[PATCH v5 0/3] Add support for AD7191

[PATCH v5 0/3] Add support for AD7191

[Alisa-Dariana Roman]

Thank you all for your feedback! Here is the updated series of patches!

Kind regards,
Alisa-Dariana Roman.

---

v4: https://lore.kernel.org/all/20250203133254.313106-1-alisa.roman@analog.com/

v4 -> v5:
	- use static arrays in the ad7191_config_setup function, instead of keeping
them in the state structure
	- added error checking for devicetree parsing of pga-value and odr-value
	- for now, it doesn't return error when the index corresponding to pga-value
or odr-value doesn't match, since index is initialized to 0, so it will use the
first value in this case (the bindings constrain the possbile values for these
2 properties, so I thought it's ok like this)
	- use gpiod_multi_set_value_cansleep()
	- move sampling frequency attribute to mask separate (the avail unmodified)
	- removed unused argument form ad7191_setup()
	- removed 2 redundant sections from docs, and renamed one to Devicetree
	- add ad7191.rst to MAINTAINERS

v3: https://lore.kernel.org/all/20250129143054.225322-1-alisa.roman@analog.com/

v3 -> v4:
	- addressed all replies for v3
	- refactored the scale and sampling frequencies configurations to use 2
different arrays for gpio case vs pinstrap case

v2: https://lore.kernel.org/all/20250122132821.126600-1-alisa.roman@analog.com/

v2 -> v3:
	- correct binding title
	- remove clksel_state and clksel_gpio, assume the clksel pin is always
pinstrapped
	- rephrase clocks description accordingly
	- simplify binding constraints
	- specify in binding description that PDOWN must be connected to SPI's
controller's CS
	- add minItems for gpios in bindings
	- make scope explicit for mutex guard
	- remove spi irq check
	- add id_table to spi_driver struct
	- changed comments as suggested
	- use spi_message_init_with_transfers()
	- default returns an error in ad7191_set_mode()
	- replace hard-coded 2 with st->pga_gpios->ndescs
	- use gpiod_set_array_value_cansleep()
	- change .storagebits to 32
	- check return value for ad_sd_init()
	- change to adi,odr-value and adi,pga-value, which now accepts the value as
suggested
	- modify variables names and refactor the setup of odr and pga gpios,
indexes and available arrays into ad7191_config_setup(), since they are all
related
	- add ad7191.rst

v1: https://lore.kernel.org/all/20241221155926.81954-1-alisa.roman@analog.com/

v1 -> v2:
	- removed patch adding function in ad_sigma_delta.h/.c
	- added a function set_cs() for asserting/deasserting the cs
	- handle pinstrapping cases
	- refactored all clock handling
	- updated bindings: corrected and added new things
	- -> address of the channels is used in set_channel()
	- addressed all the other changes

[PATCH v5 1/3] dt-bindings: iio: adc: add AD7191

[Alisa-Dariana Roman]

AD7191 is a pin-programmable, ultra-low noise 24-bit sigma-delta ADC
designed for precision bridge sensor measurements. It features two
differential analog input channels, selectable output rates,
programmable gain, internal temperature sensor and simultaneous
50Hz/60Hz rejection.

Signed-off-by: Alisa-Dariana Roman <alisa.roman@analog.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
---
 .../bindings/iio/adc/adi,ad7191.yaml          | 149 ++++++++++++++++++
 MAINTAINERS                                   |   7 +
 2 files changed, 156 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad7191.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7191.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7191.yaml
new file mode 100644
index 000000000000..801ed319ee82
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7191.yaml
@@ -0,0 +1,149 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+# Copyright 2025 Analog Devices Inc.
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/adi,ad7191.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices AD7191 ADC
+
+maintainers:
+  - Alisa-Dariana Roman <alisa.roman@analog.com>
+
+description: |
+  Bindings for the Analog Devices AD7191 ADC device. Datasheet can be
+  found here:
+  https://www.analog.com/media/en/technical-documentation/data-sheets/AD7191.pdf
+  The device's PDOWN pin must be connected to the SPI controller's chip select
+  pin.
+
+properties:
+  compatible:
+    enum:
+      - adi,ad7191
+
+  reg:
+    maxItems: 1
+
+  spi-cpol: true
+
+  spi-cpha: true
+
+  clocks:
+    maxItems: 1
+    description:
+      Must be present when CLKSEL pin is tied HIGH to select external clock
+      source (either a crystal between MCLK1 and MCLK2 pins, or a
+      CMOS-compatible clock driving MCLK2 pin). Must be absent when CLKSEL pin
+      is tied LOW to use the internal 4.92MHz clock.
+
+  interrupts:
+    maxItems: 1
+
+  avdd-supply:
+    description: AVdd voltage supply
+
+  dvdd-supply:
+    description: DVdd voltage supply
+
+  vref-supply:
+    description: Vref voltage supply
+
+  odr-gpios:
+    description:
+      ODR1 and ODR2 pins for output data rate selection. Should be defined if
+      adi,odr-value is absent.
+    minItems: 2
+    maxItems: 2
+
+  adi,odr-value:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: |
+      Should be present if ODR pins are pin-strapped. Possible values:
+      120 Hz (ODR1=0, ODR2=0)
+      60 Hz (ODR1=0, ODR2=1)
+      50 Hz (ODR1=1, ODR2=0)
+      10 Hz (ODR1=1, ODR2=1)
+      If defined, odr-gpios must be absent.
+    enum: [120, 60, 50, 10]
+
+  pga-gpios:
+    description:
+      PGA1 and PGA2 pins for gain selection. Should be defined if adi,pga-value
+      is absent.
+    minItems: 2
+    maxItems: 2
+
+  adi,pga-value:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: |
+      Should be present if PGA pins are pin-strapped. Possible values:
+      Gain 1 (PGA1=0, PGA2=0)
+      Gain 8 (PGA1=0, PGA2=1)
+      Gain 64 (PGA1=1, PGA2=0)
+      Gain 128 (PGA1=1, PGA2=1)
+      If defined, pga-gpios must be absent.
+    enum: [1, 8, 64, 128]
+
+  temp-gpios:
+    description: TEMP pin for temperature sensor enable.
+    maxItems: 1
+
+  chan-gpios:
+    description: CHAN pin for input channel selection.
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - avdd-supply
+  - dvdd-supply
+  - vref-supply
+  - spi-cpol
+  - spi-cpha
+  - temp-gpios
+  - chan-gpios
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+  - oneOf:
+      - required:
+          - adi,odr-value
+      - required:
+          - odr-gpios
+  - oneOf:
+      - required:
+          - adi,pga-value
+      - required:
+          - pga-gpios
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@0 {
+            compatible = "adi,ad7191";
+            reg = <0>;
+            spi-max-frequency = <1000000>;
+            spi-cpol;
+            spi-cpha;
+            clocks = <&ad7191_mclk>;
+            interrupts = <25 IRQ_TYPE_EDGE_FALLING>;
+            interrupt-parent = <&gpio>;
+            avdd-supply = <&avdd>;
+            dvdd-supply = <&dvdd>;
+            vref-supply = <&vref>;
+            adi,pga-value = <1>;
+            odr-gpios = <&gpio 23 GPIO_ACTIVE_HIGH>, <&gpio 24 GPIO_ACTIVE_HIGH>;
+            temp-gpios = <&gpio 22 GPIO_ACTIVE_HIGH>;
+            chan-gpios = <&gpio 27 GPIO_ACTIVE_HIGH>;
+        };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index bd04375ab4a2..ac1f61256932 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1346,6 +1346,13 @@ W:	http://ez.analog.com/community/linux-device-drivers
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad7091r*
 F:	drivers/iio/adc/ad7091r*
 
+ANALOG DEVICES INC AD7191 DRIVER
+M:	Alisa-Dariana Roman <alisa.roman@analog.com>
+L:	linux-iio@vger.kernel.org
+S:	Supported
+W:	https://ez.analog.com/linux-software-drivers
+F:	Documentation/devicetree/bindings/iio/adc/adi,ad7191.yaml
+
 ANALOG DEVICES INC AD7192 DRIVER
 M:	Alisa-Dariana Roman <alisa.roman@analog.com>
 L:	linux-iio@vger.kernel.org
-- 
2.43.0

[PATCH v5 2/3] iio: adc: ad7191: add AD7191

[Alisa-Dariana Roman]

AD7191 is a pin-programmable, ultra-low noise 24-bit sigma-delta ADC
designed for precision bridge sensor measurements. It features two
differential analog input channels, selectable output rates,
programmable gain, internal temperature sensor and simultaneous
50Hz/60Hz rejection.

