[PATCH v4 0/2] iio: adc: Add AD4134 minimum I/O support

[PATCH v4 0/2] iio: adc: Add AD4134 minimum I/O support

[Marcelo Schmitt]

This patch series adds basic support for ad4134. AD4134 is a very flexible
device that can be configured in many different ways. This series aims to
support the simplest way of interfacing with AD4134 which is called minimum I/O
mode in data sheet. This is essentially usual SPI with the addition of an ODR
(Output Data Rate) GPIO which functions as conversion start signal in minimum
I/O mode.

This set provides just one feature:
- Single-shot ADC sample read.

[PATCH 1] Device tree documentation for AD4134.
[PATCH 2] IIO Linux driver for AD4134.

Change log v3 -> v4:
[device tree]
- Renamed clock option "xtal1-xtal2" to "xtal" (making it similar to other bindings).
- Use oneOf for ldoin-supply choice.
- Dropped properties set to their defaults from the example.
[IIO]
- Added comment about minimum ODR high time.
- Split array of regulator names
- Updated to check for "xtal" clock name.
- Simplified voltage regulator initialization logic.
- Use reset framework to get and deassert device reset.
- Dropped ad4134 IIO documentation.

Link to v3: https://lore.kernel.org/linux-iio/cover.1764708608.git.marcelo.schmitt@analog.com/
Link to v2: https://lore.kernel.org/linux-iio/cover.1763478299.git.marcelo.schmitt@analog.com/
Link to v1: https://lore.kernel.org/linux-iio/cover.1762777931.git.marcelo.schmitt@analog.com/


Marcelo Schmitt (2):
  dt-bindings: iio: adc: Add AD4134
  iio: adc: Initial support for AD4134

 .../bindings/iio/adc/adi,ad4134.yaml          | 191 +++++++
 MAINTAINERS                                   |   8 +
 drivers/iio/adc/Kconfig                       |  11 +
 drivers/iio/adc/Makefile                      |   1 +
 drivers/iio/adc/ad4134.c                      | 501 ++++++++++++++++++
 5 files changed, 712 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad4134.yaml
 create mode 100644 drivers/iio/adc/ad4134.c


base-commit: fb2f4eb29a258145b0336601f00509cab6e93e7c
-- 
2.51.0

[PATCH v4 1/2] dt-bindings: iio: adc: Add AD4134

[Marcelo Schmitt]

Add device tree documentation for AD4134 24-Bit, 4-channel simultaneous
sampling, precision ADC.

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
---
Change log v3 -> v4:
- Renamed clock option "xtal1-xtal2" to "xtal" (making it similar to other bindings).
- Use oneOf for ldoin-supply choice.
- Dropped properties set to their defaults from the example.

I believe the changes were not disruptive so I kept Conor's review tag.

