cts =
                                        (shadow & IOC4_SHADOW_CTS) ? 1 : 0;
                                wake_up_interruptible
                                        (&the_port->info->delta_msr_wait);
                        }
                }

                /* rx timeout interrupt.  Must be some data available.  Put this
                 * before the check for rx_high since servicing this condition
                 * may cause that condition to clear.
                 */
                if (sio_ir & hooks->intr_rx_timer) {
                        /* ACK the interrupt */
                        writel(hooks->intr_rx_timer,
                                &port->ip_mem->sio_ir.raw);

                        if ((port->ip_notify & N_DATA_READY)
                                        && (port->ip_port)) {
                                /* ip_lock is set on call here */
                                receive_chars(port->ip_port);
                        }
                }

                /* rx high interrupt. Must be after rx_timer.  */
                else if (sio_ir & hooks->intr_rx_high) {
                        /* Data available, notify upper layer */
                        if ((port->ip_notify & N_DATA_READY)
                                                && port->ip_port) {
                                /* ip_lock is set on call here */
                                receive_chars(port->ip_port);
                        }

                        /* We can't ACK this interrupt.  If receive_chars didn't
                         * cause the condition to clear, we'll have to disable
                         * the interrupt until the data is drained.
                         * If the read was aborted, don't disable the interrupt
                         * as this may cause us to hang indefinitely.  An
                         * aborted read generally means that this interrupt
                         * hasn't been delivered to the cpu yet anyway, even
                         * though we see it as asserted when we read the sio_ir.
                         */
                        if ((sio_ir = PENDING(port)) & hooks->intr_rx_high) {
                                if ((port->ip_flags & READ_ABORTED) == 0) {
                                        port->ip_ienb &= ~hooks->intr_rx_high;
                                        port->ip_flags |= INPUT_HIGH;
                                } else {
                                        rx_high_rd_aborted++;
                                }
                        }
                }

                /* We got a low water interrupt: notify upper layer to
                 * send more data.  Must come before tx_mt since servicing
                 * this condition may cause that condition to clear.
                 */
                if (sio_ir & hooks->intr_tx_explicit) {
                        port->ip_flags &= ~LOWAT_WRITTEN;

                        /* ACK the interrupt */
                        writel(hooks->intr_tx_explicit,
                                        &port->ip_mem->sio_ir.raw);

                        if (port->ip_notify & N_OUTPUT_LOWAT)
                                ioc4_cb_output_lowat(port->ip_port);
                }

                /* Handle tx_mt.  Must come after tx_explicit.  */
                else if (sio_ir & hooks->intr_tx_mt) {
                        /* If we are expecting a lowat notification
                         * and we get to this point it probably means that for
                         * some reason the tx_explicit didn't work as expected
                         * (that can legitimately happen if the output buffer is
                         * filled up in just the right way).
                         * So send the notification now.
                         */
                        if (port->ip_notify & N_OUTPUT_LOWAT) {
                                ioc4_cb_output_lowat(port->ip_port);

                                /* We need to reload the sio_ir since the lowat
                                 * call may have caused another write to occur,
                                 * clearing the tx_mt condition.
                                 */
                                sio_ir = PENDING(port);
                        }

                        /* If the tx_mt condition still persists even after the
                         * lowat call, we've got some work to do.
                         */
                        if (sio_ir & hooks->intr_tx_mt) {

                                /* If we are not currently expecting DMA input,
                                 * and the transmitter has just gone idle,
                                 * there is no longer any reason for DMA, so
                                 * disable it.
                                 */
                                if (!(port->ip_notify
                                                & (N_DATA_READY | N_DDCD))) {
                                        BUG_ON(!(port->ip_sscr
                                                        & IOC4_SSCR_DMA_EN));
                                        port->ip_sscr &= ~IOC4_SSCR_DMA_EN;
                                        writel(port->ip_sscr,
                                           &port->ip_serial_regs->sscr);
                                }

                                /* Prevent infinite tx_mt interrupt */
                                port->ip_ienb &= ~hooks->intr_tx_mt;
                        }
                }
                sio_ir = PENDING(port);

                /* if the read was aborted and only hooks->intr_rx_high,
                 * clear hooks->intr_rx_high, so we do not loop forever.
                 */

                if (rx_high_rd_aborted && (sio_ir == hooks->intr_rx_high)) {
                        sio_ir &= ~hooks->intr_rx_high;
                }
        } while (sio_ir & hooks->intr_all);

        spin_unlock_irqrestore(&port->ip_lock, flags);