Signed-off-by: Alisa-Dariana Roman <alisa.roman@analog.com>
---
 MAINTAINERS              |   1 +
 drivers/iio/adc/Kconfig  |  10 +
 drivers/iio/adc/Makefile |   1 +
 drivers/iio/adc/ad7191.c | 553 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 565 insertions(+)
 create mode 100644 drivers/iio/adc/ad7191.c

diff --git a/MAINTAINERS b/MAINTAINERS
index ac1f61256932..87c491975ced 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1352,6 +1352,7 @@ L:	linux-iio@vger.kernel.org
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad7191.yaml
+F:	drivers/iio/adc/ad7191.c
 
 ANALOG DEVICES INC AD7192 DRIVER
 M:	Alisa-Dariana Roman <alisa.roman@analog.com>
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 27413516216c..b7ae6e0ae0df 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -142,6 +142,16 @@ config AD7173
 	  To compile this driver as a module, choose M here: the module will be
 	  called ad7173.
 
+config AD7191
+	tristate "Analog Devices AD7191 ADC driver"
+	depends on SPI
+	select AD_SIGMA_DELTA
+	help
+	  Say yes here to build support for Analog Devices AD7191.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ad7191.
+
 config AD7192
 	tristate "Analog Devices AD7192 and similar ADC driver"
 	depends on SPI
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 9f26d5eca822..3e918c3eec69 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_AD7091R5) += ad7091r5.o
 obj-$(CONFIG_AD7091R8) += ad7091r8.o
 obj-$(CONFIG_AD7124) += ad7124.o
 obj-$(CONFIG_AD7173) += ad7173.o
+obj-$(CONFIG_AD7191) += ad7191.o
 obj-$(CONFIG_AD7192) += ad7192.o
 obj-$(CONFIG_AD7266) += ad7266.o
 obj-$(CONFIG_AD7280) += ad7280a.o
diff --git a/drivers/iio/adc/ad7191.c b/drivers/iio/adc/ad7191.c
new file mode 100644
index 000000000000..f1eff7d095df
--- /dev/null
+++ b/drivers/iio/adc/ad7191.c
@@ -0,0 +1,553 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * AD7191 ADC driver
+ *
+ * Copyright 2025 Analog Devices Inc.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/mutex.h>
+#include <linux/property.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+#include <linux/types.h>
+#include <linux/units.h>
+
+#include <linux/iio/adc/ad_sigma_delta.h>
+#include <linux/iio/iio.h>
+
+#define ad_sigma_delta_to_ad7191(sigmad)	\
+	container_of((sigmad), struct ad7191_state, sd)
+
+#define AD7191_TEMP_CODES_PER_DEGREE	2815
+
+#define AD7191_EXT_CLK_ENABLE		0
+#define AD7191_INT_CLK_ENABLE		1
+
+#define AD7191_CHAN_MASK		BIT(0)
+#define AD7191_TEMP_MASK		BIT(1)
+
+enum ad7191_channel {
+	AD7191_CH_AIN1_AIN2,
+	AD7191_CH_AIN3_AIN4,
+	AD7191_CH_TEMP,
+};
+
+/*
+ * NOTE:
+ * The AD7191 features a dual-use data out ready DOUT/RDY output.
+ * In order to avoid contentions on the SPI bus, it's therefore necessary
+ * to use SPI bus locking.
+ *
+ * The DOUT/RDY output must also be wired to an interrupt-capable GPIO.
+ *
+ * The SPI controller's chip select must be connected to the PDOWN pin
+ * of the ADC. When CS (PDOWN) is high, it powers down the device and
+ * resets the internal circuitry.
+ */
+
+struct ad7191_state {
+	struct ad_sigma_delta		sd;
+	struct mutex			lock; /* Protect device state */
+
+	struct gpio_descs		*odr_gpios;
+	struct gpio_descs		*pga_gpios;
+	struct gpio_desc		*temp_gpio;
+	struct gpio_desc		*chan_gpio;
+
+	u16				int_vref_mv;
+	const u32			(*scale_avail)[2];
+	size_t				scale_avail_size;
+	u32				scale_index;
+	const u32			*samp_freq_avail;
+	size_t				samp_freq_avail_size;
+	u32				samp_freq_index;
+
+	struct clk			*mclk;
+};
+
+static int ad7191_set_channel(struct ad_sigma_delta *sd, unsigned int address)
+{
+	struct ad7191_state *st = ad_sigma_delta_to_ad7191(sd);
+	u8 temp_gpio_val, chan_gpio_val;
+
+	if (!FIELD_FIT(AD7191_CHAN_MASK | AD7191_TEMP_MASK, address))
+		return -EINVAL;
+
+	chan_gpio_val = FIELD_GET(AD7191_CHAN_MASK, address);
+	temp_gpio_val = FIELD_GET(AD7191_TEMP_MASK, address);
+
+	gpiod_set_value(st->chan_gpio, chan_gpio_val);
+	gpiod_set_value(st->temp_gpio, temp_gpio_val);
+
+	return 0;
+}
+
+static int ad7191_set_cs(struct ad_sigma_delta *sigma_delta, int assert)
+{
+	struct spi_transfer t = {
+		.len = 0,
+		.cs_change = assert,
+	};
+	struct spi_message m;
+
+	spi_message_init_with_transfers(&m, &t, 1);
+
+	return spi_sync_locked(sigma_delta->spi, &m);
+}
+
+static int ad7191_set_mode(struct ad_sigma_delta *sd,
+			   enum ad_sigma_delta_mode mode)
+{
+	struct ad7191_state *st = ad_sigma_delta_to_ad7191(sd);
+
+	switch (mode) {
+	case AD_SD_MODE_CONTINUOUS:
+	case AD_SD_MODE_SINGLE:
+		return ad7191_set_cs(&st->sd, 1);
+	case AD_SD_MODE_IDLE:
+		return ad7191_set_cs(&st->sd, 0);
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct ad_sigma_delta_info ad7191_sigma_delta_info = {
+	.set_channel = ad7191_set_channel,
+	.set_mode = ad7191_set_mode,
+	.has_registers = false,
+};
+
+static int ad7191_init_regulators(struct iio_dev *indio_dev)
+{
+	struct ad7191_state *st = iio_priv(indio_dev);
+	struct device *dev = &st->sd.spi->dev;
+	int ret;
+
+	ret = devm_regulator_get_enable(dev, "avdd");
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to enable specified AVdd supply\n");
+
+	ret = devm_regulator_get_enable(dev, "dvdd");
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to enable specified DVdd supply\n");
+
+	ret = devm_regulator_get_enable_read_voltage(dev, "vref");
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to get Vref voltage\n");
+
+	st->int_vref_mv = ret / 1000;
+
+	return 0;
+}
+
+static int ad7191_config_setup(struct iio_dev *indio_dev)
+{
+	struct ad7191_state *st = iio_priv(indio_dev);
+	struct device *dev = &st->sd.spi->dev;
+	/* Sampling frequencies in Hz, see Table 5 */
+	static const u32 samp_freq[4] = { 120, 60, 50, 10 };
+	/* Gain options, see Table 7 */
+	const u32 gain[4] = { 1, 8, 64, 128 };
+	static u32 scale_buffer[4][2];
+	int odr_value, odr_index, pga_value, pga_index, i, ret;
+	u64 scale_uv;
+
+	st->samp_freq_index = 0;
+	st->scale_index = 0;
+
+	ret = device_property_read_u32(dev, "adi,odr-value", &odr_value);
+	if (ret && ret != -EINVAL)
+		return dev_err_probe(dev, ret, "Failed to get odr value.\n");
+
+	if (ret == -EINVAL) {
+		st->odr_gpios = devm_gpiod_get_array(dev, "odr", GPIOD_OUT_LOW);
+		if (IS_ERR(st->odr_gpios))
+			return dev_err_probe(dev, PTR_ERR(st->odr_gpios),
+					     "Failed to get odr gpios.\n");
+
+		st->samp_freq_avail = samp_freq;
+		st->samp_freq_avail_size = ARRAY_SIZE(samp_freq);
+	} else {
+		for (i = 0; i < ARRAY_SIZE(samp_freq); i++) {
+			if (odr_value != samp_freq[i])
+				continue;
+			odr_index = i;
+			break;
+		}
+
+		st->samp_freq_avail = &samp_freq[odr_index];
+		st->samp_freq_avail_size = 1;
+
+		st->odr_gpios = NULL;
+	}
+
+	mutex_lock(&st->lock);
+
+	for (i = 0; i < ARRAY_SIZE(scale_buffer); i++) {
+		scale_uv = ((u64)st->int_vref_mv * NANO) >>
+			(indio_dev->channels[0].scan_type.realbits - 1);
+		do_div(scale_uv, gain[i]);
+		scale_buffer[i][1] = do_div(scale_uv, NANO);
+		scale_buffer[i][0] = scale_uv;
+	}
+
+	mutex_unlock(&st->lock);
+
+	ret = device_property_read_u32(dev, "adi,pga-value", &pga_value);
+	if (ret && ret != -EINVAL)
+		return dev_err_probe(dev, ret, "Failed to get pga value.\n");
+
+	if (ret == -EINVAL) {
+		st->pga_gpios = devm_gpiod_get_array(dev, "pga", GPIOD_OUT_LOW);
+		if (IS_ERR(st->pga_gpios))
+			return dev_err_probe(dev, PTR_ERR(st->pga_gpios),
+					     "Failed to get pga gpios.\n");
+
+		st->scale_avail = scale_buffer;
