/*
 * 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/moduleparam.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/input.h>
#include <linux/serio.h>
#include <linux/init.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");

EXPORT_SYMBOL(ps2_init);
EXPORT_SYMBOL(ps2_sendbyte);
EXPORT_SYMBOL(ps2_drain);
EXPORT_SYMBOL(ps2_command);
EXPORT_SYMBOL(ps2_schedule_command);
EXPORT_SYMBOL(ps2_handle_ack);
EXPORT_SYMBOL(ps2_handle_response);
EXPORT_SYMBOL(ps2_cmd_aborted);

/* Work structure to schedule execution of a command */
struct ps2work {
	struct work_struct work;
	struct ps2dev *ps2dev;
	int command;
	unsigned char param[0];
};


/*
 * 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;
}

/*
 * 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);
	}

	mutex_lock(&ps2dev->cmd_mutex);

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

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

static inline int ps2_is_keyboard_id(char id_byte)
{
	static 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;
}

/*
 * 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:
			/*
			 * 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;
	}

	mutex_lock_nested(&ps2dev->cmd_mutex, SINGLE_DEPTH_NESTING);

	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 arrrives.
	 */
	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 && timeout > 0) {

		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);

	mutex_unlock(&ps2dev->cmd_mutex);
	return rc;
}

/*
 * ps2_execute_scheduled_command() sends a command, previously scheduled by
 * ps2_schedule_command(), to a PS/2 device (keyboard, mouse, etc.)
 */

static void ps2_execute_scheduled_command(void *data)
{
	struct ps2work *ps2work = data;

	ps2_command(ps2work->ps2dev, ps2work->param, ps2work->command);
	kfree(ps2work);
}

/*
 * ps2_schedule_command() allows to schedule delayed execution of a PS/2
 * command and can be used to issue a command from an interrupt or softirq
 * context.
 */

int ps2_schedule_command(struct ps2dev *ps2dev, unsigned char *param, int command)
{
	struct ps2work *ps2work;
	int send = (command >> 12) & 0xf;
	int receive = (command >> 8) & 0xf;

	if (!(ps2work = kmalloc(sizeof(struct ps2work) + max(send, receive), GFP_ATOMIC)))
		return -1;

	memset(ps2work, 0, sizeof(struct ps2work));
	ps2work->ps2dev = ps2dev;
	ps2work->command = command;
	memcpy(ps2work->param, param, send);
	INIT_WORK(&ps2work->work, ps2_execute_scheduled_command, ps2work);

	if (!schedule_work(&ps2work->work)) {
		kfree(ps2work);
		return -1;
	}

	return 0;
}

/*
 * ps2_init() initializes ps2dev structure
 */

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

/*
 * 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->nak = 1;
			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->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;
}

/*
 * 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;
}

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);

	ps2dev->flags = 0;
}