class: move driver core specific parts to a private structure

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / parport / ieee1284.c

/* $Id: parport_ieee1284.c,v 1.4 1997/10/19 21:37:21 philip Exp $
 * IEEE-1284 implementation for parport.
 *
 * Authors: Phil Blundell <philb@gnu.org>
 *          Carsten Gross <carsten@sol.wohnheim.uni-ulm.de>
 *          Jose Renau <renau@acm.org>
 *          Tim Waugh <tim@cyberelk.demon.co.uk> (largely rewritten)
 *
 * This file is responsible for IEEE 1284 negotiation, and for handing
 * read/write requests to low-level drivers.
 *
 * Any part of this program may be used in documents licensed under
 * the GNU Free Documentation License, Version 1.1 or any later version
 * published by the Free Software Foundation.
 *
 * Various hacks, Fred Barnes <frmb2@ukc.ac.uk>, 04/2000
 */

#include <linux/module.h>
#include <linux/threads.h>
#include <linux/parport.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/timer.h>
#include <linux/sched.h>

#undef DEBUG /* undef me for production */

#ifdef CONFIG_LP_CONSOLE
#undef DEBUG /* Don't want a garbled console */
#endif

#ifdef DEBUG
#define DPRINTK(stuff...) printk (stuff)
#else
#define DPRINTK(stuff...)
#endif

/* Make parport_wait_peripheral wake up.
 * It will be useful to call this from an interrupt handler. */
static void parport_ieee1284_wakeup (struct parport *port)
{
        up (&port->physport->ieee1284.irq);
}

static struct parport *port_from_cookie[PARPORT_MAX];
static void timeout_waiting_on_port (unsigned long cookie)
{
        parport_ieee1284_wakeup (port_from_cookie[cookie % PARPORT_MAX]);
}

/**
 *      parport_wait_event - wait for an event on a parallel port
 *      @port: port to wait on
 *      @timeout: time to wait (in jiffies)
 *
 *      This function waits for up to @timeout jiffies for an
 *      interrupt to occur on a parallel port.  If the port timeout is
 *      set to zero, it returns immediately.
 *
 *      If an interrupt occurs before the timeout period elapses, this
 *      function returns zero immediately.  If it times out, it returns
 *      one.  An error code less than zero indicates an error (most
 *      likely a pending signal), and the calling code should finish
 *      what it's doing as soon as it can.
 */

int parport_wait_event (struct parport *port, signed long timeout)
{
        int ret;
        struct timer_list timer;

        if (!port->physport->cad->timeout)
                /* Zero timeout is special, and we can't down() the
                   semaphore. */
                return 1;

        init_timer_on_stack(&timer);
        timer.expires = jiffies + timeout;
        timer.function = timeout_waiting_on_port;
        port_from_cookie[port->number % PARPORT_MAX] = port;
        timer.data = port->number;

        add_timer (&timer);
        ret = down_interruptible (&port->physport->ieee1284.irq);
        if (!del_timer (&timer) && !ret)
                /* Timed out. */
                ret = 1;

        destroy_timer_on_stack(&timer);

        return ret;
}

/**
 *      parport_poll_peripheral - poll status lines
 *      @port: port to watch
 *      @mask: status lines to watch
 *      @result: desired values of chosen status lines
 *      @usec: timeout
 *
 *      This function busy-waits until the masked status lines have
 *      the desired values, or until the timeout period elapses.  The
 *      @mask and @result parameters are bitmasks, with the bits
 *      defined by the constants in parport.h: %PARPORT_STATUS_BUSY,
 *      and so on.
 *
 *      This function does not call schedule(); instead it busy-waits
 *      using udelay().  It currently has a resolution of 5usec.
 *
 *      If the status lines take on the desired values before the
 *      timeout period elapses, parport_poll_peripheral() returns zero
 *      immediately.  A return value greater than zero indicates
 *      a timeout.  An error code (less than zero) indicates an error,
 *      most likely a signal that arrived, and the caller should
 *      finish what it is doing as soon as possible.
*/

