iio: adc: ad4030: add averaging support

This add support for the averaging mode of AD4030 using oversampling IIO
attribute

Signed-off-by: Esteban Blanc <eblanc@baylibre.com>
Link: https://patch.msgid.link/20250214-eblanc-ad4630_v1-v4-3-135dd66cab6a@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ad4030.c

@@ -112,6 +112,11 @@ enum ad4030_out_mode {
 	AD4030_OUT_DATA_MD_32_PATTERN,
 };
 
+enum {
+	AD4030_SCAN_TYPE_NORMAL,
+	AD4030_SCAN_TYPE_AVG,
+};
+
 struct ad4030_chip_info {
 	const char *name;
 	const unsigned long *available_masks;
@@ -127,10 +132,12 @@ struct ad4030_state {
 	struct spi_device *spi;
 	struct regmap *regmap;
 	const struct ad4030_chip_info *chip;
+	const struct iio_scan_type *current_scan_type;
 	struct gpio_desc *cnv_gpio;
 	int vref_uv;
 	int vio_uv;
 	int offset_avail[3];
+	unsigned int avg_log2;
 	enum ad4030_out_mode mode;
 
 	/*
@@ -184,7 +191,11 @@ struct ad4030_state {
  * - voltage0-voltage1
  * - voltage2-voltage3
  */
-#define AD4030_CHAN_DIFF(_idx, _storage, _real, _shift) {		\
+#define AD4030_CHAN_DIFF(_idx, _scan_type) {				\
+	.info_mask_shared_by_all =					\
+		BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),			\
+	.info_mask_shared_by_all_available =				\
+		BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),			\
 	.info_mask_separate = BIT(IIO_CHAN_INFO_SCALE) |		\
 		BIT(IIO_CHAN_INFO_CALIBSCALE) |				\
 		BIT(IIO_CHAN_INFO_CALIBBIAS) |				\
@@ -198,15 +209,17 @@ struct ad4030_state {
 	.channel2 = (_idx) * 2 + 1,					\
 	.scan_index = (_idx),						\
 	.differential = true,						\
-	.scan_type = {							\
+	.has_ext_scan_type = 1,						\
-		.sign = 's',						\
+	.ext_scan_type = _scan_type,					\
-		.storagebits = _storage,				\
+	.num_ext_scan_type = ARRAY_SIZE(_scan_type),			\
-		.realbits = _real,					\
-		.shift = _shift,					\
-		.endianness = IIO_BE,					\
-	},								\
 }
 
+static const int ad4030_average_modes[] = {
+	1, 2, 4, 8, 16, 32, 64, 128,
+	256, 512, 1024, 2048, 4096, 8192, 16384, 32768,
+	65536,
+};
+
 static int ad4030_enter_config_mode(struct ad4030_state *st)
 {
 	st->tx_data[0] = AD4030_REG_ACCESS;
@@ -356,10 +369,13 @@ static int ad4030_get_chan_scale(struct iio_dev *indio_dev,
 				 int *val2)
 {
 	struct ad4030_state *st = iio_priv(indio_dev);
+	const struct iio_scan_type *scan_type;
 
 	if (chan->differential) {
+		scan_type = iio_get_current_scan_type(indio_dev,
+						      st->chip->channels);
 		*val = (st->vref_uv * 2) / MILLI;
-		*val2 = chan->scan_type.realbits;
+		*val2 = scan_type->realbits;
 		return IIO_VAL_FRACTIONAL_LOG2;
 	}
 
@@ -474,6 +490,27 @@ static int ad4030_set_chan_calibbias(struct iio_dev *indio_dev,
 				 st->tx_data, AD4030_REG_OFFSET_BYTES_NB);
 }
 
+static int ad4030_set_avg_frame_len(struct iio_dev *dev, int avg_val)
+{
+	struct ad4030_state *st = iio_priv(dev);
+	unsigned int avg_log2 = ilog2(avg_val);
+	unsigned int last_avg_idx = ARRAY_SIZE(ad4030_average_modes) - 1;
+	int ret;
+
+	if (avg_val < 0 || avg_val > ad4030_average_modes[last_avg_idx])
+		return -EINVAL;
+
+	ret = regmap_write(st->regmap, AD4030_REG_AVG,
+			   AD4030_REG_AVG_MASK_AVG_SYNC |
+			   FIELD_PREP(AD4030_REG_AVG_MASK_AVG_VAL, avg_log2));
+	if (ret)
+		return ret;
+
+	st->avg_log2 = avg_log2;
+
+	return 0;
+}
+
 static bool ad4030_is_common_byte_asked(struct ad4030_state *st,
 					unsigned int mask)
 {
@@ -484,11 +521,18 @@ static int ad4030_set_mode(struct iio_dev *indio_dev, unsigned long mask)
 {
 	struct ad4030_state *st = iio_priv(indio_dev);
 
-	if (ad4030_is_common_byte_asked(st, mask))
+	if (st->avg_log2 > 0)
+		st->mode = AD4030_OUT_DATA_MD_30_AVERAGED_DIFF;
+	else if (ad4030_is_common_byte_asked(st, mask))
 		st->mode = AD4030_OUT_DATA_MD_24_DIFF_8_COM;
 	else
 		st->mode = AD4030_OUT_DATA_MD_DIFF;
 
+	st->current_scan_type = iio_get_current_scan_type(indio_dev,
+							  st->chip->channels);
+	if (IS_ERR(st->current_scan_type))
+		return PTR_ERR(st->current_scan_type);
+
 	return regmap_update_bits(st->regmap, AD4030_REG_MODES,
 				  AD4030_REG_MODES_MASK_OUT_DATA_MODE,
 				  st->mode);
@@ -497,9 +541,11 @@ static int ad4030_set_mode(struct iio_dev *indio_dev, unsigned long mask)
 static int ad4030_conversion(struct iio_dev *indio_dev)
 {
 	struct ad4030_state *st = iio_priv(indio_dev);
-	const struct iio_scan_type scan_type = indio_dev->channels->scan_type;
+	unsigned char diff_realbytes =
-	unsigned char diff_realbytes = BITS_TO_BYTES(scan_type.realbits);
+		BITS_TO_BYTES(st->current_scan_type->realbits);
 	unsigned int bytes_to_read;
+	unsigned long cnv_nb = BIT(st->avg_log2);
+	unsigned int i;
 	int ret;
 
 	/* Number of bytes for one differential channel */
@@ -510,10 +556,12 @@ static int ad4030_conversion(struct iio_dev *indio_dev)
 	/* Mulitiply by the number of hardware channels */
 	bytes_to_read *= st->chip->num_voltage_inputs;
 
-	gpiod_set_value_cansleep(st->cnv_gpio, 1);
+	for (i = 0; i < cnv_nb; i++) {
-	ndelay(AD4030_TCNVH_NS);
+		gpiod_set_value_cansleep(st->cnv_gpio, 1);
-	gpiod_set_value_cansleep(st->cnv_gpio, 0);
+		ndelay(AD4030_TCNVH_NS);
-	ndelay(st->chip->tcyc_ns);
+		gpiod_set_value_cansleep(st->cnv_gpio, 0);
+		ndelay(st->chip->tcyc_ns);
+	}
 
 	ret = spi_read(st->spi, st->rx_data.raw, bytes_to_read);
 	if (ret)
@@ -593,6 +641,12 @@ static int ad4030_read_avail(struct iio_dev *indio_dev,
 		*type = IIO_VAL_INT_PLUS_NANO;
 		return IIO_AVAIL_RANGE;
 
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*vals = ad4030_average_modes;
+		*type = IIO_VAL_INT;
+		*length = ARRAY_SIZE(ad4030_average_modes);
+		return IIO_AVAIL_LIST;
+
 	default:
 		return -EINVAL;
 	}
@@ -602,6 +656,8 @@ static int ad4030_read_raw_dispatch(struct iio_dev *indio_dev,
 				    struct iio_chan_spec const *chan, int *val,
 				    int *val2, long info)
 {
+	struct ad4030_state *st = iio_priv(indio_dev);
+
 	switch (info) {
 	case IIO_CHAN_INFO_RAW:
 		return ad4030_single_conversion(indio_dev, chan, val);
@@ -612,6 +668,10 @@ static int ad4030_read_raw_dispatch(struct iio_dev *indio_dev,
 	case IIO_CHAN_INFO_CALIBBIAS:
 		return ad4030_get_chan_calibbias(indio_dev, chan, val);
 
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*val = BIT(st->avg_log2);
+		return IIO_VAL_INT;
+
 	default:
 		return -EINVAL;
 	}
@@ -650,6 +710,9 @@ static int ad4030_write_raw_dispatch(struct iio_dev *indio_dev,
 			return -EINVAL;
 		return ad4030_set_chan_calibbias(indio_dev, chan, val);
 
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		return ad4030_set_avg_frame_len(indio_dev, val);
+
 	default:
 		return -EINVAL;
 	}
@@ -701,12 +764,21 @@ static int ad4030_read_label(struct iio_dev *indio_dev,
 	return sprintf(label, "common-mode%lu\n", chan->address);
 }
 
+static int ad4030_get_current_scan_type(const struct iio_dev *indio_dev,
+					const struct iio_chan_spec *chan)
+{
+	struct ad4030_state *st = iio_priv(indio_dev);
+
+	return st->avg_log2 ? AD4030_SCAN_TYPE_AVG : AD4030_SCAN_TYPE_NORMAL;
+}
+
 static const struct iio_info ad4030_iio_info = {
 	.read_avail = ad4030_read_avail,
 	.read_raw = ad4030_read_raw,
 	.write_raw = ad4030_write_raw,
 	.debugfs_reg_access = ad4030_reg_access,
 	.read_label = ad4030_read_label,
+	.get_current_scan_type = ad4030_get_current_scan_type,
 };
 
 static int ad4030_buffer_preenable(struct iio_dev *indio_dev)
@@ -714,8 +786,21 @@ static int ad4030_buffer_preenable(struct iio_dev *indio_dev)
 	return ad4030_set_mode(indio_dev, *indio_dev->active_scan_mask);
 }
 
+static bool ad4030_validate_scan_mask(struct iio_dev *indio_dev,
+				      const unsigned long *scan_mask)
+{
+	struct ad4030_state *st = iio_priv(indio_dev);
+
+	/* Asking for both common channels and averaging */
+	if (st->avg_log2 && ad4030_is_common_byte_asked(st, *scan_mask))
+		return false;
+
+	return true;
+}
+
 static const struct iio_buffer_setup_ops ad4030_buffer_setup_ops = {
 	.preenable = ad4030_buffer_preenable,
+	.validate_scan_mask = ad4030_validate_scan_mask,
 };
 
 static int ad4030_regulators_get(struct ad4030_state *st)
@@ -881,11 +966,28 @@ static const unsigned long ad4030_channel_masks[] = {
 	0,
 };
 
+static const struct iio_scan_type ad4030_24_scan_types[] = {
+	[AD4030_SCAN_TYPE_NORMAL] = {
+		.sign = 's',
+		.storagebits = 32,
+		.realbits = 24,
+		.shift = 8,
+		.endianness = IIO_BE,
+	},
+	[AD4030_SCAN_TYPE_AVG] = {
+		.sign = 's',
+		.storagebits = 32,
+		.realbits = 30,
+		.shift = 2,
+		.endianness = IIO_BE,
+	},
+};
+
 static const struct ad4030_chip_info ad4030_24_chip_info = {
 	.name = "ad4030-24",
 	.available_masks = ad4030_channel_masks,
 	.channels = {
-		AD4030_CHAN_DIFF(0, 32, 24, 8),
+		AD4030_CHAN_DIFF(0, ad4030_24_scan_types),
 		AD4030_CHAN_CMO(1, 0),
 		IIO_CHAN_SOFT_TIMESTAMP(2),
 	},