[PATCH 0/4] regulator: rpi-panel-attiny: use new GPIO line value setter callbacks

[PATCH 0/4] regulator: rpi-panel-attiny: use new GPIO line value setter callbacks

[Bartosz Golaszewski]

struct gpio_chip now has callbacks for setting line values that return
an integer, allowing to indicate failures. We're in the process of
converting all GPIO drivers to using the new API. This series converts
the only GPIO controller under drivers/regulator/ and - while at it -
refactors the code a bit.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
Bartosz Golaszewski (4):
      regulator: rpi-panel-attiny: don't double-check GPIO range
      regulator: rpi-panel-attiny: use devres for mutex management
      regulator: rpi-panel-attiny: use lock guards for the state mutex
      regulator: rpi-panel-attiny: use new GPIO line value setter callbacks

 drivers/regulator/rpi-panel-attiny-regulator.c | 81 +++++++++-----------------
 1 file changed, 28 insertions(+), 53 deletions(-)
---
base-commit: 0af2f6be1b4281385b618cb86ad946eded089ac8
change-id: 20250331-gpiochip-set-rv-regulator-e12b909f5af7

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

[PATCH 1/4] regulator: rpi-panel-attiny: don't double-check GPIO range

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

GPIO core already checks GPIO ranges, there's no need to check it again
in the set() callback.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/regulator/rpi-panel-attiny-regulator.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/regulator/rpi-panel-attiny-regulator.c b/drivers/regulator/rpi-panel-attiny-regulator.c
index 6c3b6bfac961..f5ce50ced294 100644
--- a/drivers/regulator/rpi-panel-attiny-regulator.c
+++ b/drivers/regulator/rpi-panel-attiny-regulator.c
@@ -216,9 +216,6 @@ static void attiny_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
 	struct attiny_lcd *state = gpiochip_get_data(gc);
 	u8 last_val;
 
-	if (off >= NUM_GPIO)
-		return;
-
 	mutex_lock(&state->lock);
 
 	last_val = attiny_get_port_state(state, mappings[off].reg);

-- 
2.45.2

[PATCH 2/4] regulator: rpi-panel-attiny: use devres for mutex management

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Simplify the probe() code and remove the remove() callback by using
devres to manage the mutex resources.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/regulator/rpi-panel-attiny-regulator.c | 39 ++++++++------------------
 1 file changed, 12 insertions(+), 27 deletions(-)

diff --git a/drivers/regulator/rpi-panel-attiny-regulator.c b/drivers/regulator/rpi-panel-attiny-regulator.c
index f5ce50ced294..5ff348939560 100644
--- a/drivers/regulator/rpi-panel-attiny-regulator.c
+++ b/drivers/regulator/rpi-panel-attiny-regulator.c
@@ -12,6 +12,7 @@
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/regmap.h>
 #include <linux/regulator/driver.h>
 #include <linux/regulator/machine.h>
@@ -293,7 +294,10 @@ static int attiny_i2c_probe(struct i2c_client *i2c)
 	if (!state)
 		return -ENOMEM;
 
-	mutex_init(&state->lock);
+	ret = devm_mutex_init(&i2c->dev, &state->lock);
+	if (ret)
+		return ret;
+
 	i2c_set_clientdata(i2c, state);
 
 	regmap = devm_regmap_init_i2c(i2c, &attiny_regmap_config);
@@ -301,13 +305,13 @@ static int attiny_i2c_probe(struct i2c_client *i2c)
 		ret = PTR_ERR(regmap);
 		dev_err(&i2c->dev, "Failed to allocate register map: %d\n",
 			ret);
-		goto error;
+		return ret;
 	}
 
 	ret = attiny_i2c_read(i2c, REG_ID, &data);
 	if (ret < 0) {
 		dev_err(&i2c->dev, "Failed to read REG_ID reg: %d\n", ret);
-		goto error;
+		return ret;
 	}
 
 	switch (data) {
@@ -316,8 +320,7 @@ static int attiny_i2c_probe(struct i2c_client *i2c)
 		break;
 	default:
 		dev_err(&i2c->dev, "Unknown Atmel firmware revision: 0x%02x\n", data);
-		ret = -ENODEV;
-		goto error;
+		return -ENODEV;
 	}
 
 	regmap_write(regmap, REG_POWERON, 0);
@@ -333,8 +336,7 @@ static int attiny_i2c_probe(struct i2c_client *i2c)
 	rdev = devm_regulator_register(&i2c->dev, &attiny_regulator, &config);
 	if (IS_ERR(rdev)) {
 		dev_err(&i2c->dev, "Failed to register ATTINY regulator\n");
-		ret = PTR_ERR(rdev);
-		goto error;
+		return PTR_ERR(rdev);
 	}
 
