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Message-Id: <20250603-wip-bl-ad7606-calibration-v8-6-2371e7108f32@baylibre.com>
Date: Tue, 03 Jun 2025 16:36:28 +0200
From: Angelo Dureghello <adureghello@...libre.com>
To: Jonathan Cameron <jic23@...nel.org>,
David Lechner <dlechner@...libre.com>,
Nuno Sá <nuno.sa@...log.com>,
Andy Shevchenko <andy@...nel.org>, Lars-Peter Clausen <lars@...afoo.de>,
Michael Hennerich <Michael.Hennerich@...log.com>,
Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>
Cc: linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
Michael Hennerich <michael.hennerich@...log.com>,
devicetree@...r.kernel.org, Angelo Dureghello <adureghello@...libre.com>
Subject: [PATCH v8 6/6] iio: adc: ad7606: add gain calibration support
From: Angelo Dureghello <adureghello@...libre.com>
Add gain calibration support, using resistor values set on devicetree,
values to be set accordingly with ADC external RFilter, as explained in
the ad7606c-16 datasheet, rev0, page 37.
Usage example in the fdt yaml documentation.
Tested-by: David Lechner <dlechner@...libre.com>
Reviewed-by: Nuno Sá <nuno.sa@...log.com>
Signed-off-by: Angelo Dureghello <adureghello@...libre.com>
---
drivers/iio/adc/ad7606.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++
drivers/iio/adc/ad7606.h | 6 +++++
2 files changed, 72 insertions(+)
diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
index e0a666cc0e14255754e74daa9e1e88bc4ad1665c..22dcb52ced57d4305db6401605c064fc438d5be4 100644
--- a/drivers/iio/adc/ad7606.c
+++ b/drivers/iio/adc/ad7606.c
@@ -33,6 +33,10 @@
#include "ad7606.h"
+#define AD7606_CALIB_GAIN_MIN 0
+#define AD7606_CALIB_GAIN_STEP 1024
+#define AD7606_CALIB_GAIN_MAX (63 * AD7606_CALIB_GAIN_STEP)
+
/*
* Scales are computed as 5000/32768 and 10000/32768 respectively,
* so that when applied to the raw values they provide mV values.
@@ -125,6 +129,7 @@ static int ad7609_chan_scale_setup(struct iio_dev *indio_dev,
struct iio_chan_spec *chan);
static int ad7616_sw_mode_setup(struct iio_dev *indio_dev);
static int ad7606b_sw_mode_setup(struct iio_dev *indio_dev);
+static int ad7606_chan_calib_gain_setup(struct iio_dev *indio_dev);
const struct ad7606_chip_info ad7605_4_info = {
.max_samplerate = 300 * KILO,
@@ -180,6 +185,7 @@ 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_gain_setup_cb = ad7606_chan_calib_gain_setup,
.calib_offset_avail = ad7606_calib_offset_avail,
.calib_phase_avail = ad7606b_calib_phase_avail,
};
@@ -195,6 +201,7 @@ 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_gain_setup_cb = ad7606_chan_calib_gain_setup,
.calib_offset_avail = ad7606_calib_offset_avail,
.calib_phase_avail = ad7606c_calib_phase_avail,
};
@@ -246,6 +253,7 @@ 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_gain_setup_cb = ad7606_chan_calib_gain_setup,
.calib_offset_avail = ad7606c_18bit_calib_offset_avail,
.calib_phase_avail = ad7606c_calib_phase_avail,
};
@@ -355,6 +363,36 @@ static int ad7606_get_chan_config(struct iio_dev *indio_dev, int ch,
return 0;
}
+static int ad7606_chan_calib_gain_setup(struct iio_dev *indio_dev)
+{
+ struct ad7606_state *st = iio_priv(indio_dev);
+ unsigned int num_channels = st->chip_info->num_adc_channels;
+ struct device *dev = st->dev;
+ int ret;
+
+ device_for_each_child_node_scoped(dev, child) {
+ u32 reg, r_gain;
+
+ ret = fwnode_property_read_u32(child, "reg", ®);
+ if (ret)
+ return ret;
+
+ /* Chan reg is a 1-based index. */
+ if (reg < 1 || reg > num_channels)
+ return -EINVAL;
+
+ r_gain = 0;
+ ret = fwnode_property_read_u32(child, "adi,rfilter-ohms",
+ &r_gain);
+ if (r_gain > AD7606_CALIB_GAIN_MAX)
+ return -EINVAL;
+
+ st->r_gain[reg - 1] = r_gain;
+ }
+
+ return 0;
+}
+
static int ad7606c_18bit_chan_scale_setup(struct iio_dev *indio_dev,
struct iio_chan_spec *chan)
{
@@ -1352,6 +1390,21 @@ static int ad7606b_sw_mode_setup(struct iio_dev *indio_dev)
return st->bops->sw_mode_config(indio_dev);
}
+static int ad7606_set_gain_calib(struct ad7606_state *st)
+{
+ int i, ret;
+
+ for (i = 0; i < st->chip_info->num_adc_channels; i++) {
+ ret = st->bops->reg_write(st, AD7606_CALIB_GAIN(i),
+ DIV_ROUND_CLOSEST(st->r_gain[i],
+ AD7606_CALIB_GAIN_STEP));
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
static int ad7606_probe_channels(struct iio_dev *indio_dev)
{
struct ad7606_state *st = iio_priv(indio_dev);
@@ -1444,6 +1497,13 @@ static int ad7606_probe_channels(struct iio_dev *indio_dev)
if (slow_bus)
channels[i] = (struct iio_chan_spec)IIO_CHAN_SOFT_TIMESTAMP(i);
+ /* Getting gain calibration values for all channels. */
+ if (st->sw_mode_en && st->chip_info->calib_gain_setup_cb) {
+ ret = st->chip_info->calib_gain_setup_cb(indio_dev);
+ if (ret)
+ return ret;
+ }
+
indio_dev->channels = channels;
return 0;
@@ -1620,6 +1680,12 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
st->chip_info->sw_setup_cb(indio_dev);
}
+ if (st->sw_mode_en && st->chip_info->calib_gain_setup_cb) {
+ ret = ad7606_set_gain_calib(st);
+ if (ret)
+ return ret;
+ }
+
return devm_iio_device_register(dev, indio_dev);
}
EXPORT_SYMBOL_NS_GPL(ad7606_probe, "IIO_AD7606");
diff --git a/drivers/iio/adc/ad7606.h b/drivers/iio/adc/ad7606.h
index f613583a7fa4095115b0b28e3f8e51cd32b93524..a5b0d318e2f4d73d3708288536e807957c5de68c 100644
--- a/drivers/iio/adc/ad7606.h
+++ b/drivers/iio/adc/ad7606.h
@@ -50,6 +50,7 @@ struct ad7606_state;
typedef int (*ad7606_scale_setup_cb_t)(struct iio_dev *indio_dev,
struct iio_chan_spec *chan);
typedef int (*ad7606_sw_setup_cb_t)(struct iio_dev *indio_dev);
+typedef int (*ad7606_calib_gain_setup_cb_t)(struct iio_dev *indio_dev);
/**
* struct ad7606_chip_info - chip specific information
@@ -66,6 +67,7 @@ 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_gain_setup_cb: callback to setup of gain calibration
* @calib_offset_avail: pointer to offset calibration range/limits array
* @calib_phase_avail: pointer to phase calibration range/limits array
*/
@@ -81,6 +83,7 @@ struct ad7606_chip_info {
bool os_req_reset;
unsigned long init_delay_ms;
u8 offload_storagebits;
+ ad7606_calib_gain_setup_cb_t calib_gain_setup_cb;
const int *calib_offset_avail;
const int (*calib_phase_avail)[2];
};
@@ -131,6 +134,7 @@ struct ad7606_chan_scale {
* @data: buffer for reading data from the device
* @offload_en: SPI offload enabled
* @bus_data: bus-specific variables
+ * @r_gain: array to store gain calibration resistor value in ohm
* @d16: be16 buffer for reading data from the device
*/
struct ad7606_state {
@@ -161,6 +165,8 @@ struct ad7606_state {
bool offload_en;
void *bus_data;
+ int r_gain[AD760X_MAX_CHANNELS];
+
/*
* DMA (thus cache coherency maintenance) may require the
* transfer buffers to live in their own cache lines.
--
2.49.0
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