        /* Re-enable interrupts before returning from interrupt handler.
         * Getting interrupted here is okay.  It'll just v() our semaphore, and
         * we'll come through the loop again.
         */

        write_ireg(port->ip_ioc4_soft, port->ip_ienb, IOC4_W_IES,
                                                        IOC4_SIO_INTR_TYPE);
}

/*
 * ioc4_cb_post_ncs - called for some basic errors
 * @port: port to use
 * @ncs: event
 */
static void ioc4_cb_post_ncs(struct uart_port *the_port, int ncs)
{
        struct uart_icount *icount;

        icount = &the_port->icount;

        if (ncs & NCS_BREAK)
                icount->brk++;
        if (ncs & NCS_FRAMING)
                icount->frame++;
        if (ncs & NCS_OVERRUN)
                icount->overrun++;
        if (ncs & NCS_PARITY)
                icount->parity++;
}

/**
 * do_read - Read in bytes from the port.  Return the number of bytes
 *                      actually read.
 * @the_port: port to use
 * @buf: place to put the stuff we read
 * @len: how big 'buf' is
 */

static inline int do_read(struct uart_port *the_port, unsigned char *buf,
                                int len)
{
        int prod_ptr, cons_ptr, total;
        struct ioc4_port *port = get_ioc4_port(the_port, 0);
        struct ring *inring;
        struct ring_entry *entry;
        struct hooks *hooks = port->ip_hooks;
        int byte_num;
        char *sc;
        int loop_counter;

        BUG_ON(!(len >= 0));
        BUG_ON(!port);

        /* There is a nasty timing issue in the IOC4. When the rx_timer
         * expires or the rx_high condition arises, we take an interrupt.
         * At some point while servicing the interrupt, we read bytes from
         * the ring buffer and re-arm the rx_timer.  However the rx_timer is
         * not started until the first byte is received *after* it is armed,
         * and any bytes pending in the rx construction buffers are not drained
         * to memory until either there are 4 bytes available or the rx_timer
         * expires.  This leads to a potential situation where data is left
         * in the construction buffers forever - 1 to 3 bytes were received
         * after the interrupt was generated but before the rx_timer was
         * re-armed. At that point as long as no subsequent bytes are received
         * the timer will never be started and the bytes will remain in the
         * construction buffer forever.  The solution is to execute a DRAIN
         * command after rearming the timer.  This way any bytes received before
         * the DRAIN will be drained to memory, and any bytes received after
         * the DRAIN will start the TIMER and be drained when it expires.
         * Luckily, this only needs to be done when the DMA buffer is empty
         * since there is no requirement that this function return all
         * available data as long as it returns some.
         */
        /* Re-arm the timer */
        writel(port->ip_rx_cons | IOC4_SRCIR_ARM, &port->ip_serial_regs->srcir);

        prod_ptr = readl(&port->ip_serial_regs->srpir) & PROD_CONS_MASK;
        cons_ptr = port->ip_rx_cons;

        if (prod_ptr == cons_ptr) {
                int reset_dma = 0;

                /* Input buffer appears empty, do a flush. */

                /* DMA must be enabled for this to work. */
                if (!(port->ip_sscr & IOC4_SSCR_DMA_EN)) {
                        port->ip_sscr |= IOC4_SSCR_DMA_EN;
                        reset_dma = 1;
                }

                /* Potential race condition: we must reload the srpir after
                 * issuing the drain command, otherwise we could think the rx
                 * buffer is empty, then take a very long interrupt, and when
                 * we come back it's full and we wait forever for the drain to
                 * complete.
                 */
                writel(port->ip_sscr | IOC4_SSCR_RX_DRAIN,
                                &port->ip_serial_regs->sscr);
                prod_ptr = readl(&port->ip_serial_regs->srpir)
                                & PROD_CONS_MASK;

                /* We must not wait for the DRAIN to complete unless there are
                 * at least 8 bytes (2 ring entries) available to receive the
                 * data otherwise the DRAIN will never complete and we'll
                 * deadlock here.
                 * In fact, to make things easier, I'll just ignore the flush if
                 * there is any data at all now available.
                 */
                if (prod_ptr == cons_ptr) {
                        loop_counter = 0;
                        while (readl(&port->ip_serial_regs->sscr) &
                                                IOC4_SSCR_RX_DRAIN) {
                                loop_counter++;
                                if (loop_counter > MAXITER)
                                        return -1;
                        }