+		st->scale_avail_size = ARRAY_SIZE(scale_buffer);
+	} else {
+		for (i = 0; i < ARRAY_SIZE(gain); i++) {
+			if (pga_value != gain[i])
+				continue;
+			pga_index = i;
+			break;
+		}
+
+		st->scale_avail = &scale_buffer[pga_index];
+		st->scale_avail_size = 1;
+
+		st->pga_gpios = NULL;
+	}
+
+	st->temp_gpio = devm_gpiod_get(dev, "temp", GPIOD_OUT_LOW);
+	if (IS_ERR(st->temp_gpio))
+		return dev_err_probe(dev, PTR_ERR(st->temp_gpio),
+				     "Failed to get temp gpio.\n");
+
+	st->chan_gpio = devm_gpiod_get(dev, "chan", GPIOD_OUT_LOW);
+	if (IS_ERR(st->chan_gpio))
+		return dev_err_probe(dev, PTR_ERR(st->chan_gpio),
+				     "Failed to get chan gpio.\n");
+
+	return 0;
+}
+
+static int ad7191_clock_setup(struct ad7191_state *st)
+{
+	struct device *dev = &st->sd.spi->dev;
+
+	st->mclk = devm_clk_get_optional_enabled(dev, "mclk");
+	if (IS_ERR(st->mclk))
+		return dev_err_probe(dev, PTR_ERR(st->mclk),
+				     "Failed to get mclk.\n");
+
+	return 0;
+}
+
+static int ad7191_setup(struct iio_dev *indio_dev)
+{
+	struct ad7191_state *st = iio_priv(indio_dev);
+	int ret;
+
+	ret = ad7191_init_regulators(indio_dev);
+	if (ret)
+		return ret;
+
+	ret = ad7191_config_setup(indio_dev);
+	if (ret)
+		return ret;
+
+	return ad7191_clock_setup(st);
+}
+
+static int ad7191_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan, int *val,
+			   int *val2, long m)
+{
+	struct ad7191_state *st = iio_priv(indio_dev);
+
+	switch (m) {
+	case IIO_CHAN_INFO_RAW:
+		return ad_sigma_delta_single_conversion(indio_dev, chan, val);
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_VOLTAGE: {
+			guard(mutex)(&st->lock);
+			*val = st->scale_avail[st->scale_index][0];
+			*val2 = st->scale_avail[st->scale_index][1];
+			return IIO_VAL_INT_PLUS_NANO;
+		}
+		case IIO_TEMP:
+			*val = 0;
+			*val2 = NANO / AD7191_TEMP_CODES_PER_DEGREE;
+			return IIO_VAL_INT_PLUS_NANO;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_OFFSET:
+		*val = -(1 << (chan->scan_type.realbits - 1));
+		switch (chan->type) {
+		case IIO_VOLTAGE:
+			return IIO_VAL_INT;
+		case IIO_TEMP:
+			*val -= 273 * AD7191_TEMP_CODES_PER_DEGREE;
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = st->samp_freq_avail[st->samp_freq_index];
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad7191_set_gain(struct ad7191_state *st, int gain_index)
+{
+	unsigned long value = gain_index;
+
+	st->scale_index = gain_index;
+
+	return gpiod_multi_set_value_cansleep(st->pga_gpios, &value);
+}
+
+static int ad7191_set_samp_freq(struct ad7191_state *st, int samp_freq_index)
+{
+	unsigned long value = samp_freq_index;
+
+	st->samp_freq_index = samp_freq_index;
+
+	return gpiod_multi_set_value_cansleep(st->odr_gpios, &value);
+}
+
+static int __ad7191_write_raw(struct ad7191_state *st,
+			      struct iio_chan_spec const *chan,
+			      int val, int val2, long mask)
+{
+	int i;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE: {
+		if (!st->pga_gpios)
+			return -EPERM;
+		guard(mutex)(&st->lock);
+		for (i = 0; i < st->scale_avail_size; i++) {
+			if (val2 != st->scale_avail[i][1])
+				continue;
+			return ad7191_set_gain(st, i);
+		}
+		return -EINVAL;
+	}
+	case IIO_CHAN_INFO_SAMP_FREQ: {
+		if (!st->odr_gpios)
+			return -EPERM;
+		guard(mutex)(&st->lock);
+		for (i = 0; i < st->samp_freq_avail_size; i++) {
+			if (val != st->samp_freq_avail[i])
+				continue;
+			return ad7191_set_samp_freq(st, i);
+		}
+		return -EINVAL;
+	}
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad7191_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan, int val, int val2,
+			    long mask)
+{
+	struct ad7191_state *st = iio_priv(indio_dev);
+	int ret;
+
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return ret;
+
+	ret = __ad7191_write_raw(st, chan, val, val2, mask);
+
+	iio_device_release_direct_mode(indio_dev);
+
+	return ret;
+}
+
+static int ad7191_write_raw_get_fmt(struct iio_dev *indio_dev,
+				    struct iio_chan_spec const *chan, long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		return IIO_VAL_INT_PLUS_NANO;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad7191_read_avail(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, const int **vals,
+			     int *type, int *length, long mask)
+{
+	struct ad7191_state *st = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		*vals = (int *)st->scale_avail;
+		*type = IIO_VAL_INT_PLUS_NANO;
+		*length = st->scale_avail_size * 2;
+		return IIO_AVAIL_LIST;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*vals = (int *)st->samp_freq_avail;
+		*type = IIO_VAL_INT;
+		*length = st->samp_freq_avail_size;
+		return IIO_AVAIL_LIST;
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_info ad7191_info = {
+	.read_raw = ad7191_read_raw,
+	.write_raw = ad7191_write_raw,
+	.write_raw_get_fmt = ad7191_write_raw_get_fmt,
+	.read_avail = ad7191_read_avail,
+	.validate_trigger = ad_sd_validate_trigger,
+};
+
+static const struct iio_chan_spec ad7191_channels[] = {
+	{
+		.type = IIO_TEMP,
+		.address = AD7191_CH_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_OFFSET) |
+				      BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 24,
+			.storagebits = 32,
+			.endianness = IIO_BE,
+		},
+	},
+	{
+		.type = IIO_VOLTAGE,
+		.differential = 1,
+		.indexed = 1,
+		.channel = 1,
+		.channel2 = 2,
+		.address = AD7191_CH_AIN1_AIN2,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_OFFSET) |
+				      BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = 1,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 24,
+			.storagebits = 32,
+			.endianness = IIO_BE,
+		},
+	},
+	{
+		.type = IIO_VOLTAGE,
+		.differential = 1,
+		.indexed = 1,
+		.channel = 3,
+		.channel2 = 4,
+		.address = AD7191_CH_AIN3_AIN4,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_OFFSET) |
+				      BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = 2,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 24,
+			.storagebits = 32,
+			.endianness = IIO_BE,
+		},
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(3),
+};
+
+static int ad7191_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct ad7191_state *st;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+
+	ret = devm_mutex_init(dev, &st->lock);
+	if (ret)
+		return ret;
+
+	indio_dev->name = "ad7191";
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = ad7191_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ad7191_channels);
+	indio_dev->info = &ad7191_info;
+
+	ret = ad_sd_init(&st->sd, indio_dev, spi, &ad7191_sigma_delta_info);
+	if (ret)
+		return ret;
+
+	ret = devm_ad_sd_setup_buffer_and_trigger(dev, indio_dev);
+	if (ret)
+		return ret;
+
+	ret = ad7191_setup(indio_dev);
+	if (ret)
+		return ret;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct of_device_id ad7191_of_match[] = {
+	{
+		.compatible = "adi,ad7191",
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ad7191_of_match);
+
+static const struct spi_device_id ad7191_id_table[] = {
+	{ "ad7191" },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, ad7191_id_table);
+
+static struct spi_driver ad7191_driver = {
+	.driver = {
+		.name = "ad7191",
+		.of_match_table = ad7191_of_match,
+	},
+	.probe = ad7191_probe,
+	.id_table = ad7191_id_table,
+};
+module_spi_driver(ad7191_driver);
+
+MODULE_AUTHOR("Alisa-Dariana Roman <alisa.roman@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD7191 ADC");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(IIO_AD_SIGMA_DELTA);
-- 
2.43.0

