drivers/input/serio/libps2.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * PS/2 driver library
  *
  * Copyright (c) 1999-2002 Vojtech Pavlik
  * Copyright (c) 2004 Dmitry Torokhov
  */


 #include <linux/delay.h>
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/interrupt.h>
 #include <linux/input.h>
 #include <linux/kmsan-checks.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");

 static int ps2_do_sendbyte(struct ps2dev *ps2dev, u8 byte,
 			   unsigned int timeout, unsigned int max_attempts)
 	__releases(&ps2dev->serio->lock) __acquires(&ps2dev->serio->lock)
 {
 	int attempt = 0;
 	int error;

 	lockdep_assert_held(&ps2dev->serio->lock);

 	do {
 		ps2dev->nak = 1;
 		ps2dev->flags |= PS2_FLAG_ACK;

 		serio_continue_rx(ps2dev->serio);

 		error = serio_write(ps2dev->serio, byte);
 		if (error)
 			dev_dbg(&ps2dev->serio->dev,
 				"failed to write %#02x: %d\n", byte, error);
 		else
 			wait_event_timeout(ps2dev->wait,
 					   !(ps2dev->flags & PS2_FLAG_ACK),
 					   msecs_to_jiffies(timeout));

 		serio_pause_rx(ps2dev->serio);
 	} while (ps2dev->nak == PS2_RET_NAK && ++attempt < max_attempts);

 	ps2dev->flags &= ~PS2_FLAG_ACK;

 	if (!error) {
 		switch (ps2dev->nak) {
 		case 0:
 			break;
 		case PS2_RET_NAK:
 			error = -EAGAIN;
 			break;
 		case PS2_RET_ERR:
 			error = -EPROTO;
 			break;
 		default:
 			error = -EIO;
 			break;
 		}
 	}

 	if (error || attempt > 1)
 		dev_dbg(&ps2dev->serio->dev,
 			"%02x - %d (%x), attempt %d\n",
 			byte, error, ps2dev->nak, attempt);

 	return error;
 }

 /*
  * ps2_sendbyte() sends a byte to the device and waits for acknowledge.
  * It doesn't handle retransmission, the caller is expected to handle
  * it when needed.
  *
  * ps2_sendbyte() can only be called from a process context.
  */

 int ps2_sendbyte(struct ps2dev *ps2dev, u8 byte, unsigned int timeout)
 {
 	int retval;

 	serio_pause_rx(ps2dev->serio);

 	retval = ps2_do_sendbyte(ps2dev, byte, timeout, 1);
 	dev_dbg(&ps2dev->serio->dev, "%02x - %x\n", byte, ps2dev->nak);

 	serio_continue_rx(ps2dev->serio);

 	return retval;
 }
 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, size_t maxbytes, unsigned 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.
  */

 bool ps2_is_keyboard_id(u8 id_byte)
 {
 	static const u8 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,
 			      unsigned int command, unsigned 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, u8 *param, unsigned int command)
 {
 	unsigned int timeout;
 	unsigned int send = (command >> 12) & 0xf;
 	unsigned int receive = (command >> 8) & 0xf;
 	int rc;
 	int i;
 	u8 send_param[16];

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

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

 	memcpy(send_param, param, send);

 	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];

 	/* Signal that we are sending the command byte */
 	ps2dev->flags |= PS2_FLAG_ACK_CMD;

 	/*
 	 * Some devices (Synaptics) peform the reset before
 	 * ACKing the reset command, and so it can take a long
 	 * time before the ACK arrives.
 	 */
 	timeout = command == PS2_CMD_RESET_BAT ? 1000 : 200;

 	rc = ps2_do_sendbyte(ps2dev, command & 0xff, timeout, 2);
 	if (rc)
 		goto out_reset_flags;

 	/* Now we are sending command parameters, if any */
 	ps2dev->flags &= ~PS2_FLAG_ACK_CMD;

 	for (i = 0; i < send; i++) {
 		rc = ps2_do_sendbyte(ps2dev, param[i], 200, 2);
 		if (rc)
 			goto out_reset_flags;
 	}

 	serio_continue_rx(ps2dev->serio);

 	/*
 	 * 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];
 		kmsan_unpoison_memory(param, receive);
 	}

 	if (ps2dev->cmdcnt &&
 	    (command != PS2_CMD_RESET_BAT || ps2dev->cmdcnt != 1)) {
 		rc = -EPROTO;
 		goto out_reset_flags;
 	}

 	rc = 0;

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

 	dev_dbg(&ps2dev->serio->dev,
 		"%02x [%*ph] - %x/%08lx [%*ph]\n",
 		command & 0xff, send, send_param,
 		ps2dev->nak, ps2dev->flags,
 		receive, param ?: send_param);