 .../bindings/iio/adc/adi,ad4134.yaml          | 191 ++++++++++++++++++
 MAINTAINERS                                   |   7 +
 2 files changed, 198 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad4134.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad4134.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad4134.yaml
new file mode 100644
index 000000000000..ea6d7e026419
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad4134.yaml
@@ -0,0 +1,191 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/adi,ad4134.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices AD4134 ADC
+
+maintainers:
+  - Marcelo Schmitt <marcelo.schmitt@analog.com>
+
+description: |
+  The AD4134 is a quad channel, low noise, simultaneous sampling, precision
+  analog-to-digital converter (ADC).
+  Specifications can be found at:
+    https://www.analog.com/media/en/technical-documentation/data-sheets/ad4134.pdf
+
+$ref: /schemas/spi/spi-peripheral-props.yaml#
+
+properties:
+  compatible:
+    enum:
+      - adi,ad4134
+
+  reg:
+    maxItems: 1
+
+  spi-max-frequency:
+    maximum: 50000000
+
+  avdd5-supply:
+    description: A 5V supply that powers the chip's analog circuitry.
+
+  dvdd5-supply:
+    description: A 5V supply that powers the chip's digital circuitry.
+
+  iovdd-supply:
+    description:
+      A 1.8V supply that sets the logic levels for the digital interface pins.
+
+  refin-supply:
+    description:
+      A 4.096V or 5V supply that serves as reference for ADC conversions.
+
+  avdd1v8-supply:
+    description: A 1.8V supply used by the analog circuitry.
+
+  dvdd1v8-supply:
+    description: A 1.8V supply used by the digital circuitry.
+
+  clkvdd-supply:
+    description: A 1.8V supply for the chip's clock management circuit.
+
+  ldoin-supply:
+    description:
+      A 2.6V to 5.5V supply that generates 1.8V for AVDD1V8, DVDD1V8, and CLKVDD
+      pins.
+
+  clocks:
+    maxItems: 1
+    description:
+      Required external clock source. Can specify either a crystal or CMOS clock
+      source. If an external crystal is set, connect the CLKSEL pin to IOVDD.
+      Otherwise, connect the CLKSEL pin to IOGND and the external CMOS clock
+      signal to the XTAL2/CLKIN pin.
+
+  clock-names:
+    enum:
+      - xtal
+      - clkin
+    default: clkin
+
+  '#clock-cells':
+    const: 0
+
+  clock-output-names:
+    maxItems: 1
+
+  regulators:
+    type: object
+    description:
+      list of regulators provided by this controller.
+
+    properties:
+      vcm-output:
+        $ref: /schemas/regulator/regulator.yaml#
+        type: object
+        unevaluatedProperties: false
+
+    additionalProperties: false
+
+  reset-gpios:
+    maxItems: 1
+
+  powerdown-gpios:
+    description:
+      Active low GPIO connected to the /PDN pin. Forces the device into full
+      power-down mode when brought low. Pull this input to IOVDD for normal
+      operation.
+    maxItems: 1
+
+  odr-gpios:
+    description:
+      GPIO connected to ODR pin. Used to sample ADC data in minimum I/O mode.
+    maxItems: 1
+
+  adi,asrc-mode:
+    $ref: /schemas/types.yaml#/definitions/string
+    description:
+      Asynchronous Sample Rate Converter (ASRC) operation mode control input.
+      Describes whether the MODE pin is set to a high level (for master mode
+      operation) or to a low level (for slave mode operation).
+    enum: [ high, low ]
+    default: low
+
+  adi,dclkio:
+    description:
+      DCLK pin I/O direction control for when the device operates in Pin Control
+      Slave Mode or in SPI Control Mode. Describes if DEC0/DCLKIO pin is at a
+      high level (which configures DCLK as an output) or to set to a low level
+      (configuring DCLK for input).
+    enum: [ out, in ]
+    default: in
+
+  adi,dclkmode:
+    description:
+      DCLK mode control for when the device operates in Pin Control Slave Mode
+      or in SPI Control Mode. Describes whether the DEC1/DCLKMODE pin is set to
+      a high level (configuring the DCLK to operate in free running mode) or
+      to a low level (to configure DCLK to operate in gated mode).
+    enum: [ free-running, gated ]
+    default: gated
+
+required:
+  - compatible
+  - reg
+  - avdd5-supply
+  - dvdd5-supply
+  - iovdd-supply
+  - refin-supply
+  - clocks
+  - clock-names
+
+oneOf:
+  - required:
+      - ldoin-supply
+  - required:
+      - avdd1v8-supply
+      - dvdd1v8-supply
+      - clkvdd-supply
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@0 {
+            compatible = "adi,ad4134";
+            reg = <0>;
+
+            spi-max-frequency = <1000000>;
+
+            reset-gpios = <&gpio0 86 GPIO_ACTIVE_LOW>;
+            odr-gpios = <&gpio0 87 GPIO_ACTIVE_HIGH>;
+            powerdown-gpios = <&gpio0 88 GPIO_ACTIVE_LOW>;
+
+            clocks = <&sys_clk>;
+            clock-names = "clkin";
+
+            avdd5-supply = <&avdd5>;
+            dvdd5-supply = <&dvdd5>;
+            iovdd-supply = <&iovdd>;
+            refin-supply = <&refin>;
+            avdd1v8-supply = <&avdd1v8>;
+            dvdd1v8-supply = <&dvdd1v8>;
+            clkvdd-supply = <&clkvdd>;
+
+            regulators {
+                vcm_reg: vcm-output {
+                    regulator-name = "ad4134-vcm";
+                };
+            };
+
+        };
+    };
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index 2e8825b8ccef..3f9f6dd96ae4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1458,6 +1458,13 @@ F:	Documentation/ABI/testing/sysfs-bus-iio-adc-ad4130
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad4130.yaml
 F:	drivers/iio/adc/ad4130.c
 
