[PATCH v2 3/5] iio: adc: ad7606: add offset and phase calibration support

Angelo Dureghello
2025-05-02T13:28:21Z

From: Angelo Dureghello <adureghello@baylibre.com>

Add support for offset and phase calibration, only for
devices that support software mode, that are:

ad7606b
ad7606c-16
ad7606c-18

Signed-off-by: Angelo Dureghello <adureghello@baylibre.com>
---
drivers/iio/adc/ad7606.c | 160 +++++++++++++++++++++++++++++++++++++++++++++++
drivers/iio/adc/ad7606.h | 9 +++
2 files changed, 169 insertions(+)

diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
index ad5e6b5e1d5d2edc7f8ac7ed9a8a4e6e43827b85..139d8b3f9bb39dd631a71c70539005d719fb5b7b 100644
--- a/drivers/iio/adc/ad7606.c
+++ b/drivers/iio/adc/ad7606.c
@@ -95,6 +95,22 @@ static const unsigned int ad7616_oversampling_avail[8] = {
1, 2, 4, 8, 16, 32, 64, 128,
};

+static const int ad7606_calib_offset_avail[3] = {
+ -128, 1, 127,
+};
+
+static const int ad7606c_18bit_calib_offset_avail[3] = {
+ -512, 4, 508,
+};
+
+static const int ad7606b_calib_phase_avail[][2] = {
+ { 0, 0 }, { 0, 1250 }, { 0, 318750 },
+};
+
+static const int ad7606c_calib_phase_avail[][2] = {
+ { 0, 0 }, { 0, 1000 }, { 0, 255000 },
+};
+
static int ad7606c_18bit_chan_scale_setup(struct iio_dev *indio_dev,
struct iio_chan_spec *chan);
static int ad7606c_16bit_chan_scale_setup(struct iio_dev *indio_dev,
@@ -164,6 +180,8 @@ const struct ad7606_chip_info ad7606b_info = {
.scale_setup_cb = ad7606_16bit_chan_scale_setup,
.sw_setup_cb = ad7606b_sw_mode_setup,
.offload_storagebits = 32,
+ .calib_offset_avail = ad7606_calib_offset_avail,
+ .calib_phase_avail = ad7606b_calib_phase_avail,
};
EXPORT_SYMBOL_NS_GPL(ad7606b_info, "IIO_AD7606");

@@ -177,6 +195,8 @@ const struct ad7606_chip_info ad7606c_16_info = {
.scale_setup_cb = ad7606c_16bit_chan_scale_setup,
.sw_setup_cb = ad7606b_sw_mode_setup,
.offload_storagebits = 32,
+ .calib_offset_avail = ad7606_calib_offset_avail,
+ .calib_phase_avail = ad7606c_calib_phase_avail,
};
EXPORT_SYMBOL_NS_GPL(ad7606c_16_info, "IIO_AD7606");

@@ -226,6 +246,8 @@ const struct ad7606_chip_info ad7606c_18_info = {
.scale_setup_cb = ad7606c_18bit_chan_scale_setup,
.sw_setup_cb = ad7606b_sw_mode_setup,
.offload_storagebits = 32,
+ .calib_offset_avail = ad7606c_18bit_calib_offset_avail,
+ .calib_phase_avail = ad7606c_calib_phase_avail,
};
EXPORT_SYMBOL_NS_GPL(ad7606c_18_info, "IIO_AD7606");

@@ -683,6 +705,40 @@ static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch,
return ret;
}