 	/*
 	 * ps_command() handles resends itself, so do not leak -EAGAIN
 	 * to the callers.
 	 */
 	return rc != -EAGAIN ? rc : -EPROTO;
 }
 EXPORT_SYMBOL(__ps2_command);

 int ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned 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_sliced_command() sends an extended PS/2 command to the mouse
  * using sliced syntax, understood by advanced devices, such as Logitech
  * or Synaptics touchpads. The command is encoded as:
  * 0xE6 0xE8 rr 0xE8 ss 0xE8 tt 0xE8 uu where (rr*64)+(ss*16)+(tt*4)+uu
  * is the command.
  */

 int ps2_sliced_command(struct ps2dev *ps2dev, u8 command)
 {
 	int i;
 	int retval;

 	ps2_begin_command(ps2dev);

 	retval = __ps2_command(ps2dev, NULL, PS2_CMD_SETSCALE11);
 	if (retval)
 		goto out;

 	for (i = 6; i >= 0; i -= 2) {
 		u8 d = (command >> i) & 3;
 		retval = __ps2_command(ps2dev, &d, PS2_CMD_SETRES);
 		if (retval)
 			break;
 	}

 out:
 	dev_dbg(&ps2dev->serio->dev, "%02x - %d\n", command, retval);
 	ps2_end_command(ps2dev);
 	return retval;
 }
 EXPORT_SYMBOL(ps2_sliced_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.
  */

 bool ps2_handle_ack(struct ps2dev *ps2dev, u8 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;
 		}
 		fallthrough;

 	/*
 	 * 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;
 		}
 		fallthrough;
 	default:
 		/*
 		 * Do not signal errors if we get unexpected reply while
 		 * waiting for an ACK to the initial (first) command byte:
 		 * the device might not be quiesced yet and continue
 		 * delivering data.
 		 * Note that we reset PS2_FLAG_WAITID flag, so the workaround
 		 * for mice not acknowledging the Get ID command only triggers
 		 * on the 1st byte; if device spews data we really want to see
 		 * a real ACK from it.
 		 */
 		dev_dbg(&ps2dev->serio->dev, "unexpected %#02x\n", data);
 		ps2dev->flags &= ~PS2_FLAG_WAITID;
 		return ps2dev->flags & PS2_FLAG_ACK_CMD;
 	}

 	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 true;
 }
 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.
  */

 bool ps2_handle_response(struct ps2dev *ps2dev, u8 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 true;
 }
 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);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* PS/2 driver library
	*
	* Copyright (c) 1999-2002 Vojtech Pavlik
	* Copyright (c) 2004 Dmitry Torokhov
	*/


	#include <linux/delay.h>
	#include <linux/module.h>
	#include <linux/sched.h>
	#include <linux/interrupt.h>
	#include <linux/input.h>
	#include <linux/kmsan-checks.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");

	static int ps2_do_sendbyte(struct ps2dev *ps2dev, u8 byte,
	unsigned int timeout, unsigned int max_attempts)
	__releases(&ps2dev->serio->lock) __acquires(&ps2dev->serio->lock)
	{
	int attempt = 0;
	int error;

	lockdep_assert_held(&ps2dev->serio->lock);

	do {
	ps2dev->nak = 1;
	ps2dev->flags \|= PS2_FLAG_ACK;

	serio_continue_rx(ps2dev->serio);

	error = serio_write(ps2dev->serio, byte);
	if (error)
	dev_dbg(&ps2dev->serio->dev,
	"failed to write %#02x: %d\n", byte, error);
	else
	wait_event_timeout(ps2dev->wait,
	!(ps2dev->flags & PS2_FLAG_ACK),
	msecs_to_jiffies(timeout));

	serio_pause_rx(ps2dev->serio);
	} while (ps2dev->nak == PS2_RET_NAK && ++attempt < max_attempts);

	ps2dev->flags &= ~PS2_FLAG_ACK;

	if (!error) {
	switch (ps2dev->nak) {
	case 0:
	break;
	case PS2_RET_NAK:
	error = -EAGAIN;
	break;
	case PS2_RET_ERR:
	error = -EPROTO;
	break;
	default:
	error = -EIO;
	break;
	}
	}

	if (error \|\| attempt > 1)
	dev_dbg(&ps2dev->serio->dev,
	"%02x - %d (%x), attempt %d\n",
	byte, error, ps2dev->nak, attempt);

	return error;
	}

	/*
	* ps2_sendbyte() sends a byte to the device and waits for acknowledge.
	* It doesn't handle retransmission, the caller is expected to handle
	* it when needed.
	*
	* ps2_sendbyte() can only be called from a process context.
	*/