+ANALOG DEVICES INC AD4134 DRIVER
+M:	Marcelo Schmitt <marcelo.schmitt@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,ad4134.yaml
+
 ANALOG DEVICES INC AD4170-4 DRIVER
 M:	Marcelo Schmitt <marcelo.schmitt@analog.com>
 L:	linux-iio@vger.kernel.org
-- 
2.51.0

[PATCH v4 2/2] iio: adc: Initial support for AD4134

[Marcelo Schmitt]

AD4134 is a 24-bit, 4-channel, simultaneous sampling, precision
analog-to-digital converter (ADC). The device can be managed through SPI or
direct control of pin logical levels (pin control mode). The AD4134 design
also features a dedicated bus for ADC sample data output. Though, this
initial driver for AD4134 only supports usual SPI connections.

Add basic support for AD4134 that enables single-shot ADC sample read.

Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
---
Change log v3 -> v4:
- Added comment about minimum ODR high time.
- Split array of regulator names
- Updated to check for "xtal" clock name.
- Simplified voltage regulator initialization logic.
- Use reset framework to get and deassert device reset.
- Dropped ad4134 IIO documentation.

 MAINTAINERS              |   1 +
 drivers/iio/adc/Kconfig  |  11 +
 drivers/iio/adc/Makefile |   1 +
 drivers/iio/adc/ad4134.c | 501 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 514 insertions(+)
 create mode 100644 drivers/iio/adc/ad4134.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 3f9f6dd96ae4..4dd9f758a871 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1464,6 +1464,7 @@ L:	linux-iio@vger.kernel.org
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad4134.yaml
+F:	drivers/iio/adc/ad4134.c
 
 ANALOG DEVICES INC AD4170-4 DRIVER
 M:	Marcelo Schmitt <marcelo.schmitt@analog.com>
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 89a6486135f6..b4295aa415bf 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -112,6 +112,17 @@ config AD4130
 	  To compile this driver as a module, choose M here: the module will be
 	  called ad4130.
 
+config AD4134
+	tristate "Analog Device AD4134 ADC Driver"
+	depends on SPI
+	select REGMAP_SPI
+	select CRC8
+	help
+	  Say yes here to build support for Analog Devices AD4134 SPI analog to
+	  digital converters (ADC).
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called ad4134_spi.
 
