libps2.c

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/*
 * PS/2 driver library
 *
 * Copyright (c) 1999-2002 Vojtech Pavlik
 * Copyright (c) 2004 Dmitry Torokhov
 */

/*
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */

#include <linux/delay.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/input.h>
#include <linux/serio.h>
#include <linux/i8042.h>
#include <linux/init.h>
#include <linux/libps2.h>

#define DRIVER_DESC "PS/2 driver library"

MODULE_AUTHOR("Dmitry Torokhov <[email protected]>");
MODULE_DESCRIPTION("PS/2 driver library");
MODULE_LICENSE("GPL");

/*
 * ps2_sendbyte() sends a byte to the device and waits for acknowledge.
 * It doesn't handle retransmission, though it could - because if there
 * is a need for retransmissions device has to be replaced anyway.
 *
 * ps2_sendbyte() can only be called from a process context.
 */

int ps2_sendbyte(struct ps2dev *ps2dev, unsigned char byte, int timeout)
{
    serio_pause_rx(ps2dev->serio);
    ps2dev->nak = 1;
    ps2dev->flags |= PS2_FLAG_ACK;
    serio_continue_rx(ps2dev->serio);

    if (serio_write(ps2dev->serio, byte) == 0)
        wait_event_timeout(ps2dev->wait,
                   !(ps2dev->flags & PS2_FLAG_ACK),
                   msecs_to_jiffies(timeout));

    serio_pause_rx(ps2dev->serio);
    ps2dev->flags &= ~PS2_FLAG_ACK;
    serio_continue_rx(ps2dev->serio);

    return -ps2dev->nak;
}
EXPORT_SYMBOL(ps2_sendbyte);

void ps2_begin_command(struct ps2dev *ps2dev)
{
    mutex_lock(&ps2dev->cmd_mutex);

    if (i8042_check_port_owner(ps2dev->serio))
        i8042_lock_chip();
}
EXPORT_SYMBOL(ps2_begin_command);

void ps2_end_command(struct ps2dev *ps2dev)
{
    if (i8042_check_port_owner(ps2dev->serio))
        i8042_unlock_chip();

    mutex_unlock(&ps2dev->cmd_mutex);
}
EXPORT_SYMBOL(ps2_end_command);

/*
 * ps2_drain() waits for device to transmit requested number of bytes
 * and discards them.
 */

void ps2_drain(struct ps2dev *ps2dev, int maxbytes, int timeout)
{
    if (maxbytes > sizeof(ps2dev->cmdbuf)) {
        WARN_ON(1);
        maxbytes = sizeof(ps2dev->cmdbuf);
    }

    ps2_begin_command(ps2dev);

    serio_pause_rx(ps2dev->serio);
    ps2dev->flags = PS2_FLAG_CMD;
    ps2dev->cmdcnt = maxbytes;
    serio_continue_rx(ps2dev->serio);

    wait_event_timeout(ps2dev->wait,
               !(ps2dev->flags & PS2_FLAG_CMD),
               msecs_to_jiffies(timeout));

    ps2_end_command(ps2dev);
}
EXPORT_SYMBOL(ps2_drain);

/*
 * ps2_is_keyboard_id() checks received ID byte against the list of
 * known keyboard IDs.
 */

int ps2_is_keyboard_id(char id_byte)
{
    static const char keyboard_ids[] = {
        0xab,   /* Regular keyboards        */
        0xac,   /* NCD Sun keyboard     */
        0x2b,   /* Trust keyboard, translated   */
        0x5d,   /* Trust keyboard       */
        0x60,   /* NMB SGI keyboard, translated */
        0x47,   /* NMB SGI keyboard     */
    };

    return memchr(keyboard_ids, id_byte, sizeof(keyboard_ids)) != NULL;
}
EXPORT_SYMBOL(ps2_is_keyboard_id);

/*
 * ps2_adjust_timeout() is called after receiving 1st byte of command
 * response and tries to reduce remaining timeout to speed up command
 * completion.
 */

static int ps2_adjust_timeout(struct ps2dev *ps2dev, int command, int timeout)
{
    switch (command) {
        case PS2_CMD_RESET_BAT:
            /*
             * Device has sent the first response byte after
             * reset command, reset is thus done, so we can
             * shorten the timeout.
             * The next byte will come soon (keyboard) or not
             * at all (mouse).
             */
            if (timeout > msecs_to_jiffies(100))
                timeout = msecs_to_jiffies(100);
            break;

        case PS2_CMD_GETID:
            /*
             * Microsoft Natural Elite keyboard responds to
             * the GET ID command as it were a mouse, with
             * a single byte. Fail the command so atkbd will
             * use alternative probe to detect it.
             */
            if (ps2dev->cmdbuf[1] == 0xaa) {
                serio_pause_rx(ps2dev->serio);
                ps2dev->flags = 0;
                serio_continue_rx(ps2dev->serio);
                timeout = 0;
            }

            /*
             * If device behind the port is not a keyboard there
             * won't be 2nd byte of ID response.
             */
            if (!ps2_is_keyboard_id(ps2dev->cmdbuf[1])) {
                serio_pause_rx(ps2dev->serio);
                ps2dev->flags = ps2dev->cmdcnt = 0;
                serio_continue_rx(ps2dev->serio);
                timeout = 0;
            }
            break;

        default:
            break;
    }

    return timeout;
}

/*
 * ps2_command() sends a command and its parameters to the mouse,
 * then waits for the response and puts it in the param array.
 *
 * ps2_command() can only be called from a process context
 */

int __ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
{
    int timeout;
    int send = (command >> 12) & 0xf;
    int receive = (command >> 8) & 0xf;
    int rc = -1;
    int i;

    if (receive > sizeof(ps2dev->cmdbuf)) {
        WARN_ON(1);
        return -1;
    }

    if (send && !param) {
        WARN_ON(1);
        return -1;
    }

    serio_pause_rx(ps2dev->serio);
    ps2dev->flags = command == PS2_CMD_GETID ? PS2_FLAG_WAITID : 0;
    ps2dev->cmdcnt = receive;
    if (receive && param)
        for (i = 0; i < receive; i++)
            ps2dev->cmdbuf[(receive - 1) - i] = param[i];
    serio_continue_rx(ps2dev->serio);

    /*
     * Some devices (Synaptics) peform the reset before
     * ACKing the reset command, and so it can take a long
     * time before the ACK arrives.
     */
    if (ps2_sendbyte(ps2dev, command & 0xff,
             command == PS2_CMD_RESET_BAT ? 1000 : 200))
        goto out;

    for (i = 0; i < send; i++)
        if (ps2_sendbyte(ps2dev, param[i], 200))
            goto out;

    /*
     * The reset command takes a long time to execute.
     */
    timeout = msecs_to_jiffies(command == PS2_CMD_RESET_BAT ? 4000 : 500);

    timeout = wait_event_timeout(ps2dev->wait,
                     !(ps2dev->flags & PS2_FLAG_CMD1), timeout);

    if (ps2dev->cmdcnt && !(ps2dev->flags & PS2_FLAG_CMD1)) {

        timeout = ps2_adjust_timeout(ps2dev, command, timeout);
        wait_event_timeout(ps2dev->wait,
                   !(ps2dev->flags & PS2_FLAG_CMD), timeout);
    }

    if (param)
        for (i = 0; i < receive; i++)
            param[i] = ps2dev->cmdbuf[(receive - 1) - i];

    if (ps2dev->cmdcnt && (command != PS2_CMD_RESET_BAT || ps2dev->cmdcnt != 1))
        goto out;

    rc = 0;

 out:
    serio_pause_rx(ps2dev->serio);
    ps2dev->flags = 0;
    serio_continue_rx(ps2dev->serio);

    return rc;
}
EXPORT_SYMBOL(__ps2_command);

int ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
{
    int rc;

    ps2_begin_command(ps2dev);
    rc = __ps2_command(ps2dev, param, command);
    ps2_end_command(ps2dev);

    return rc;
}
EXPORT_SYMBOL(ps2_command);

/*
 * ps2_init() initializes ps2dev structure
 */

void ps2_init(struct ps2dev *ps2dev, struct serio *serio)
{
    mutex_init(&ps2dev->cmd_mutex);
    lockdep_set_subclass(&ps2dev->cmd_mutex, serio->depth);
    init_waitqueue_head(&ps2dev->wait);
    ps2dev->serio = serio;
}
EXPORT_SYMBOL(ps2_init);

/*
 * ps2_handle_ack() is supposed to be used in interrupt handler
 * to properly process ACK/NAK of a command from a PS/2 device.
 */

int ps2_handle_ack(struct ps2dev *ps2dev, unsigned char data)
{
    switch (data) {
        case PS2_RET_ACK:
            ps2dev->nak = 0;
            break;

        case PS2_RET_NAK:
            ps2dev->flags |= PS2_FLAG_NAK;
            ps2dev->nak = PS2_RET_NAK;
            break;

        case PS2_RET_ERR:
            if (ps2dev->flags & PS2_FLAG_NAK) {
                ps2dev->flags &= ~PS2_FLAG_NAK;
                ps2dev->nak = PS2_RET_ERR;
                break;
            }

        /*
         * Workaround for mice which don't ACK the Get ID command.
         * These are valid mouse IDs that we recognize.
         */
        case 0x00:
        case 0x03:
        case 0x04:
            if (ps2dev->flags & PS2_FLAG_WAITID) {
                ps2dev->nak = 0;
                break;
            }
            /* Fall through */
        default:
            return 0;
    }


    if (!ps2dev->nak) {
        ps2dev->flags &= ~PS2_FLAG_NAK;
        if (ps2dev->cmdcnt)
            ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
    }

    ps2dev->flags &= ~PS2_FLAG_ACK;
    wake_up(&ps2dev->wait);

    if (data != PS2_RET_ACK)
        ps2_handle_response(ps2dev, data);

    return 1;
}
EXPORT_SYMBOL(ps2_handle_ack);

/*
 * ps2_handle_response() is supposed to be used in interrupt handler
 * to properly store device's response to a command and notify process
 * waiting for completion of the command.
 */

int ps2_handle_response(struct ps2dev *ps2dev, unsigned char data)
{
    if (ps2dev->cmdcnt)
        ps2dev->cmdbuf[--ps2dev->cmdcnt] = data;

    if (ps2dev->flags & PS2_FLAG_CMD1) {
        ps2dev->flags &= ~PS2_FLAG_CMD1;
        if (ps2dev->cmdcnt)
            wake_up(&ps2dev->wait);
    }

    if (!ps2dev->cmdcnt) {
        ps2dev->flags &= ~PS2_FLAG_CMD;
        wake_up(&ps2dev->wait);
    }

    return 1;
}
EXPORT_SYMBOL(ps2_handle_response);

void ps2_cmd_aborted(struct ps2dev *ps2dev)
{
    if (ps2dev->flags & PS2_FLAG_ACK)
        ps2dev->nak = 1;

    if (ps2dev->flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
        wake_up(&ps2dev->wait);

    /* reset all flags except last nack */
    ps2dev->flags &= PS2_FLAG_NAK;
}
EXPORT_SYMBOL(ps2_cmd_aborted);