iio: dac: ad5791: Add reset, clr and ldac gpios

The ad7591 has reset, clr and ldac gpios. For the DAC to output data
continuously written to the data register the state of these gpios needs
to be set by the driver.

Add these gpios to the driver making them optional in case they are fixed
on the pcb.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Axel Haslam <ahaslam@baylibre.com>
Link: https://patch.msgid.link/20241031071746.848694-5-ahaslam@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/dac/ad5791.c b/drivers/iio/dac/ad5791.c
index f6b9a40..c5d4d75 100644 (file)
--- a/drivers/iio/dac/ad5791.c
+++ b/drivers/iio/dac/ad5791.c
@@ -9,6 +9,7 @@
 #include <linux/interrupt.h>
 #include <linux/fs.h>
 #include <linux/device.h>
+#include <linux/delay.h>
 #include <linux/kernel.h>
 #include <linux/spi/spi.h>
 #include <linux/slab.h>
@@ -76,6 +77,9 @@ struct ad5791_chip_info {
  * @spi:                       spi_device
  * @reg_vdd:           positive supply regulator
  * @reg_vss:           negative supply regulator
+ * @gpio_reset:                reset gpio
+ * @gpio_clear:                clear gpio
+ * @gpio_ldac:         load dac gpio
  * @chip_info:         chip model specific constants
  * @vref_mv:           actual reference voltage used
  * @vref_neg_mv:       voltage of the negative supply
@@ -88,6 +92,9 @@ struct ad5791_state {
        struct spi_device               *spi;
        struct regulator                *reg_vdd;
        struct regulator                *reg_vss;
+       struct gpio_desc                *gpio_reset;
+       struct gpio_desc                *gpio_clear;
+       struct gpio_desc                *gpio_ldac;
        const struct ad5791_chip_info   *chip_info;
        unsigned short                  vref_mv;
        unsigned int                    vref_neg_mv;
@@ -337,6 +344,22 @@ static int ad5791_probe(struct spi_device *spi)
        if (!indio_dev)
                return -ENOMEM;
        st = iio_priv(indio_dev);
+
+       st->gpio_reset = devm_gpiod_get_optional(&spi->dev, "reset",
+                                                GPIOD_OUT_HIGH);
+       if (IS_ERR(st->gpio_reset))
+               return PTR_ERR(st->gpio_reset);
+
+       st->gpio_clear = devm_gpiod_get_optional(&spi->dev, "clear",
+                                                GPIOD_OUT_LOW);
+       if (IS_ERR(st->gpio_clear))
+               return PTR_ERR(st->gpio_clear);
+
+       st->gpio_ldac = devm_gpiod_get_optional(&spi->dev, "ldac",
+                                               GPIOD_OUT_HIGH);
+       if (IS_ERR(st->gpio_ldac))
+               return PTR_ERR(st->gpio_ldac);
+
        st->reg_vdd = devm_regulator_get(&spi->dev, "vdd");
        if (!IS_ERR(st->reg_vdd)) {
                ret = regulator_enable(st->reg_vdd);
@@ -382,9 +405,14 @@ static int ad5791_probe(struct spi_device *spi)
                dev_warn(&spi->dev, "reference voltage unspecified\n");
        }
 
-       ret = ad5791_spi_write(st, AD5791_ADDR_SW_CTRL, AD5791_SWCTRL_RESET);
-       if (ret)
-               goto error_disable_reg_neg;
+       if (st->gpio_reset) {
+               fsleep(20);
+               gpiod_set_value_cansleep(st->gpio_reset, 0);
+       } else {
+               ret = ad5791_spi_write(st, AD5791_ADDR_SW_CTRL, AD5791_SWCTRL_RESET);
+               if (ret)
+                       goto error_disable_reg_neg;
+       }
 
        st->chip_info = spi_get_device_match_data(spi);
        if (!st->chip_info)