+static int ad7606_get_calib_offset(struct ad7606_state *st, int ch, int *val)
+{
+ int ret;
+
+ ret = st->bops->reg_read(st, AD7606_CALIB_OFFSET(ch));
+ if (ret < 0)
+ return ret;
+
+ *val = st->chip_info->calib_offset_avail[0] +
+ ret * st->chip_info->calib_offset_avail[1];
+
+ return 0;
+}
+
+static int ad7606_get_calib_phase(struct ad7606_state *st, int ch, int *val,
+ int *val2)
+{
+ int ret;
+
+ ret = st->bops->reg_read(st, AD7606_CALIB_PHASE(ch));
+ if (ret < 0)
+ return ret;
+
+ *val = 0;
+
+ /*
+ * ad7606b: phase delay from 0 to 318.75 μs in steps of 1.25 μs.
+ * ad7606c-16/18: phase delay from 0 µs to 255 µs in steps of 1 µs.
+ */
+ *val2 = ret * st->chip_info->calib_phase_avail[1][1];
+
+ return 0;
+}
+
static int ad7606_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val,
@@ -717,6 +773,22 @@ static int ad7606_read_raw(struct iio_dev *indio_dev,
pwm_get_state(st->cnvst_pwm, &cnvst_pwm_state);
*val = DIV_ROUND_CLOSEST_ULL(NSEC_PER_SEC, cnvst_pwm_state.period);
return IIO_VAL_INT;
+ case IIO_CHAN_INFO_CALIBBIAS:
+ if (!iio_device_claim_direct(indio_dev))
+ return -EBUSY;
+ ret = ad7606_get_calib_offset(st, chan->scan_index, val);
+ iio_device_release_direct(indio_dev);
+ if (ret)
+ return ret;
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_CALIBCONV_DELAY:
+ if (!iio_device_claim_direct(indio_dev))
+ return -EBUSY;
+ ret = ad7606_get_calib_phase(st, chan->scan_index, val, val2);
+ iio_device_release_direct(indio_dev);
+ if (ret)
+ return ret;
+ return IIO_VAL_INT_PLUS_NANO;
}
return -EINVAL;
}
@@ -767,6 +839,64 @@ static int ad7606_write_os_hw(struct iio_dev *indio_dev, int val)
return 0;
}

+static int ad7606_set_calib_offset(struct ad7606_state *st, int ch, int val)
+{
+ int start_val, step_val, stop_val;
+
+ start_val = st->chip_info->calib_offset_avail[0];
+ step_val = st->chip_info->calib_offset_avail[1];
+ stop_val = st->chip_info->calib_offset_avail[2];
+
+ if (val < start_val || val > stop_val)
+ return -EINVAL;
+
+ val -= start_val;
+ val /= step_val;
+
+ return st->bops->reg_write(st, AD7606_CALIB_OFFSET(ch), val);
+}
+
+static int ad7606_set_calib_phase(struct ad7606_state *st, int ch, int val,
+ int val2)
+{
+ int wreg, start_ns, step_ns, stop_ns;
+
+ if (val != 0)
+ return -EINVAL;
+
+ start_ns = st->chip_info->calib_phase_avail[0][1];
+ step_ns = st->chip_info->calib_phase_avail[1][1];
+ stop_ns = st->chip_info->calib_phase_avail[2][1];
+
+ /*
+ * ad7606b: phase dielay from 0 to 318.75 μs in steps of 1.25 μs.
+ * ad7606c-16/18: phase delay from 0 µs to 255 µs in steps of 1 µs.
+ */
+ if (val2 < start_ns || val2 > stop_ns)
+ return -EINVAL;
+
+ wreg = val2 / step_ns;
+
+ return st->bops->reg_write(st, AD7606_CALIB_PHASE(ch), wreg);
+}
+
+static int ad7606_write_raw_get_fmt(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan, long info)
+{
+ switch (info) {
+ case IIO_CHAN_INFO_SCALE:
+ return IIO_VAL_INT_PLUS_MICRO;
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+ case IIO_CHAN_INFO_CALIBBIAS:
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_CALIBCONV_DELAY:
+ return IIO_VAL_INT_PLUS_NANO;
+ default:
+ return -EINVAL;
+ }
+}
+
static int ad7606_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int val,
@@ -820,6 +950,18 @@ static int ad7606_write_raw(struct iio_dev *indio_dev,
if (val < 0 && val2 != 0)
return -EINVAL;
return ad7606_set_sampling_freq(st, val);
+ case IIO_CHAN_INFO_CALIBBIAS:
+ if (!iio_device_claim_direct(indio_dev))
+ return -EBUSY;
+ ret = ad7606_set_calib_offset(st, chan->scan_index, val);
+ iio_device_release_direct(indio_dev);
+ return ret;
+ case IIO_CHAN_INFO_CALIBCONV_DELAY:
+ if (!iio_device_claim_direct(indio_dev))
+ return -EBUSY;
+ ret = ad7606_set_calib_phase(st, chan->scan_index, val, val2);
+ iio_device_release_direct(indio_dev);
+ return ret;
default:
return -EINVAL;
}
@@ -998,6 +1140,14 @@ static int ad7606_read_avail(struct iio_dev *indio_dev,
*type = IIO_VAL_INT_PLUS_MICRO;