[PATCH v5 3/3] docs: iio: add AD7191

[Alisa-Dariana Roman]

Add documentation for AD7191 driver.

Signed-off-by: Alisa-Dariana Roman <alisa.roman@analog.com>
---
 Documentation/iio/ad7191.rst | 129 +++++++++++++++++++++++++++++++++++
 Documentation/iio/index.rst  |   1 +
 MAINTAINERS                  |   1 +
 3 files changed, 131 insertions(+)
 create mode 100644 Documentation/iio/ad7191.rst

diff --git a/Documentation/iio/ad7191.rst b/Documentation/iio/ad7191.rst
new file mode 100644
index 000000000000..6ab615ea457b
--- /dev/null
+++ b/Documentation/iio/ad7191.rst
@@ -0,0 +1,129 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+=============
+AD7191 driver
+=============
+
+Device driver for Analog Devices AD7191 ADC.
+
+=================
+Supported devices
+=================
+
+* `AD7191 <https://www.analog.com/AD7191>`_
+
+The AD7191 is a high precision, low noise, 24-bit Σ-Δ ADC with integrated PGA.
+It features two differential input channels, an internal temperature sensor, and
+configurable sampling rates.
+
+==========
+Devicetree
+==========
+
+-----------------
+Pin Configuration
+-----------------
+
+The driver supports both pin-strapped and GPIO-controlled configurations for ODR
+(Output Data Rate) and PGA (Programmable Gain Amplifier) settings. These
+configurations are mutually exclusive - you must use either pin-strapped or GPIO
+control for each setting, not both.
+
+^^^^^^^^^^^^^^^^^
+ODR Configuration
+^^^^^^^^^^^^^^^^^
+
+The ODR can be configured either through GPIO control or pin-strapping:
+
+- When using GPIO control, specify the "odr-gpios" property in the device tree
+- For pin-strapped configuration, specify the "adi,odr-value" property in the
+  device tree
+
+Available ODR settings:
+
+  - 120 Hz (ODR1=0, ODR2=0)
+  - 60 Hz (ODR1=0, ODR2=1)
+  - 50 Hz (ODR1=1, ODR2=0)
+  - 10 Hz (ODR1=1, ODR2=1)
+
+^^^^^^^^^^^^^^^^^
+PGA Configuration
+^^^^^^^^^^^^^^^^^
+
+The PGA can be configured either through GPIO control or pin-strapping:
+
+- When using GPIO control, specify the "pga-gpios" property in the device tree
+- For pin-strapped configuration, specify the "adi,pga-value" property in the
+  device tree
+
+Available PGA gain settings:
+
+  - 1x (PGA1=0, PGA2=0)
+  - 8x (PGA1=0, PGA2=1)
+  - 64x (PGA1=1, PGA2=0)
+  - 128x (PGA1=1, PGA2=1)
+
+-------------------
+Clock Configuration
+-------------------
+
+The AD7191 supports both internal and external clock sources:
+
+- When CLKSEL pin is tied LOW: Uses internal 4.92MHz clock (no clock property
+  needed)
+- When CLKSEL pin is tied HIGH: Requires external clock source
+  - Can be a crystal between MCLK1 and MCLK2 pins
+  - Or a CMOS-compatible clock driving MCLK2 pin
+  - Must specify the "clocks" property in device tree when using external clock
+
+--------------------------
+SPI Interface Requirements
+--------------------------
+
+The AD7191 has specific SPI interface requirements:
+
+- The DOUT/RDY output is dual-purpose and requires SPI bus locking
+- DOUT/RDY must be connected to an interrupt-capable GPIO
+- The SPI controller's chip select must be connected to the PDOWN pin of the ADC
+- When CS (PDOWN) is high, the device powers down and resets internal circuitry
+- SPI mode 3 operation (CPOL=1, CPHA=1) is required
+
+-------------------------
+Power Supply Requirements
+-------------------------
+
+The device requires the following power supplies:
+
+- AVdd: Analog power supply
+- DVdd: Digital power supply
+- Vref: Reference voltage supply (external)
+
+All power supplies must be specified in the device tree.
+
+=====================
+Channel Configuration
+=====================
+
+The device provides three channels:
+
+1. Temperature Sensor
+   - 24-bit unsigned
+   - Internal temperature measurement
+   - Temperature in millidegrees Celsius
+
+2. Differential Input (AIN1-AIN2)
+   - 24-bit unsigned
+   - Differential voltage measurement
+   - Configurable gain via PGA
+
+3. Differential Input (AIN3-AIN4)
+   - 24-bit unsigned
+   - Differential voltage measurement
+   - Configurable gain via PGA
+
+==============
+Buffer Support
+==============
+
+This driver supports IIO triggered buffers. See Documentation/iio/iio_devbuf.rst
+for more information about IIO triggered buffers.
diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst
index 2d334be2b7f2..edc984a38b3b 100644
--- a/Documentation/iio/index.rst
+++ b/Documentation/iio/index.rst
@@ -21,6 +21,7 @@ Industrial I/O Kernel Drivers
    ad4000
    ad4030
    ad4695
+   ad7191
    ad7380
    ad7606
    ad7625
diff --git a/MAINTAINERS b/MAINTAINERS
index 87c491975ced..0547a3bb528c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1352,6 +1352,7 @@ L:	linux-iio@vger.kernel.org
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad7191.yaml
+F:	Documentation/iio/ad7191.rst
 F:	drivers/iio/adc/ad7191.c
 
