[PATCH v3] staging: iio: adc: ad7816: Use devm_gpiod_get_optional() for busy GPIO
From: Taha Narimani
Date: Fri Jul 10 2026 - 12:09:05 EST
The driver currently utilizes devm_gpiod_get() for the 'busy' line,
which makes the GPIO mandatory. However, the busy pin is hardware-optional
depending on the specific board configuration.
Switch to devm_gpiod_get_optional() to allow boards that do not have
this pin wired up to still probe the driver successfully. Clean up
the redundant busy_pin conditional checks as gpiod_get_value() safely
handles NULL descriptors. Additionally, use dev_err_probe() to prevent
bootlog spamming during deferred probing.
Fixes: 3e5971b2ddb6 ("base: original ad7816.c")
Signed-off-by: Taha Narimani <tahanarimani3443@xxxxxxxxx>
---
Changes in v3:
- Removed redundant conditional check around gpiod_get_value() as suggested by Andy Shevchenko and Dan Carpenter.
- Switched to dev_err_probe() to avoid deferred probe spamming.
- Introduced local struct device *dev pointer in probe and kept the GPIO request on a single line for better readability.
- Added the missing Fixes tag requested by Jonathan Cameron.
drivers/staging/iio/adc/ad7816.c | 67 +++++++++++++-------------------
1 file changed, 28 insertions(+), 39 deletions(-)
diff --git a/drivers/staging/iio/adc/ad7816.c b/drivers/staging/iio/adc/ad7816.c
index 988eee3..807cf57 100644
--- a/drivers/staging/iio/adc/ad7816.c
Changes in v3:
- Removed redundant conditional check around gpiod_get_value() as suggested by Andy Shevchenko and Dan Carpenter.
- Switched to dev_err_probe() to avoid deferred probe spamming.
- Introduced local struct device *dev pointer in probe and kept the GPIO request on a single line for better readability.
- Added the missing Fixes tag requested by Jonathan Cameron.
+++ b/drivers/staging/iio/adc/ad7816.c
@@ -22,20 +22,20 @@
/*
* AD7816 config masks
*/
-#define AD7816_FULL 0x1
-#define AD7816_PD 0x2
-#define AD7816_CS_MASK 0x7
-#define AD7816_CS_MAX 0x4
+#define AD7816_FULL 0x1
+#define AD7816_PD 0x2
+#define AD7816_CS_MASK 0x7
+#define AD7816_CS_MAX 0x4
/*
* AD7816 temperature masks
*/
-#define AD7816_VALUE_OFFSET 6
-#define AD7816_BOUND_VALUE_BASE 0x8
-#define AD7816_BOUND_VALUE_MIN -95
-#define AD7816_BOUND_VALUE_MAX 152
-#define AD7816_TEMP_FLOAT_OFFSET 2
-#define AD7816_TEMP_FLOAT_MASK 0x3
+#define AD7816_VALUE_OFFSET 6
+#define AD7816_BOUND_VALUE_BASE 0x8
+#define AD7816_BOUND_VALUE_MIN -95
+#define AD7816_BOUND_VALUE_MAX 152
+#define AD7816_TEMP_FLOAT_OFFSET 2
+#define AD7816_TEMP_FLOAT_MASK 0x3
/*
* struct ad7816_chip_info - chip specific information
@@ -48,7 +48,7 @@ struct ad7816_chip_info {
struct gpio_desc *convert_pin;
struct gpio_desc *busy_pin;
u8 oti_data[AD7816_CS_MAX + 1];
- u8 channel_id; /* 0 always be temperature */
+ u8 channel_id; /* 0 always be temperature */
u8 mode;
};
@@ -84,10 +84,8 @@ static int ad7816_spi_read(struct ad7816_chip_info *chip, u16 *data)
gpiod_set_value(chip->convert_pin, 1);
}
-if (chip->id == ID_AD7816 || chip->id == ID_AD7817) {
- while (gpiod_get_value(chip->busy_pin))
- cpu_relax();
- }
+ while (gpiod_get_value(chip->busy_pin))