int parport_poll_peripheral(struct parport *port,
                            unsigned char mask,
                            unsigned char result,
                            int usec)
{
        /* Zero return code is success, >0 is timeout. */
        int count = usec / 5 + 2;
        int i;
        unsigned char status;
        for (i = 0; i < count; i++) {
                status = parport_read_status (port);
                if ((status & mask) == result)
                        return 0;
                if (signal_pending (current))
                        return -EINTR;
                if (need_resched())
                        break;
                if (i >= 2)
                        udelay (5);
        }

        return 1;
}

/**
 *      parport_wait_peripheral - wait for status lines to change in 35ms
 *      @port: port to watch
 *      @mask: status lines to watch
 *      @result: desired values of chosen status lines
 *
 *      This function waits until the masked status lines have the
 *      desired values, or until 35ms have elapsed (see IEEE 1284-1994
 *      page 24 to 25 for why this value in particular is hardcoded).
 *      The @mask and @result parameters are bitmasks, with the bits
 *      defined by the constants in parport.h: %PARPORT_STATUS_BUSY,
 *      and so on.
 *
 *      The port is polled quickly to start off with, in anticipation
 *      of a fast response from the peripheral.  This fast polling
 *      time is configurable (using /proc), and defaults to 500usec.
 *      If the timeout for this port (see parport_set_timeout()) is
 *      zero, the fast polling time is 35ms, and this function does
 *      not call schedule().
 *
 *      If the timeout for this port is non-zero, after the fast
 *      polling fails it uses parport_wait_event() to wait for up to
 *      10ms, waking up if an interrupt occurs.
 */

int parport_wait_peripheral(struct parport *port,
                            unsigned char mask, 
                            unsigned char result)
{
        int ret;
        int usec;
        unsigned long deadline;
        unsigned char status;

        usec = port->physport->spintime; /* usecs of fast polling */
        if (!port->physport->cad->timeout)
                /* A zero timeout is "special": busy wait for the
                   entire 35ms. */
                usec = 35000;

        /* Fast polling.
         *
         * This should be adjustable.
         * How about making a note (in the device structure) of how long
         * it takes, so we know for next time?
         */
        ret = parport_poll_peripheral (port, mask, result, usec);
        if (ret != 1)
                return ret;

        if (!port->physport->cad->timeout)
                /* We may be in an interrupt handler, so we can't poll
                 * slowly anyway. */
                return 1;

        /* 40ms of slow polling. */
        deadline = jiffies + msecs_to_jiffies(40);
        while (time_before (jiffies, deadline)) {
                int ret;

                if (signal_pending (current))
                        return -EINTR;

                /* Wait for 10ms (or until an interrupt occurs if
                 * the handler is set) */
                if ((ret = parport_wait_event (port, msecs_to_jiffies(10))) < 0)
                        return ret;

                status = parport_read_status (port);
                if ((status & mask) == result)
                        return 0;

                if (!ret) {
                        /* parport_wait_event didn't time out, but the
                         * peripheral wasn't actually ready either.
                         * Wait for another 10ms. */
                        schedule_timeout_interruptible(msecs_to_jiffies(10));
                }
        }

        return 1;
}

#ifdef CONFIG_PARPORT_1284
/* Terminate a negotiated mode. */
static void parport_ieee1284_terminate (struct parport *port)
{
        int r;
        port = port->physport;

        /* EPP terminates differently. */
        switch (port->ieee1284.mode) {
        case IEEE1284_MODE_EPP:
        case IEEE1284_MODE_EPPSL:
        case IEEE1284_MODE_EPPSWE:
                /* Terminate from EPP mode. */

                /* Event 68: Set nInit low */
                parport_frob_control (port, PARPORT_CONTROL_INIT, 0);
                udelay (50);

                /* Event 69: Set nInit high, nSelectIn low */
                parport_frob_control (port,
                                      PARPORT_CONTROL_SELECT
                                      | PARPORT_CONTROL_INIT,
                                      PARPORT_CONTROL_SELECT
                                      | PARPORT_CONTROL_INIT);
                break;

        case IEEE1284_MODE_ECP:
        case IEEE1284_MODE_ECPRLE:
        case IEEE1284_MODE_ECPSWE:
                /* In ECP we can only terminate from fwd idle phase. */
                if (port->ieee1284.phase != IEEE1284_PH_FWD_IDLE) {
                        /* Event 47: Set nInit high */
                        parport_frob_control (port,
                                              PARPORT_CONTROL_INIT
                                              | PARPORT_CONTROL_AUTOFD,
                                              PARPORT_CONTROL_INIT
                                              | PARPORT_CONTROL_AUTOFD);