 ANALOG DEVICES INC AD7192 DRIVER
-- 
2.43.0

Re: [PATCH v5 2/3] iio: adc: ad7191: add AD7191

[David Lechner]

On 2/26/25 5:53 AM, Alisa-Dariana Roman wrote:
> AD7191 is a pin-programmable, ultra-low noise 24-bit sigma-delta ADC
> designed for precision bridge sensor measurements. It features two
> differential analog input channels, selectable output rates,
> programmable gain, internal temperature sensor and simultaneous
> 50Hz/60Hz rejection.
> 
> Signed-off-by: Alisa-Dariana Roman <alisa.roman@analog.com>
> ---
>  MAINTAINERS              |   1 +
>  drivers/iio/adc/Kconfig  |  10 +
>  drivers/iio/adc/Makefile |   1 +
>  drivers/iio/adc/ad7191.c | 553 +++++++++++++++++++++++++++++++++++++++
>  4 files changed, 565 insertions(+)
>  create mode 100644 drivers/iio/adc/ad7191.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index ac1f61256932..87c491975ced 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1352,6 +1352,7 @@ L:	linux-iio@vger.kernel.org
>  S:	Supported
>  W:	https://ez.analog.com/linux-software-drivers
>  F:	Documentation/devicetree/bindings/iio/adc/adi,ad7191.yaml
> +F:	drivers/iio/adc/ad7191.c
>  
>  ANALOG DEVICES INC AD7192 DRIVER
>  M:	Alisa-Dariana Roman <alisa.roman@analog.com>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 27413516216c..b7ae6e0ae0df 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -142,6 +142,16 @@ config AD7173
>  	  To compile this driver as a module, choose M here: the module will be
>  	  called ad7173.
>  
> +config AD7191
> +	tristate "Analog Devices AD7191 ADC driver"
> +	depends on SPI
> +	select AD_SIGMA_DELTA
> +	help
> +	  Say yes here to build support for Analog Devices AD7191.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called ad7191.
> +
>  config AD7192
>  	tristate "Analog Devices AD7192 and similar ADC driver"
>  	depends on SPI
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 9f26d5eca822..3e918c3eec69 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -16,6 +16,7 @@ obj-$(CONFIG_AD7091R5) += ad7091r5.o
>  obj-$(CONFIG_AD7091R8) += ad7091r8.o
>  obj-$(CONFIG_AD7124) += ad7124.o
>  obj-$(CONFIG_AD7173) += ad7173.o
> +obj-$(CONFIG_AD7191) += ad7191.o
>  obj-$(CONFIG_AD7192) += ad7192.o
>  obj-$(CONFIG_AD7266) += ad7266.o
>  obj-$(CONFIG_AD7280) += ad7280a.o
> diff --git a/drivers/iio/adc/ad7191.c b/drivers/iio/adc/ad7191.c
> new file mode 100644
> index 000000000000..f1eff7d095df
> --- /dev/null
> +++ b/drivers/iio/adc/ad7191.c
> @@ -0,0 +1,553 @@
> +// SPDX-License-Identifier: GPL-2.0

Prefer GPL-2.0-only or GPL-2.0-or-later depending on your intention.

> +/*
> + * AD7191 ADC driver
> + *
> + * Copyright 2025 Analog Devices Inc.
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/clk.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>

I think we tend to avoid including kernel.h since it includes way
more than we actually need.

> +#include <linux/mod_devicetable.h>
> +#include <linux/mutex.h>
> +#include <linux/property.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>
> +#include <linux/types.h>
> +#include <linux/units.h>
> +
> +#include <linux/iio/adc/ad_sigma_delta.h>
> +#include <linux/iio/iio.h>
> +
> +#define ad_sigma_delta_to_ad7191(sigmad)	\
> +	container_of((sigmad), struct ad7191_state, sd)
> +
> +#define AD7191_TEMP_CODES_PER_DEGREE	2815
> +
> +#define AD7191_EXT_CLK_ENABLE		0
> +#define AD7191_INT_CLK_ENABLE		1

Unused macros?

> +
> +#define AD7191_CHAN_MASK		BIT(0)
> +#define AD7191_TEMP_MASK		BIT(1)
> +
> +enum ad7191_channel {
> +	AD7191_CH_AIN1_AIN2,
> +	AD7191_CH_AIN3_AIN4,
> +	AD7191_CH_TEMP,
> +};
> +
> +/*
> + * NOTE:
> + * The AD7191 features a dual-use data out ready DOUT/RDY output.
> + * In order to avoid contentions on the SPI bus, it's therefore necessary
> + * to use SPI bus locking.
> + *
> + * The DOUT/RDY output must also be wired to an interrupt-capable GPIO.
> + *
> + * The SPI controller's chip select must be connected to the PDOWN pin
> + * of the ADC. When CS (PDOWN) is high, it powers down the device and
> + * resets the internal circuitry.
> + */
> +
> +struct ad7191_state {
> +	struct ad_sigma_delta		sd;
> +	struct mutex			lock; /* Protect device state */
> +
> +	struct gpio_descs		*odr_gpios;
> +	struct gpio_descs		*pga_gpios;
> +	struct gpio_desc		*temp_gpio;
> +	struct gpio_desc		*chan_gpio;
> +
> +	u16				int_vref_mv;
> +	const u32			(*scale_avail)[2];
> +	size_t				scale_avail_size;
> +	u32				scale_index;
> +	const u32			*samp_freq_avail;
> +	size_t				samp_freq_avail_size;
> +	u32				samp_freq_index;
> +
> +	struct clk			*mclk;
> +};
> +
> +static int ad7191_set_channel(struct ad_sigma_delta *sd, unsigned int address)
> +{
> +	struct ad7191_state *st = ad_sigma_delta_to_ad7191(sd);
> +	u8 temp_gpio_val, chan_gpio_val;
> +
> +	if (!FIELD_FIT(AD7191_CHAN_MASK | AD7191_TEMP_MASK, address))
> +		return -EINVAL;
> +
> +	chan_gpio_val = FIELD_GET(AD7191_CHAN_MASK, address);
> +	temp_gpio_val = FIELD_GET(AD7191_TEMP_MASK, address);
> +
> +	gpiod_set_value(st->chan_gpio, chan_gpio_val);
> +	gpiod_set_value(st->temp_gpio, temp_gpio_val);
> +
> +	return 0;
> +}
> +
> +static int ad7191_set_cs(struct ad_sigma_delta *sigma_delta, int assert)
> +{
> +	struct spi_transfer t = {
> +		.len = 0,
> +		.cs_change = assert,
> +	};
> +	struct spi_message m;
> +
> +	spi_message_init_with_transfers(&m, &t, 1);
> +
> +	return spi_sync_locked(sigma_delta->spi, &m);
> +}
> +
> +static int ad7191_set_mode(struct ad_sigma_delta *sd,
> +			   enum ad_sigma_delta_mode mode)
> +{
> +	struct ad7191_state *st = ad_sigma_delta_to_ad7191(sd);
> +
> +	switch (mode) {
> +	case AD_SD_MODE_CONTINUOUS:
> +	case AD_SD_MODE_SINGLE:
> +		return ad7191_set_cs(&st->sd, 1);
> +	case AD_SD_MODE_IDLE:
> +		return ad7191_set_cs(&st->sd, 0);
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct ad_sigma_delta_info ad7191_sigma_delta_info = {
> +	.set_channel = ad7191_set_channel,
> +	.set_mode = ad7191_set_mode,
> +	.has_registers = false,
> +};
> +
> +static int ad7191_init_regulators(struct iio_dev *indio_dev)
> +{
> +	struct ad7191_state *st = iio_priv(indio_dev);
> +	struct device *dev = &st->sd.spi->dev;
> +	int ret;
> +
> +	ret = devm_regulator_get_enable(dev, "avdd");
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to enable specified AVdd supply\n");
> +
> +	ret = devm_regulator_get_enable(dev, "dvdd");
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to enable specified DVdd supply\n");
> +
> +	ret = devm_regulator_get_enable_read_voltage(dev, "vref");
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "Failed to get Vref voltage\n");
> +
> +	st->int_vref_mv = ret / 1000;
> +
> +	return 0;
> +}
> +
> +static int ad7191_config_setup(struct iio_dev *indio_dev)
> +{
> +	struct ad7191_state *st = iio_priv(indio_dev);
> +	struct device *dev = &st->sd.spi->dev;
> +	/* Sampling frequencies in Hz, see Table 5 */
> +	static const u32 samp_freq[4] = { 120, 60, 50, 10 };
> +	/* Gain options, see Table 7 */
> +	const u32 gain[4] = { 1, 8, 64, 128 };
> +	static u32 scale_buffer[4][2];
> +	int odr_value, odr_index, pga_value, pga_index, i, ret;
> +	u64 scale_uv;
> +
> +	st->samp_freq_index = 0;
> +	st->scale_index = 0;
> +
> +	ret = device_property_read_u32(dev, "adi,odr-value", &odr_value);
> +	if (ret && ret != -EINVAL)
> +		return dev_err_probe(dev, ret, "Failed to get odr value.\n");
> +
> +	if (ret == -EINVAL) {
> +		st->odr_gpios = devm_gpiod_get_array(dev, "odr", GPIOD_OUT_LOW);
> +		if (IS_ERR(st->odr_gpios))
> +			return dev_err_probe(dev, PTR_ERR(st->odr_gpios),
> +					     "Failed to get odr gpios.\n");

