1 files changed, 437 insertions, 186 deletions

diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c
index 07a8363f3c5c..269df83a167d 100644
--- a/drivers/input/serio/libps2.c
+++ b/drivers/input/serio/libps2.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * PS/2 driver library
  *
@@ -5,80 +6,153 @@
  * 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/export.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/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");
+#define PS2_CMD_SETSCALE11	0x00e6
+#define PS2_CMD_SETRES		0x10e8
+#define PS2_CMD_EX_SETLEDS	0x20eb
+#define PS2_CMD_SETLEDS		0x10ed
+#define PS2_CMD_GETID		0x02f2
+#define PS2_CMD_SETREP		0x10f3 /* Set repeat rate/set report rate */
+#define PS2_CMD_RESET_BAT	0x02ff
+
+#define PS2_RET_BAT		0xaa
+#define PS2_RET_ID		0x00
+#define PS2_RET_ACK		0xfa
+#define PS2_RET_NAK		0xfe
+#define PS2_RET_ERR		0xfc
+
+#define PS2_FLAG_ACK		BIT(0)	/* Waiting for ACK/NAK */
+#define PS2_FLAG_CMD		BIT(1)	/* Waiting for a command to finish */
+#define PS2_FLAG_CMD1		BIT(2)	/* Waiting for the first byte of command response */
+#define PS2_FLAG_WAITID		BIT(3)	/* Command executing is GET ID */
+#define PS2_FLAG_NAK		BIT(4)	/* Last transmission was NAKed */
+#define PS2_FLAG_PASS_NOACK	BIT(5)	/* Pass non-ACK byte to receive handler */
+
+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;
 
-/*
- * 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.
+	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 wait for acknowledgement
+ * @ps2dev: a PS/2 device to send the data to
+ * @byte: data to be sent to the device
+ * @timeout: timeout for sending the data and receiving an acknowledge
+ *
+ * The function 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, unsigned char byte, int timeout)
+int ps2_sendbyte(struct ps2dev *ps2dev, u8 byte, unsigned int timeout)
 {
-	serio_pause_rx(ps2dev->serio);
-	ps2dev->nak = 1;
-	ps2dev->flags |= PS2_FLAG_ACK;
-	serio_continue_rx(ps2dev->serio);
+	int retval;
 
-	if (serio_write(ps2dev->serio, byte) == 0)
-		wait_event_timeout(ps2dev->wait,
-				   !(ps2dev->flags & PS2_FLAG_ACK),
-				   msecs_to_jiffies(timeout));
+	guard(serio_pause_rx)(ps2dev->serio);
 
-	serio_pause_rx(ps2dev->serio);
-	ps2dev->flags &= ~PS2_FLAG_ACK;
-	serio_continue_rx(ps2dev->serio);
+	retval = ps2_do_sendbyte(ps2dev, byte, timeout, 1);
+	dev_dbg(&ps2dev->serio->dev, "%02x - %x\n", byte, ps2dev->nak);
 
-	return -ps2dev->nak;
+	return retval;
 }
 EXPORT_SYMBOL(ps2_sendbyte);
 
+/**
+ * ps2_begin_command - mark beginning of execution of a complex command
+ * @ps2dev: a PS/2 device executing the command
+ *
+ * Serializes a complex/compound command. Once command is finished
+ * ps2_end_command() should be called.
+ */
 void ps2_begin_command(struct ps2dev *ps2dev)
 {
-	mutex_lock(&ps2dev->cmd_mutex);
+	struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
 
-	if (i8042_check_port_owner(ps2dev->serio))
-		i8042_lock_chip();
+	mutex_lock(m);
 }
 EXPORT_SYMBOL(ps2_begin_command);
 
+/**
+ * ps2_end_command - mark end of execution of a complex command
+ * @ps2dev: a PS/2 device executing the command
+ */
 void ps2_end_command(struct ps2dev *ps2dev)
 {
-	if (i8042_check_port_owner(ps2dev->serio))
-		i8042_unlock_chip();
+	struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
 
-	mutex_unlock(&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.
+/**
+ * ps2_drain - waits for device to transmit requested number of bytes
+ * and discards them
+ * @ps2dev: the PS/2 device that should be drained
+ * @maxbytes: maximum number of bytes to be drained
+ * @timeout: time to drain the device
  */
-
-void ps2_drain(struct ps2dev *ps2dev, int maxbytes, int timeout)
+void ps2_drain(struct ps2dev *ps2dev, size_t maxbytes, unsigned int timeout)
 {
 	if (maxbytes > sizeof(ps2dev->cmdbuf)) {
 		WARN_ON(1);
@@ -87,10 +161,10 @@ void ps2_drain(struct ps2dev *ps2dev, int maxbytes, int timeout)
 
 	ps2_begin_command(ps2dev);
 
