iio: adc: ad7380: add support for pseudo-differential parts

Add support for AD7383, AD7384 pseudo-differential compatible parts.
Pseudo differential parts require common mode voltage supplies so add
the support for them and add the support of IIO_CHAN_INFO_OFFSET to
retrieve the offset

Signed-off-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Julien Stephan <jstephan@baylibre.com>
Link: https://lore.kernel.org/r/20240528-adding-new-ad738x-driver-v7-4-4cd70a4c12c8@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/ad7380.c b/drivers/iio/adc/ad7380.c
index dac7e11755ffa2005459bcf13a78b2f647455cc6..4ad283cf970d158a7899b5068948810f2ac312fe 100644 (file)
--- a/drivers/iio/adc/ad7380.c
+++ b/drivers/iio/adc/ad7380.c
@@ -7,6 +7,7 @@
  *
  * Datasheets of supported parts:
  * ad7380/1 : https://www.analog.com/media/en/technical-documentation/data-sheets/AD7380-7381.pdf
+ * ad7383/4 : https://www.analog.com/media/en/technical-documentation/data-sheets/ad7383-7384.pdf
  */
 
 #include <linux/bitfield.h>
@@ -66,16 +67,19 @@ struct ad7380_chip_info {
        const char *name;
        const struct iio_chan_spec *channels;
        unsigned int num_channels;
+       const char * const *vcm_supplies;
+       unsigned int num_vcm_supplies;
 };
 
-#define AD7380_CHANNEL(index, bits) {                          \
+#define AD7380_CHANNEL(index, bits, diff) {                    \
        .type = IIO_VOLTAGE,                                    \
-       .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
+       .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |          \
+               ((diff) ? 0 : BIT(IIO_CHAN_INFO_OFFSET)),       \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
        .indexed = 1,                                           \
-       .differential = 1,                                      \
-       .channel = 2 * (index),                                 \
-       .channel2 = 2 * (index) + 1,                            \
+       .differential = (diff),                                 \
+       .channel = (diff) ? (2 * (index)) : (index),            \
+       .channel2 = (diff) ? (2 * (index) + 1) : 0,             \
        .scan_index = (index),                                  \
        .scan_type = {                                          \
                .sign = 's',                                    \
@@ -85,15 +89,23 @@ struct ad7380_chip_info {
        },                                                      \
 }
 
-#define DEFINE_AD7380_2_CHANNEL(name, bits)    \
-static const struct iio_chan_spec name[] = {   \
-       AD7380_CHANNEL(0, bits),                \
-       AD7380_CHANNEL(1, bits),                \
-       IIO_CHAN_SOFT_TIMESTAMP(2),             \
+#define DEFINE_AD7380_2_CHANNEL(name, bits, diff)      \
+static const struct iio_chan_spec name[] = {           \
+       AD7380_CHANNEL(0, bits, diff),                  \
+       AD7380_CHANNEL(1, bits, diff),                  \
+       IIO_CHAN_SOFT_TIMESTAMP(2),                     \
 }
 
-DEFINE_AD7380_2_CHANNEL(ad7380_channels, 16);
-DEFINE_AD7380_2_CHANNEL(ad7381_channels, 14);
+/* fully differential */
+DEFINE_AD7380_2_CHANNEL(ad7380_channels, 16, 1);
+DEFINE_AD7380_2_CHANNEL(ad7381_channels, 14, 1);
+/* pseudo differential */
+DEFINE_AD7380_2_CHANNEL(ad7383_channels, 16, 0);
+DEFINE_AD7380_2_CHANNEL(ad7384_channels, 14, 0);
+
+static const char * const ad7380_2_channel_vcm_supplies[] = {
+       "aina", "ainb",
+};
 
 /* Since this is simultaneous sampling, we don't allow individual channels. */
 static const unsigned long ad7380_2_channel_scan_masks[] = {
@@ -113,11 +125,28 @@ static const struct ad7380_chip_info ad7381_chip_info = {
        .num_channels = ARRAY_SIZE(ad7381_channels),
 };
 