 config AD4170_4
 	tristate "Analog Device AD4170-4 ADC Driver"
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 0a199630c081..c76550415ff1 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_AD4030) += ad4030.o
 obj-$(CONFIG_AD4062) += ad4062.o
 obj-$(CONFIG_AD4080) += ad4080.o
 obj-$(CONFIG_AD4130) += ad4130.o
+obj-$(CONFIG_AD4134) += ad4134.o
 obj-$(CONFIG_AD4170_4) += ad4170-4.o
 obj-$(CONFIG_AD4695) += ad4695.o
 obj-$(CONFIG_AD4851) += ad4851.o
diff --git a/drivers/iio/adc/ad4134.c b/drivers/iio/adc/ad4134.c
new file mode 100644
index 000000000000..ec8c25efd66d
--- /dev/null
+++ b/drivers/iio/adc/ad4134.c
@@ -0,0 +1,501 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2026 Analog Devices, Inc.
+ * Author: Marcelo Schmitt <marcelo.schmitt@analog.com>
+ */
+
+#include <linux/array_size.h>
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/crc8.h>
+#include <linux/delay.h>
+#include <linux/dev_printk.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/gpio/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/types.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/reset.h>
+#include <linux/spi/spi.h>
+#include <linux/time.h>
+#include <linux/types.h>
+#include <linux/unaligned.h>
+#include <linux/units.h>
+
+#define AD4134_RESET_TIME_US			(10 * USEC_PER_SEC)
+
+#define AD4134_REG_READ_MASK			BIT(7)
+#define AD4134_SPI_MAX_XFER_LEN			3
+
+#define AD4134_EXT_CLOCK_MHZ			(48 * HZ_PER_MHZ)
+
+#define AD4134_NUM_CHANNELS			4
+#define AD4134_CHAN_PRECISION_BITS		24
+
+#define AD4134_IFACE_CONFIG_A_REG		0x00
+#define AD4134_IFACE_CONFIG_B_REG		0x01
+#define AD4134_IFACE_CONFIG_B_SINGLE_INSTR	BIT(7)
+
+#define AD4134_DEVICE_CONFIG_REG		0x02
+#define AD4134_DEVICE_CONFIG_POWER_MODE_MASK	BIT(0)
+#define AD4134_POWER_MODE_HIGH_PERF		0x1
+
+#define AD4134_SILICON_REV_REG			0x07
+#define AD4134_SCRATCH_PAD_REG			0x0A
+#define AD4134_STREAM_MODE_REG			0x0E
+#define AD4134_SDO_PIN_SRC_SEL_REG		0x10
+#define AD4134_SDO_PIN_SRC_SEL_SDO_SEL_MASK	BIT(2)
+
+#define AD4134_DATA_PACKET_CONFIG_REG		0x11
+#define AD4134_DATA_PACKET_CONFIG_FRAME_MASK	GENMASK(5, 4)
+#define AD4134_DATA_PACKET_24BIT_FRAME		0x2
+
+#define AD4134_DIG_IF_CFG_REG			0x12
+#define AD4134_DIF_IF_CFG_FORMAT_MASK		GENMASK(1, 0)
+#define AD4134_DATA_FORMAT_SINGLE_CH_MODE	0x0
+
+#define AD4134_PW_DOWN_CTRL_REG			0x13
+#define AD4134_DEVICE_STATUS_REG		0x15
+#define AD4134_ODR_VAL_INT_LSB_REG		0x16
+#define AD4134_CH3_OFFSET_MSB_REG		0x3E
+#define AD4134_AIN_OR_ERROR_REG			0x48
+
+/*
+ * AD4134 register map ends at address 0x48 and there is no register for
+ * retrieving ADC sample data. Though, to make use of Linux regmap API both
+ * for register access and sample read, we define one virtual register for each
+ * ADC channel. AD4134_CH_VREG(x) maps a channel number to it's virtual register
+ * address while AD4134_VREG_CH(x) tells which channel given the address.
+ */
+#define AD4134_CH_VREG(x)			((x) + 0x50)
+#define AD4134_VREG_CH(x)			((x) - 0x50)
+
+#define AD4134_SPI_CRC_POLYNOM			0x07
+#define AD4134_SPI_CRC_INIT_VALUE		0xA5
+static unsigned char ad4134_spi_crc_table[CRC8_TABLE_SIZE];
+
+#define AD4134_CHANNEL(_index) {						\
+	.type = IIO_VOLTAGE,							\
+	.indexed = 1,								\
+	.channel = (_index),							\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),				\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),			\
+}
+
+static const struct iio_chan_spec ad4134_chan_set[] = {
+	AD4134_CHANNEL(0),
+	AD4134_CHANNEL(1),
+	AD4134_CHANNEL(2),
+	AD4134_CHANNEL(3),
+};
+
+struct ad4134_state {
+	struct spi_device *spi;
+	struct regmap *regmap;
+	unsigned long sys_clk_hz;
+	struct gpio_desc *odr_gpio;
+	int refin_mv;
+	/*
+	 * DMA (thus cache coherency maintenance) requires the transfer buffers
+	 * to live in their own cache lines.
+	 */
+	u8 rx_buf[AD4134_SPI_MAX_XFER_LEN] __aligned(IIO_DMA_MINALIGN);
+	u8 tx_buf[AD4134_SPI_MAX_XFER_LEN];
+};
+
+static const struct regmap_range ad4134_regmap_rd_range[] = {
+	regmap_reg_range(AD4134_IFACE_CONFIG_A_REG, AD4134_SILICON_REV_REG),
+	regmap_reg_range(AD4134_SCRATCH_PAD_REG, AD4134_PW_DOWN_CTRL_REG),
+	regmap_reg_range(AD4134_DEVICE_STATUS_REG, AD4134_AIN_OR_ERROR_REG),
+	regmap_reg_range(AD4134_CH_VREG(0), AD4134_CH_VREG(AD4134_NUM_CHANNELS)),
+};
+
+static const struct regmap_range ad4134_regmap_wr_range[] = {
+	regmap_reg_range(AD4134_IFACE_CONFIG_A_REG, AD4134_DEVICE_CONFIG_REG),
+	regmap_reg_range(AD4134_SCRATCH_PAD_REG, AD4134_SCRATCH_PAD_REG),
+	regmap_reg_range(AD4134_STREAM_MODE_REG, AD4134_PW_DOWN_CTRL_REG),
+	regmap_reg_range(AD4134_ODR_VAL_INT_LSB_REG, AD4134_CH3_OFFSET_MSB_REG),
+};
+
+static const struct regmap_access_table ad4134_regmap_rd_table = {
+	.yes_ranges = ad4134_regmap_rd_range,
+	.n_yes_ranges = ARRAY_SIZE(ad4134_regmap_rd_range),
+};
+
+static const struct regmap_access_table ad4134_regmap_wr_table = {
+	.yes_ranges = ad4134_regmap_wr_range,
+	.n_yes_ranges = ARRAY_SIZE(ad4134_regmap_wr_range),
+};
+
+static int ad4134_calc_spi_crc(u8 inst, u8 data)
+{
+	u8 buf[] = { inst, data };
+
+	return crc8(ad4134_spi_crc_table, buf, ARRAY_SIZE(buf),
+		    AD4134_SPI_CRC_INIT_VALUE);
+}
+
+static void ad4134_prepare_spi_tx_buf(u8 inst, u8 data, u8 *buf)
+{
+	buf[0] = inst;
+	buf[1] = data;
+	buf[2] = ad4134_calc_spi_crc(inst, data);
+}
+
+static int ad4134_reg_write(void *context, unsigned int reg, unsigned int val)
+{
+	struct ad4134_state *st = context;
+	struct spi_transfer xfer = {
+		.tx_buf = st->tx_buf,
+		.rx_buf = st->rx_buf,
+		.len = AD4134_SPI_MAX_XFER_LEN,
+	};
+	int ret;
+
+	ad4134_prepare_spi_tx_buf(reg, val, st->tx_buf);
+
+	ret = spi_sync_transfer(st->spi, &xfer, 1);
+	if (ret)
+		return ret;
+
+	if (st->rx_buf[2] != st->tx_buf[2])
+		dev_dbg(&st->spi->dev, "reg write CRC check failed\n");
+
+	return 0;
+}
+
+static int ad4134_data_read(struct ad4134_state *st, unsigned int reg,
+			    unsigned int *val)
+{
+	unsigned int i;
+	int ret;
+
+	/*
+	 * To be able to read data from all 4 channels through a single line, we
+	 * set DOUTx output format to 0 in the digital interface config register
+	 * (0x12). With that, data from all four channels is serialized and
+	 * output on DOUT0. During the probe, we also set SDO_PIN_SRC_SEL in
+	 * DEVICE_CONFIG_1 register to duplicate DOUT0 on the SDO pin. Combined,
+	 * those configurations enable ADC data read through a conventional SPI
+	 * interface. Now we read data from all channels but keep only the bits
+	 * from the requested one.
+	 */
+	for (i = 0; i < ARRAY_SIZE(ad4134_chan_set); i++) {
+		ret = spi_write_then_read(st->spi, NULL, 0, st->rx_buf,
+					  BITS_TO_BYTES(AD4134_CHAN_PRECISION_BITS));
+		if (ret)
+			return ret;
+
+		/*
+		 * AD4134 has a built-in feature that flags when data transfers
+		 * don't run enough clock cycles to read the entire data frame.
+		 * Clock out data from all channels to avoid that.
+		 */
+		if (i == AD4134_VREG_CH(reg))
+			*val = get_unaligned_be24(st->rx_buf);
+	}
+
+	return 0;
+}
+
+static int ad4134_register_read(struct ad4134_state *st, unsigned int reg,
+				unsigned int *val)
+{
+	struct spi_transfer xfer = {
+		.tx_buf = st->tx_buf,
+		.rx_buf = st->rx_buf,
+		.len = AD4134_SPI_MAX_XFER_LEN,
+	};
+	unsigned int inst;
+	int ret;
+
+	inst = AD4134_REG_READ_MASK | reg;
+	ad4134_prepare_spi_tx_buf(inst, 0, st->tx_buf);
+
+	ret = spi_sync_transfer(st->spi, &xfer, 1);
+	if (ret)
+		return ret;
+
+	*val = st->rx_buf[1];
+
+	/* Check CRC */
+	if (st->rx_buf[2] != st->tx_buf[2])
+		dev_dbg(&st->spi->dev, "reg read CRC check failed\n");
+
+	return 0;
+}
+
+static int ad4134_reg_read(void *context, unsigned int reg, unsigned int *val)
+{
+	struct ad4134_state *st = context;
+
+	if (reg >= AD4134_CH_VREG(0))
+		return ad4134_data_read(st, reg, val);
+
+	return ad4134_register_read(st, reg, val);
+}
+
+static const struct regmap_config ad4134_regmap_config = {
+	.reg_read = ad4134_reg_read,
+	.reg_write = ad4134_reg_write,
+	.rd_table = &ad4134_regmap_rd_table,
+	.wr_table = &ad4134_regmap_wr_table,
+	.max_register = AD4134_CH_VREG(ARRAY_SIZE(ad4134_chan_set)),
+};
+
+static int ad4134_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2, long info)
+{
+	struct ad4134_state *st = iio_priv(indio_dev);
+	int ret;
+
+	switch (info) {
+	case IIO_CHAN_INFO_RAW:
+		gpiod_set_value_cansleep(st->odr_gpio, 1);
+		/*
+		 * For slave mode gated DCLK (data sheet page 11), the minimum
+		 * ODR high time is 3 * tDIGCLK. The internal digital clock
+		 * period is tDIGCLK = 1/fDIGCLK = 2/fSYSCLK.
+		 * The System clock frequency (fSYSCLK) is typically 48 MHz.
+		 * Thus, ODR high time = 3 * (2 / (48 * HZ_PER_MHZ))
+		 * ODR high time = 0.000000125 s = 125 ns
+		 * 1 micro second should be more than enough. Not worth it
+		 * tweaking for shorter dealy since this is not a fast data path.
+		 */
+		fsleep(1);
+		gpiod_set_value_cansleep(st->odr_gpio, 0);
+		ret = regmap_read(st->regmap, AD4134_CH_VREG(chan->channel), val);
+		if (ret)
+			return ret;
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = st->refin_mv;
+		*val2 = AD4134_CHAN_PRECISION_BITS - 1;
+
+		return IIO_VAL_FRACTIONAL_LOG2;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad4134_debugfs_reg_access(struct iio_dev *indio_dev,
+				     unsigned int reg, unsigned int writeval,
+				     unsigned int *readval)
+{
+	struct ad4134_state *st = iio_priv(indio_dev);
+
+	if (readval)
+		return regmap_read(st->regmap, reg, readval);
+
+	return regmap_write(st->regmap, reg, writeval);
+}
+
+static int ad4134_min_io_mode_setup(struct ad4134_state *st)
+{
+	struct device *dev = &st->spi->dev;
+	int ret;
+
+	st->odr_gpio = devm_gpiod_get(dev, "odr", GPIOD_OUT_LOW);
+	if (IS_ERR(st->odr_gpio))
+		return dev_err_probe(dev, PTR_ERR(st->odr_gpio),
+				     "failed to get ODR GPIO\n");
+
+	ret = regmap_update_bits(st->regmap, AD4134_DIG_IF_CFG_REG,
+				 AD4134_DIF_IF_CFG_FORMAT_MASK,
+				 FIELD_PREP(AD4134_DIF_IF_CFG_FORMAT_MASK,
+					    AD4134_DATA_FORMAT_SINGLE_CH_MODE));
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "failed to set single channel mode\n");
+
+	ret = regmap_set_bits(st->regmap, AD4134_SDO_PIN_SRC_SEL_REG,
+			      AD4134_SDO_PIN_SRC_SEL_SDO_SEL_MASK);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "failed to set SDO source selection\n");
+
+	return regmap_set_bits(st->regmap, AD4134_IFACE_CONFIG_B_REG,
+			       AD4134_IFACE_CONFIG_B_SINGLE_INSTR);
+}
+
+static const struct iio_info ad4134_info = {
+	.read_raw = ad4134_read_raw,
+	.debugfs_reg_access = ad4134_debugfs_reg_access,
+};
+
+static const char * const ad4143_required_regulators[] = {
+	"avdd5", "dvdd5", "iovdd",
+};
+
+static const char * const ad4143_optional_regulators[] = {
+	"avdd1v8", "dvdd1v8", "clkvdd",
+};
+
+static int ad4134_regulator_setup(struct ad4134_state *st)
+{
+	struct device *dev = &st->spi->dev;
+	int ret;
+
+	ret = devm_regulator_bulk_get_enable(dev, ARRAY_SIZE(ad4143_required_regulators),
+					     ad4143_required_regulators);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to enable power supplies\n");
+
+	/* Required regulator that we need to read the voltage */
+	ret = devm_regulator_get_enable_read_voltage(dev, "refin");
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "failed to get REFIN voltage.\n");
+
+	st->refin_mv = ret / (MICRO / MILLI);
+
+	ret = devm_regulator_get_enable_optional(dev, "ldoin");
+	if (ret < 0 && ret != -ENODEV)
+		return dev_err_probe(dev, ret, "failed to enable ldoin supply\n");
+
+	/* If ldoin was provided, then use the use the internal LDO regulators */