                        /* SIGH. We have to reload the prod_ptr *again* since
                         * the drain may have caused it to change
                         */
                        prod_ptr = readl(&port->ip_serial_regs->srpir)
                                                        & PROD_CONS_MASK;
                }
                if (reset_dma) {
                        port->ip_sscr &= ~IOC4_SSCR_DMA_EN;
                        writel(port->ip_sscr, &port->ip_serial_regs->sscr);
                }
        }
        inring = port->ip_inring;
        port->ip_flags &= ~READ_ABORTED;

        total = 0;
        loop_counter = 0xfffff; /* to avoid hangs */

        /* Grab bytes from the hardware */
        while ((prod_ptr != cons_ptr) && (len > 0)) {
                entry = (struct ring_entry *)((caddr_t)inring + cons_ptr);

                if ( loop_counter-- <= 0 ) {
                        printk(KERN_WARNING "IOC4 serial: "
                                        "possible hang condition/"
                                        "port stuck on read.\n");
                        break;
                }

                /* According to the producer pointer, this ring entry
                 * must contain some data.  But if the PIO happened faster
                 * than the DMA, the data may not be available yet, so let's
                 * wait until it arrives.
                 */
                if ((entry->ring_allsc & RING_ANY_VALID) == 0) {
                        /* Indicate the read is aborted so we don't disable
                         * the interrupt thinking that the consumer is
                         * congested.
                         */
                        port->ip_flags |= READ_ABORTED;
                        len = 0;
                        break;
                }

                /* Load the bytes/status out of the ring entry */
                for (byte_num = 0; byte_num < 4 && len > 0; byte_num++) {
                        sc = &(entry->ring_sc[byte_num]);

                        /* Check for change in modem state or overrun */
                        if ((*sc & IOC4_RXSB_MODEM_VALID)
                                                && (port->ip_notify & N_DDCD)) {
                                /* Notify upper layer if DCD dropped */

                                if ((port->ip_flags & DCD_ON)
                                                && !(*sc & IOC4_RXSB_DCD)) {

                                        /* If we have already copied some data,
                                         * return it.  We'll pick up the carrier
                                         * drop on the next pass.  That way we
                                         * don't throw away the data that has
                                         * already been copied back to
                                         * the caller's buffer.
                                         */
                                        if (total > 0) {
                                                len = 0;
                                                break;
                                        }
                                        port->ip_flags &= ~DCD_ON;

                                        /* Turn off this notification so the
                                         * carrier drop protocol won't see it
                                         * again when it does a read.
                                         */
                                        *sc &= ~IOC4_RXSB_MODEM_VALID;

                                        /* To keep things consistent, we need
                                         * to update the consumer pointer so
                                         * the next reader won't come in and
                                         * try to read the same ring entries
                                         * again. This must be done here before
                                         * the dcd change.
                                         */

                                        if ((entry->ring_allsc & RING_ANY_VALID)
                                                                        == 0) {
                                                cons_ptr += (int)sizeof
                                                        (struct ring_entry);
                                                cons_ptr &= PROD_CONS_MASK;
                                        }
                                        writel(cons_ptr,
                                                &port->ip_serial_regs->srcir);
                                        port->ip_rx_cons = cons_ptr;

                                        /* Notify upper layer of carrier drop */
                                        if ((port->ip_notify & N_DDCD)
                                                   && port->ip_port) {
                                                the_port->icount.dcd = 0;
                                                wake_up_interruptible
                                                    (&the_port->info->
                                                        delta_msr_wait);
                                        }

                                        /* If we had any data to return, we
                                         * would have returned it above.
                                         */
                                        return 0;
                                }
                        }
                        if (*sc & IOC4_RXSB_MODEM_VALID) {
                                /* Notify that an input overrun occurred */
                                if ((*sc & IOC4_RXSB_OVERRUN)
                                    && (port->ip_notify & N_OVERRUN_ERROR)) {
                                        ioc4_cb_post_ncs(the_port, NCS_OVERRUN);
                                }
                                /* Don't look at this byte again */
                                *sc &= ~IOC4_RXSB_MODEM_VALID;
                        }

