Merge branch 'for-5.15/goodix' into for-linus

- power management improvement for Goodix driver

Author: Jiri Kosina

drivers/hid/i2c-hid/i2c-hid-of-goodix.c

@@ -26,49 +26,84 @@ struct i2c_hid_of_goodix {
 	struct i2chid_ops ops;
 
 	struct regulator *vdd;
+	struct notifier_block nb;
+	struct mutex regulator_mutex;
 	struct gpio_desc *reset_gpio;
 	const struct goodix_i2c_hid_timing_data *timings;
 };
 
-static int goodix_i2c_hid_power_up(struct i2chid_ops *ops)
+static void goodix_i2c_hid_deassert_reset(struct i2c_hid_of_goodix *ihid_goodix,
+					  bool regulator_just_turned_on)
 {
-	struct i2c_hid_of_goodix *ihid_goodix =
-		container_of(ops, struct i2c_hid_of_goodix, ops);
-	int ret;
-
-	ret = regulator_enable(ihid_goodix->vdd);
-	if (ret)
-		return ret;
-
-	if (ihid_goodix->timings->post_power_delay_ms)
+	if (regulator_just_turned_on && ihid_goodix->timings->post_power_delay_ms)
 		msleep(ihid_goodix->timings->post_power_delay_ms);
 
 	gpiod_set_value_cansleep(ihid_goodix->reset_gpio, 0);
 	if (ihid_goodix->timings->post_gpio_reset_delay_ms)
 		msleep(ihid_goodix->timings->post_gpio_reset_delay_ms);
+}
 
-	return 0;
+static int goodix_i2c_hid_power_up(struct i2chid_ops *ops)
+{
+	struct i2c_hid_of_goodix *ihid_goodix =
+		container_of(ops, struct i2c_hid_of_goodix, ops);
+
+	return regulator_enable(ihid_goodix->vdd);
 }
 
 static void goodix_i2c_hid_power_down(struct i2chid_ops *ops)
 {
 	struct i2c_hid_of_goodix *ihid_goodix =
 		container_of(ops, struct i2c_hid_of_goodix, ops);
 
-	gpiod_set_value_cansleep(ihid_goodix->reset_gpio, 1);
 	regulator_disable(ihid_goodix->vdd);
 }
 
+static int ihid_goodix_vdd_notify(struct notifier_block *nb,
+				    unsigned long event,
+				    void *ignored)
+{
+	struct i2c_hid_of_goodix *ihid_goodix =
+		container_of(nb, struct i2c_hid_of_goodix, nb);
+	int ret = NOTIFY_OK;
+
+	mutex_lock(&ihid_goodix->regulator_mutex);
+
+	switch (event) {
+	case REGULATOR_EVENT_PRE_DISABLE:
+		gpiod_set_value_cansleep(ihid_goodix->reset_gpio, 1);
+		break;
+
+	case REGULATOR_EVENT_ENABLE:
+		goodix_i2c_hid_deassert_reset(ihid_goodix, true);
+		break;
+
+	case REGULATOR_EVENT_ABORT_DISABLE:
+		goodix_i2c_hid_deassert_reset(ihid_goodix, false);
+		break;
+
+	default:
+		ret = NOTIFY_DONE;
+		break;
+	}
+
+	mutex_unlock(&ihid_goodix->regulator_mutex);
+
+	return ret;
+}
+
 static int i2c_hid_of_goodix_probe(struct i2c_client *client,
 				   const struct i2c_device_id *id)
 {
 	struct i2c_hid_of_goodix *ihid_goodix;
-
+	int ret;
 	ihid_goodix = devm_kzalloc(&client->dev, sizeof(*ihid_goodix),
 				   GFP_KERNEL);
 	if (!ihid_goodix)
 		return -ENOMEM;
 
+	mutex_init(&ihid_goodix->regulator_mutex);
+
 	ihid_goodix->ops.power_up = goodix_i2c_hid_power_up;
 	ihid_goodix->ops.power_down = goodix_i2c_hid_power_down;
 
@@ -84,6 +119,37 @@ static int i2c_hid_of_goodix_probe(struct i2c_client *client,
 
 	ihid_goodix->timings = device_get_match_data(&client->dev);
 
+	/*
+	 * We need to control the "reset" line in lockstep with the regulator
+	 * actually turning on an off instead of just when we make the request.
+	 * This matters if the regulator is shared with another consumer.
+	 * - If the regulator is off then we must assert reset. The reset
+	 *   line is active low and on some boards it could cause a current
+	 *   leak if left high.
+	 * - If the regulator is on then we don't want reset asserted for very
+	 *   long. Holding the controller in reset apparently draws extra
+	 *   power.
+	 */
+	mutex_lock(&ihid_goodix->regulator_mutex);
+	ihid_goodix->nb.notifier_call = ihid_goodix_vdd_notify;
+	ret = devm_regulator_register_notifier(ihid_goodix->vdd, &ihid_goodix->nb);
+	if (ret) {
+		mutex_unlock(&ihid_goodix->regulator_mutex);
+		return dev_err_probe(&client->dev, ret,
+			"regulator notifier request failed\n");
+	}
+
+	/*
+	 * If someone else is holding the regulator on (or the regulator is
+	 * an always-on one) we might never be told to deassert reset. Do it
+	 * now. Here we'll assume that someone else might have _just
+	 * barely_ turned the regulator on so we'll do the full
+	 * "post_power_delay" just in case.
+	 */
+	if (ihid_goodix->reset_gpio && regulator_is_enabled(ihid_goodix->vdd))
+		goodix_i2c_hid_deassert_reset(ihid_goodix, true);
+	mutex_unlock(&ihid_goodix->regulator_mutex);
+
 	return i2c_hid_core_probe(client, &ihid_goodix->ops, 0x0001);
 }