Might also be worthwhile to check st->odr_gpios->ndescs to make sure we
have the right number.

> +
> +		st->samp_freq_avail = samp_freq;
> +		st->samp_freq_avail_size = ARRAY_SIZE(samp_freq);
> +	} else {
> +		for (i = 0; i < ARRAY_SIZE(samp_freq); i++) {
> +			if (odr_value != samp_freq[i])
> +				continue;
> +			odr_index = i;
> +			break;
> +		}
> +
> +		st->samp_freq_avail = &samp_freq[odr_index];
> +		st->samp_freq_avail_size = 1;
> +
> +		st->odr_gpios = NULL;
> +	}
> +
> +	mutex_lock(&st->lock);
> +
> +	for (i = 0; i < ARRAY_SIZE(scale_buffer); i++) {
> +		scale_uv = ((u64)st->int_vref_mv * NANO) >>
> +			(indio_dev->channels[0].scan_type.realbits - 1);
> +		do_div(scale_uv, gain[i]);
> +		scale_buffer[i][1] = do_div(scale_uv, NANO);
> +		scale_buffer[i][0] = scale_uv;

Just asthetics, but setting [0] before [1] seems more logical.

> +	}
> +
> +	mutex_unlock(&st->lock);
> +
> +	ret = device_property_read_u32(dev, "adi,pga-value", &pga_value);
> +	if (ret && ret != -EINVAL)
> +		return dev_err_probe(dev, ret, "Failed to get pga value.\n");
> +
> +	if (ret == -EINVAL) {
> +		st->pga_gpios = devm_gpiod_get_array(dev, "pga", GPIOD_OUT_LOW);
> +		if (IS_ERR(st->pga_gpios))
> +			return dev_err_probe(dev, PTR_ERR(st->pga_gpios),
> +					     "Failed to get pga gpios.\n");

Same comment about checking ndescs here.

> +
> +		st->scale_avail = scale_buffer;
> +		st->scale_avail_size = ARRAY_SIZE(scale_buffer);
> +	} else {
> +		for (i = 0; i < ARRAY_SIZE(gain); i++) {
> +			if (pga_value != gain[i])
> +				continue;
> +			pga_index = i;
> +			break;
> +		}
> +
> +		st->scale_avail = &scale_buffer[pga_index];
> +		st->scale_avail_size = 1;
> +
> +		st->pga_gpios = NULL;
> +	}
> +
> +	st->temp_gpio = devm_gpiod_get(dev, "temp", GPIOD_OUT_LOW);
> +	if (IS_ERR(st->temp_gpio))
> +		return dev_err_probe(dev, PTR_ERR(st->temp_gpio),
> +				     "Failed to get temp gpio.\n");
> +
> +	st->chan_gpio = devm_gpiod_get(dev, "chan", GPIOD_OUT_LOW);
> +	if (IS_ERR(st->chan_gpio))
> +		return dev_err_probe(dev, PTR_ERR(st->chan_gpio),
> +				     "Failed to get chan gpio.\n");
> +
> +	return 0;
> +}
> +
> +static int ad7191_clock_setup(struct ad7191_state *st)
> +{
> +	struct device *dev = &st->sd.spi->dev;
> +
> +	st->mclk = devm_clk_get_optional_enabled(dev, "mclk");
> +	if (IS_ERR(st->mclk))
> +		return dev_err_probe(dev, PTR_ERR(st->mclk),
> +				     "Failed to get mclk.\n");
> +
> +	return 0;
> +}
> +
> +static int ad7191_setup(struct iio_dev *indio_dev)
> +{
> +	struct ad7191_state *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	ret = ad7191_init_regulators(indio_dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = ad7191_config_setup(indio_dev);
> +	if (ret)
> +		return ret;
> +
> +	return ad7191_clock_setup(st);
> +}
> +
> +static int ad7191_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan, int *val,
> +			   int *val2, long m)
> +{
> +	struct ad7191_state *st = iio_priv(indio_dev);
> +
> +	switch (m) {
> +	case IIO_CHAN_INFO_RAW:
> +		return ad_sigma_delta_single_conversion(indio_dev, chan, val);
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->type) {
> +		case IIO_VOLTAGE: {
> +			guard(mutex)(&st->lock);

I don't think the mutex helps here. The caller receives pointers to
these arrays and uses them _after_ this function returns so the mutex
will no longer be held while the arrays are actually being used.

As long as st->scale_avail is filled in during probe and never changes
after probe, we should not need to worry about any locking, so I think
it is OK to just drop the mutex from the driver.