                        /* Check for valid data or RX errors */
                        if ((*sc & IOC4_RXSB_DATA_VALID) &&
                                        ((*sc & (IOC4_RXSB_PAR_ERR
                                                        | IOC4_RXSB_FRAME_ERR
                                                        | IOC4_RXSB_BREAK))
                                        && (port->ip_notify & (N_PARITY_ERROR
                                                        | N_FRAMING_ERROR
                                                        | N_BREAK)))) {
                                /* There is an error condition on the next byte.
                                 * If we have already transferred some bytes,
                                 * we'll stop here. Otherwise if this is the
                                 * first byte to be read, we'll just transfer
                                 * it alone after notifying the
                                 * upper layer of its status.
                                 */
                                if (total > 0) {
                                        len = 0;
                                        break;
                                } else {
                                        if ((*sc & IOC4_RXSB_PAR_ERR) &&
                                           (port->ip_notify & N_PARITY_ERROR)) {
                                                ioc4_cb_post_ncs(the_port,
                                                                NCS_PARITY);
                                        }
                                        if ((*sc & IOC4_RXSB_FRAME_ERR) &&
                                           (port->ip_notify & N_FRAMING_ERROR)){
                                                ioc4_cb_post_ncs(the_port,
                                                                NCS_FRAMING);
                                        }
                                        if ((*sc & IOC4_RXSB_BREAK)
                                            && (port->ip_notify & N_BREAK)) {
                                                        ioc4_cb_post_ncs
                                                                    (the_port,
                                                                     NCS_BREAK);
                                        }
                                        len = 1;
                                }
                        }
                        if (*sc & IOC4_RXSB_DATA_VALID) {
                                *sc &= ~IOC4_RXSB_DATA_VALID;
                                *buf = entry->ring_data[byte_num];
                                buf++;
                                len--;
                                total++;
                        }
                }

                /* If we used up this entry entirely, go on to the next one,
                 * otherwise we must have run out of buffer space, so
                 * leave the consumer pointer here for the next read in case
                 * there are still unread bytes in this entry.
                 */
                if ((entry->ring_allsc & RING_ANY_VALID) == 0) {
                        cons_ptr += (int)sizeof(struct ring_entry);
                        cons_ptr &= PROD_CONS_MASK;
                }
        }

        /* Update consumer pointer and re-arm rx timer interrupt */
        writel(cons_ptr, &port->ip_serial_regs->srcir);
        port->ip_rx_cons = cons_ptr;

        /* If we have now dipped below the rx high water mark and we have
         * rx_high interrupt turned off, we can now turn it back on again.
         */
        if ((port->ip_flags & INPUT_HIGH) && (((prod_ptr - cons_ptr)
                        & PROD_CONS_MASK) < ((port->ip_sscr &
                                IOC4_SSCR_RX_THRESHOLD)
                                        << IOC4_PROD_CONS_PTR_OFF))) {
                port->ip_flags &= ~INPUT_HIGH;
                enable_intrs(port, hooks->intr_rx_high);
        }
        return total;
}

/**
 * receive_chars - upper level read. Called with ip_lock.
 * @the_port: port to read from
 */
static void receive_chars(struct uart_port *the_port)
{
        struct tty_struct *tty;
        unsigned char ch[IOC4_MAX_CHARS];
        int read_count, request_count = IOC4_MAX_CHARS;
        struct uart_icount *icount;
        struct uart_info *info = the_port->info;
        unsigned long pflags;

        /* Make sure all the pointers are "good" ones */
        if (!info)
                return;
        if (!info->port.tty)
                return;

        spin_lock_irqsave(&the_port->lock, pflags);
        tty = info->port.tty;

        request_count = tty_buffer_request_room(tty, IOC4_MAX_CHARS);

        if (request_count > 0) {
                icount = &the_port->icount;
                read_count = do_read(the_port, ch, request_count);
                if (read_count > 0) {
                        tty_insert_flip_string(tty, ch, read_count);
                        icount->rx += read_count;
                }
        }

        spin_unlock_irqrestore(&the_port->lock, pflags);

        tty_flip_buffer_push(tty);
}

/**
 * ic4_type - What type of console are we?
 * @port: Port to operate with (we ignore since we only have one port)
 *
 */
static const char *ic4_type(struct uart_port *the_port)
{
        if (the_port->mapbase == PROTO_RS232)
                return "SGI IOC4 Serial [rs232]";
        else
                return "SGI IOC4 Serial [rs422]";
}

/**
 * ic4_tx_empty - Is the transmitter empty?
 * @port: Port to operate on
 *
 */
static unsigned int ic4_tx_empty(struct uart_port *the_port)
{
        struct ioc4_port *port = get_ioc4_port(the_port, 0);
        unsigned int ret = 0;

        if (port_is_active(port, the_port)) {
                if (readl(&port->ip_serial_regs->shadow) & IOC4_SHADOW_TEMT)
                        ret = TIOCSER_TEMT;
        }
        return ret;
}

