/*
   * 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)
  {
  	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);