                        /* Event 49: PError goes high */
                        r = parport_wait_peripheral (port,
                                                     PARPORT_STATUS_PAPEROUT,
                                                     PARPORT_STATUS_PAPEROUT);
                        if (r)
                                DPRINTK (KERN_INFO "%s: Timeout at event 49\n",
                                         port->name);

                        parport_data_forward (port);
                        DPRINTK (KERN_DEBUG "%s: ECP direction: forward\n",
                                 port->name);
                        port->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
                }

                /* fall-though.. */

        default:
                /* Terminate from all other modes. */

                /* Event 22: Set nSelectIn low, nAutoFd high */
                parport_frob_control (port,
                                      PARPORT_CONTROL_SELECT
                                      | PARPORT_CONTROL_AUTOFD,
                                      PARPORT_CONTROL_SELECT);

                /* Event 24: nAck goes low */
                r = parport_wait_peripheral (port, PARPORT_STATUS_ACK, 0);
                if (r)
                        DPRINTK (KERN_INFO "%s: Timeout at event 24\n",
                                 port->name);

                /* Event 25: Set nAutoFd low */
                parport_frob_control (port,
                                      PARPORT_CONTROL_AUTOFD,
                                      PARPORT_CONTROL_AUTOFD);

                /* Event 27: nAck goes high */
                r = parport_wait_peripheral (port,
                                             PARPORT_STATUS_ACK, 
                                             PARPORT_STATUS_ACK);
                if (r)
                        DPRINTK (KERN_INFO "%s: Timeout at event 27\n",
                                 port->name);

                /* Event 29: Set nAutoFd high */
                parport_frob_control (port, PARPORT_CONTROL_AUTOFD, 0);
        }

        port->ieee1284.mode = IEEE1284_MODE_COMPAT;
        port->ieee1284.phase = IEEE1284_PH_FWD_IDLE;

        DPRINTK (KERN_DEBUG "%s: In compatibility (forward idle) mode\n",
                 port->name);
}               
#endif /* IEEE1284 support */

/**
 *      parport_negotiate - negotiate an IEEE 1284 mode
 *      @port: port to use
 *      @mode: mode to negotiate to
 *
 *      Use this to negotiate to a particular IEEE 1284 transfer mode.
 *      The @mode parameter should be one of the constants in
 *      parport.h starting %IEEE1284_MODE_xxx.
 *
 *      The return value is 0 if the peripheral has accepted the
 *      negotiation to the mode specified, -1 if the peripheral is not
 *      IEEE 1284 compliant (or not present), or 1 if the peripheral
 *      has rejected the negotiation.
 */

int parport_negotiate (struct parport *port, int mode)
{
#ifndef CONFIG_PARPORT_1284
        if (mode == IEEE1284_MODE_COMPAT)
                return 0;
        printk (KERN_ERR "parport: IEEE1284 not supported in this kernel\n");
        return -1;
#else
        int m = mode & ~IEEE1284_ADDR;
        int r;
        unsigned char xflag;

        port = port->physport;

        /* Is there anything to do? */
        if (port->ieee1284.mode == mode)
                return 0;

        /* Is the difference just an address-or-not bit? */
        if ((port->ieee1284.mode & ~IEEE1284_ADDR) == (mode & ~IEEE1284_ADDR)){
                port->ieee1284.mode = mode;
                return 0;
        }