+	if (ret == 0)
+		return 0;
+
+	/*
+	 * If ldoin is not provided, then avdd1v8, dvdd1v8, and clkvdd are
+	 * required.
+	 */
+	ret = devm_regulator_bulk_get_enable(dev, ARRAY_SIZE(ad4143_optional_regulators),
+					     ad4143_optional_regulators);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to enable 1V8 power supplies\n");
+
+	return 0;
+}
+
+static int ad4134_clock_select(struct ad4134_state *st)
+{
+	struct device *dev = &st->spi->dev;
+	struct clk *xtal_clk, *clkin_clk;
+
+	/*
+	 * AD4134 requires one external clock source and only one external clock
+	 * source can be provided at a time. Try to get a crystal provided clock.
+	 * If that fails, try to get a CMOS clock.
+	 */
+	xtal_clk = devm_clk_get_optional_enabled(dev, "xtal");
+	if (!xtal_clk)
+		xtal_clk = devm_clk_get_optional_enabled(dev, "xtal");
+	if (IS_ERR(xtal_clk))
+		return dev_err_probe(dev, PTR_ERR(xtal_clk),
+				     "failed to get xtal\n");
+
+	clkin_clk = devm_clk_get_optional_enabled(dev, "clkin");
+	if (!clkin_clk)
+		clkin_clk = devm_clk_get_optional_enabled(dev, "clkin");
+	if (IS_ERR(clkin_clk))
+		return dev_err_probe(dev, PTR_ERR(clkin_clk),
+				     "failed to get clkin\n");
+
+	st->sys_clk_hz = clk_get_rate(xtal_clk) | clk_get_rate(clkin_clk);
+	if (st->sys_clk_hz != AD4134_EXT_CLOCK_MHZ)
+		dev_warn(dev, "invalid external clock frequency %lu\n",
+			 st->sys_clk_hz);
+
+	return 0;
+}
+
+static int ad4134_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct reset_control *rst;
+	struct iio_dev *indio_dev;
+	struct ad4134_state *st;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	st->spi = spi;
+
+	indio_dev->name = "ad4134";
+	indio_dev->channels = ad4134_chan_set;
+	indio_dev->num_channels = ARRAY_SIZE(ad4134_chan_set);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &ad4134_info;
+
+	ret = ad4134_regulator_setup(st);
+	if (ret)
+		return ret;
+
+	ret = ad4134_clock_select(st);
+	if (ret)
+		return ret;
+
+	rst = devm_reset_control_get_optional_exclusive_deasserted(dev, NULL);
+	if (IS_ERR(rst))
+		return dev_err_probe(dev, PTR_ERR(rst),
+				     "failed to get and deassert reset\n");
+
+	crc8_populate_msb(ad4134_spi_crc_table, AD4134_SPI_CRC_POLYNOM);
+
+	st->regmap = devm_regmap_init(dev, NULL, st, &ad4134_regmap_config);
+	if (IS_ERR(st->regmap))
+		return dev_err_probe(dev, PTR_ERR(st->regmap),
+				     "failed to initialize regmap");
+
+	ret = ad4134_min_io_mode_setup(st);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "failed to setup minimum I/O mode\n");
+
+	/* Bump precision to 24-bit */
+	ret = regmap_update_bits(st->regmap, AD4134_DATA_PACKET_CONFIG_REG,
+				 AD4134_DATA_PACKET_CONFIG_FRAME_MASK,
+				 FIELD_PREP(AD4134_DATA_PACKET_CONFIG_FRAME_MASK,
+					    AD4134_DATA_PACKET_24BIT_FRAME));
+	if (ret)
+		return ret;
+
+	/* Set high performance power mode */
+	ret = regmap_update_bits(st->regmap, AD4134_DEVICE_CONFIG_REG,
+				 AD4134_DEVICE_CONFIG_POWER_MODE_MASK,
+				 FIELD_PREP(AD4134_DEVICE_CONFIG_POWER_MODE_MASK,
+					    AD4134_POWER_MODE_HIGH_PERF));
+	if (ret)
+		return ret;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct spi_device_id ad4134_id[] = {
+	{ "ad4134" },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, ad4134_id);
+
+static const struct of_device_id ad4134_of_match[] = {
+	{ .compatible = "adi,ad4134" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ad4134_of_match);
+
+static struct spi_driver ad4134_driver = {
+	.driver = {
+		.name = "ad4134",
+		.of_match_table = ad4134_of_match,
+	},
+	.probe = ad4134_probe,
+	.id_table = ad4134_id,
+};
+module_spi_driver(ad4134_driver);
+
+MODULE_AUTHOR("Marcelo Schmitt <marcelo.schmitt@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD4134 SPI driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("IIO_AD4134");
-- 
2.51.0