+ cpu_relax();
gpiod_set_value(chip->rdwr_pin, 0);
gpiod_set_value(chip->rdwr_pin, 1);
@@ -254,8 +252,8 @@ static const struct attribute_group ad7816_attribute_group = {
* temperature bound events
*/
-#define IIO_EVENT_CODE_AD7816_OTI IIO_UNMOD_EVENT_CODE(IIO_TEMP, \
- 0, \
+#define IIO_EVENT_CODE_AD7816_OTI IIO_UNMOD_EVENT_CODE(IIO_TEMP, \
+ 0, \
IIO_EV_TYPE_THRESH, \
IIO_EV_DIR_FALLING)
@@ -351,11 +349,12 @@ static const struct iio_info ad7816_info = {
static int ad7816_probe(struct spi_device *spi_dev)
{
+ struct device *dev = &spi_dev->dev;
struct ad7816_chip_info *chip;
struct iio_dev *indio_dev;
int i, ret;
- indio_dev = devm_iio_device_alloc(&spi_dev->dev, sizeof(*chip));
+ indio_dev = devm_iio_device_alloc(dev, sizeof(*chip));
if (!indio_dev)
return -ENOMEM;
chip = iio_priv(indio_dev);
@@ -365,31 +364,22 @@ static int ad7816_probe(struct spi_device *spi_dev)
chip->oti_data[i] = 203;
chip->id = spi_get_device_id(spi_dev)->driver_data;
- chip->rdwr_pin = devm_gpiod_get(&spi_dev->dev, "rdwr", GPIOD_OUT_HIGH);
+ chip->rdwr_pin = devm_gpiod_get(dev, "rdwr", GPIOD_OUT_HIGH);
if (IS_ERR(chip->rdwr_pin)) {
ret = PTR_ERR(chip->rdwr_pin);
- dev_err(&spi_dev->dev, "Failed to request rdwr GPIO: %d\n",
- ret);
+ dev_err(dev, "Failed to request rdwr GPIO: %d\n", ret);
return ret;
}
- chip->convert_pin = devm_gpiod_get(&spi_dev->dev, "convert",
- GPIOD_OUT_HIGH);
+ chip->convert_pin = devm_gpiod_get(dev, "convert", GPIOD_OUT_HIGH);
if (IS_ERR(chip->convert_pin)) {
ret = PTR_ERR(chip->convert_pin);
- dev_err(&spi_dev->dev, "Failed to request convert GPIO: %d\n",
- ret);
+ dev_err(dev, "Failed to request convert GPIO: %d\n", ret);
return ret;
}
- if (chip->id == ID_AD7816 || chip->id == ID_AD7817) {
- chip->busy_pin = devm_gpiod_get(&spi_dev->dev, "busy",
- GPIOD_IN);
- if (IS_ERR(chip->busy_pin)) {
- ret = PTR_ERR(chip->busy_pin);
- dev_err(&spi_dev->dev, "Failed to request busy GPIO: %d\n",
- ret);
- return ret;
- }
- }
+
+ chip->busy_pin = devm_gpiod_get_optional(dev, "busy", GPIOD_IN);
+ if (IS_ERR(chip->busy_pin))
+ return dev_err_probe(dev, PTR_ERR(chip->busy_pin), "Failed to request busy GPIO\n");
indio_dev->name = spi_get_device_id(spi_dev)->name;
indio_dev->info = &ad7816_info;
@@ -397,7 +387,7 @@ static int ad7816_probe(struct spi_device *spi_dev)
if (spi_dev->irq) {
/* Only low trigger is supported in ad7816/7/8 */
- ret = devm_request_threaded_irq(&spi_dev->dev, spi_dev->irq,
+ ret = devm_request_threaded_irq(dev, spi_dev->irq,
NULL,
&ad7816_event_handler,
IRQF_TRIGGER_LOW | IRQF_ONESHOT,
@@ -407,11 +397,11 @@ static int ad7816_probe(struct spi_device *spi_dev)
return ret;
}
- ret = devm_iio_device_register(&spi_dev->dev, indio_dev);
+ ret = devm_iio_device_register(dev, indio_dev);
if (ret)
return ret;
- dev_info(&spi_dev->dev, "%s temperature sensor and ADC registered.\n",
+ dev_info(dev, "%s temperature sensor and ADC registered.\n",
indio_dev->name);
return 0;
@@ -431,7 +421,6 @@ static const struct spi_device_id ad7816_id[] = {
{ "ad7818", ID_AD7818 },
{ }
};
-
MODULE_DEVICE_TABLE(spi, ad7816_id);
static struct spi_driver ad7816_driver = {
--
2.53.0