/**
 * ic4_stop_tx - stop the transmitter
 * @port: Port to operate on
 *
 */
static void ic4_stop_tx(struct uart_port *the_port)
{
        struct ioc4_port *port = get_ioc4_port(the_port, 0);

        if (port_is_active(port, the_port))
                set_notification(port, N_OUTPUT_LOWAT, 0);
}

/**
 * null_void_function -
 * @port: Port to operate on
 *
 */
static void null_void_function(struct uart_port *the_port)
{
}

/**
 * ic4_shutdown - shut down the port - free irq and disable
 * @port: Port to shut down
 *
 */
static void ic4_shutdown(struct uart_port *the_port)
{
        unsigned long port_flags;
        struct ioc4_port *port;
        struct uart_info *info;

        port = get_ioc4_port(the_port, 0);
        if (!port)
                return;

        info = the_port->info;
        port->ip_port = NULL;

        wake_up_interruptible(&info->delta_msr_wait);

        if (info->port.tty)
                set_bit(TTY_IO_ERROR, &info->port.tty->flags);

        spin_lock_irqsave(&the_port->lock, port_flags);
        set_notification(port, N_ALL, 0);
        port->ip_flags = PORT_INACTIVE;
        spin_unlock_irqrestore(&the_port->lock, port_flags);
}

/**
 * ic4_set_mctrl - set control lines (dtr, rts, etc)
 * @port: Port to operate on
 * @mctrl: Lines to set/unset
 *
 */
static void ic4_set_mctrl(struct uart_port *the_port, unsigned int mctrl)
{
        unsigned char mcr = 0;
        struct ioc4_port *port;

        port = get_ioc4_port(the_port, 0);
        if (!port_is_active(port, the_port))
                return;

        if (mctrl & TIOCM_RTS)
                mcr |= UART_MCR_RTS;
        if (mctrl & TIOCM_DTR)
                mcr |= UART_MCR_DTR;
        if (mctrl & TIOCM_OUT1)
                mcr |= UART_MCR_OUT1;
        if (mctrl & TIOCM_OUT2)
                mcr |= UART_MCR_OUT2;
        if (mctrl & TIOCM_LOOP)
                mcr |= UART_MCR_LOOP;

        set_mcr(the_port, mcr, IOC4_SHADOW_DTR);
}

/**
 * ic4_get_mctrl - get control line info
 * @port: port to operate on
 *
 */
static unsigned int ic4_get_mctrl(struct uart_port *the_port)
{
        struct ioc4_port *port = get_ioc4_port(the_port, 0);
        uint32_t shadow;
        unsigned int ret = 0;

        if (!port_is_active(port, the_port))
                return 0;

        shadow = readl(&port->ip_serial_regs->shadow);
        if (shadow & IOC4_SHADOW_DCD)
                ret |= TIOCM_CAR;
        if (shadow & IOC4_SHADOW_DR)
                ret |= TIOCM_DSR;
        if (shadow & IOC4_SHADOW_CTS)
                ret |= TIOCM_CTS;
        return ret;
}

/**
 * ic4_start_tx - Start transmitter, flush any output
 * @port: Port to operate on
 *
 */
static void ic4_start_tx(struct uart_port *the_port)
{
        struct ioc4_port *port = get_ioc4_port(the_port, 0);

        if (port_is_active(port, the_port)) {
                set_notification(port, N_OUTPUT_LOWAT, 1);
                enable_intrs(port, port->ip_hooks->intr_tx_mt);
        }
}

/**
 * ic4_break_ctl - handle breaks
 * @port: Port to operate on
 * @break_state: Break state
 *
 */
static void ic4_break_ctl(struct uart_port *the_port, int break_state)
{
}

/**
 * ic4_startup - Start up the serial port
 * @port: Port to operate on
 *
 */
static int ic4_startup(struct uart_port *the_port)
{
        int retval;
        struct ioc4_port *port;
        struct ioc4_control *control;
        struct uart_info *info;
        unsigned long port_flags;

        if (!the_port)
                return -ENODEV;
        port = get_ioc4_port(the_port, 1);
        if (!port)
                return -ENODEV;
        info = the_port->info;

        control = port->ip_control;
        if (!control) {
                port->ip_port = NULL;
                return -ENODEV;
        }

        /* Start up the serial port */
        spin_lock_irqsave(&the_port->lock, port_flags);
        retval = ic4_startup_local(the_port);
        spin_unlock_irqrestore(&the_port->lock, port_flags);
        return retval;
}

