Input: i8042 - don't use negation to mark AUX data

Currently i8042_command() negates data coming from the AUX port
of keyboard controller; this is not a very reliable indicator.
Change i8042_command() to fail if response to I8042_CMD_AUX_LOOP
is not coming from AUX channel and get rid of negation.

Based on patch by Vojtech Pavlik.
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/serio/i8042.c

@@ -191,41 +191,45 @@ static int i8042_flush(void)
 static int i8042_command(unsigned char *param, int command)
 {
 	unsigned long flags;
-	int retval = 0, i = 0;
+	int i, retval, auxerr = 0;
 
 	if (i8042_noloop && command == I8042_CMD_AUX_LOOP)
 		return -1;
 
 	spin_lock_irqsave(&i8042_lock, flags);
 
-	retval = i8042_wait_write();
-	if (!retval) {
+	if ((retval = i8042_wait_write()))
+		goto out;
+
 	dbg("%02x -> i8042 (command)", command & 0xff);
 	i8042_write_command(command & 0xff);
-	}
 
-	if (!retval)
 	for (i = 0; i < ((command >> 12) & 0xf); i++) {
-			if ((retval = i8042_wait_write())) break;
+		if ((retval = i8042_wait_write()))
+			goto out;
 		dbg("%02x -> i8042 (parameter)", param[i]);
 		i8042_write_data(param[i]);
 	}
 
-	if (!retval)
 	for (i = 0; i < ((command >> 8) & 0xf); i++) {
-			if ((retval = i8042_wait_read())) break;
-			if (i8042_read_status() & I8042_STR_AUXDATA)
-				param[i] = ~i8042_read_data();
-			else
+		if ((retval = i8042_wait_read()))
+			goto out;
+
+		if (command == I8042_CMD_AUX_LOOP &&
+		    !(i8042_read_status() & I8042_STR_AUXDATA)) {
+			retval = auxerr = -1;
+			goto out;
+		}
+
 		param[i] = i8042_read_data();
 		dbg("%02x <- i8042 (return)", param[i]);
 	}
 
-	spin_unlock_irqrestore(&i8042_lock, flags);
-
 	if (retval)
-		dbg("     -- i8042 (timeout)");
+		dbg("     -- i8042 (%s)", auxerr ? "auxerr" : "timeout");
 
+ out:
+	spin_unlock_irqrestore(&i8042_lock, flags);
 	return retval;
 }
 
@@ -507,17 +511,17 @@ static int i8042_set_mux_mode(unsigned int mode, unsigned char *mux_version)
  */
 
 	param = 0xf0;
-	if (i8042_command(&param, I8042_CMD_AUX_LOOP) || param != 0x0f)
+	if (i8042_command(&param, I8042_CMD_AUX_LOOP) || param != 0xf0)
 		return -1;
 	param = mode ? 0x56 : 0xf6;
-	if (i8042_command(&param, I8042_CMD_AUX_LOOP) || param != (mode ? 0xa9 : 0x09))
+	if (i8042_command(&param, I8042_CMD_AUX_LOOP) || param != (mode ? 0x56 : 0xf6))
 		return -1;
 	param = mode ? 0xa4 : 0xa5;
-	if (i8042_command(&param, I8042_CMD_AUX_LOOP) || param == (mode ? 0x5b : 0x5a))
+	if (i8042_command(&param, I8042_CMD_AUX_LOOP) || param == (mode ? 0xa4 : 0xa5))
 		return -1;
 
 	if (mux_version)
-		*mux_version = ~param;
+		*mux_version = param;
 
 	return 0;
 }
@@ -619,7 +623,7 @@ static int __init i8042_check_aux(void)
  */
 
 	param = 0x5a;
-	if (i8042_command(&param, I8042_CMD_AUX_LOOP) || param != 0xa5) {
+	if (i8042_command(&param, I8042_CMD_AUX_LOOP) || param != 0x5a) {
 
 /*
  * External connection test - filters out AT-soldered PS/2 i8042's