	int ps2_sendbyte(struct ps2dev *ps2dev, u8 byte, unsigned int timeout)
	{
	int retval;

	serio_pause_rx(ps2dev->serio);

	retval = ps2_do_sendbyte(ps2dev, byte, timeout, 1);
	dev_dbg(&ps2dev->serio->dev, "%02x - %x\n", byte, ps2dev->nak);

	serio_continue_rx(ps2dev->serio);

	return retval;
	}
	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, size_t maxbytes, unsigned 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.
	*/

	bool ps2_is_keyboard_id(u8 id_byte)
	{
	static const u8 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,
	unsigned int command, unsigned 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, u8 param, unsigned int command)
	{
	unsigned int timeout;
	unsigned int send = (command >> 12) & 0xf;
	unsigned int receive = (command >> 8) & 0xf;
	int rc;
	int i;
	u8 send_param[16];

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

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

	memcpy(send_param, param, send);

	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];

	/* Signal that we are sending the command byte */
	ps2dev->flags \|= PS2_FLAG_ACK_CMD;

	/*
	* Some devices (Synaptics) peform the reset before
	* ACKing the reset command, and so it can take a long
	* time before the ACK arrives.
	*/
	timeout = command == PS2_CMD_RESET_BAT ? 1000 : 200;

	rc = ps2_do_sendbyte(ps2dev, command & 0xff, timeout, 2);
	if (rc)
	goto out_reset_flags;

	/* Now we are sending command parameters, if any */
	ps2dev->flags &= ~PS2_FLAG_ACK_CMD;

	for (i = 0; i < send; i++) {
	rc = ps2_do_sendbyte(ps2dev, param[i], 200, 2);
	if (rc)
	goto out_reset_flags;
	}

	serio_continue_rx(ps2dev->serio);

	/*
	* 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];
	kmsan_unpoison_memory(param, receive);
	}

	if (ps2dev->cmdcnt &&
	(command != PS2_CMD_RESET_BAT \|\| ps2dev->cmdcnt != 1)) {
	rc = -EPROTO;
	goto out_reset_flags;
	}

	rc = 0;

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

	dev_dbg(&ps2dev->serio->dev,
	"%02x [%ph] - %x/%08lx [%ph]\n",
	command & 0xff, send, send_param,
	ps2dev->nak, ps2dev->flags,
	receive, param ?: send_param);

	/*
	* ps_command() handles resends itself, so do not leak -EAGAIN
	* to the callers.
	*/
	return rc != -EAGAIN ? rc : -EPROTO;
	}
	EXPORT_SYMBOL(__ps2_command);

	int ps2_command(struct ps2dev ps2dev, u8 param, unsigned 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_sliced_command() sends an extended PS/2 command to the mouse
	* using sliced syntax, understood by advanced devices, such as Logitech
	* or Synaptics touchpads. The command is encoded as:
	* 0xE6 0xE8 rr 0xE8 ss 0xE8 tt 0xE8 uu where (rr64)+(ss16)+(tt*4)+uu
	* is the command.
	*/

	int ps2_sliced_command(struct ps2dev *ps2dev, u8 command)
	{
	int i;
	int retval;

	ps2_begin_command(ps2dev);

	retval = __ps2_command(ps2dev, NULL, PS2_CMD_SETSCALE11);
	if (retval)
	goto out;

	for (i = 6; i >= 0; i -= 2) {
	u8 d = (command >> i) & 3;
	retval = __ps2_command(ps2dev, &d, PS2_CMD_SETRES);
	if (retval)
	break;
	}

	out:
	dev_dbg(&ps2dev->serio->dev, "%02x - %d\n", command, retval);
	ps2_end_command(ps2dev);
	return retval;
	}
	EXPORT_SYMBOL(ps2_sliced_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.
	*/

	bool ps2_handle_ack(struct ps2dev *ps2dev, u8 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;
	}
	fallthrough;

	/*
	* 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;
	}
	fallthrough;
	default:
	/*
	* Do not signal errors if we get unexpected reply while
	* waiting for an ACK to the initial (first) command byte:
	* the device might not be quiesced yet and continue
	* delivering data.
	* Note that we reset PS2_FLAG_WAITID flag, so the workaround
	* for mice not acknowledging the Get ID command only triggers
	* on the 1st byte; if device spews data we really want to see
	* a real ACK from it.
	*/
	dev_dbg(&ps2dev->serio->dev, "unexpected %#02x\n", data);
	ps2dev->flags &= ~PS2_FLAG_WAITID;
	return ps2dev->flags & PS2_FLAG_ACK_CMD;
	}

	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 true;
	}
	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.
	*/

	bool ps2_handle_response(struct ps2dev *ps2dev, u8 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 true;
	}
	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);