[PATCH v5 3/5] staging: iio: adc: ad7816: Introduce chip_info and use pointer matching

Gabriel Shahrouzi
2025-04-20T01:49:15Z

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