HID: google: whiskers: more robust tablet mode detection

The USB interface may get detected before the platform/EC one, so let's
note the state of the base (if we receive event) and use it to correctly
initialize the tablet mode switch state.

Also let's start the HID interface immediately when probing, this will
ensure that we correctly process "base folded" events that may be sent
as we initialize the base. Note that this requires us to add a remove()
function where we stop and close the hardware and switch the LED
registration away from devm interface as we need to make sure that we
destroy the LED instance before we stop the hardware.

Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-google-hammer.c

@@ -35,6 +35,7 @@ struct cbas_ec {
 	struct device *dev;	/* The platform device (EC) */
 	struct input_dev *input;
 	bool base_present;
+	bool base_folded;
 	struct notifier_block notifier;
 };
 
@@ -208,7 +209,14 @@ static int __cbas_ec_probe(struct platform_device *pdev)
 		return error;
 	}
 
-	input_report_switch(input, SW_TABLET_MODE, !cbas_ec.base_present);
+	if (!cbas_ec.base_present)
+		cbas_ec.base_folded = false;
+
+	dev_dbg(&pdev->dev, "%s: base: %d, folded: %d\n", __func__,
+		cbas_ec.base_present, cbas_ec.base_folded);
+
+	input_report_switch(input, SW_TABLET_MODE,
+			    !cbas_ec.base_present || cbas_ec.base_folded);
 
 	cbas_ec_set_input(input);
 
@@ -322,10 +330,9 @@ static int hammer_kbd_brightness_set_blocking(struct led_classdev *cdev,
 static int hammer_register_leds(struct hid_device *hdev)
 {
 	struct hammer_kbd_leds *kbd_backlight;
+	int error;
 
-	kbd_backlight = devm_kzalloc(&hdev->dev,
-				     sizeof(*kbd_backlight),
-				     GFP_KERNEL);
+	kbd_backlight = kzalloc(sizeof(*kbd_backlight), GFP_KERNEL);
 	if (!kbd_backlight)
 		return -ENOMEM;
 
@@ -339,7 +346,26 @@ static int hammer_register_leds(struct hid_device *hdev)
 	/* Set backlight to 0% initially. */
 	hammer_kbd_brightness_set_blocking(&kbd_backlight->cdev, 0);
 
-	return devm_led_classdev_register(&hdev->dev, &kbd_backlight->cdev);
+	error = led_classdev_register(&hdev->dev, &kbd_backlight->cdev);
+	if (error)
+		goto err_free_mem;
+
+	hid_set_drvdata(hdev, kbd_backlight);
+	return 0;
+
+err_free_mem:
+	kfree(kbd_backlight);
+	return error;
+}
+
+static void hammer_unregister_leds(struct hid_device *hdev)
+{
+	struct hammer_kbd_leds *kbd_backlight = hid_get_drvdata(hdev);
+
+	if (kbd_backlight) {
+		led_classdev_unregister(&kbd_backlight->cdev);
+		kfree(kbd_backlight);
+	}
 }
 
 #define HID_UP_GOOGLEVENDOR	0xffd10000
@@ -376,8 +402,9 @@ static int hammer_event(struct hid_device *hid, struct hid_field *field,
 	    usage->hid == WHISKERS_KBD_FOLDED) {
 		spin_lock_irqsave(&cbas_ec_lock, flags);
 
+		cbas_ec.base_folded = value;
 		hid_dbg(hid, "%s: base: %d, folded: %d\n", __func__,
-			cbas_ec.base_present, value);
+			cbas_ec.base_present, cbas_ec.base_folded);
 
 		/*
 		 * We should not get event if base is detached, but in case
@@ -436,23 +463,27 @@ static int hammer_probe(struct hid_device *hdev,
 {
 	int error;
 
+	error = hid_parse(hdev);
+	if (error)
+		return error;
+
+	error = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (error)
+		return error;
+
 	/*
 	 * We always want to poll for, and handle tablet mode events from
 	 * Whiskers, even when nobody has opened the input device. This also
 	 * prevents the hid core from dropping early tablet mode events from
 	 * the device.
 	 */
 	if (hdev->product == USB_DEVICE_ID_GOOGLE_WHISKERS &&
-			hammer_is_keyboard_interface(hdev))
+	    hammer_is_keyboard_interface(hdev)) {
 		hdev->quirks |= HID_QUIRK_ALWAYS_POLL;
-
-	error = hid_parse(hdev);
-	if (error)
-		return error;
-
-	error = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
-	if (error)
-		return error;
+		error = hid_hw_open(hdev);
+		if (error)
+			return error;
+	}
 
 	if (hammer_has_backlight_control(hdev)) {
 		error = hammer_register_leds(hdev);
@@ -465,6 +496,15 @@ static int hammer_probe(struct hid_device *hdev,
 	return 0;
 }
 
+static void hammer_remove(struct hid_device *hdev)
+{
+	if (hdev->product == USB_DEVICE_ID_GOOGLE_WHISKERS &&
+			hammer_is_keyboard_interface(hdev))
+		hid_hw_close(hdev);
+
+	hammer_unregister_leds(hdev);
+	hid_hw_stop(hdev);
+}
 
 static const struct hid_device_id hammer_devices[] = {
 	{ HID_DEVICE(BUS_USB, HID_GROUP_GENERIC,
@@ -483,6 +523,7 @@ static struct hid_driver hammer_driver = {
 	.name = "hammer",
 	.id_table = hammer_devices,
 	.probe = hammer_probe,
+	.remove = hammer_remove,
 	.input_mapping = hammer_input_mapping,
 	.event = hammer_event,
 };