/**
 * ic4_set_termios - set termios stuff
 * @port: port to operate on
 * @termios: New settings
 * @termios: Old
 *
 */
static void
ic4_set_termios(struct uart_port *the_port,
                struct ktermios *termios, struct ktermios *old_termios)
{
        unsigned long port_flags;

        spin_lock_irqsave(&the_port->lock, port_flags);
        ioc4_change_speed(the_port, termios, old_termios);
        spin_unlock_irqrestore(&the_port->lock, port_flags);
}

/**
 * ic4_request_port - allocate resources for port - no op....
 * @port: port to operate on
 *
 */
static int ic4_request_port(struct uart_port *port)
{
        return 0;
}

/* Associate the uart functions above - given to serial core */

static struct uart_ops ioc4_ops = {
        .tx_empty       = ic4_tx_empty,
        .set_mctrl      = ic4_set_mctrl,
        .get_mctrl      = ic4_get_mctrl,
        .stop_tx        = ic4_stop_tx,
        .start_tx       = ic4_start_tx,
        .stop_rx        = null_void_function,
        .enable_ms      = null_void_function,
        .break_ctl      = ic4_break_ctl,
        .startup        = ic4_startup,
        .shutdown       = ic4_shutdown,
        .set_termios    = ic4_set_termios,
        .type           = ic4_type,
        .release_port   = null_void_function,
        .request_port   = ic4_request_port,
};

/*
 * Boot-time initialization code
 */

static struct uart_driver ioc4_uart_rs232 = {
        .owner          = THIS_MODULE,
        .driver_name    = "ioc4_serial_rs232",
        .dev_name       = DEVICE_NAME_RS232,
        .major          = DEVICE_MAJOR,
        .minor          = DEVICE_MINOR_RS232,
        .nr             = IOC4_NUM_CARDS * IOC4_NUM_SERIAL_PORTS,
};

static struct uart_driver ioc4_uart_rs422 = {
        .owner          = THIS_MODULE,
        .driver_name    = "ioc4_serial_rs422",
        .dev_name       = DEVICE_NAME_RS422,
        .major          = DEVICE_MAJOR,
        .minor          = DEVICE_MINOR_RS422,
        .nr             = IOC4_NUM_CARDS * IOC4_NUM_SERIAL_PORTS,
};


/**
 * ioc4_serial_remove_one - detach function
 *
 * @idd: IOC4 master module data for this IOC4
 */

static int ioc4_serial_remove_one(struct ioc4_driver_data *idd)
{
        int port_num, port_type;
        struct ioc4_control *control;
        struct uart_port *the_port;
        struct ioc4_port *port;
        struct ioc4_soft *soft;

        /* If serial driver did not attach, don't try to detach */
        control = idd->idd_serial_data;
        if (!control)
                return 0;

        for (port_num = 0; port_num < IOC4_NUM_SERIAL_PORTS; port_num++) {
                for (port_type = UART_PORT_MIN;
                                        port_type < UART_PORT_COUNT;
                                        port_type++) {
                        the_port = &control->ic_port[port_num].icp_uart_port
                                                        [port_type];
                        if (the_port) {
                                switch (port_type) {
                                case UART_PORT_RS422:
                                        uart_remove_one_port(&ioc4_uart_rs422,
                                                        the_port);
                                        break;
                                default:
                                case UART_PORT_RS232:
                                        uart_remove_one_port(&ioc4_uart_rs232,
                                                        the_port);
                                        break;
                                }
                        }
                }
                port = control->ic_port[port_num].icp_port;
                /* we allocate in pairs */
                if (!(port_num & 1) && port) {
                        pci_free_consistent(port->ip_pdev,
                                        TOTAL_RING_BUF_SIZE,
                                        port->ip_cpu_ringbuf,
                                        port->ip_dma_ringbuf);
                        kfree(port);
                }
        }
        soft = control->ic_soft;
        if (soft) {
                free_irq(control->ic_irq, soft);
                if (soft->is_ioc4_serial_addr) {
                        iounmap(soft->is_ioc4_serial_addr);
                        release_mem_region((unsigned long)
                             soft->is_ioc4_serial_addr,
                                sizeof(struct ioc4_serial));
                }
                kfree(soft);
        }
        kfree(control);
        idd->idd_serial_data = NULL;

        return 0;
}


/**
 * ioc4_serial_core_attach_rs232 - register with serial core
 *              This is done during pci probing
 * @pdev: handle for this card
 */
static inline int
ioc4_serial_core_attach(struct pci_dev *pdev, int port_type)
{
        struct ioc4_port *port;
        struct uart_port *the_port;
        struct ioc4_driver_data *idd = pci_get_drvdata(pdev);
        struct ioc4_control *control = idd->idd_serial_data;
        int port_num;
        int port_type_idx;
        struct uart_driver *u_driver;


