arch/powerpc/kernel/udbg_16550.c

   1 /*
   2  * udbg for for NS16550 compatable serial ports
   3  *
   4  * Copyright (C) 2001-2005 PPC 64 Team, IBM Corp
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      as published by the Free Software Foundation; either version
   9  *      2 of the License, or (at your option) any later version.
  10  */
  11 #include <linux/types.h>
  12 #include <asm/udbg.h>
  13 #include <asm/io.h>
  14
  15 extern u8 real_readb(volatile u8 __iomem  *addr);
  16 extern void real_writeb(u8 data, volatile u8 __iomem *addr);
  17 extern u8 real_205_readb(volatile u8 __iomem  *addr);
  18 extern void real_205_writeb(u8 data, volatile u8 __iomem *addr);
  19
  20 struct NS16550 {
  21         /* this struct must be packed */
  22         unsigned char rbr;  /* 0 */
  23         unsigned char ier;  /* 1 */
  24         unsigned char fcr;  /* 2 */
  25         unsigned char lcr;  /* 3 */
  26         unsigned char mcr;  /* 4 */
  27         unsigned char lsr;  /* 5 */
  28         unsigned char msr;  /* 6 */
  29         unsigned char scr;  /* 7 */
  30 };
  31
  32 #define thr rbr
  33 #define iir fcr
  34 #define dll rbr
  35 #define dlm ier
  36 #define dlab lcr
  37
  38 #define LSR_DR   0x01  /* Data ready */
  39 #define LSR_OE   0x02  /* Overrun */
  40 #define LSR_PE   0x04  /* Parity error */
  41 #define LSR_FE   0x08  /* Framing error */
  42 #define LSR_BI   0x10  /* Break */
  43 #define LSR_THRE 0x20  /* Xmit holding register empty */
  44 #define LSR_TEMT 0x40  /* Xmitter empty */
  45 #define LSR_ERR  0x80  /* Error */
  46
  47 #define LCR_DLAB 0x80
  48
  49 static volatile struct NS16550 __iomem *udbg_comport;
  50
  51 static void udbg_550_putc(char c)
  52 {
  53         if (udbg_comport) {
  54                 while ((in_8(&udbg_comport->lsr) & LSR_THRE) == 0)
  55                         /* wait for idle */;
  56                 out_8(&udbg_comport->thr, c);
  57                 if (c == '\n')
  58                         udbg_550_putc('\r');
  59         }
  60 }
  61
  62 static int udbg_550_getc_poll(void)
  63 {
  64         if (udbg_comport) {
  65                 if ((in_8(&udbg_comport->lsr) & LSR_DR) != 0)
  66                         return in_8(&udbg_comport->rbr);
  67                 else
  68                         return -1;
  69         }
  70         return -1;
  71 }
  72
  73 static int udbg_550_getc(void)
  74 {
  75         if (udbg_comport) {
  76                 while ((in_8(&udbg_comport->lsr) & LSR_DR) == 0)
  77                         /* wait for char */;
  78                 return in_8(&udbg_comport->rbr);
  79         }
  80         return -1;
  81 }
  82
  83 void udbg_init_uart(void __iomem *comport, unsigned int speed,
  84                     unsigned int clock)
  85 {
  86         unsigned int dll, base_bauds;
  87
  88         if (clock == 0)
  89                 clock = 1843200;
  90         if (speed == 0)
  91                 speed = 9600;
  92
  93         base_bauds = clock / 16;
  94         dll = base_bauds / speed;
  95
  96         if (comport) {
  97                 udbg_comport = (struct NS16550 __iomem *)comport;
  98                 out_8(&udbg_comport->lcr, 0x00);
  99                 out_8(&udbg_comport->ier, 0xff);
 100                 out_8(&udbg_comport->ier, 0x00);
 101                 out_8(&udbg_comport->lcr, LCR_DLAB);
 102                 out_8(&udbg_comport->dll, dll & 0xff);
 103                 out_8(&udbg_comport->dlm, dll >> 8);
 104                 /* 8 data, 1 stop, no parity */
 105                 out_8(&udbg_comport->lcr, 0x03);
 106                 /* RTS/DTR */
 107                 out_8(&udbg_comport->mcr, 0x03);
 108                 /* Clear & enable FIFOs */
 109                 out_8(&udbg_comport->fcr ,0x07);
 110                 udbg_putc = udbg_550_putc;
 111                 udbg_getc = udbg_550_getc;
 112                 udbg_getc_poll = udbg_550_getc_poll;
 113         }
 114 }
 115
 116 unsigned int udbg_probe_uart_speed(void __iomem *comport, unsigned int clock)
 117 {
 118         unsigned int dll, dlm, divisor, prescaler, speed;
 119         u8 old_lcr;
 120         volatile struct NS16550 __iomem *port = comport;
 121
 122         old_lcr = in_8(&port->lcr);
 123
 124         /* select divisor latch registers.  */
 125         out_8(&port->lcr, LCR_DLAB);
 126
 127         /* now, read the divisor */
 128         dll = in_8(&port->dll);
 129         dlm = in_8(&port->dlm);
 130         divisor = dlm << 8 | dll;
 131
 132         /* check prescaling */
 133         if (in_8(&port->mcr) & 0x80)
 134                 prescaler = 4;
 135         else
 136                 prescaler = 1;
 137
 138         /* restore the LCR */
 139         out_8(&port->lcr, old_lcr);
 140
 141         /* calculate speed */
 142         speed = (clock / prescaler) / (divisor * 16);
 143
 144         /* sanity check */
 145         if (speed < 0 || speed > (clock / 16))
 146                 speed = 9600;
 147
 148         return speed;
 149 }
 150
 151 #ifdef CONFIG_PPC_MAPLE
 152 void udbg_maple_real_putc(char c)
 153 {
 154         if (udbg_comport) {
 155                 while ((real_readb(&udbg_comport->lsr) & LSR_THRE) == 0)
 156                         /* wait for idle */;
 157                 real_writeb(c, &udbg_comport->thr); eieio();
 158                 if (c == '\n')
 159                         udbg_maple_real_putc('\r');
 160         }
 161 }
 162
 163 void __init udbg_init_maple_realmode(void)
 164 {
 165         udbg_comport = (volatile struct NS16550 __iomem *)0xf40003f8;
 166
 167         udbg_putc = udbg_maple_real_putc;
 168         udbg_getc = NULL;
 169         udbg_getc_poll = NULL;
 170 }
 171 #endif /* CONFIG_PPC_MAPLE */
 172
 173 #ifdef CONFIG_PPC_PASEMI
 174 void udbg_pas_real_putc(char c)
 175 {
 176         if (udbg_comport) {
 177                 while ((real_205_readb(&udbg_comport->lsr) & LSR_THRE) == 0)
 178                         /* wait for idle */;
 179                 real_205_writeb(c, &udbg_comport->thr); eieio();
 180                 if (c == '\n')
 181                         udbg_pas_real_putc('\r');
 182         }
 183 }
 184
 185 void udbg_init_pas_realmode(void)
 186 {
 187         udbg_comport = (volatile struct NS16550 __iomem *)0xfcff03f8UL;
 188
 189         udbg_putc = udbg_pas_real_putc;
 190         udbg_getc = NULL;
 191         udbg_getc_poll = NULL;
 192 }
 193 #endif /* CONFIG_PPC_MAPLE */