        /* Go to compability forward idle mode */
        if (port->ieee1284.mode != IEEE1284_MODE_COMPAT)
                parport_ieee1284_terminate (port);

        if (mode == IEEE1284_MODE_COMPAT)
                /* Compatibility mode: no negotiation. */
                return 0; 

        switch (mode) {
        case IEEE1284_MODE_ECPSWE:
                m = IEEE1284_MODE_ECP;
                break;
        case IEEE1284_MODE_EPPSL:
        case IEEE1284_MODE_EPPSWE:
                m = IEEE1284_MODE_EPP;
                break;
        case IEEE1284_MODE_BECP:
                return -ENOSYS; /* FIXME (implement BECP) */
        }

        if (mode & IEEE1284_EXT_LINK)
                m = 1<<7; /* request extensibility link */

        port->ieee1284.phase = IEEE1284_PH_NEGOTIATION;

        /* Start off with nStrobe and nAutoFd high, and nSelectIn low */
        parport_frob_control (port,
                              PARPORT_CONTROL_STROBE
                              | PARPORT_CONTROL_AUTOFD
                              | PARPORT_CONTROL_SELECT,
                              PARPORT_CONTROL_SELECT);
        udelay(1);

        /* Event 0: Set data */
        parport_data_forward (port);
        parport_write_data (port, m);
        udelay (400); /* Shouldn't need to wait this long. */

        /* Event 1: Set nSelectIn high, nAutoFd low */
        parport_frob_control (port,
                              PARPORT_CONTROL_SELECT
                              | PARPORT_CONTROL_AUTOFD,
                              PARPORT_CONTROL_AUTOFD);

        /* Event 2: PError, Select, nFault go high, nAck goes low */
        if (parport_wait_peripheral (port,
                                     PARPORT_STATUS_ERROR
                                     | PARPORT_STATUS_SELECT
                                     | PARPORT_STATUS_PAPEROUT
                                     | PARPORT_STATUS_ACK,
                                     PARPORT_STATUS_ERROR
                                     | PARPORT_STATUS_SELECT
                                     | PARPORT_STATUS_PAPEROUT)) {
                /* Timeout */
                parport_frob_control (port,
                                      PARPORT_CONTROL_SELECT
                                      | PARPORT_CONTROL_AUTOFD,
                                      PARPORT_CONTROL_SELECT);
                DPRINTK (KERN_DEBUG
                         "%s: Peripheral not IEEE1284 compliant (0x%02X)\n",
                         port->name, parport_read_status (port));
                port->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
                return -1; /* Not IEEE1284 compliant */
        }

        /* Event 3: Set nStrobe low */
        parport_frob_control (port,
                              PARPORT_CONTROL_STROBE,
                              PARPORT_CONTROL_STROBE);

        /* Event 4: Set nStrobe and nAutoFd high */
        udelay (5);
        parport_frob_control (port,
                              PARPORT_CONTROL_STROBE
                              | PARPORT_CONTROL_AUTOFD,
                              0);

        /* Event 6: nAck goes high */
        if (parport_wait_peripheral (port,
                                     PARPORT_STATUS_ACK,
                                     PARPORT_STATUS_ACK)) {
                /* This shouldn't really happen with a compliant device. */
                DPRINTK (KERN_DEBUG
                         "%s: Mode 0x%02x not supported? (0x%02x)\n",
                         port->name, mode, port->ops->read_status (port));
                parport_ieee1284_terminate (port);
                return 1;
        }

        xflag = parport_read_status (port) & PARPORT_STATUS_SELECT;

        /* xflag should be high for all modes other than nibble (0). */
        if (mode && !xflag) {
                /* Mode not supported. */
                DPRINTK (KERN_DEBUG "%s: Mode 0x%02x rejected by peripheral\n",
                         port->name, mode);
                parport_ieee1284_terminate (port);
                return 1;
        }

        /* More to do if we've requested extensibility link. */
        if (mode & IEEE1284_EXT_LINK) {
                m = mode & 0x7f;
                udelay (1);
                parport_write_data (port, m);
                udelay (1);

                /* Event 51: Set nStrobe low */
                parport_frob_control (port,
                                      PARPORT_CONTROL_STROBE,
                                      PARPORT_CONTROL_STROBE);

                /* Event 52: nAck goes low */
                if (parport_wait_peripheral (port, PARPORT_STATUS_ACK, 0)) {
                        /* This peripheral is _very_ slow. */
                        DPRINTK (KERN_DEBUG
                                 "%s: Event 52 didn't happen\n",
                                 port->name);
                        parport_ieee1284_terminate (port);
                        return 1;
                }