        DPRINT_CONFIG(("%s: attach pdev 0x%p - control 0x%p\n",
                        __func__, pdev, (void *)control));

        if (!control)
                return -ENODEV;

        port_type_idx = (port_type == PROTO_RS232) ? UART_PORT_RS232
                                                : UART_PORT_RS422;

        u_driver = (port_type == PROTO_RS232)   ? &ioc4_uart_rs232
                                                : &ioc4_uart_rs422;

        /* once around for each port on this card */
        for (port_num = 0; port_num < IOC4_NUM_SERIAL_PORTS; port_num++) {
                the_port = &control->ic_port[port_num].icp_uart_port
                                                        [port_type_idx];
                port = control->ic_port[port_num].icp_port;
                port->ip_all_ports[port_type_idx] = the_port;

                DPRINT_CONFIG(("%s: attach the_port 0x%p / port 0x%p : type %s\n",
                                __func__, (void *)the_port,
                                (void *)port,
                                port_type == PROTO_RS232 ? "rs232" : "rs422"));

                /* membase, iobase and mapbase just need to be non-0 */
                the_port->membase = (unsigned char __iomem *)1;
                the_port->iobase = (pdev->bus->number << 16) |  port_num;
                the_port->line = (Num_of_ioc4_cards << 2) | port_num;
                the_port->mapbase = port_type;
                the_port->type = PORT_16550A;
                the_port->fifosize = IOC4_FIFO_CHARS;
                the_port->ops = &ioc4_ops;
                the_port->irq = control->ic_irq;
                the_port->dev = &pdev->dev;
                spin_lock_init(&the_port->lock);
                if (uart_add_one_port(u_driver, the_port) < 0) {
                        printk(KERN_WARNING
                           "%s: unable to add port %d bus %d\n",
                               __func__, the_port->line, pdev->bus->number);
                } else {
                        DPRINT_CONFIG(
                            ("IOC4 serial port %d irq = %d, bus %d\n",
                               the_port->line, the_port->irq, pdev->bus->number));
                }
        }
        return 0;
}

/**
 * ioc4_serial_attach_one - register attach function
 *              called per card found from IOC4 master module.
 * @idd: Master module data for this IOC4
 */
int
ioc4_serial_attach_one(struct ioc4_driver_data *idd)
{
        unsigned long tmp_addr1;
        struct ioc4_serial __iomem *serial;
        struct ioc4_soft *soft;
        struct ioc4_control *control;
        int ret = 0;


        DPRINT_CONFIG(("%s (0x%p, 0x%p)\n", __func__, idd->idd_pdev,
                                                        idd->idd_pci_id));

        /* PCI-RT does not bring out serial connections.
         * Do not attach to this particular IOC4.
         */
        if (idd->idd_variant == IOC4_VARIANT_PCI_RT)
                return 0;

        /* request serial registers */
        tmp_addr1 = idd->idd_bar0 + IOC4_SERIAL_OFFSET;

        if (!request_mem_region(tmp_addr1, sizeof(struct ioc4_serial),
                                        "sioc4_uart")) {
                printk(KERN_WARNING
                        "ioc4 (%p): unable to get request region for "
                                "uart space\n", (void *)idd->idd_pdev);
                ret = -ENODEV;
                goto out1;
        }
        serial = ioremap(tmp_addr1, sizeof(struct ioc4_serial));
        if (!serial) {
                printk(KERN_WARNING
                         "ioc4 (%p) : unable to remap ioc4 serial register\n",
                                (void *)idd->idd_pdev);
                ret = -ENODEV;
                goto out2;
        }
        DPRINT_CONFIG(("%s : mem 0x%p, serial 0x%p\n",
                                __func__, (void *)idd->idd_misc_regs,
                                (void *)serial));

        /* Get memory for the new card */
        control = kzalloc(sizeof(struct ioc4_control), GFP_KERNEL);

        if (!control) {
                printk(KERN_WARNING "ioc4_attach_one"
                       ": unable to get memory for the IOC4\n");
                ret = -ENOMEM;
                goto out2;
        }
        idd->idd_serial_data = control;

