[PATCH 5/5] Input: aw86927 - stop playback over suspend and on shutdown

[Qianhui Xu]

The chip keeps playing whatever was programmed into it when the system
suspends or reboots, so the actuator can still be buzzing after the screen
is off.  Stop playback, drain the work item and park the part in reset on
both paths.

Suspending also has to stop the memless effect timer from queueing new
work, otherwise a queued event re-arms playback after the stop.  Use a
suspended flag protected by the input event lock for that, and take the
input mutex around the whole sequence so that open()/close() cannot race
the drain.  The magnitude is read once per work run, so a concurrent
event cannot change it between the check and the register write.

Signed-off-by: Qianhui Xu <xiaqinghuan@xxxxxxxxxxxxxxxx>
---
 drivers/input/misc/aw86927.c | 75 +++++++++++++++++++++++++++++++++---
 1 file changed, 69 insertions(+), 6 deletions(-)

diff --git a/drivers/input/misc/aw86927.c b/drivers/input/misc/aw86927.c
index e8fd880ac..6d45c310a 100644
--- a/drivers/input/misc/aw86927.c
+++ b/drivers/input/misc/aw86927.c
@@ -15,6 +15,7 @@
 #include <linux/interrupt.h>
 #include <linux/input.h>
 #include <linux/module.h>
+#include <linux/pm.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
 #include <linux/types.h>
@@ -204,6 +205,7 @@ struct aw86927_data {
 	struct i2c_client *client;
 	struct regmap *regmap;
 	struct gpio_desc *reset_gpio;
+	bool suspended;
 	u16 level;
 };
 
@@ -366,22 +368,26 @@ static int aw86927_haptics_play(struct input_dev *dev, void *data, struct ff_eff
 	struct aw86927_data *haptics = input_get_drvdata(dev);
 	int level;
 
+	/* The chip is powered down; a queued event would only fail. */
+	if (haptics->suspended)
+		return 0;
+
 	level = effect->u.rumble.strong_magnitude;
 	if (!level)
 		level = effect->u.rumble.weak_magnitude;
 
 	/* If level does not change, don't restart playback */
-	if (haptics->level == level)
+	if (READ_ONCE(haptics->level) == level)
 		return 0;
 
-	haptics->level = level;
+	WRITE_ONCE(haptics->level, level);
 
 	schedule_work(&haptics->play_work);
 
 	return 0;
 }
 
-static int aw86927_play_sine(struct aw86927_data *haptics)
+static int aw86927_play_sine(struct aw86927_data *haptics, u16 level)
 {
 	int err;
 
@@ -426,7 +432,8 @@ static int aw86927_play_sine(struct aw86927_data *haptics)
 	if (err)
 		return err;
 
-	err = regmap_write(haptics->regmap, AW86927_PLAYCFG2_REG, haptics->level * 0x80 / 0xffff);
+	err = regmap_write(haptics->regmap, AW86927_PLAYCFG2_REG,
+			   level * 0x80 / 0xffff);
 	if (err)
 		return err;
 
@@ -445,6 +452,7 @@ static void aw86927_close(struct input_dev *input)
 	int err;
 
 	cancel_work_sync(&haptics->play_work);
+	WRITE_ONCE(haptics->level, 0);
 
 	err = aw86927_stop(haptics);
 	if (err)
@@ -456,10 +464,11 @@ static void aw86927_haptics_play_work(struct work_struct *work)
 	struct aw86927_data *haptics =
 		container_of(work, struct aw86927_data, play_work);
 	struct device *dev = &haptics->client->dev;
+	u16 level = READ_ONCE(haptics->level);
 	int err;
 
-	if (haptics->level)
-		err = aw86927_play_sine(haptics);
+	if (level)
+		err = aw86927_play_sine(haptics, level);
 	else
 		err = aw86927_stop(haptics);
 
@@ -900,6 +909,58 @@ static int aw86927_probe(struct i2c_client *client)
 	return 0;
 }
 
+static void aw86927_reset(void *data)
+{
+	struct aw86927_data *haptics = data;
+
+	gpiod_set_value_cansleep(haptics->reset_gpio, 1);
+}
+
+static void aw86927_shutdown(struct i2c_client *client)
+{
+	struct aw86927_data *haptics = i2c_get_clientdata(client);
+
+	disable_work_sync(&haptics->play_work);
+	aw86927_reset(haptics);
+}
+
+static int aw86927_suspend(struct device *dev)
+{
+	struct aw86927_data *haptics = dev_get_drvdata(dev);
+	int err;
+
+	guard(mutex)(&haptics->input_dev->mutex);
+
+	/* Block events from the memless effect timer before draining the work. */
+	scoped_guard(spinlock_irq, &haptics->input_dev->event_lock)
+		haptics->suspended = true;
+
+	cancel_work_sync(&haptics->play_work);
+	err = aw86927_stop(haptics);
+
+	scoped_guard(spinlock_irq, &haptics->input_dev->event_lock) {
+		if (err)
+			haptics->suspended = false;
+		else
+			WRITE_ONCE(haptics->level, 0);
+	}
+
+	return err;
+}
+
+static int aw86927_resume(struct device *dev)
+{
+	struct aw86927_data *haptics = dev_get_drvdata(dev);
+
+	guard(mutex)(&haptics->input_dev->mutex);
+	guard(spinlock_irq)(&haptics->input_dev->event_lock);
+	haptics->suspended = false;
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(aw86927_pm_ops, aw86927_suspend, aw86927_resume);
+
 static const struct of_device_id aw86927_of_id[] = {
 	{ .compatible = "awinic,aw86927" },
 	{ /* sentinel */ }
@@ -911,8 +972,10 @@ static struct i2c_driver aw86927_driver = {
 	.driver = {
 		.name = "aw86927-haptics",
 		.of_match_table = aw86927_of_id,
+		.pm = pm_sleep_ptr(&aw86927_pm_ops),
 	},
 	.probe = aw86927_probe,
+	.shutdown = aw86927_shutdown,
 };
 
 module_i2c_driver(aw86927_driver);
-- 
2.53.0