                /* Event 53: Set nStrobe high */
                parport_frob_control (port,
                                      PARPORT_CONTROL_STROBE,
                                      0);

                /* Event 55: nAck goes high */
                if (parport_wait_peripheral (port,
                                             PARPORT_STATUS_ACK,
                                             PARPORT_STATUS_ACK)) {
                        /* This shouldn't really happen with a compliant
                         * device. */
                        DPRINTK (KERN_DEBUG
                                 "%s: Mode 0x%02x not supported? (0x%02x)\n",
                                 port->name, mode,
                                 port->ops->read_status (port));
                        parport_ieee1284_terminate (port);
                        return 1;
                }

                /* Event 54: Peripheral sets XFlag to reflect support */
                xflag = parport_read_status (port) & PARPORT_STATUS_SELECT;

                /* xflag should be high. */
                if (!xflag) {
                        /* Extended mode not supported. */
                        DPRINTK (KERN_DEBUG "%s: Extended mode 0x%02x not "
                                 "supported\n", port->name, mode);
                        parport_ieee1284_terminate (port);
                        return 1;
                }

                /* Any further setup is left to the caller. */
        }

        /* Mode is supported */
        DPRINTK (KERN_DEBUG "%s: In mode 0x%02x\n", port->name, mode);
        port->ieee1284.mode = mode;

        /* But ECP is special */
        if (!(mode & IEEE1284_EXT_LINK) && (m & IEEE1284_MODE_ECP)) {
                port->ieee1284.phase = IEEE1284_PH_ECP_SETUP;

                /* Event 30: Set nAutoFd low */
                parport_frob_control (port,
                                      PARPORT_CONTROL_AUTOFD,
                                      PARPORT_CONTROL_AUTOFD);

                /* Event 31: PError goes high. */
                r = parport_wait_peripheral (port,
                                             PARPORT_STATUS_PAPEROUT,
                                             PARPORT_STATUS_PAPEROUT);
                if (r) {
                        DPRINTK (KERN_INFO "%s: Timeout at event 31\n",
                                port->name);
                }

                port->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
                DPRINTK (KERN_DEBUG "%s: ECP direction: forward\n",
                         port->name);
        } else switch (mode) {
        case IEEE1284_MODE_NIBBLE:
        case IEEE1284_MODE_BYTE:
                port->ieee1284.phase = IEEE1284_PH_REV_IDLE;
                break;
        default:
                port->ieee1284.phase = IEEE1284_PH_FWD_IDLE;
        }


        return 0;
#endif /* IEEE1284 support */
}

/* Acknowledge that the peripheral has data available.
 * Events 18-20, in order to get from Reverse Idle phase
 * to Host Busy Data Available.
 * This will most likely be called from an interrupt.
 * Returns zero if data was available.
 */
#ifdef CONFIG_PARPORT_1284
static int parport_ieee1284_ack_data_avail (struct parport *port)
{
        if (parport_read_status (port) & PARPORT_STATUS_ERROR)
                /* Event 18 didn't happen. */
                return -1;

        /* Event 20: nAutoFd goes high. */
        port->ops->frob_control (port, PARPORT_CONTROL_AUTOFD, 0);
        port->ieee1284.phase = IEEE1284_PH_HBUSY_DAVAIL;
        return 0;
}
#endif /* IEEE1284 support */

/* Handle an interrupt. */
void parport_ieee1284_interrupt (void *handle)
{
        struct parport *port = handle;
        parport_ieee1284_wakeup (port);

#ifdef CONFIG_PARPORT_1284
        if (port->ieee1284.phase == IEEE1284_PH_REV_IDLE) {
                /* An interrupt in this phase means that data
                 * is now available. */
                DPRINTK (KERN_DEBUG "%s: Data available\n", port->name);
                parport_ieee1284_ack_data_avail (port);
        }
#endif /* IEEE1284 support */
}