return IIO_AVAIL_LIST;
+ case IIO_CHAN_INFO_CALIBBIAS:
+ *vals = st->chip_info->calib_offset_avail;
+ *type = IIO_VAL_INT;
+ return IIO_AVAIL_RANGE;
+ case IIO_CHAN_INFO_CALIBCONV_DELAY:
+ *vals = (const int *)st->chip_info->calib_phase_avail;
+ *type = IIO_VAL_INT_PLUS_NANO;
+ return IIO_AVAIL_RANGE;
}
return -EINVAL;
}
@@ -1060,6 +1210,7 @@ static const struct iio_info ad7606_info_sw_mode = {
.read_raw = &ad7606_read_raw,
.write_raw = &ad7606_write_raw,
.read_avail = &ad7606_read_avail,
+ .write_raw_get_fmt = ad7606_write_raw_get_fmt,
.debugfs_reg_access = &ad7606_reg_access,
.validate_trigger = &ad7606_validate_trigger,
.update_scan_mode = &ad7606_update_scan_mode,
@@ -1252,6 +1403,15 @@ static int ad7606_probe_channels(struct iio_dev *indio_dev)
chan->info_mask_separate_available |=
BIT(IIO_CHAN_INFO_SCALE);

+ if (st->chip_info->calib_offset_avail) {
+ chan->info_mask_separate |=
+ BIT(IIO_CHAN_INFO_CALIBBIAS) |
+ BIT(IIO_CHAN_INFO_CALIBCONV_DELAY);
+ chan->info_mask_separate_available |=
+ BIT(IIO_CHAN_INFO_CALIBBIAS) |
+ BIT(IIO_CHAN_INFO_CALIBCONV_DELAY);
+ }
+
/*
* All chips with software mode support oversampling,
* so we skip the oversampling_available check. And the
diff --git a/drivers/iio/adc/ad7606.h b/drivers/iio/adc/ad7606.h
index 89d49551eaf515bab9706c12bff056dfcb707b67..4c39de36154ffb80dfbb01bb4f812826bdc55967 100644
--- a/drivers/iio/adc/ad7606.h
+++ b/drivers/iio/adc/ad7606.h
@@ -40,6 +40,11 @@
#define AD7606_RANGE_CH_ADDR(ch) (0x03 + ((ch) >> 1))
#define AD7606_OS_MODE 0x08

+#define AD7606_CALIB_GAIN(ch) (0x09 + (ch))
+#define AD7606_CALIB_GAIN_MASK GENMASK(5, 0)
+#define AD7606_CALIB_OFFSET(ch) (0x11 + (ch))
+#define AD7606_CALIB_PHASE(ch) (0x19 + (ch))
+
struct ad7606_state;

typedef int (*ad7606_scale_setup_cb_t)(struct iio_dev *indio_dev,
@@ -61,6 +66,8 @@ typedef int (*ad7606_sw_setup_cb_t)(struct iio_dev *indio_dev);
* @init_delay_ms: required delay in milliseconds for initialization
* after a restart
* @offload_storagebits: storage bits used by the offload hw implementation
+ * @calib_offset_avail: pointer to offset calibration range/limits array
+ * @calib_phase_avail: pointer to phase calibration range/limits array
*/
struct ad7606_chip_info {
unsigned int max_samplerate;
@@ -74,6 +81,8 @@ struct ad7606_chip_info {
bool os_req_reset;
unsigned long init_delay_ms;
u8 offload_storagebits;
+ const int *calib_offset_avail;
+ const int (*calib_phase_avail)[2];
};

/**

--
2.49.0