2 files changed, 65 insertions, 4 deletions

diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index eb3ff94af58c..bc56e52b945f 100644
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c
@@ -87,8 +87,22 @@ static bool i8042_bypass_aux_irq_test;
 
 #include "i8042.h"
 
+/*
+ * i8042_lock protects serialization between i8042_command and
+ * the interrupt handler.
+ */
 static DEFINE_SPINLOCK(i8042_lock);
 
+/*
+ * Writers to AUX and KBD ports as well as users issuing i8042_command
+ * directly should acquire i8042_mutex (by means of calling
+ * i8042_lock_chip() and i8042_unlock_ship() helpers) to ensure that
+ * they do not disturb each other (unfortunately in many i8042
+ * implementations write to one of the ports will immediately abort
+ * command that is being processed by another port).
+ */
+static DEFINE_MUTEX(i8042_mutex);
+
 struct i8042_port {
 	struct serio *serio;
 	int irq;
@@ -113,6 +127,18 @@ static struct platform_device *i8042_platform_device;
 
 static irqreturn_t i8042_interrupt(int irq, void *dev_id);
 
+void i8042_lock_chip(void)
+{
+	mutex_lock(&i8042_mutex);
+}
+EXPORT_SYMBOL(i8042_lock_chip);
+
+void i8042_unlock_chip(void)
+{
+	mutex_unlock(&i8042_mutex);
+}
+EXPORT_SYMBOL(i8042_unlock_chip);
+
 /*
  * The i8042_wait_read() and i8042_wait_write functions wait for the i8042 to
  * be ready for reading values from it / writing values to it.
@@ -1161,6 +1187,21 @@ static void __devexit i8042_unregister_ports(void)
 	}
 }
 
+/*
+ * Checks whether port belongs to i8042 controller.
+ */
+bool i8042_check_port_owner(const struct serio *port)
+{
+	int i;
+
+	for (i = 0; i < I8042_NUM_PORTS; i++)
+		if (i8042_ports[i].serio == port)
+			return true;
+
+	return false;
+}
+EXPORT_SYMBOL(i8042_check_port_owner);
+
 static void i8042_free_irqs(void)
 {
 	if (i8042_aux_irq_registered)
diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c
index 3a95b508bf27..769ba65a585a 100644
--- a/drivers/input/serio/libps2.c
+++ b/drivers/input/serio/libps2.c
@@ -17,6 +17,7 @@
 #include <linux/interrupt.h>
 #include <linux/input.h>
 #include <linux/serio.h>
+#include <linux/i8042.h>
 #include <linux/init.h>
 #include <linux/libps2.h>
 
@@ -54,6 +55,24 @@ int ps2_sendbyte(struct ps2dev *ps2dev, unsigned char byte, int timeout)
 }
 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.
@@ -66,7 +85,7 @@ void ps2_drain(struct ps2dev *ps2dev, int maxbytes, int timeout)
 		maxbytes = sizeof(ps2dev->cmdbuf);
 	}
 
-	mutex_lock(&ps2dev->cmd_mutex);
+	ps2_begin_command(ps2dev);
 
 	serio_pause_rx(ps2dev->serio);
 	ps2dev->flags = PS2_FLAG_CMD;
@@ -76,7 +95,8 @@ void ps2_drain(struct ps2dev *ps2dev, int maxbytes, int timeout)
 	wait_event_timeout(ps2dev->wait,
 			   !(ps2dev->flags & PS2_FLAG_CMD),
 			   msecs_to_jiffies(timeout));
-	mutex_unlock(&ps2dev->cmd_mutex);
+
+	ps2_end_command(ps2dev);
 }
 EXPORT_SYMBOL(ps2_drain);
 
@@ -237,9 +257,9 @@ int ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
 {
 	int rc;
 
-	mutex_lock(&ps2dev->cmd_mutex);
+	ps2_begin_command(ps2dev);
 	rc = __ps2_command(ps2dev, param, command);
-	mutex_unlock(&ps2dev->cmd_mutex);
+	ps2_end_command(ps2dev);
 
 	return rc;
 }