dm355evm_keys review updates

Address feedback from Dmitry:
 - input_sync() per event
 - maintain dev->keybit when remapping keys
 - since we handle remapping, keycodemax and keycodesize aren't used
 - on probe error, don't input_free_device() unless it registered

Also:
 - avoid reporting excess events
 - more bad-parameter paranoia in the remapping code

The excess event issue is basically that we don't have a way to
distinguish "button press" events from "button release" ones or
autorepeat events, so we should try being a bit smarter about
synthesizing them.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

drivers/input/keyboard/dm355evm_keys.c

@@ -28,6 +28,8 @@
  * using a work_struct.  The IRQ is active low, but we use it through
  * the GPIO controller so we can trigger on falling edges.
  *
+ * Note that physically there can only be one of these devices.
+ *
  * This driver was tested with firmware revision A4.
  */
 struct dm355evm_keys {
@@ -120,6 +122,8 @@ static void dm355evm_keys_work(struct work_struct *work)
 	 * Reading INPUT_LOW decrements the count.
 	 */
 	for (;;) {
+		static u16	last_event;
+
 		u16		event;
 		int		keycode;
 		int		i;
@@ -142,6 +146,23 @@ static void dm355evm_keys_work(struct work_struct *work)
 		if (event == 0xdead)
 			break;
 
+		/* Press and release a button:  two events, same code.
+		 * Press and hold (autorepeat), then release: N events
+		 * (N > 2), same code.  For RC5 buttons the toggle bits
+		 * distinguish (for example) "1-autorepeat" from "1 1";
+		 * but PCB buttons don't support that bit.
+		 *
+		 * So we must synthesize release events.  We do that by
+		 * mapping events to a press/release event pair; then
+		 * to avoid adding extra events, skip the second event
+		 * of each pair.
+		 */
+		if (event == last_event) {
+			last_event = 0;
+			continue;
+		}
+		last_event = event;
+
 		/* ignore the RC5 toggle bit */
 		event &= ~0x0800;
 
@@ -157,28 +178,38 @@ static void dm355evm_keys_work(struct work_struct *work)
 			"input event 0x%04x--> keycode %d\n",
 			event, keycode);
 
-		/* Report press + release ... we can't tell if
-		 * this is an autorepeat, and we need to guess
-		 * about the release.
-		 */
+		/* report press + release */
 		input_report_key(keys->input, keycode, 1);
+		input_sync(keys->input);
 		input_report_key(keys->input, keycode, 0);
+		input_sync(keys->input);
 	}
-	input_sync(keys->input);
 }
 
 static int dm355evm_setkeycode(struct input_dev *dev, int index, int keycode)
 {
-	if (index >= ARRAY_SIZE(dm355evm_keys))
+	u16		old_keycode;
+	unsigned	i;
+
+	if (((unsigned)index) >= ARRAY_SIZE(dm355evm_keys))
 		return -EINVAL;
 
+	old_keycode = dm355evm_keys[index].keycode;
 	dm355evm_keys[index].keycode = keycode;
+	set_bit(keycode, dev->keybit);
+
+	for (i = 0; i < ARRAY_SIZE(dm355evm_keys); i++) {
+		if (dm355evm_keys[index].keycode == old_keycode)
+			goto done;
+	}
+	clear_bit(old_keycode, dev->keybit);
+done:
 	return 0;
 }
 
 static int dm355evm_getkeycode(struct input_dev *dev, int index, int *keycode)
 {
-	if (index >= ARRAY_SIZE(dm355evm_keys))
+	if (((unsigned)index) >= ARRAY_SIZE(dm355evm_keys))
 		return -EINVAL;
 
 	return dm355evm_keys[index].keycode;
@@ -219,8 +250,6 @@ static int __devinit dm355evm_keys_probe(struct platform_device *pdev)
 	for (i = 0; i < ARRAY_SIZE(dm355evm_keys); i++)
 		set_bit(dm355evm_keys[i].keycode, input->keybit);
 
-	input->keycodemax = ARRAY_SIZE(dm355evm_keys);
-	input->keycodesize = sizeof(dm355evm_keys[0]);
 	input->keycode = dm355evm_keys;
 	input->setkeycode = dm355evm_setkeycode;
 	input->getkeycode = dm355evm_getkeycode;
@@ -237,7 +266,7 @@ static int __devinit dm355evm_keys_probe(struct platform_device *pdev)
 	/* register */
 	status = input_register_device(input);
 	if (status < 0)
-		goto fail1;
+		goto fail0;
 
 	/* start reporting events */
 	status = request_irq(keys->irq, dm355evm_keys_irq,