Introduce struct ad7816_chip_info to centralize static properties (e.g.
name, max channels) that differ between chip variants (AD7816/7/8) but
are constant for any specific type.

Store pointers to these instances in the of_device_id (.data) and
spi_device_id (driver_data) tables. Retrieve the pointer in probe()
using the firmware-independent device_get_match_data() and store it in
the ad7816_state struct.

Signed-off-by: Gabriel Shahrouzi <gshahrouzi@gmail.com>
---
 drivers/staging/iio/adc/ad7816.c | 55 +++++++++++++++++++++-----------
 1 file changed, 37 insertions(+), 18 deletions(-)

diff --git a/drivers/staging/iio/adc/ad7816.c b/drivers/staging/iio/adc/ad7816.c
index cad2e55aff3f9..39310ade770d0 100644
--- a/drivers/staging/iio/adc/ad7816.c
+++ b/drivers/staging/iio/adc/ad7816.c
@@ -41,8 +41,28 @@
  * struct ad7816_state - chip specific information
  */
 
+struct ad7816_chip_info {
+	const char *name;
+	u8 max_channels;
+};
+
+static const struct ad7816_chip_info ad7816_info_ad7816 = {
+	.name = "ad7816",
+	.max_channels = 0,
+};
+
+static const struct ad7816_chip_info ad7817_info_ad7817 = {
+	.name = "ad7817",
+	.max_channels = 3,
+};
+
+static const struct ad7816_chip_info ad7818_info_ad7818 = {
+	.name = "ad7818",
+	.max_channels = 1,
+};
+
 struct ad7816_state {
-	kernel_ulong_t id;
+	const struct ad7816_chip_info *chip_info;
 	struct spi_device *spi_dev;
 	struct gpio_desc *rdwr_pin;
 	struct gpio_desc *convert_pin;
@@ -52,12 +72,6 @@ struct ad7816_state {
 	u8  mode;
 };
 
-enum ad7816_type {
-	ID_AD7816,
-	ID_AD7817,
-	ID_AD7818,
-};
-
 /*
  * ad7816 data access by SPI
  */
@@ -84,7 +98,7 @@ static int ad7816_spi_read(struct ad7816_state *chip, u16 *data)
 		gpiod_set_value(chip->convert_pin, 1);
 	}
 
-	if (chip->id == ID_AD7816 || chip->id == ID_AD7817) {
+	if (chip->chip_info == &ad7816_info_ad7816 || chip->chip_info == &ad7817_info_ad7817) {
 		while (gpiod_get_value(chip->busy_pin))
 			cpu_relax();
 	}
@@ -353,6 +367,7 @@ static int ad7816_probe(struct spi_device *spi_dev)
 {
 	struct ad7816_state *chip;
 	struct iio_dev *indio_dev;
+	const struct ad7816_chip_info *info;
 	int i, ret;
 
 	indio_dev = devm_iio_device_alloc(&spi_dev->dev, sizeof(*chip));
@@ -362,11 +377,15 @@ static int ad7816_probe(struct spi_device *spi_dev)
 	/* this is only used for device removal purposes */
 	dev_set_drvdata(&spi_dev->dev, indio_dev);
 
+	info = device_get_match_data(&spi_dev->dev);
+	if (!info)
+		return -ENODEV;
+	chip->chip_info = info;
+
 	chip->spi_dev = spi_dev;
 	for (i = 0; i <= AD7816_CS_MAX; i++)
 		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);
 	if (IS_ERR(chip->rdwr_pin)) {
 		ret = PTR_ERR(chip->rdwr_pin);
@@ -382,7 +401,7 @@ static int ad7816_probe(struct spi_device *spi_dev)
 			ret);
 		return ret;
 	}
-	if (chip->id == ID_AD7816 || chip->id == ID_AD7817) {
+	if (chip->chip_info == &ad7816_info_ad7816 || chip->chip_info == &ad7817_info_ad7817) {
 		chip->busy_pin = devm_gpiod_get(&spi_dev->dev, "busy",
 						GPIOD_IN);
 		if (IS_ERR(chip->busy_pin)) {
@@ -393,7 +412,7 @@ static int ad7816_probe(struct spi_device *spi_dev)
 		}
 	}
 
-	indio_dev->name = spi_get_device_id(spi_dev)->name;
+	indio_dev->name = chip->chip_info->name;
 	indio_dev->info = &ad7816_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 
@@ -420,18 +439,18 @@ static int ad7816_probe(struct spi_device *spi_dev)
 }
 
 static const struct of_device_id ad7816_of_match[] = {
-	{ .compatible = "adi,ad7816", },
-	{ .compatible = "adi,ad7817", },
-	{ .compatible = "adi,ad7818", },
+	{ .compatible = "adi,ad7816", .data = &ad7816_info_ad7816 },
+	{ .compatible = "adi,ad7817", .data = &ad7817_info_ad7817 },
+	{ .compatible = "adi,ad7818", .data = &ad7818_info_ad7818 },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, ad7816_of_match);
 
 static const struct spi_device_id ad7816_id[] = {
-	{ "ad7816", ID_AD7816 },
-	{ "ad7817", ID_AD7817 },
-	{ "ad7818", ID_AD7818 },
-	{}
+	{ "ad7816", (kernel_ulong_t)&ad7816_info_ad7816 },
+	{ "ad7817", (kernel_ulong_t)&ad7817_info_ad7817 },
+	{ "ad7818", (kernel_ulong_t)&ad7818_info_ad7818 },
+	{ }
 };
 
 MODULE_DEVICE_TABLE(spi, ad7816_id);
-- 
2.43.0

On Sat, Apr 19, 2025 at 09:56:36AM -0400, Gabriel Shahrouzi wrote:
> @@ -84,7 +98,7 @@ static int ad7816_spi_read(struct ad7816_state *chip, u16 *data)
>  		gpiod_set_value(chip->convert_pin, 1);
>  	}
>  
> -	if (chip->id == ID_AD7816 || chip->id == ID_AD7817) {
> +	if (chip->chip_info == &ad7816_info_ad7816 || chip->chip_info == &ad7817_info_ad7817) {
>  		while (gpiod_get_value(chip->busy_pin))
>  			cpu_relax();
>  	}
> @@ -353,6 +367,7 @@ static int ad7816_probe(struct spi_device *spi_dev)
>  {
>  	struct ad7816_state *chip;
>  	struct iio_dev *indio_dev;
> +	const struct ad7816_chip_info *info;
>  	int i, ret;
>  
>  	indio_dev = devm_iio_device_alloc(&spi_dev->dev, sizeof(*chip));
> @@ -362,11 +377,15 @@ static int ad7816_probe(struct spi_device *spi_dev)
>  	/* this is only used for device removal purposes */
>  	dev_set_drvdata(&spi_dev->dev, indio_dev);
>  
> +	info = device_get_match_data(&spi_dev->dev);
> +	if (!info)
> +		return -ENODEV;
> +	chip->chip_info = info;
> +
>  	chip->spi_dev = spi_dev;
>  	for (i = 0; i <= AD7816_CS_MAX; i++)
>  		chip->oti_data[i] = 203;
>  
> -	chip->id = spi_get_device_id(spi_dev)->driver_data;

Delete the struct ad7816_state ->id member since you are no longer setting
or using it.

Btw, this patch didn't apply for me on linux-next.

regards,
dan carpenter