 	props.type = BACKLIGHT_RAW;
@@ -345,10 +347,8 @@ static int attiny_i2c_probe(struct i2c_client *i2c)
 	bl = devm_backlight_device_register(&i2c->dev, dev_name(&i2c->dev),
 					    &i2c->dev, state, &attiny_bl,
 					    &props);
-	if (IS_ERR(bl)) {
-		ret = PTR_ERR(bl);
-		goto error;
-	}
+	if (IS_ERR(bl))
+		return PTR_ERR(bl);
 
 	bl->props.brightness = 0xff;
 
@@ -363,26 +363,12 @@ static int attiny_i2c_probe(struct i2c_client *i2c)
 	state->gc.can_sleep = true;
 
 	ret = devm_gpiochip_add_data(&i2c->dev, &state->gc, state);
-	if (ret) {
+	if (ret)
 		dev_err(&i2c->dev, "Failed to create gpiochip: %d\n", ret);
-		goto error;
-	}
-
-	return 0;
-
-error:
-	mutex_destroy(&state->lock);
 
 	return ret;
 }
 
-static void attiny_i2c_remove(struct i2c_client *client)
-{
-	struct attiny_lcd *state = i2c_get_clientdata(client);
-
-	mutex_destroy(&state->lock);
-}
-
 static const struct of_device_id attiny_dt_ids[] = {
 	{ .compatible = "raspberrypi,7inch-touchscreen-panel-regulator" },
 	{},
@@ -396,7 +382,6 @@ static struct i2c_driver attiny_regulator_driver = {
 		.of_match_table = attiny_dt_ids,
 	},
 	.probe = attiny_i2c_probe,
-	.remove	= attiny_i2c_remove,
 };
 
 module_i2c_driver(attiny_regulator_driver);

-- 
2.45.2

[PATCH 3/4] regulator: rpi-panel-attiny: use lock guards for the state mutex

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Use mutex lock guards from linux/cleanup.h to simplify the driver code.

Note that ret must be initialized in order to avoid a build warning as
scoped_guard() is implemented as a for loop.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/regulator/rpi-panel-attiny-regulator.c | 35 ++++++++++----------------
 1 file changed, 13 insertions(+), 22 deletions(-)

diff --git a/drivers/regulator/rpi-panel-attiny-regulator.c b/drivers/regulator/rpi-panel-attiny-regulator.c
index 5ff348939560..43a7c4737cb4 100644
--- a/drivers/regulator/rpi-panel-attiny-regulator.c
+++ b/drivers/regulator/rpi-panel-attiny-regulator.c
@@ -6,6 +6,7 @@
  */
 
 #include <linux/backlight.h>
+#include <linux/cleanup.h>
 #include <linux/err.h>
 #include <linux/gpio/driver.h>
 #include <linux/i2c.h>
@@ -94,7 +95,7 @@ static int attiny_lcd_power_enable(struct regulator_dev *rdev)
 {
 	struct attiny_lcd *state = rdev_get_drvdata(rdev);
 
-	mutex_lock(&state->lock);
+	guard(mutex)(&state->lock);
 
 	/* Ensure bridge, and tp stay in reset */
 	attiny_set_port_state(state, REG_PORTC, 0);
@@ -115,8 +116,6 @@ static int attiny_lcd_power_enable(struct regulator_dev *rdev)
 
 	msleep(80);
 
-	mutex_unlock(&state->lock);
-
 	return 0;
 }
 
@@ -124,7 +123,7 @@ static int attiny_lcd_power_disable(struct regulator_dev *rdev)
 {
 	struct attiny_lcd *state = rdev_get_drvdata(rdev);
 
-	mutex_lock(&state->lock);
+	guard(mutex)(&state->lock);
 
 	regmap_write(rdev->regmap, REG_PWM, 0);
 	usleep_range(5000, 10000);
@@ -136,8 +135,6 @@ static int attiny_lcd_power_disable(struct regulator_dev *rdev)
 	attiny_set_port_state(state, REG_PORTC, 0);
 	msleep(30);
 
-	mutex_unlock(&state->lock);
-
 	return 0;
 }
 
@@ -145,19 +142,17 @@ static int attiny_lcd_power_is_enabled(struct regulator_dev *rdev)
 {
 	struct attiny_lcd *state = rdev_get_drvdata(rdev);
 	unsigned int data;
-	int ret, i;
+	int ret = 0, i;
 