/**
 *      parport_write - write a block of data to a parallel port
 *      @port: port to write to
 *      @buffer: data buffer (in kernel space)
 *      @len: number of bytes of data to transfer
 *
 *      This will write up to @len bytes of @buffer to the port
 *      specified, using the IEEE 1284 transfer mode most recently
 *      negotiated to (using parport_negotiate()), as long as that
 *      mode supports forward transfers (host to peripheral).
 *
 *      It is the caller's responsibility to ensure that the first
 *      @len bytes of @buffer are valid.
 *
 *      This function returns the number of bytes transferred (if zero
 *      or positive), or else an error code.
 */

ssize_t parport_write (struct parport *port, const void *buffer, size_t len)
{
#ifndef CONFIG_PARPORT_1284
        return port->ops->compat_write_data (port, buffer, len, 0);
#else
        ssize_t retval;
        int mode = port->ieee1284.mode;
        int addr = mode & IEEE1284_ADDR;
        size_t (*fn) (struct parport *, const void *, size_t, int);

        /* Ignore the device-ID-request bit and the address bit. */
        mode &= ~(IEEE1284_DEVICEID | IEEE1284_ADDR);

        /* Use the mode we're in. */
        switch (mode) {
        case IEEE1284_MODE_NIBBLE:
        case IEEE1284_MODE_BYTE:
                parport_negotiate (port, IEEE1284_MODE_COMPAT);
        case IEEE1284_MODE_COMPAT:
                DPRINTK (KERN_DEBUG "%s: Using compatibility mode\n",
                         port->name);
                fn = port->ops->compat_write_data;
                break;

        case IEEE1284_MODE_EPP:
                DPRINTK (KERN_DEBUG "%s: Using EPP mode\n", port->name);
                if (addr) {
                        fn = port->ops->epp_write_addr;
                } else {
                        fn = port->ops->epp_write_data;
                }
                break;
        case IEEE1284_MODE_EPPSWE:
                DPRINTK (KERN_DEBUG "%s: Using software-emulated EPP mode\n",
                        port->name);
                if (addr) {
                        fn = parport_ieee1284_epp_write_addr;
                } else {
                        fn = parport_ieee1284_epp_write_data;
                }
                break;
        case IEEE1284_MODE_ECP:
        case IEEE1284_MODE_ECPRLE:
                DPRINTK (KERN_DEBUG "%s: Using ECP mode\n", port->name);
                if (addr) {
                        fn = port->ops->ecp_write_addr;
                } else {
                        fn = port->ops->ecp_write_data;
                }
                break;

        case IEEE1284_MODE_ECPSWE:
                DPRINTK (KERN_DEBUG "%s: Using software-emulated ECP mode\n",
                         port->name);
                /* The caller has specified that it must be emulated,
                 * even if we have ECP hardware! */
                if (addr) {
                        fn = parport_ieee1284_ecp_write_addr;
                } else {
                        fn = parport_ieee1284_ecp_write_data;
                }
                break;

        default:
                DPRINTK (KERN_DEBUG "%s: Unknown mode 0x%02x\n", port->name,
                        port->ieee1284.mode);
                return -ENOSYS;
        }

        retval = (*fn) (port, buffer, len, 0);
        DPRINTK (KERN_DEBUG "%s: wrote %d/%d bytes\n", port->name, retval, len);
        return retval;
#endif /* IEEE1284 support */
}

/**
 *      parport_read - read a block of data from a parallel port
 *      @port: port to read from
 *      @buffer: data buffer (in kernel space)
 *      @len: number of bytes of data to transfer
 *
 *      This will read up to @len bytes of @buffer to the port
 *      specified, using the IEEE 1284 transfer mode most recently
 *      negotiated to (using parport_negotiate()), as long as that
 *      mode supports reverse transfers (peripheral to host).
 *
 *      It is the caller's responsibility to ensure that the first
 *      @len bytes of @buffer are available to write to.
 *
 *      This function returns the number of bytes transferred (if zero
 *      or positive), or else an error code.
 */

ssize_t parport_read (struct parport *port, void *buffer, size_t len)
{
#ifndef CONFIG_PARPORT_1284
        printk (KERN_ERR "parport: IEEE1284 not supported in this kernel\n");
        return -ENODEV;
#else
        int mode = port->physport->ieee1284.mode;
        int addr = mode & IEEE1284_ADDR;
        size_t (*fn) (struct parport *, void *, size_t, int);