> +			*val = st->scale_avail[st->scale_index][0];
> +			*val2 = st->scale_avail[st->scale_index][1];
> +			return IIO_VAL_INT_PLUS_NANO;
> +		}
> +		case IIO_TEMP:
> +			*val = 0;
> +			*val2 = NANO / AD7191_TEMP_CODES_PER_DEGREE;
> +			return IIO_VAL_INT_PLUS_NANO;
> +		default:
> +			return -EINVAL;
> +		}
> +	case IIO_CHAN_INFO_OFFSET:
> +		*val = -(1 << (chan->scan_type.realbits - 1));
> +		switch (chan->type) {
> +		case IIO_VOLTAGE:
> +			return IIO_VAL_INT;
> +		case IIO_TEMP:
> +			*val -= 273 * AD7191_TEMP_CODES_PER_DEGREE;
> +			return IIO_VAL_INT;
> +		default:
> +			return -EINVAL;
> +		}
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		*val = st->samp_freq_avail[st->samp_freq_index];
> +		return IIO_VAL_INT;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int ad7191_set_gain(struct ad7191_state *st, int gain_index)
> +{
> +	unsigned long value = gain_index;

Maybe a bit better style to not rely on implementation detail of bitmaps.
This can be replaced with:

	DECLARE_BITMAP(bitmap, 2) = { };

	bitmap_write(bitmap, gain_index, 0, 2);

> +
> +	st->scale_index = gain_index;
> +
> +	return gpiod_multi_set_value_cansleep(st->pga_gpios, &value);

	return gpiod_multi_set_value_cansleep(st->pga_gpios, bitmap);

> +}
> +
> +static int ad7191_set_samp_freq(struct ad7191_state *st, int samp_freq_index)
> +{
> +	unsigned long value = samp_freq_index;

ditto

> +
> +	st->samp_freq_index = samp_freq_index;
> +
> +	return gpiod_multi_set_value_cansleep(st->odr_gpios, &value);
> +}
> +
> +static int __ad7191_write_raw(struct ad7191_state *st,
> +			      struct iio_chan_spec const *chan,
> +			      int val, int val2, long mask)
> +{
> +	int i;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE: {
> +		if (!st->pga_gpios)
> +			return -EPERM;
> +		guard(mutex)(&st->lock);
> +		for (i = 0; i < st->scale_avail_size; i++) {
> +			if (val2 != st->scale_avail[i][1])
> +				continue;
> +			return ad7191_set_gain(st, i);

Could save a line by inverting the if and dropping the continue.

> +		}
> +		return -EINVAL;
> +	}
> +	case IIO_CHAN_INFO_SAMP_FREQ: {
> +		if (!st->odr_gpios)
> +			return -EPERM;
> +		guard(mutex)(&st->lock);
> +		for (i = 0; i < st->samp_freq_avail_size; i++) {
> +			if (val != st->samp_freq_avail[i])
> +				continue;
> +			return ad7191_set_samp_freq(st, i);
> +		}
> +		return -EINVAL;
> +	}
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int ad7191_write_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan, int val, int val2,
> +			    long mask)
> +{
> +	struct ad7191_state *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	ret = iio_device_claim_direct_mode(indio_dev);
> +	if (ret)
> +		return ret;

Jonathan's mass changes are in the togreg branch now, so we can do
the "new" way that works better with static checkers:

	if (!iio_device_claim_direct(indio_dev))
		return -EBUSY;

> +
> +	ret = __ad7191_write_raw(st, chan, val, val2, mask);
> +
> +	iio_device_release_direct_mode(indio_dev);

	iio_device_release_direct(indio_dev);

> +
> +	return ret;
> +}
> +
> +static int ad7191_write_raw_get_fmt(struct iio_dev *indio_dev,
> +				    struct iio_chan_spec const *chan, long mask)
> +{
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE:
> +		return IIO_VAL_INT_PLUS_NANO;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		return IIO_VAL_INT;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int ad7191_read_avail(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan, const int **vals,
> +			     int *type, int *length, long mask)
> +{
> +	struct ad7191_state *st = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE:
> +		*vals = (int *)st->scale_avail;
> +		*type = IIO_VAL_INT_PLUS_NANO;
> +		*length = st->scale_avail_size * 2;
> +		return IIO_AVAIL_LIST;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		*vals = (int *)st->samp_freq_avail;
> +		*type = IIO_VAL_INT;
> +		*length = st->samp_freq_avail_size;
> +		return IIO_AVAIL_LIST;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info ad7191_info = {
> +	.read_raw = ad7191_read_raw,
> +	.write_raw = ad7191_write_raw,
> +	.write_raw_get_fmt = ad7191_write_raw_get_fmt,
> +	.read_avail = ad7191_read_avail,
> +	.validate_trigger = ad_sd_validate_trigger,
> +};
> +
> +static const struct iio_chan_spec ad7191_channels[] = {
> +	{
> +		.type = IIO_TEMP,
> +		.address = AD7191_CH_TEMP,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_OFFSET) |
> +				      BIT(IIO_CHAN_INFO_SAMP_FREQ),
> +		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
> +		.scan_type = {
> +			.sign = 'u',
> +			.realbits = 24,
> +			.storagebits = 32,
> +			.endianness = IIO_BE,
> +		},
> +	},
> +	{
> +		.type = IIO_VOLTAGE,
> +		.differential = 1,
> +		.indexed = 1,
> +		.channel = 1,
> +		.channel2 = 2,
> +		.address = AD7191_CH_AIN1_AIN2,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_OFFSET) |
> +				      BIT(IIO_CHAN_INFO_SAMP_FREQ),
> +		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
> +		.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SCALE),
> +		.scan_index = 1,
> +		.scan_type = {
> +			.sign = 'u',
> +			.realbits = 24,
> +			.storagebits = 32,
> +			.endianness = IIO_BE,
> +		},
> +	},
> +	{
> +		.type = IIO_VOLTAGE,
> +		.differential = 1,
> +		.indexed = 1,
> +		.channel = 3,
> +		.channel2 = 4,
> +		.address = AD7191_CH_AIN3_AIN4,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_OFFSET) |
> +				      BIT(IIO_CHAN_INFO_SAMP_FREQ),
> +		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
> +		.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SCALE),
> +		.scan_index = 2,
> +		.scan_type = {
> +			.sign = 'u',
> +			.realbits = 24,
> +			.storagebits = 32,
> +			.endianness = IIO_BE,
> +		},
> +	},
> +	IIO_CHAN_SOFT_TIMESTAMP(3),
> +};
> +
> +static int ad7191_probe(struct spi_device *spi)
> +{
> +	struct device *dev = &spi->dev;
> +	struct ad7191_state *st;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +
> +	ret = devm_mutex_init(dev, &st->lock);
> +	if (ret)
> +		return ret;
> +
> +	indio_dev->name = "ad7191";
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = ad7191_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(ad7191_channels);
> +	indio_dev->info = &ad7191_info;
> +
> +	ret = ad_sd_init(&st->sd, indio_dev, spi, &ad7191_sigma_delta_info);
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_ad_sd_setup_buffer_and_trigger(dev, indio_dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = ad7191_setup(indio_dev);
> +	if (ret)
> +		return ret;
> +
> +	return devm_iio_device_register(dev, indio_dev);
> +}
> +
> +static const struct of_device_id ad7191_of_match[] = {
> +	{
> +		.compatible = "adi,ad7191",
> +	},

This could fit on one line.

> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, ad7191_of_match);
> +
> +static const struct spi_device_id ad7191_id_table[] = {
> +	{ "ad7191" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(spi, ad7191_id_table);
> +
> +static struct spi_driver ad7191_driver = {
> +	.driver = {
> +		.name = "ad7191",
> +		.of_match_table = ad7191_of_match,
> +	},
> +	.probe = ad7191_probe,
> +	.id_table = ad7191_id_table,
> +};
> +module_spi_driver(ad7191_driver);
> +
> +MODULE_AUTHOR("Alisa-Dariana Roman <alisa.roman@analog.com>");
> +MODULE_DESCRIPTION("Analog Devices AD7191 ADC");
> +MODULE_LICENSE("GPL");
> +MODULE_IMPORT_NS(IIO_AD_SIGMA_DELTA);

Re: [PATCH v5 3/3] docs: iio: add AD7191

[David Lechner]

On 2/26/25 5:53 AM, Alisa-Dariana Roman wrote:
> Add documentation for AD7191 driver.
> 
> Signed-off-by: Alisa-Dariana Roman <alisa.roman@analog.com>
> ---
>  Documentation/iio/ad7191.rst | 129 +++++++++++++++++++++++++++++++++++
>  Documentation/iio/index.rst  |   1 +
>  MAINTAINERS                  |   1 +
>  3 files changed, 131 insertions(+)
>  create mode 100644 Documentation/iio/ad7191.rst
> 
> diff --git a/Documentation/iio/ad7191.rst b/Documentation/iio/ad7191.rst
> new file mode 100644
> index 000000000000..6ab615ea457b
> --- /dev/null
> +++ b/Documentation/iio/ad7191.rst
> @@ -0,0 +1,129 @@
> +.. SPDX-License-Identifier: GPL-2.0-only
> +
> +=============
> +AD7191 driver
> +=============

In .rst, the page title really should be a different heading level
from the rest of the section headings on the page.

