[PATCH v2 3/5] iio: light: tcs3472: use devm for resource management

[Aldo Conte <aldocontelk@gmail.com>]

Convert the driver to use device-managed resource allocation:
- Add tcs3472_powerdown_action() and register it with
  devm_add_action_or_reset() to ensure the device is powered down on
  cleanup. Before this patch, the chip remained powered if probe
  failed after enabling it.
- Replace iio_triggered_buffer_setup() with
  devm_iio_triggered_buffer_setup().
- Replace request_threaded_irq() with devm_request_threaded_irq().
- Replace iio_device_register() with devm_iio_device_register().
- Remove tcs3472_remove() as all cleanup is now handled by devm.

Rewrite the read-modify-write pattern in tcs3472_powerdown() and
tcs3472_resume() so the new register value is computed first, written
to the chip, and committed to data->enable only on success.

Use a local 'dev = &client->dev' in tcs3472_probe() to keep the devm
calls compact.

Suggested-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Aldo Conte <aldocontelk@gmail.com>
---
v2:
(Suggested by Andy)
- Rewrote read-modify-write in tcs3472_powerdown() and tcs3472_resume()
- Use local 'struct device *dev = &client->dev' in probe.
- Dropped "Compiled with W=1" and test details from the commit message.

 drivers/iio/light/tcs3472.c | 107 +++++++++++++++++-------------------
 1 file changed, 51 insertions(+), 56 deletions(-)

diff --git a/drivers/iio/light/tcs3472.c b/drivers/iio/light/tcs3472.c
index 4fd4fd74d0d6..7a6dc8360326 100644
--- a/drivers/iio/light/tcs3472.c
+++ b/drivers/iio/light/tcs3472.c
@@ -427,13 +427,38 @@ static const struct iio_info tcs3472_info = {
 	.attrs = &tcs3472_attribute_group,
 };
 
+static int tcs3472_powerdown(struct tcs3472_data *data)
+{
+	u8 enable_mask = TCS3472_ENABLE_AEN | TCS3472_ENABLE_PON;
+	u8 value;
+	int ret;
+
+	guard(mutex)(&data->lock);
+
+	value = data->enable & ~enable_mask;
+
+	ret = i2c_smbus_write_byte_data(data->client, TCS3472_ENABLE, value);
+	if (ret)
+		return ret;
+
+	data->enable = value;
+
+	return 0;
+}
+
+static void tcs3472_powerdown_action(void *data)
+{
+	tcs3472_powerdown(data);
+}
+
 static int tcs3472_probe(struct i2c_client *client)
 {
+	struct device *dev = &client->dev;
 	struct tcs3472_data *data;
 	struct iio_dev *indio_dev;
 	int ret;
 
-	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
 	if (indio_dev == NULL)
 		return -ENOMEM;
 
@@ -453,9 +478,9 @@ static int tcs3472_probe(struct i2c_client *client)
 		return ret;
 
 	if (ret == 0x44)
-		dev_info(&client->dev, "TCS34721/34725 found\n");
+		dev_info(dev, "TCS34721/34725 found\n");
 	else if (ret == 0x4d)
-		dev_info(&client->dev, "TCS34723/34727 found\n");
+		dev_info(dev, "TCS34723/34727 found\n");
 	else
 		return -ENODEV;
 
@@ -497,59 +522,26 @@ static int tcs3472_probe(struct i2c_client *client)
 	if (ret < 0)
 		return ret;
 
-	ret = iio_triggered_buffer_setup(indio_dev, NULL,
-		tcs3472_trigger_handler, NULL);
+	ret = devm_add_action_or_reset(dev, tcs3472_powerdown_action, data);
+	if (ret)
+		return ret;
+
+	ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
+					      tcs3472_trigger_handler, NULL);
 	if (ret < 0)
 		return ret;
 
 	if (client->irq) {
-		ret = request_threaded_irq(client->irq, NULL,
-					   tcs3472_event_handler,
-					   IRQF_TRIGGER_FALLING | IRQF_SHARED |
-					   IRQF_ONESHOT,
-					   client->name, indio_dev);
+		ret = devm_request_threaded_irq(dev, client->irq, NULL,
+						tcs3472_event_handler,
+						IRQF_TRIGGER_FALLING | IRQF_SHARED |
+						IRQF_ONESHOT,
+						client->name, indio_dev);
 		if (ret)
-			goto buffer_cleanup;
+			return ret;
 	}
 
-	ret = iio_device_register(indio_dev);
-	if (ret < 0)
-		goto free_irq;
-
-	return 0;
-
-free_irq:
-	if (client->irq)
-		free_irq(client->irq, indio_dev);
-buffer_cleanup:
-	iio_triggered_buffer_cleanup(indio_dev);
-	return ret;
-}
-
-static int tcs3472_powerdown(struct tcs3472_data *data)
-{
-	int ret;
-	u8 enable_mask = TCS3472_ENABLE_AEN | TCS3472_ENABLE_PON;
-
-	guard(mutex)(&data->lock);
-
-	ret = i2c_smbus_write_byte_data(data->client, TCS3472_ENABLE,
-		data->enable & ~enable_mask);
-	if (!ret)
-		data->enable &= ~enable_mask;
-
-	return ret;
-}
-
-static void tcs3472_remove(struct i2c_client *client)
-{
-	struct iio_dev *indio_dev = i2c_get_clientdata(client);
-
-	iio_device_unregister(indio_dev);
-	if (client->irq)
-		free_irq(client->irq, indio_dev);
-	iio_triggered_buffer_cleanup(indio_dev);
-	tcs3472_powerdown(iio_priv(indio_dev));
+	return devm_iio_device_register(dev, indio_dev);
 }
 
 static int tcs3472_suspend(struct device *dev)
@@ -563,17 +555,21 @@ static int tcs3472_resume(struct device *dev)
 {
 	struct tcs3472_data *data = iio_priv(i2c_get_clientdata(
 		to_i2c_client(dev)));
-	int ret;
 	u8 enable_mask = TCS3472_ENABLE_AEN | TCS3472_ENABLE_PON;
+	u8 value;
+	int ret;
 
 	guard(mutex)(&data->lock);
 
-	ret = i2c_smbus_write_byte_data(data->client, TCS3472_ENABLE,
-		data->enable | enable_mask);
-	if (!ret)
-		data->enable |= enable_mask;
+	value = data->enable | enable_mask;
 
-	return ret;
+	ret = i2c_smbus_write_byte_data(data->client, TCS3472_ENABLE, value);
+	if (ret)
+		return ret;
+
+	data->enable = value;
+
+	return 0;
 }
 
 static DEFINE_SIMPLE_DEV_PM_OPS(tcs3472_pm_ops, tcs3472_suspend,
@@ -591,7 +587,6 @@ static struct i2c_driver tcs3472_driver = {
 		.pm	= pm_sleep_ptr(&tcs3472_pm_ops),
 	},
 	.probe		= tcs3472_probe,
-	.remove		= tcs3472_remove,
 	.id_table	= tcs3472_id,
 };
 module_i2c_driver(tcs3472_driver);
-- 
2.54.0