[PATCH v3 07/14] iio: adc: ad7768: Add calibration controls

[Janani Sunil <janani.sunil@analog.com>]

Expose the per-channel offset and gain calibration registers through the
IIO calibbias and calibscale attributes.

Use bulk regmap operations and unaligned big-endian helpers to transfer
the three register bytes.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/adc/ad7768.c | 119 ++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 108 insertions(+), 11 deletions(-)

diff --git a/drivers/iio/adc/ad7768.c b/drivers/iio/adc/ad7768.c
index 3849f544a1e5..08721079bb37 100644
--- a/drivers/iio/adc/ad7768.c
+++ b/drivers/iio/adc/ad7768.c
@@ -25,6 +25,7 @@
 #include <linux/reset.h>
 #include <linux/spi/spi.h>
 #include <linux/types.h>
+#include <linux/unaligned.h>
 
 #include <linux/iio/backend.h>
 #include <linux/iio/iio.h>
@@ -98,6 +99,7 @@
 #define   MAX_FREQ_PER_MODE			6
 #define   AD7768_MAX_CHANNEL  8
 #define   AD7768_NUM_CHANNEL_MODES		2
+#define   AD7768_CALIB_REG_MSK			GENMASK(23, 0)
 #define   AD7768_REV_ID_VAL			0x06
 #define   AD7768_WIDEBAND_SETTLING_SAMPLES	68
 #define   AD7768_SINC5_SETTLING_SAMPLES		7
@@ -209,6 +211,18 @@ static u8 ad7768_all_channels_mask(const struct ad7768_state *st)
 	return mask;
 }
 
+static unsigned int ad7768_offset_reg(const struct ad7768_state *st,
+				      unsigned int ch)
+{
+	return AD7768_REG_OFFSET(st->chip_info->chan_map[ch]);
+}
+
+static unsigned int ad7768_gain_reg(const struct ad7768_state *st,
+				    unsigned int ch)
+{
+	return AD7768_REG_GAIN(st->chip_info->chan_map[ch]);
+}
+
 static u8 ad7768_precharge_buf1_mask(const struct ad7768_state *st, u16 val)
 {
 	return val & GENMASK(st->chip_info->prebuf_split - 1, 0);
@@ -327,6 +341,48 @@ static const struct regmap_config ad7768_4_regmap_config = {
 	.readable_reg = ad7768_4_readable_reg,
 };
 
+static unsigned int ad7768_get_calib_reg_base(struct ad7768_state *st,
+					      const struct iio_chan_spec *chan,
+					      bool is_gain)
+{
+	if (is_gain)
+		return ad7768_gain_reg(st, chan->address);
+
+	return ad7768_offset_reg(st, chan->address);
+}
+
+static int ad7768_read_calib_value(struct ad7768_state *st,
+				   unsigned int base_reg, unsigned int *val)
+{
+	u8 data[3];
+	int ret;
+
+	guard(mutex)(&st->lock);
+
+	ret = regmap_bulk_read(st->regmap, base_reg, data, ARRAY_SIZE(data));
+	if (ret)
+		return ret;
+
+	*val = get_unaligned_be24(data);
+
+	return 0;
+}
+
+static int ad7768_write_calib_value(struct ad7768_state *st,
+				    unsigned int base_reg, unsigned int val)
+{
+	u8 data[3];
+
+	if (val > AD7768_CALIB_REG_MSK)
+		return -EINVAL;
+
+	put_unaligned_be24(val, data);
+
+	guard(mutex)(&st->lock);
+
+	return regmap_bulk_write(st->regmap, base_reg, data, ARRAY_SIZE(data));
+}
+
 static int ad7768_reg_access(struct iio_dev *indio_dev,
 			     unsigned int reg,
 			     unsigned int writeval,
@@ -650,6 +706,8 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 			   int *val, int *val2, long info)
 {
 	struct ad7768_state *st = iio_priv(indio_dev);
+	unsigned int base_reg;
+	unsigned int calib;
 	int ret;
 
 	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(regmap_get_device(st->regmap), pm);
@@ -657,22 +715,44 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 	if (ret)
 		return ret;
 
-	if (info != IIO_CHAN_INFO_SAMP_FREQ)
-		return -EINVAL;
+	switch (info) {
+	case IIO_CHAN_INFO_SAMP_FREQ: {
+		guard(mutex)(&st->lock);
+		*val = st->ch_freq[chan->channel];
+		return IIO_VAL_INT;
+	}
+	case IIO_CHAN_INFO_CALIBBIAS:
+		base_reg = ad7768_get_calib_reg_base(st, chan, false);
+		ret = ad7768_read_calib_value(st, base_reg, &calib);
+		if (ret)
+			return ret;
 
-	guard(mutex)(&st->lock);
-	*val = st->ch_freq[chan->channel];
+		*val = calib;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_CALIBSCALE:
+		base_reg = ad7768_get_calib_reg_base(st, chan, true);
+		ret = ad7768_read_calib_value(st, base_reg, &calib);
+		if (ret)
+			return ret;
 
-	return IIO_VAL_INT;
+		*val = calib;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
 }
 
 static int ad7768_write_raw_get_fmt(struct iio_dev *indio_dev,
 				    struct iio_chan_spec const *chan, long info)
 {
-	if (info == IIO_CHAN_INFO_SAMP_FREQ)
+	switch (info) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+	case IIO_CHAN_INFO_CALIBBIAS:
+	case IIO_CHAN_INFO_CALIBSCALE:
 		return IIO_VAL_INT;
-
-	return -EINVAL;
+	default:
+		return -EINVAL;
+	}
 }
 
 static int ad7768_write_raw(struct iio_dev *indio_dev,
@@ -680,6 +760,7 @@ static int ad7768_write_raw(struct iio_dev *indio_dev,
 			    int val, int val2, long info)
 {
 	struct ad7768_state *st = iio_priv(indio_dev);
+	unsigned int base_reg;
 	int ret;
 
 	IIO_DEV_ACQUIRE_DIRECT_MODE(indio_dev, claim);
@@ -691,10 +772,24 @@ static int ad7768_write_raw(struct iio_dev *indio_dev,
 	if (ret)
 		return ret;
 
-	if (info == IIO_CHAN_INFO_SAMP_FREQ)
+	switch (info) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
 		return ad7768_set_sampling_freq(indio_dev, val, chan->channel);
+	case IIO_CHAN_INFO_CALIBBIAS:
+		if (val < 0 || val > AD7768_CALIB_REG_MSK)
+			return -EINVAL;
 
-	return -EINVAL;
+		base_reg = ad7768_get_calib_reg_base(st, chan, false);
+		return ad7768_write_calib_value(st, base_reg, val);
+	case IIO_CHAN_INFO_CALIBSCALE:
+		if (val < 0 || val > AD7768_CALIB_REG_MSK)
+			return -EINVAL;
+
+		base_reg = ad7768_get_calib_reg_base(st, chan, true);
+		return ad7768_write_calib_value(st, base_reg, val);
+	default:
+		return -EINVAL;
+	}
 }
 
 static int ad7768_read_avail(struct iio_dev *indio_dev,
@@ -983,7 +1078,9 @@ static int ad7768_parse_config(struct iio_dev *indio_dev,
 
 		chan[chan_idx] = (struct iio_chan_spec) {
 			.type = IIO_VOLTAGE,
-			.info_mask_separate = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+			.info_mask_separate = BIT(IIO_CHAN_INFO_CALIBBIAS) |
+					      BIT(IIO_CHAN_INFO_CALIBSCALE) |
+					      BIT(IIO_CHAN_INFO_SAMP_FREQ),
 			.info_mask_separate_available =
 				BIT(IIO_CHAN_INFO_SAMP_FREQ),
 			.indexed = 1,

-- 
2.43.0