Re: [PATCH v4 2/2] iio: adc: Initial support for AD4134

[Andy Shevchenko]

On Wed, Jan 07, 2026 at 11:47:59AM -0300, Marcelo Schmitt wrote:
> AD4134 is a 24-bit, 4-channel, simultaneous sampling, precision
> analog-to-digital converter (ADC). The device can be managed through SPI or
> direct control of pin logical levels (pin control mode). The AD4134 design
> also features a dedicated bus for ADC sample data output. Though, this
> initial driver for AD4134 only supports usual SPI connections.
> 
> Add basic support for AD4134 that enables single-shot ADC sample read.

I have been on a few weeks leave and do not remember much, but it looks like
this version has all my previous comments being addressed.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>

...

> +#include <linux/array_size.h>
> +#include <linux/bitfield.h>

> +#include <linux/bitops.h>

> +#include <linux/bits.h>

No need, as bitops.h implies (and guarantees) that BIT()/GENMASK() are provided
with it.

> +#include <linux/clk.h>
> +#include <linux/crc8.h>
> +#include <linux/delay.h>
> +#include <linux/dev_printk.h>
> +#include <linux/err.h>
> +#include <linux/export.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/types.h>
> +#include <linux/module.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/reset.h>
> +#include <linux/spi/spi.h>
> +#include <linux/time.h>
> +#include <linux/types.h>
> +#include <linux/unaligned.h>
> +#include <linux/units.h>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v4 2/2] iio: adc: Initial support for AD4134

[Jonathan Cameron]

On Wed, 7 Jan 2026 18:22:23 +0200
Andy Shevchenko <andriy.shevchenko@intel.com> wrote:

> On Wed, Jan 07, 2026 at 11:47:59AM -0300, Marcelo Schmitt wrote:
> > AD4134 is a 24-bit, 4-channel, simultaneous sampling, precision
> > analog-to-digital converter (ADC). The device can be managed through SPI or
> > direct control of pin logical levels (pin control mode). The AD4134 design
> > also features a dedicated bus for ADC sample data output. Though, this
> > initial driver for AD4134 only supports usual SPI connections.
> > 
> > Add basic support for AD4134 that enables single-shot ADC sample read.  
> 
> I have been on a few weeks leave and do not remember much, but it looks like
> this version has all my previous comments being addressed.
> 
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
I tweaked to drop the explicit bits.h include and applied to the togreg
branch of iio.git, initially pushed out as testing.

thanks,

Jonathan

> 
> ...
> 
> > +#include <linux/array_size.h>
> > +#include <linux/bitfield.h>  
> 
> > +#include <linux/bitops.h>  
> 
> > +#include <linux/bits.h>  
> 
> No need, as bitops.h implies (and guarantees) that BIT()/GENMASK() are provided
> with it.
> 
> > +#include <linux/clk.h>
> > +#include <linux/crc8.h>
> > +#include <linux/delay.h>
> > +#include <linux/dev_printk.h>
> > +#include <linux/err.h>
> > +#include <linux/export.h>
> > +#include <linux/gpio/consumer.h>
> > +#include <linux/iio/iio.h>
> > +#include <linux/iio/types.h>
> > +#include <linux/module.h>
> > +#include <linux/mod_devicetable.h>
> > +#include <linux/regmap.h>
> > +#include <linux/regulator/consumer.h>
> > +#include <linux/reset.h>
> > +#include <linux/spi/spi.h>
> > +#include <linux/time.h>
> > +#include <linux/types.h>
> > +#include <linux/unaligned.h>
> > +#include <linux/units.h>  
>