/*
 * 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/libps2.h>

#define DRIVER_DESC     "PS/2 driver library"

MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
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)
{
        struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;

        mutex_lock(m);
}
EXPORT_SYMBOL(ps2_begin_command);

void ps2_end_command(struct ps2dev *ps2dev)
{
        struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;

        mutex_unlock(m);
}
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)) {
                serio_pause_rx(ps2dev->serio);
                goto out_reset_flags;
        }

        for (i = 0; i < send; i++) {
                if (ps2_sendbyte(ps2dev, param[i], 200)) {
                        serio_pause_rx(ps2dev->serio);
                        goto out_reset_flags;
                }
        }

        /*
         * 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);
        }

        serio_pause_rx(ps2dev->serio);

        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_reset_flags;

        rc = 0;

 out_reset_flags:
        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);