-	serio_pause_rx(ps2dev->serio);
-	ps2dev->flags = PS2_FLAG_CMD;
-	ps2dev->cmdcnt = maxbytes;
-	serio_continue_rx(ps2dev->serio);
+	scoped_guard(serio_pause_rx, ps2dev->serio) {
+		ps2dev->flags = PS2_FLAG_CMD;
+		ps2dev->cmdcnt = maxbytes;
+	}
 
 	wait_event_timeout(ps2dev->wait,
 			   !(ps2dev->flags & PS2_FLAG_CMD),
@@ -100,14 +174,14 @@ void ps2_drain(struct ps2dev *ps2dev, int maxbytes, int timeout)
 }
 EXPORT_SYMBOL(ps2_drain);
 
-/*
- * ps2_is_keyboard_id() checks received ID byte against the list of
- * known keyboard IDs.
+/**
+ * ps2_is_keyboard_id - checks received ID byte against the list of
+ *   known keyboard IDs
+ * @id_byte: data byte that should be checked
  */
-
-int ps2_is_keyboard_id(char id_byte)
+bool ps2_is_keyboard_id(u8 id_byte)
 {
-	static const char keyboard_ids[] = {
+	static const u8 keyboard_ids[] = {
 		0xab,	/* Regular keyboards		*/
 		0xac,	/* NCD Sun keyboard		*/
 		0x2b,	/* Trust keyboard, translated	*/
@@ -125,100 +199,144 @@ EXPORT_SYMBOL(ps2_is_keyboard_id);
  * response and tries to reduce remaining timeout to speed up command
  * completion.
  */
-
-static int ps2_adjust_timeout(struct ps2dev *ps2dev, int command, int timeout)
+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_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);
+	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) {
+			scoped_guard(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);
+
+			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])) {
+			scoped_guard(serio_pause_rx, ps2dev->serio)
 				ps2dev->flags = ps2dev->cmdcnt = 0;
-				serio_continue_rx(ps2dev->serio);
-				timeout = 0;
-			}
-			break;
 
-		default:
-			break;
+			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 - send a command to PS/2 device
+ * @ps2dev: the PS/2 device that should execute the command
+ * @param: a buffer containing parameters to be sent along with the command,
+ *   or place where the results of the command execution will be deposited,
+ *   or both
+ * @command: command word that encodes the command itself, as well as number of
+ *   additional parameter bytes that should be sent to the device and expected
+ *   length of the command response
  *
- * ps2_command() can only be called from a process context
+ * Not serialized. Callers should use ps2_begin_command() and ps2_end_command()
+ * to ensure proper serialization for complex commands.
  */
-
-int __ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
+int __ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
 {
-	int timeout;
-	int send = (command >> 12) & 0xf;
-	int receive = (command >> 8) & 0xf;
-	int rc = -1;
+	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 -1;
+		return -EINVAL;
 	}
 
 	if (send && !param) {
 		WARN_ON(1);
-		return -1;
+		return -EINVAL;
 	}
 
+	memcpy(send_param, param, send);
+
+	/*
+	 * Not using guard notation because we need to break critical
+	 * section below while waiting for the response.
+	 */
 	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);
+
+	switch (command) {
+	case PS2_CMD_GETID:
+		/*
+		 * Some mice do not ACK the "get ID" command, prepare to
+		 * handle this.
+		 */
+		ps2dev->flags = PS2_FLAG_WAITID;
+		break;
+
+	case PS2_CMD_SETLEDS:
+	case PS2_CMD_EX_SETLEDS:
+	case PS2_CMD_SETREP:
+		ps2dev->flags = PS2_FLAG_PASS_NOACK;
+		break;
+
+	default:
+		ps2dev->flags = 0;
+		break;
+	}
+
+	if (receive) {
+		/* Indicate that we expect response to the command. */
+		ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
+		if (param)
+			for (i = 0; i < receive; i++)
+				ps2dev->cmdbuf[(receive - 1) - i] = param[i];
+	}
 
 	/*
-	 * Some devices (Synaptics) peform the reset before
+	 * Some devices (Synaptics) perform 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;
+	timeout = command == PS2_CMD_RESET_BAT ? 1000 : 200;
+
+	rc = ps2_do_sendbyte(ps2dev, command & 0xff, timeout, 2);
+	if (rc)
+		goto out_reset_flags;
+
+	/* Send command parameters, if any. */
+	for (i = 0; i < send; i++) {
+		rc = ps2_do_sendbyte(ps2dev, param[i], 200, 2);
+		if (rc)
+			goto out_reset_flags;
+	}
 
-	for (i = 0; i < send; i++)
-		if (ps2_sendbyte(ps2dev, param[i], 200))
-			goto out;
+	serio_continue_rx(ps2dev->serio);
 
 	/*
 	 * The reset command takes a long time to execute.
@@ -235,25 +353,55 @@ int __ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
 				   !(ps2dev->flags & PS2_FLAG_CMD), timeout);
 	}
 
-	if (param)
+	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))
-		goto out;
+	if (ps2dev->cmdcnt &&
+	    (command != PS2_CMD_RESET_BAT || ps2dev->cmdcnt != 1)) {
+		rc = -EPROTO;
+		goto out_reset_flags;
+	}
 
 	rc = 0;
 
- out:
-	serio_pause_rx(ps2dev->serio);
+ out_reset_flags:
 	ps2dev->flags = 0;
 	serio_continue_rx(ps2dev->serio);
 
-	return rc;
+	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, unsigned char *param, int command)
+/**
+ * ps2_command - send a command to PS/2 device
+ * @ps2dev: the PS/2 device that should execute the command
+ * @param: a buffer containing parameters to be sent along with the command,
+ *   or place where the results of the command execution will be deposited,
+ *   or both
+ * @command: command word that encodes the command itself, as well as number of
+ *   additional parameter bytes that should be sent to the device and expected
+ *   length of the command response
+ *
+ * Note: ps2_command() serializes the command execution so that only one
+ * command can be executed at a time for either individual port or the entire
+ * 8042 controller.
+ */
+int ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
 {
 	int rc;
 
@@ -265,111 +413,214 @@ int ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
 }
 EXPORT_SYMBOL(ps2_command);
 
-/*
- * ps2_init() initializes ps2dev structure
+/**
+ * ps2_sliced_command - sends an extended PS/2 command to a mouse
+ * @ps2dev: the PS/2 device that should execute the command
+ * @command: command byte
+ *
+ * The command is sent 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;
 
-void ps2_init(struct ps2dev *ps2dev, struct serio *serio)
+	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
+ * @ps2dev: structure to be initialized
+ * @serio: serio port associated with the PS/2 device
+ * @pre_receive_handler: validation handler to check basic communication state
+ * @receive_handler: main protocol handler
+ *
+ * Prepares ps2dev structure for use in drivers for PS/2 devices.
+ */
+void ps2_init(struct ps2dev *ps2dev, struct serio *serio,
+	      ps2_pre_receive_handler_t pre_receive_handler,
+	      ps2_receive_handler_t receive_handler)
 {
+	ps2dev->pre_receive_handler = pre_receive_handler;
+	ps2dev->receive_handler = receive_handler;
+
 	mutex_init(&ps2dev->cmd_mutex);
 	lockdep_set_subclass(&ps2dev->cmd_mutex, serio->depth);
 	init_waitqueue_head(&ps2dev->wait);
 	ps2dev->serio = serio;
+	serio_set_drvdata(serio, ps2dev);
 }
 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.
+ * ps2_handle_response() stores device's response to a command and notifies
+ * the process waiting for completion of the command. Note that there is a
+ * distinction between waiting for the first byte of the response, and
+ * waiting for subsequent bytes. It is done so that callers could shorten
+ * timeouts once first byte of response is received.
  */
+static void ps2_handle_response(struct ps2dev *ps2dev, u8 data)
+{
+	if (ps2dev->cmdcnt)
+		ps2dev->cmdbuf[--ps2dev->cmdcnt] = data;
 
-int ps2_handle_ack(struct ps2dev *ps2dev, unsigned char 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);
+	}
+}
+
+/*
+ * ps2_handle_ack() processes ACK/NAK of a command from a PS/2 device,
+ * possibly applying workarounds for mice not acknowledging the "get ID"
+ * command.
+ */
+static void ps2_handle_ack(struct ps2dev *ps2dev, u8 data)
 {
 	switch (data) {
-		case PS2_RET_ACK:
-			ps2dev->nak = 0;
+	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;
 
-		case PS2_RET_NAK:
-			ps2dev->flags |= PS2_FLAG_NAK;
-			ps2dev->nak = PS2_RET_NAK;
+	/*
+	 * 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;
-
-		case PS2_RET_ERR:
-			if (ps2dev->flags & PS2_FLAG_NAK) {
-				ps2dev->flags &= ~PS2_FLAG_NAK;
-				ps2dev->nak = PS2_RET_ERR;
-				break;
-			}
-
+		}
+		fallthrough;
+	default:
 		/*
-		 * Workaround for mice which don't ACK the Get ID command.
-		 * These are valid mouse IDs that we recognize.
+		 * 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. For certain commands (such as set leds and
+		 * set repeat rate) that can be used during normal device
+		 * operation, we even pass this data byte to the normal receive
+		 * handler.
+		 * 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.
 		 */
-		case 0x00:
-		case 0x03:
-		case 0x04:
-			if (ps2dev->flags & PS2_FLAG_WAITID) {
-				ps2dev->nak = 0;
-				break;
-			}
-			/* Fall through */
-		default:
-			return 0;
+		dev_dbg(&ps2dev->serio->dev, "unexpected %#02x\n", data);
+		if (ps2dev->flags & PS2_FLAG_PASS_NOACK)
+			ps2dev->receive_handler(ps2dev, data);
+		ps2dev->flags &= ~(PS2_FLAG_WAITID | PS2_FLAG_PASS_NOACK);
+		return;
 	}
 
-
-	if (!ps2dev->nak) {
+	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)
+	if (!ps2dev->nak && data != PS2_RET_ACK)
 		ps2_handle_response(ps2dev, data);
-
-	return 1;
+	else
+		wake_up(&ps2dev->wait);
 }
-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.
+ * Clears state of PS/2 device after communication error by resetting majority
+ * of flags and waking up waiters, if any.
  */
-
-int ps2_handle_response(struct ps2dev *ps2dev, unsigned char data)
+static void ps2_cleanup(struct ps2dev *ps2dev)
 {
-	if (ps2dev->cmdcnt)
-		ps2dev->cmdbuf[--ps2dev->cmdcnt] = data;
+	unsigned long old_flags = ps2dev->flags;
 
-	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);
+	/* reset all flags except last nak */
+	ps2dev->flags &= PS2_FLAG_NAK;
 
-void ps2_cmd_aborted(struct ps2dev *ps2dev)
-{
-	if (ps2dev->flags & PS2_FLAG_ACK)
+	if (old_flags & PS2_FLAG_ACK)
 		ps2dev->nak = 1;
 
-	if (ps2dev->flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
+	if (old_flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
 		wake_up(&ps2dev->wait);
+}
 
-	/* reset all flags except last nack */
-	ps2dev->flags &= PS2_FLAG_NAK;
+/**
+ * ps2_interrupt - common interrupt handler for PS/2 devices
+ * @serio: serio port for the device
+ * @data: a data byte received from the device
+ * @flags: flags such as %SERIO_PARITY or %SERIO_TIMEOUT indicating state of
+ *   the data transfer
+ *
+ * ps2_interrupt() invokes pre-receive handler, optionally handles command
+ * acknowledgement and response from the device, and finally passes the data
+ * to the main protocol handler for future processing.
+ */
+irqreturn_t ps2_interrupt(struct serio *serio, u8 data, unsigned int flags) {
+	struct ps2dev *ps2dev = serio_get_drvdata(serio);
+	enum ps2_disposition rc;
+
+	rc = ps2dev->pre_receive_handler(ps2dev, data, flags);
+	switch (rc) {
+	case PS2_ERROR:
+		ps2_cleanup(ps2dev);
+		break;
+
+	case PS2_IGNORE:
+		break;
+
+	case PS2_PROCESS:
+		if (ps2dev->flags & PS2_FLAG_ACK)
+			ps2_handle_ack(ps2dev, data);
+		else if (ps2dev->flags & PS2_FLAG_CMD)
+			ps2_handle_response(ps2dev, data);
+		else
+			ps2dev->receive_handler(ps2dev, data);
+		break;
+	}
+
+	return IRQ_HANDLED;
 }
-EXPORT_SYMBOL(ps2_cmd_aborted);
+EXPORT_SYMBOL(ps2_interrupt);
+
+MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
+MODULE_DESCRIPTION("PS/2 driver library");
+MODULE_LICENSE("GPL");