        /* Ignore the device-ID-request bit and the address bit. */
        mode &= ~(IEEE1284_DEVICEID | IEEE1284_ADDR);

        /* Use the mode we're in. */
        switch (mode) {
        case IEEE1284_MODE_COMPAT:
                /* if we can tri-state use BYTE mode instead of NIBBLE mode,
                 * if that fails, revert to NIBBLE mode -- ought to store somewhere
                 * the device's ability to do BYTE mode reverse transfers, so we don't
                 * end up needlessly calling negotiate(BYTE) repeately..  (fb)
                 */
                if ((port->physport->modes & PARPORT_MODE_TRISTATE) &&
                    !parport_negotiate (port, IEEE1284_MODE_BYTE)) {
                        /* got into BYTE mode OK */
                        DPRINTK (KERN_DEBUG "%s: Using byte mode\n", port->name);
                        fn = port->ops->byte_read_data;
                        break;
                }
                if (parport_negotiate (port, IEEE1284_MODE_NIBBLE)) {
                        return -EIO;
                }
                /* fall through to NIBBLE */
        case IEEE1284_MODE_NIBBLE:
                DPRINTK (KERN_DEBUG "%s: Using nibble mode\n", port->name);
                fn = port->ops->nibble_read_data;
                break;

        case IEEE1284_MODE_BYTE:
                DPRINTK (KERN_DEBUG "%s: Using byte mode\n", port->name);
                fn = port->ops->byte_read_data;
                break;

        case IEEE1284_MODE_EPP:
                DPRINTK (KERN_DEBUG "%s: Using EPP mode\n", port->name);
                if (addr) {
                        fn = port->ops->epp_read_addr;
                } else {
                        fn = port->ops->epp_read_data;
                }
                break;
        case IEEE1284_MODE_EPPSWE:
                DPRINTK (KERN_DEBUG "%s: Using software-emulated EPP mode\n",
                        port->name);
                if (addr) {
                        fn = parport_ieee1284_epp_read_addr;
                } else {
                        fn = parport_ieee1284_epp_read_data;
                }
                break;
        case IEEE1284_MODE_ECP:
        case IEEE1284_MODE_ECPRLE:
                DPRINTK (KERN_DEBUG "%s: Using ECP mode\n", port->name);
                fn = port->ops->ecp_read_data;
                break;

        case IEEE1284_MODE_ECPSWE:
                DPRINTK (KERN_DEBUG "%s: Using software-emulated ECP mode\n",
                         port->name);
                fn = parport_ieee1284_ecp_read_data;
                break;

        default:
                DPRINTK (KERN_DEBUG "%s: Unknown mode 0x%02x\n", port->name,
                         port->physport->ieee1284.mode);
                return -ENOSYS;
        }

        return (*fn) (port, buffer, len, 0);
#endif /* IEEE1284 support */
}

/**
 *      parport_set_timeout - set the inactivity timeout for a device
 *      @dev: device on a port
 *      @inactivity: inactivity timeout (in jiffies)
 *
 *      This sets the inactivity timeout for a particular device on a
 *      port.  This affects functions like parport_wait_peripheral().
 *      The special value 0 means not to call schedule() while dealing
 *      with this device.
 *
 *      The return value is the previous inactivity timeout.
 *
 *      Any callers of parport_wait_event() for this device are woken
 *      up.
 */

long parport_set_timeout (struct pardevice *dev, long inactivity)
{
        long int old = dev->timeout;

        dev->timeout = inactivity;

        if (dev->port->physport->cad == dev)
                parport_ieee1284_wakeup (dev->port);

        return old;
}

/* Exported symbols for modules. */

EXPORT_SYMBOL(parport_negotiate);
EXPORT_SYMBOL(parport_write);
EXPORT_SYMBOL(parport_read);
EXPORT_SYMBOL(parport_wait_peripheral);
EXPORT_SYMBOL(parport_wait_event);
EXPORT_SYMBOL(parport_set_timeout);
EXPORT_SYMBOL(parport_ieee1284_interrupt);