Input: libps2 - additional locking for i8042 ports

The serio ports on i8042 are not completely isolated; while we provide
enough locking to ensure proper serialization when accessing control
and data registers AUX and KBD ports can still have an effect on each
other on PS/2 protocol level. The most prominent effect is that
issuing a command for the device connected to one port may cause
abort of the command currently executing by the device connected to
another port.

Since i8042 nor serio subsystem are not aware of the details of the
PS/2 protocol (length of the commands and their replies and so on) the
locking should be done on libps2 level by adding special handling when
we see that we are dealing with serio port on i8042.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

2 files changed, 32 insertions, 0 deletions

diff --git a/include/linux/i8042.h b/include/linux/i8042.h
index 7907a72403e..60c3360ef6a 100644
--- a/include/linux/i8042.h
+++ b/include/linux/i8042.h
@@ -7,6 +7,7 @@
  * the Free Software Foundation.
  */
 
+#include <linux/types.h>
 
 /*
  * Standard commands.
@@ -30,6 +31,35 @@
 #define I8042_CMD_MUX_PFX	0x0090
 #define I8042_CMD_MUX_SEND	0x1090
 
+struct serio;
+
+#if defined(CONFIG_SERIO_I8042) || defined(CONFIG_SERIO_I8042_MODULE)
+
+void i8042_lock_chip(void);
+void i8042_unlock_chip(void);
 int i8042_command(unsigned char *param, int command);
+bool i8042_check_port_owner(const struct serio *);
+
+#else
+
+void i8042_lock_chip(void)
+{
+}
+
+void i8042_unlock_chip(void)
+{
+}
+
+int i8042_command(unsigned char *param, int command)
+{
+	return -ENOSYS;
+}
+
+bool i8042_check_port_owner(const struct serio *serio)
+{
+	return false;
+}
+
+#endif
 
 #endif
diff --git a/include/linux/libps2.h b/include/linux/libps2.h
index fcf5fbe6a50..79603a6c356 100644
--- a/include/linux/libps2.h
+++ b/include/linux/libps2.h
@@ -44,6 +44,8 @@ struct ps2dev {
 void ps2_init(struct ps2dev *ps2dev, struct serio *serio);
 int ps2_sendbyte(struct ps2dev *ps2dev, unsigned char byte, int timeout);
 void ps2_drain(struct ps2dev *ps2dev, int maxbytes, int timeout);
+void ps2_begin_command(struct ps2dev *ps2dev);
+void ps2_end_command(struct ps2dev *ps2dev);
 int __ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command);
 int ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command);
 int ps2_handle_ack(struct ps2dev *ps2dev, unsigned char data);