iio: adc: ad7192: Add aincom supply

AINCOM should actually be a supply. AINx inputs are referenced to AINCOM
in pseudo-differential operation mode. AINCOM voltage represents the
offset of corresponding channels.

Signed-off-by: Alisa-Dariana Roman <alisa.roman@analog.com>
Link: https://lore.kernel.org/r/20240514120222.56488-4-alisa.roman@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/ad7192.c b/drivers/iio/adc/ad7192.c
index ace81e3817a1a6024a897ccf902604b80dbf6dbc..7160929d32c90e98f98439c10c1f1461b1c5fb31 100644 (file)
--- a/drivers/iio/adc/ad7192.c
+++ b/drivers/iio/adc/ad7192.c
@@ -20,6 +20,7 @@
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/property.h>
+#include <linux/units.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
@@ -186,6 +187,7 @@ struct ad7192_state {
        struct regulator                *vref;
        struct clk                      *mclk;
        u16                             int_vref_mv;
+       u32                             aincom_mv;
        u32                             fclk;
        u32                             mode;
        u32                             conf;
@@ -742,10 +744,24 @@ static int ad7192_read_raw(struct iio_dev *indio_dev,
                        *val = -(1 << (chan->scan_type.realbits - 1));
                else
                        *val = 0;
+
+               switch (chan->type) {
+               case IIO_VOLTAGE:
+                       /*
+                        * Only applies to pseudo-differential inputs.
+                        * AINCOM voltage has to be converted to "raw" units.
+                        */
+                       if (st->aincom_mv && !chan->differential)
+                               *val += DIV_ROUND_CLOSEST_ULL((u64)st->aincom_mv * NANO,
+                                                             st->scale_avail[gain][1]);
+                       return IIO_VAL_INT;
                /* Kelvin to Celsius */
-               if (chan->type == IIO_TEMP)
+               case IIO_TEMP:
                        *val -= 273 * ad7192_get_temp_scale(unipolar);
-               return IIO_VAL_INT;
+                       return IIO_VAL_INT;
+               default:
+                       return -EINVAL;
+               }
        case IIO_CHAN_INFO_SAMP_FREQ:
                *val = DIV_ROUND_CLOSEST(ad7192_get_f_adc(st), 1024);
                return IIO_VAL_INT;
@@ -1052,6 +1068,7 @@ static int ad7192_probe(struct spi_device *spi)
 {
        struct ad7192_state *st;
        struct iio_dev *indio_dev;
+       struct regulator *aincom;
        int ret;
 
        if (!spi->irq) {
@@ -1067,6 +1084,35 @@ static int ad7192_probe(struct spi_device *spi)
 
        mutex_init(&st->lock);
 
+       /*
+        * Regulator aincom is optional to maintain compatibility with older DT.
+        * Newer firmware should provide a zero volt fixed supply if wired to
+        * ground.
+        */
+       aincom = devm_regulator_get_optional(&spi->dev, "aincom");
+       if (IS_ERR(aincom)) {
+               if (PTR_ERR(aincom) != -ENODEV)
+                       return dev_err_probe(&spi->dev, PTR_ERR(aincom),
+                                            "Failed to get AINCOM supply\n");
+
+               st->aincom_mv = 0;
+       } else {
+               ret = regulator_enable(aincom);
+               if (ret)
+                       return dev_err_probe(&spi->dev, ret,
+                                            "Failed to enable specified AINCOM supply\n");
+
+               ret = devm_add_action_or_reset(&spi->dev, ad7192_reg_disable, aincom);
+               if (ret)
+                       return ret;
+
+               ret = regulator_get_voltage(aincom);
+               if (ret < 0)
+                       return dev_err_probe(&spi->dev, ret,
+                                            "Device tree error, AINCOM voltage undefined\n");
+               st->aincom_mv = ret / MILLI;
+       }
+
        st->avdd = devm_regulator_get(&spi->dev, "avdd");
        if (IS_ERR(st->avdd))
                return PTR_ERR(st->avdd);