-	mutex_lock(&state->lock);
-
-	for (i = 0; i < 10; i++) {
-		ret = regmap_read(rdev->regmap, REG_PORTC, &data);
-		if (!ret)
-			break;
-		usleep_range(10000, 12000);
+	scoped_guard(mutex, &state->lock) {
+		for (i = 0; i < 10; i++) {
+			ret = regmap_read(rdev->regmap, REG_PORTC, &data);
+			if (!ret)
+				break;
+			usleep_range(10000, 12000);
+		}
 	}
 
-	mutex_unlock(&state->lock);
-
 	if (ret < 0)
 		return ret;
 
@@ -190,7 +185,7 @@ static int attiny_update_status(struct backlight_device *bl)
 	int brightness = backlight_get_brightness(bl);
 	int ret, i;
 
-	mutex_lock(&state->lock);
+	guard(mutex)(&state->lock);
 
 	for (i = 0; i < 10; i++) {
 		ret = regmap_write(regmap, REG_PWM, brightness);
@@ -198,8 +193,6 @@ static int attiny_update_status(struct backlight_device *bl)
 			break;
 	}
 
-	mutex_unlock(&state->lock);
-
 	return ret;
 }
 
@@ -217,7 +210,7 @@ static void attiny_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
 	struct attiny_lcd *state = gpiochip_get_data(gc);
 	u8 last_val;
 
-	mutex_lock(&state->lock);
+	guard(mutex)(&state->lock);
 
 	last_val = attiny_get_port_state(state, mappings[off].reg);
 	if (val)
@@ -239,8 +232,6 @@ static void attiny_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
 
 		msleep(100);
 	}
-
-	mutex_unlock(&state->lock);
 }
 
 static int attiny_i2c_read(struct i2c_client *client, u8 reg, unsigned int *buf)

-- 
2.45.2

[PATCH 4/4] regulator: rpi-panel-attiny: use new GPIO line value setter callbacks

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

struct gpio_chip now has callbacks for setting line values that return
an integer, allowing to indicate failures. Convert the driver to using
them.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/regulator/rpi-panel-attiny-regulator.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/regulator/rpi-panel-attiny-regulator.c b/drivers/regulator/rpi-panel-attiny-regulator.c
index 43a7c4737cb4..58dbf8bffa5d 100644
--- a/drivers/regulator/rpi-panel-attiny-regulator.c
+++ b/drivers/regulator/rpi-panel-attiny-regulator.c
@@ -205,7 +205,7 @@ static int attiny_gpio_get_direction(struct gpio_chip *gc, unsigned int off)
 	return GPIO_LINE_DIRECTION_OUT;
 }
 
-static void attiny_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
+static int attiny_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
 {
 	struct attiny_lcd *state = gpiochip_get_data(gc);
 	u8 last_val;
@@ -232,6 +232,8 @@ static void attiny_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
 
 		msleep(100);
 	}
+
+	return 0;
 }
 
 static int attiny_i2c_read(struct i2c_client *client, u8 reg, unsigned int *buf)
@@ -349,7 +351,7 @@ static int attiny_i2c_probe(struct i2c_client *i2c)
 	state->gc.base = -1;
 	state->gc.ngpio = NUM_GPIO;
 
-	state->gc.set = attiny_gpio_set;
+	state->gc.set_rv = attiny_gpio_set;
 	state->gc.get_direction = attiny_gpio_get_direction;
 	state->gc.can_sleep = true;
 

-- 
2.45.2

Re: [PATCH 0/4] regulator: rpi-panel-attiny: use new GPIO line value setter callbacks

[Mark Brown]

On Tue, 08 Apr 2025 09:36:27 +0200, Bartosz Golaszewski wrote:
> struct gpio_chip now has callbacks for setting line values that return
> an integer, allowing to indicate failures. We're in the process of
> converting all GPIO drivers to using the new API. This series converts
> the only GPIO controller under drivers/regulator/ and - while at it -
> refactors the code a bit.
> 
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git for-next

Thanks!

[1/4] regulator: rpi-panel-attiny: don't double-check GPIO range
      commit: 06bab1f101337ae9469a7d2c6ac4de5db64e8160
[2/4] regulator: rpi-panel-attiny: use devres for mutex management
      commit: 1326e295d6b4ffc9647bd4f073b787b4f79d6b6e
[3/4] regulator: rpi-panel-attiny: use lock guards for the state mutex
      commit: 50faedda12e46918a11194a30c2bedf2b983fae2
[4/4] regulator: rpi-panel-attiny: use new GPIO line value setter callbacks
      commit: 936df52c29b0d422665c5e84b0cffae61611411b

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark