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Message-Id: <20250508-wip-bl-ad7606-calibration-v4-5-91a3f2837e6b@baylibre.com>
Date: Thu, 08 May 2025 12:06:09 +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 v4 5/5] 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 | 61 ++++++++++++++++++++++++++++++++++++++++++++++++
drivers/iio/adc/ad7606.h | 3 +++
2 files changed, 64 insertions(+)
diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
index a986eb1284106da4980ac36cb0b5990e4e3bd948..be86e14ba85d07398e870ad680764958aa6ef471 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,
};
@@ -357,6 +365,52 @@ 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;
+
+ /*
+ * This function is called once, and parses all the channel nodes,
+ * so continuing on next channel node on errors, informing of them.
+ */
+ device_for_each_child_node_scoped(dev, child) {
+ u32 reg, r_gain;
+
+ ret = fwnode_property_read_u32(child, "reg", ®);
+ if (ret)
+ continue;
+
+ /* Chan reg is a 1-based index. */
+ if (reg < 1 || reg > num_channels) {
+ dev_warn(dev, "wrong ch number (ignoring): %d\n", reg);
+ continue;
+ }
+
+ ret = fwnode_property_read_u32(child, "adi,rfilter-ohms",
+ &r_gain);
+ if (ret)
+ /* Keep the default register value. */
+ continue;
+
+ if (r_gain > AD7606_CALIB_GAIN_MAX) {
+ dev_warn(dev, "wrong gain calibration value");
+ continue;
+ }
+
+ ret = st->bops->reg_write(st, AD7606_CALIB_GAIN(reg - 1),
+ DIV_ROUND_CLOSEST(r_gain, AD7606_CALIB_GAIN_STEP));
+ if (ret) {
+ dev_warn(dev, "error writing r_gain");
+ continue;
+ }
+ }
+
+ return 0;
+}
+
static int ad7606c_18bit_chan_scale_setup(struct iio_dev *indio_dev,
struct iio_chan_spec *chan)
{
@@ -1448,6 +1502,13 @@ static int ad7606_probe_channels(struct iio_dev *indio_dev)
if (slow_bus)
channels[i] = (struct iio_chan_spec)IIO_CHAN_SOFT_TIMESTAMP(i);
+ /* Setting up gain calibration for all channels. */
+ if (st->sw_mode_en && st->chip_info->calib_offset_avail) {
+ ret = st->chip_info->calib_gain_setup_cb(indio_dev);
+ if (ret)
+ return ret;
+ }
+
indio_dev->channels = channels;
return 0;
diff --git a/drivers/iio/adc/ad7606.h b/drivers/iio/adc/ad7606.h
index f613583a7fa4095115b0b28e3f8e51cd32b93524..6313eea2bd0ccf97222a50dc26d8ec65042d0db7 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];
};
--
2.49.0
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