        /* Allocate the soft structure */
        soft = kzalloc(sizeof(struct ioc4_soft), GFP_KERNEL);
        if (!soft) {
                printk(KERN_WARNING
                       "ioc4 (%p): unable to get memory for the soft struct\n",
                       (void *)idd->idd_pdev);
                ret = -ENOMEM;
                goto out3;
        }

        spin_lock_init(&soft->is_ir_lock);
        soft->is_ioc4_misc_addr = idd->idd_misc_regs;
        soft->is_ioc4_serial_addr = serial;

        /* Init the IOC4 */
        writel(0xf << IOC4_SIO_CR_CMD_PULSE_SHIFT,
               &idd->idd_misc_regs->sio_cr.raw);

        /* Enable serial port mode select generic PIO pins as outputs */
        writel(IOC4_GPCR_UART0_MODESEL | IOC4_GPCR_UART1_MODESEL
                | IOC4_GPCR_UART2_MODESEL | IOC4_GPCR_UART3_MODESEL,
                &idd->idd_misc_regs->gpcr_s.raw);

        /* Clear and disable all serial interrupts */
        write_ireg(soft, ~0, IOC4_W_IEC, IOC4_SIO_INTR_TYPE);
        writel(~0, &idd->idd_misc_regs->sio_ir.raw);
        write_ireg(soft, IOC4_OTHER_IR_SER_MEMERR, IOC4_W_IEC,
                   IOC4_OTHER_INTR_TYPE);
        writel(IOC4_OTHER_IR_SER_MEMERR, &idd->idd_misc_regs->other_ir.raw);
        control->ic_soft = soft;

        /* Hook up interrupt handler */
        if (!request_irq(idd->idd_pdev->irq, ioc4_intr, IRQF_SHARED,
                                "sgi-ioc4serial", soft)) {
                control->ic_irq = idd->idd_pdev->irq;
        } else {
                printk(KERN_WARNING
                    "%s : request_irq fails for IRQ 0x%x\n ",
                        __func__, idd->idd_pdev->irq);
        }
        ret = ioc4_attach_local(idd);
        if (ret)
                goto out4;

        /* register port with the serial core - 1 rs232, 1 rs422 */

        if ((ret = ioc4_serial_core_attach(idd->idd_pdev, PROTO_RS232)))
                goto out4;

        if ((ret = ioc4_serial_core_attach(idd->idd_pdev, PROTO_RS422)))
                goto out5;

        Num_of_ioc4_cards++;

        return ret;

        /* error exits that give back resources */
out5:
        ioc4_serial_remove_one(idd);
out4:
        kfree(soft);
out3:
        kfree(control);
out2:
        if (serial)
                iounmap(serial);
        release_mem_region(tmp_addr1, sizeof(struct ioc4_serial));
out1:

        return ret;
}


static struct ioc4_submodule ioc4_serial_submodule = {
        .is_name = "IOC4_serial",
        .is_owner = THIS_MODULE,
        .is_probe = ioc4_serial_attach_one,
        .is_remove = ioc4_serial_remove_one,
};

/**
 * ioc4_serial_init - module init
 */
int ioc4_serial_init(void)
{
        int ret;

        /* register with serial core */
        if ((ret = uart_register_driver(&ioc4_uart_rs232)) < 0) {
                printk(KERN_WARNING
                        "%s: Couldn't register rs232 IOC4 serial driver\n",
                        __func__);
                return ret;
        }
        if ((ret = uart_register_driver(&ioc4_uart_rs422)) < 0) {
                printk(KERN_WARNING
                        "%s: Couldn't register rs422 IOC4 serial driver\n",
                        __func__);
                return ret;
        }

        /* register with IOC4 main module */
        return ioc4_register_submodule(&ioc4_serial_submodule);
}

static void __devexit ioc4_serial_exit(void)
{
        ioc4_unregister_submodule(&ioc4_serial_submodule);
        uart_unregister_driver(&ioc4_uart_rs232);
        uart_unregister_driver(&ioc4_uart_rs422);
}

late_initcall(ioc4_serial_init); /* Call only after tty init is done */
module_exit(ioc4_serial_exit);

MODULE_AUTHOR("Pat Gefre - Silicon Graphics Inc. (SGI) <pfg@sgi.com>");
MODULE_DESCRIPTION("Serial PCI driver module for SGI IOC4 Base-IO Card");
MODULE_LICENSE("GPL");