+static const struct ad7380_chip_info ad7383_chip_info = {
+       .name = "ad7383",
+       .channels = ad7383_channels,
+       .num_channels = ARRAY_SIZE(ad7383_channels),
+       .vcm_supplies = ad7380_2_channel_vcm_supplies,
+       .num_vcm_supplies = ARRAY_SIZE(ad7380_2_channel_vcm_supplies),
+};
+
+static const struct ad7380_chip_info ad7384_chip_info = {
+       .name = "ad7384",
+       .channels = ad7384_channels,
+       .num_channels = ARRAY_SIZE(ad7384_channels),
+       .vcm_supplies = ad7380_2_channel_vcm_supplies,
+       .num_vcm_supplies = ARRAY_SIZE(ad7380_2_channel_vcm_supplies),
+};
+
 struct ad7380_state {
        const struct ad7380_chip_info *chip_info;
        struct spi_device *spi;
        struct regmap *regmap;
        unsigned int vref_mv;
+       unsigned int vcm_mv[2];
        /*
         * DMA (thus cache coherency maintenance) requires the
         * transfer buffers to live in their own cache lines.
@@ -288,13 +317,24 @@ static int ad7380_read_raw(struct iio_dev *indio_dev,
                unreachable();
        case IIO_CHAN_INFO_SCALE:
                /*
-                * According to the datasheet, the LSB size for fully differential ADC is
-                * (2 × VREF) / 2^N, where N is the ADC resolution (i.e realbits)
+                * According to the datasheet, the LSB size is:
+                *    * (2 × VREF) / 2^N, for differential chips
+                *    * VREF / 2^N, for pseudo-differential chips
+                * where N is the ADC resolution (i.e realbits)
                 */
                *val = st->vref_mv;
-               *val2 = chan->scan_type.realbits - 1;
+               *val2 = chan->scan_type.realbits - chan->differential;
 
                return IIO_VAL_FRACTIONAL_LOG2;
+       case IIO_CHAN_INFO_OFFSET:
+               /*
+                * According to IIO ABI, offset is applied before scale,
+                * so offset is: vcm_mv / scale
+                */
+               *val = st->vcm_mv[chan->channel] * (1 << chan->scan_type.realbits)
+                       / st->vref_mv;
+
+               return IIO_VAL_INT;
        default:
                return -EINVAL;
        }
@@ -341,7 +381,7 @@ static int ad7380_probe(struct spi_device *spi)
        struct iio_dev *indio_dev;
        struct ad7380_state *st;
        struct regulator *vref;
-       int ret;
+       int ret, i;
 
        indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
        if (!indio_dev)
@@ -385,6 +425,40 @@ static int ad7380_probe(struct spi_device *spi)
                st->vref_mv = AD7380_INTERNAL_REF_MV;
        }
 
+       if (st->chip_info->num_vcm_supplies > ARRAY_SIZE(st->vcm_mv))
+               return dev_err_probe(&spi->dev, -EINVAL,
+                                    "invalid number of VCM supplies\n");
+
+       /*
+        * pseudo-differential chips have common mode supplies for the negative
+        * input pin.
+        */
+       for (i = 0; i < st->chip_info->num_vcm_supplies; i++) {
+               struct regulator *vcm;
+
+               vcm = devm_regulator_get(&spi->dev,
+                                        st->chip_info->vcm_supplies[i]);
+               if (IS_ERR(vcm))
+                       return dev_err_probe(&spi->dev, PTR_ERR(vcm),
+                                            "Failed to get %s regulator\n",
+                                            st->chip_info->vcm_supplies[i]);
+
+               ret = regulator_enable(vcm);
+               if (ret)
+                       return ret;
+
+               ret = devm_add_action_or_reset(&spi->dev,
+                                              ad7380_regulator_disable, vcm);
+               if (ret)
+                       return ret;
+
+               ret = regulator_get_voltage(vcm);
+               if (ret < 0)
+                       return ret;
+
+               st->vcm_mv[i] = ret / 1000;
+       }
+
        st->regmap = devm_regmap_init(&spi->dev, NULL, st, &ad7380_regmap_config);
        if (IS_ERR(st->regmap))
                return dev_err_probe(&spi->dev, PTR_ERR(st->regmap),
@@ -413,12 +487,16 @@ static int ad7380_probe(struct spi_device *spi)
 static const struct of_device_id ad7380_of_match_table[] = {
        { .compatible = "adi,ad7380", .data = &ad7380_chip_info },
        { .compatible = "adi,ad7381", .data = &ad7381_chip_info },
+       { .compatible = "adi,ad7383", .data = &ad7383_chip_info },
+       { .compatible = "adi,ad7384", .data = &ad7384_chip_info },
        { }
 };
 
 static const struct spi_device_id ad7380_id_table[] = {
        { "ad7380", (kernel_ulong_t)&ad7380_chip_info },
        { "ad7381", (kernel_ulong_t)&ad7381_chip_info },
+       { "ad7383", (kernel_ulong_t)&ad7383_chip_info },
+       { "ad7384", (kernel_ulong_t)&ad7384_chip_info },
        { }
 };
 MODULE_DEVICE_TABLE(spi, ad7380_id_table);