> +
> +Device driver for Analog Devices AD7191 ADC.
> +
> +=================
> +Supported devices
> +=================
> +

Re: [PATCH v5 2/3] iio: adc: ad7191: add AD7191

[kernel test robot]

Hi Alisa-Dariana,

kernel test robot noticed the following build warnings:

[auto build test WARNING on jic23-iio/togreg]
[also build test WARNING on robh/for-next linus/master v6.14-rc4 next-20250227]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Alisa-Dariana-Roman/dt-bindings-iio-adc-add-AD7191/20250226-195853
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git togreg
patch link:    https://lore.kernel.org/r/20250226115451.249361-3-alisa.roman%40analog.com
patch subject: [PATCH v5 2/3] iio: adc: ad7191: add AD7191
config: hexagon-allyesconfig (https://download.01.org/0day-ci/archive/20250228/202502280702.31rbuGw8-lkp@intel.com/config)
compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250228/202502280702.31rbuGw8-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202502280702.31rbuGw8-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/iio/adc/ad7191.c:217:15: warning: variable 'pga_index' is used uninitialized whenever 'for' loop exits because its condition is false [-Wsometimes-uninitialized]
     217 |                 for (i = 0; i < ARRAY_SIZE(gain); i++) {
         |                             ^~~~~~~~~~~~~~~~~~~~
   drivers/iio/adc/ad7191.c:224:35: note: uninitialized use occurs here
     224 |                 st->scale_avail = &scale_buffer[pga_index];
         |                                                 ^~~~~~~~~
   drivers/iio/adc/ad7191.c:217:15: note: remove the condition if it is always true
     217 |                 for (i = 0; i < ARRAY_SIZE(gain); i++) {
         |                             ^~~~~~~~~~~~~~~~~~~~
   drivers/iio/adc/ad7191.c:160:48: note: initialize the variable 'pga_index' to silence this warning
     160 |         int odr_value, odr_index, pga_value, pga_index, i, ret;
         |                                                       ^
         |                                                        = 0
>> drivers/iio/adc/ad7191.c:179:15: warning: variable 'odr_index' is used uninitialized whenever 'for' loop exits because its condition is false [-Wsometimes-uninitialized]
     179 |                 for (i = 0; i < ARRAY_SIZE(samp_freq); i++) {
         |                             ^~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/iio/adc/ad7191.c:186:36: note: uninitialized use occurs here
     186 |                 st->samp_freq_avail = &samp_freq[odr_index];
         |                                                  ^~~~~~~~~
   drivers/iio/adc/ad7191.c:179:15: note: remove the condition if it is always true
     179 |                 for (i = 0; i < ARRAY_SIZE(samp_freq); i++) {
         |                             ^~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/iio/adc/ad7191.c:160:26: note: initialize the variable 'odr_index' to silence this warning
     160 |         int odr_value, odr_index, pga_value, pga_index, i, ret;
         |                                 ^
         |                                  = 0
   drivers/iio/adc/ad7191.c:553:18: error: expected ';' after top level declarator
     553 | MODULE_IMPORT_NS(IIO_AD_SIGMA_DELTA);
         |                  ^
   2 warnings and 1 error generated.


vim +217 drivers/iio/adc/ad7191.c

   150	
   151	static int ad7191_config_setup(struct iio_dev *indio_dev)
   152	{
   153		struct ad7191_state *st = iio_priv(indio_dev);
   154		struct device *dev = &st->sd.spi->dev;
   155		/* Sampling frequencies in Hz, see Table 5 */
   156		static const u32 samp_freq[4] = { 120, 60, 50, 10 };
   157		/* Gain options, see Table 7 */
   158		const u32 gain[4] = { 1, 8, 64, 128 };
   159		static u32 scale_buffer[4][2];
   160		int odr_value, odr_index, pga_value, pga_index, i, ret;
   161		u64 scale_uv;
   162	
   163		st->samp_freq_index = 0;
   164		st->scale_index = 0;
   165	
   166		ret = device_property_read_u32(dev, "adi,odr-value", &odr_value);
   167		if (ret && ret != -EINVAL)
   168			return dev_err_probe(dev, ret, "Failed to get odr value.\n");
   169	
   170		if (ret == -EINVAL) {
   171			st->odr_gpios = devm_gpiod_get_array(dev, "odr", GPIOD_OUT_LOW);
   172			if (IS_ERR(st->odr_gpios))
   173				return dev_err_probe(dev, PTR_ERR(st->odr_gpios),
   174						     "Failed to get odr gpios.\n");
   175	
   176			st->samp_freq_avail = samp_freq;
   177			st->samp_freq_avail_size = ARRAY_SIZE(samp_freq);
   178		} else {
 > 179			for (i = 0; i < ARRAY_SIZE(samp_freq); i++) {
   180				if (odr_value != samp_freq[i])
   181					continue;
   182				odr_index = i;
   183				break;
   184			}
   185	
   186			st->samp_freq_avail = &samp_freq[odr_index];
   187			st->samp_freq_avail_size = 1;
   188	
   189			st->odr_gpios = NULL;
   190		}
   191	
   192		mutex_lock(&st->lock);
   193	
   194		for (i = 0; i < ARRAY_SIZE(scale_buffer); i++) {
   195			scale_uv = ((u64)st->int_vref_mv * NANO) >>
   196				(indio_dev->channels[0].scan_type.realbits - 1);
   197			do_div(scale_uv, gain[i]);
   198			scale_buffer[i][1] = do_div(scale_uv, NANO);
   199			scale_buffer[i][0] = scale_uv;
   200		}
   201	
   202		mutex_unlock(&st->lock);
   203	
   204		ret = device_property_read_u32(dev, "adi,pga-value", &pga_value);
   205		if (ret && ret != -EINVAL)
   206			return dev_err_probe(dev, ret, "Failed to get pga value.\n");
   207	
   208		if (ret == -EINVAL) {
   209			st->pga_gpios = devm_gpiod_get_array(dev, "pga", GPIOD_OUT_LOW);
   210			if (IS_ERR(st->pga_gpios))
   211				return dev_err_probe(dev, PTR_ERR(st->pga_gpios),
   212						     "Failed to get pga gpios.\n");
   213	
   214			st->scale_avail = scale_buffer;
   215			st->scale_avail_size = ARRAY_SIZE(scale_buffer);
   216		} else {
 > 217			for (i = 0; i < ARRAY_SIZE(gain); i++) {
   218				if (pga_value != gain[i])
   219					continue;
   220				pga_index = i;
   221				break;
   222			}
   223	
   224			st->scale_avail = &scale_buffer[pga_index];
   225			st->scale_avail_size = 1;
   226	
   227			st->pga_gpios = NULL;
   228		}
   229	
   230		st->temp_gpio = devm_gpiod_get(dev, "temp", GPIOD_OUT_LOW);
   231		if (IS_ERR(st->temp_gpio))
   232			return dev_err_probe(dev, PTR_ERR(st->temp_gpio),
   233					     "Failed to get temp gpio.\n");
   234	
   235		st->chan_gpio = devm_gpiod_get(dev, "chan", GPIOD_OUT_LOW);
   236		if (IS_ERR(st->chan_gpio))
   237			return dev_err_probe(dev, PTR_ERR(st->chan_gpio),
   238					     "Failed to get chan gpio.\n");
   239	
   240		return 0;
   241	}
   242	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki