[PATCH v4 0/2] iio: dac: Add support for MAX22007 DAC

[PATCH v4 0/2] iio: dac: Add support for MAX22007 DAC

[Janani Sunil]

This patch series introduces support for the Analog Devices MAX22007, a
quad-channel, 12-bit digital-to-analog converter (DAC) with integrated
precision output amplifiers and configurable voltage/current output capability.

**Device Overview:**
The MAX22007 features four independent DAC channels that can each be configured
for either voltage output (0-12.5V) or current output (0-25mA) mode. The device
communicates via SPI interface with built-in CRC8 error checking for data integrity.

**Features Implemented:**
- Support for all 4 DAC channels with 12-bit resolution
- Per-channel voltage/current mode configuration via device tree
  property `adi,ch-func = [voltage, current]`
- Independent power control for each channel (attribute)
- Hardware reset support via GPIO (during probe)
- CRC8 error checking for SPI communication

**Patch Summary:**
1. dt-bindings: Binding documentation with channel configuration
2. driver: Implement IIO DAC driver

**Testing:**
The driver was hardware tested on a Raspberry Pi4 on top of v6.12.y
kernel using the MAX22007EVKIT evaluation board.

Janani Sunil (3):

dt-bindings: iio: dac: Add max22007
iio: dac: Add MAX22007 DAC driver support
---
To: Lars-Peter Clausen <lars@metafoo.de>
To: Michael Hennerich <Michael.Hennerich@analog.com>
To: Jonathan Cameron <jic23@kernel.org>
To: Rob Herring <robh@kernel.org>
To: Krzysztof Kozlowski <krzk+dt@kernel.org>
To: Conor Dooley <conor+dt@kernel.org>
To: Jonathan Corbet <corbet@lwn.net>
Cc: linux-iio@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: jan.sun97@gmail.com
Cc: gastmaier@gmail.com
Signed-off-by: Janani Sunil <janani.sunil@analog.com>

---
Changes in v4:
- Re-sent of improper v3 (at v3 I *accidentaly* reverted the dt-binding
  commit to v1 after a rebase).
- Corrected description for reset GPIO in the dt-binding
- Wrap commit description at 75 columns
- Link to v3: https://lore.kernel.org/r/20260114-max22007-patch-v3-0-769298f50b8a@analog.com

Changes in v3:
- Remove node defined for power supplies in the devicetree documentaiton
- Made use of CRC8_TABLE_SIZE macro in the crc table definition
- Corrected casting of reg address in the SPI read function
- Applied reverse christmas tree variable ordering
- Added a macro fro the reference voltage and reused the same in the
  scale factor
- Removed usage of 'supplies' in enabling bulk regulator and removed
  unused variable 'i'
- Added step n the probe function to toggle the reset GPIO
- Updated spacing in macro definitions
- Link to v2: https://lore.kernel.org/r/20260108-max22007-dev-v2-0-2506c738784f@analog.com/

Changes in v2:
- Wrap commit messages as per coding guidelines
- Removed all driver references from the hardware
- Update property description for reset-gpio
- Removed allOf
- Added minimum/maximum limits for channel number in the devicetree
  binding
- Replaced adi,type with adi,ch-func.
- Added reference to required supplies in the binding, configured them
  in the driver
- Channels are not a required property anymore.
- Replaced instances of 'channel' in macros to just 'ch'
- Added trailing commas wherever necessary, removed them as per comments
- Add explicit values for enum- max22007_channel_power
- Replace channel spec structure member 'iio_chan' with 'iio_chans'
- Use spi_write_then_read() API in the max22007_spi_read() API
- Check for reg_size ==1 and hardcode the size otherwise
- Wrap lines in the driver to 80 characters
- Update in-line comment on the resolution
- Separate declarations with assignment, from the ones that don't
- Update the usage of channel template
- Add a local device descriptor to point to the SPI device
- Add a transition of the Reset GPIO from low to high in the probe
- Make use of regmap_set_bits() instead of regmap_update_bits during CRC
  Enable function call.
- Remove the documentation commit, as it is not needed anymore.
- Link to v1: https://lore.kernel.org/r/20251219-max22007-dev-v1-0-242da2c2b868@analog.com

---
Janani Sunil (2):
      dt-bindings: iio: dac: Add max22007
      iio: dac: Add MAX22007 DAC driver support

 .../devicetree/bindings/iio/dac/adi,max22007.yaml  | 120 +++++
 MAINTAINERS                                        |   8 +
 drivers/iio/dac/Kconfig                            |  13 +
 drivers/iio/dac/Makefile                           |   1 +
 drivers/iio/dac/max22007.c                         | 488 +++++++++++++++++++++
 5 files changed, 630 insertions(+)
---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20260114-max22007-patch-6b5c48e37457

Best regards,
-- 
Janani Sunil <janani.sunil@analog.com>

[PATCH v4 1/2] dt-bindings: iio: dac: Add max22007

[Janani Sunil]

Devicetree bindings for MAX22007 4-channel 12-bit DAC that drives a
voltage or current output on each channel

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 .../devicetree/bindings/iio/dac/adi,max22007.yaml  | 120 +++++++++++++++++++++
 MAINTAINERS                                        |   7 ++
 2 files changed, 127 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/dac/adi,max22007.yaml b/Documentation/devicetree/bindings/iio/dac/adi,max22007.yaml
new file mode 100644
index 000000000000..93d95f6b4c08
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/dac/adi,max22007.yaml
@@ -0,0 +1,120 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/dac/adi,max22007.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices MAX22007 DAC
+
+maintainers:
+  - Janani Sunil <janani.sunil@analog.com>
+
+description:
+  The MAX22007 is a quad-channel, 12-bit digital-to-analog converter (DAC)
+  with integrated precision output amplifiers and current output capability.
+  Each channel can be independently configured for voltage or current output.
+  Datasheet available at https://www.analog.com/en/products/max22007.html
+
+$ref: /schemas/spi/spi-peripheral-props.yaml#
+
+properties:
+  compatible:
+    const: adi,max22007
+
+  reg:
+    maxItems: 1
+
+  spi-max-frequency:
+    maximum: 500000
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+  vdd-supply:
+    description: Low-Voltage Power Supply from +2.7V to +5.5V.
+
+  hvdd-supply:
+    description:
+      Positive High-Voltage Power Supply from +8V to (HVSS +24V) for
+      the Output Channels.
+
+  hvss-supply:
+    description:
+      Optional Negative High-Voltage Power Supply from -2V to 0V for the Output
+      Channels. For most applications HVSS can be connected to GND (0V), but for
+      applications requiring output down to true 0V or 0mA, connect to a -2V supply.
+
+  reset-gpios:
+    maxItems: 1
+    description:
+      Active low GPIO.
+
+patternProperties:
+  "^channel@[0-3]$":
+    $ref: /schemas/iio/dac/dac.yaml#
+    type: object
+    description:
+      Represents the external channels which are connected to the DAC.
+
+    properties:
+      reg:
+        description: Channel number
+        items:
+          minimum: 0
+          maximum: 3
+
+      adi,ch-func:
+        description:
+          Channel output type. Use CH_FUNC_VOLTAGE_OUTPUT for voltage
+          output or CH_FUNC_CURRENT_OUTPUT for current output.
+        $ref: /schemas/types.yaml#/definitions/uint32
+        enum: [1, 2]
+
+    required:
+      - reg
+      - adi,ch-func
+
+    unevaluatedProperties: false
+
+required:
+  - compatible
+  - reg
+  - vdd-supply
+  - hvdd-supply
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/iio/addac/adi,ad74413r.h>
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        dac@0 {
+            compatible = "adi,max22007";
+            reg = <0>;
+            spi-max-frequency = <500000>;
+            reset-gpios = <&gpio 19 GPIO_ACTIVE_LOW>;
+            vdd-supply = <&vdd_reg>;
+            hvdd-supply = <&hvdd_reg>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            channel@0 {
+                reg = <0>;
+                adi,ch-func = <CH_FUNC_VOLTAGE_OUTPUT>;
+            };
+
+            channel@1 {
+                reg = <1>;
+                adi,ch-func = <CH_FUNC_CURRENT_OUTPUT>;
+            };
+        };
+    };
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index 5b11839cba9d..48559d2625b3 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1594,6 +1594,13 @@ W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/dac/adi,ad9739a.yaml
 F:	drivers/iio/dac/ad9739a.c
 
+ANALOG DEVICES INC MAX22007 DRIVER
+M:	Janani Sunil <janani.sunil@analog.com>
+L:	linux-iio@vger.kernel.org
+S:	Supported
+W:	https://ez.analog.com/linux-software-drivers
+F:	Documentation/devicetree/bindings/iio/dac/adi,max22007.yaml
+
 ANALOG DEVICES INC ADA4250 DRIVER
 M:	Antoniu Miclaus <antoniu.miclaus@analog.com>
 L:	linux-iio@vger.kernel.org

-- 
2.43.0

[PATCH v4 2/2] iio: dac: Add MAX22007 DAC driver support

[Janani Sunil]

Add support for the MAX22007 4 channel DAC that drives a voltage or
current output on each channel.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 MAINTAINERS                |   1 +
 drivers/iio/dac/Kconfig    |  13 ++
 drivers/iio/dac/Makefile   |   1 +
 drivers/iio/dac/max22007.c | 488 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 503 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 48559d2625b3..f54150e81fe8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1600,6 +1600,7 @@ L:	linux-iio@vger.kernel.org
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/dac/adi,max22007.yaml
+F:	drivers/iio/dac/max22007.c
 
 ANALOG DEVICES INC ADA4250 DRIVER
 M:	Antoniu Miclaus <antoniu.miclaus@analog.com>
diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 7cd3caec1262..4a31993f5b14 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -482,6 +482,19 @@ config MAX517
 	  This driver can also be built as a module.  If so, the module
 	  will be called max517.
 
+config MAX22007
+	tristate "Analog Devices MAX22007 DAC Driver"
+	depends on SPI
+	select REGMAP_SPI
+	select CRC8
+	help
+	  Say Y here if you want to build a driver for Analog Devices MAX22007.
+
+	  MAX22007 is a quad-channel, 12-bit, voltage-output digital to
+	  analog converter (DAC) with SPI interface.
+
+	  If compiled as a module, it will be called max22007.
+
 config MAX5522
 	tristate "Maxim MAX5522 DAC driver"
 	depends on SPI_MASTER
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index e6ac4c67e337..0bbc6d09d22c 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -48,6 +48,7 @@ obj-$(CONFIG_LTC2664) += ltc2664.o
 obj-$(CONFIG_LTC2688) += ltc2688.o
 obj-$(CONFIG_M62332) += m62332.o
 obj-$(CONFIG_MAX517) += max517.o
+obj-$(CONFIG_MAX22007) += max22007.o
 obj-$(CONFIG_MAX5522) += max5522.o
 obj-$(CONFIG_MAX5821) += max5821.o
 obj-$(CONFIG_MCP4725) += mcp4725.o
diff --git a/drivers/iio/dac/max22007.c b/drivers/iio/dac/max22007.c
new file mode 100644
index 000000000000..e95036a10991
--- /dev/null
+++ b/drivers/iio/dac/max22007.c
@@ -0,0 +1,488 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * max22007.c - MAX22007 DAC driver
+ *
+ * Driver for Analog Devices MAX22007 Digital to Analog Converter.
+ *
+ * Copyright (c) 2026 Analog Devices Inc.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/crc8.h>
+#include <linux/dev_printk.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/gpio/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/kstrtox.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/types.h>
+
+#include <dt-bindings/iio/addac/adi,ad74413r.h>
+
+#define MAX22007_NUM_CHANNELS				4
+#define MAX22007_REV_ID_REG				0x00
+#define MAX22007_STAT_INTR_REG				0x01
+#define MAX22007_INTERRUPT_EN_REG			0x02
+#define MAX22007_CONFIG_REG				0x03
+#define MAX22007_CONTROL_REG				0x04
+#define MAX22007_CHANNEL_MODE_REG			0x05
+#define MAX22007_SOFT_RESET_REG				0x06
+#define MAX22007_DAC_CHANNEL_REG(ch)			(0x07 + (ch))
+#define MAX22007_GPIO_CTRL_REG				0x0B
+#define MAX22007_GPIO_DATA_REG				0x0C
+#define MAX22007_GPI_EDGE_INT_CTRL_REG			0x0D
+#define MAX22007_GPI_INT_STATUS_REG			0x0E
+
+/* Channel mask definitions */
+#define     MAX22007_CH_MODE_CH_MASK(ch)		BIT(12 + (ch))
+#define     MAX22007_CH_PWRON_CH_MASK(ch)		BIT(8 + (ch))
+#define     MAX22007_DAC_LATCH_MODE_MASK(ch)		BIT(12 + (ch))
+#define     MAX22007_LDAC_UPDATE_MASK(ch)		BIT(12 + (ch))
+#define     MAX22007_SW_RST_MASK			BIT(8)
+#define     MAX22007_SW_CLR_MASK			BIT(12)
+#define     MAX22007_SOFT_RESET_BITS_MASK		(MAX22007_SW_RST_MASK | \
+							 MAX22007_SW_CLR_MASK)
+#define     MAX22007_DAC_DATA_MASK			GENMASK(15, 4)
+#define     MAX22007_DAC_MAX_RAW			GENMASK(11, 0)
+#define     MAX22007_CRC8_POLYNOMIAL			0x8C
+#define     MAX22007_CRC_EN_MASK			BIT(0)
+#define     MAX22007_RW_MASK				BIT(0)
+#define     MAX22007_CRC_OVERHEAD			1
+#define     MAX22007_NUM_SUPPLIES			3
+#define     MAX22007_REF_MV				2500
+
+/* Field value preparation macros with masking */
+#define     MAX22007_CH_PWR_VAL(ch, val)		(((val) & 0x1) << (8 + (ch)))
+#define     MAX22007_CH_MODE_VAL(ch, val)		(((val) & 0x1) << (12 + (ch)))
+#define     MAX22007_DAC_LATCH_MODE_VAL(ch, val)	(((val) & 0x1) << (12 + (ch)))
+
+static u8 max22007_crc8_table[CRC8_TABLE_SIZE];
+
+static const char * const max22007_supply_names[MAX22007_NUM_SUPPLIES] = {
+	"vdd",
+	"hvdd",
+	"hvss",
+};
+
+struct max22007_state {
+	struct spi_device *spi;
+	struct regmap *regmap;
+	struct iio_chan_spec *iio_chans;
+	u8 tx_buf[4] __aligned(IIO_DMA_MINALIGN);
+	u8 rx_buf[4];
+};
+
+static int max22007_spi_read(void *context, const void *reg, size_t reg_size,
+			     void *val, size_t val_size)
+{
+	struct max22007_state *st = context;
+	u8 calculated_crc, received_crc;
+	u8 rx_buf[4];
+	u8 reg_byte;
+	int ret;
+
+	if (reg_size != 1)
+		return -EINVAL;
+
+	if (val_size == 0 || val_size > 3)
+		return -EINVAL;
+
+	memcpy(&reg_byte, reg, 1);
+
+	ret = spi_write_then_read(st->spi, &reg_byte, 1, rx_buf,
+				  val_size + MAX22007_CRC_OVERHEAD);
+	if (ret) {
+		dev_err(&st->spi->dev, "SPI transfer failed: %d\n", ret);
+		return ret;
+	}
+
+	calculated_crc = crc8(max22007_crc8_table, &reg_byte, 1, 0x00);
+	calculated_crc = crc8(max22007_crc8_table, rx_buf, 2, calculated_crc);
+	received_crc = rx_buf[val_size];
+
+	if (calculated_crc != received_crc) {
+		dev_err(&st->spi->dev, "CRC mismatch on read register %02x\n", reg_byte);
+		return -EIO;
+	}
+
+	memcpy(val, rx_buf, val_size);
+
+	return 0;
+}
+
+static int max22007_spi_write(void *context, const void *data, size_t count)
+{
+	struct max22007_state *st = context;
+	struct spi_transfer xfer = {
+		.tx_buf = st->tx_buf,
+		.rx_buf = st->rx_buf,
+	};
+
+	if (count + MAX22007_CRC_OVERHEAD > sizeof(st->tx_buf))
+		return -EINVAL;
+
+	memset(st->tx_buf, 0, sizeof(st->tx_buf));
+
+	xfer.len = count + MAX22007_CRC_OVERHEAD;
+
+	memcpy(st->tx_buf, data, count);
+	st->tx_buf[count] = crc8(max22007_crc8_table, st->tx_buf,
+				 sizeof(st->tx_buf) - 1, 0x00);
+
+	return spi_sync_transfer(st->spi, &xfer, 1);
+}
+
+static bool max22007_reg_readable(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MAX22007_REV_ID_REG:
+	case MAX22007_STAT_INTR_REG:
+	case MAX22007_CONFIG_REG:
+	case MAX22007_CONTROL_REG:
+	case MAX22007_CHANNEL_MODE_REG:
+	case MAX22007_SOFT_RESET_REG:
+	case MAX22007_GPIO_CTRL_REG:
+	case MAX22007_GPIO_DATA_REG:
+	case MAX22007_GPI_EDGE_INT_CTRL_REG:
+	case MAX22007_GPI_INT_STATUS_REG:
+		return true;
+	case MAX22007_DAC_CHANNEL_REG(0) ... MAX22007_DAC_CHANNEL_REG(MAX22007_NUM_CHANNELS - 1):
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool max22007_reg_writable(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MAX22007_CONFIG_REG:
+	case MAX22007_CONTROL_REG:
+	case MAX22007_CHANNEL_MODE_REG:
+	case MAX22007_SOFT_RESET_REG:
+	case MAX22007_GPIO_CTRL_REG:
+	case MAX22007_GPIO_DATA_REG:
+	case MAX22007_GPI_EDGE_INT_CTRL_REG:
+		return true;
+	case MAX22007_DAC_CHANNEL_REG(0) ... MAX22007_DAC_CHANNEL_REG(MAX22007_NUM_CHANNELS - 1):
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_bus max22007_regmap_bus = {
+	.read = max22007_spi_read,
+	.write = max22007_spi_write,
+	.read_flag_mask = MAX22007_RW_MASK,
+	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
+	.val_format_endian_default = REGMAP_ENDIAN_BIG,
+};
+
+static const struct regmap_config max22007_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 16,
+	.reg_shift = -1,
+	.readable_reg = max22007_reg_readable,
+	.writeable_reg = max22007_reg_writable,
+	.max_register = 0x0E,
+};
+
+static int max22007_write_channel_data(struct max22007_state *st,
+				       unsigned int channel, int data)
+{
+	unsigned int reg_val;
+
+	if (data < 0 || data > MAX22007_DAC_MAX_RAW)
+		return -EINVAL;
+
+	reg_val = FIELD_PREP(MAX22007_DAC_DATA_MASK, data);
+
+	return regmap_write(st->regmap, MAX22007_DAC_CHANNEL_REG(channel), reg_val);
+}
+
+static int max22007_read_channel_data(struct max22007_state *st,
+				      unsigned int channel, int *data)
+{
+	unsigned int reg_val;
+	int ret;
+
+	ret = regmap_read(st->regmap, MAX22007_DAC_CHANNEL_REG(channel), &reg_val);
+	if (ret)
+		return ret;
+
+	*data = FIELD_GET(MAX22007_DAC_DATA_MASK, reg_val);
+
+	return 0;
+}
+
+static int max22007_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct max22007_state *st = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = max22007_read_channel_data(st, chan->channel, val);
+		if (ret)
+			return ret;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		if (chan->type == IIO_VOLTAGE)
+			*val = 5 * MAX22007_REF_MV;  /* 5 * Vref in mV */
+		else
+			*val = 25;  /* Vref / (2 * Rsense) = MAX22007_REF_MV / 100 */
+		*val2 = 12;  /* 12-bit DAC resolution */
+		return IIO_VAL_FRACTIONAL_LOG2;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int max22007_write_raw(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      int val, int val2, long mask)
+{
+	struct max22007_state *st = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		return max22007_write_channel_data(st, chan->channel, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info max22007_info = {
+	.read_raw = max22007_read_raw,
+	.write_raw = max22007_write_raw,
+};
+
+static ssize_t max22007_read_dac_powerdown(struct iio_dev *indio_dev,
+					   uintptr_t private,
+					   const struct iio_chan_spec *chan,
+					   char *buf)
+{
+	struct max22007_state *st = iio_priv(indio_dev);
+	unsigned int reg_val;
+	bool powerdown;
+	int ret;
+
+	ret = regmap_read(st->regmap, MAX22007_CHANNEL_MODE_REG, &reg_val);
+	if (ret)
+		return ret;
+
+	powerdown = !(reg_val & MAX22007_CH_PWRON_CH_MASK(chan->channel));
+
+	return sysfs_emit(buf, "%d\n", powerdown);
+}
+
+static ssize_t max22007_write_dac_powerdown(struct iio_dev *indio_dev,
+					    uintptr_t private,
+					    const struct iio_chan_spec *chan,
+					    const char *buf, size_t len)
+{
+	struct max22007_state *st = iio_priv(indio_dev);
+	bool powerdown;
+	int ret;
+
+	ret = kstrtobool(buf, &powerdown);
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(st->regmap, MAX22007_CHANNEL_MODE_REG,
+				 MAX22007_CH_PWRON_CH_MASK(chan->channel),
+				 MAX22007_CH_PWR_VAL(chan->channel, powerdown ? 0 : 1));
+	if (ret)
+		return ret;
+
+	return len;
+}
+
+static const struct iio_chan_spec_ext_info max22007_ext_info[] = {
+	{
+		.name = "powerdown",
+		.read = max22007_read_dac_powerdown,
+		.write = max22007_write_dac_powerdown,
+		.shared = IIO_SEPARATE,
+	},
+	{ }
+};
+
+static int max22007_parse_channel_cfg(struct max22007_state *st, u8 *num_channels)
+{
+	struct device *dev = &st->spi->dev;
+	int ret, num_chan;
+	int i = 0;
+	u32 reg;
+
+	num_chan = device_get_child_node_count(dev);
+	if (!num_chan)
+		return dev_err_probe(dev, -ENODEV, "no channels configured\n");
+
+	st->iio_chans = devm_kcalloc(dev, num_chan, sizeof(*st->iio_chans), GFP_KERNEL);
+	if (!st->iio_chans)
+		return -ENOMEM;
+
+	device_for_each_child_node_scoped(dev, child) {
+		u32 ch_func;
+		enum iio_chan_type chan_type;
+
+		ret = fwnode_property_read_u32(child, "reg", &reg);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "failed to read reg property of %pfwP\n", child);
+
+		if (reg >= MAX22007_NUM_CHANNELS)
+			return dev_err_probe(dev, -EINVAL,
+					     "reg out of range in %pfwP\n", child);
+
+		ret = fwnode_property_read_u32(child, "adi,ch-func", &ch_func);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "missing adi,ch-func property for %pfwP\n", child);
+
+		switch (ch_func) {
+		case CH_FUNC_VOLTAGE_OUTPUT:
+			chan_type = IIO_VOLTAGE;
+			break;
+		case CH_FUNC_CURRENT_OUTPUT:
+			chan_type = IIO_CURRENT;
+			break;
+		default:
+			return dev_err_probe(dev, -EINVAL,
+					     "invalid adi,ch-func %u for %pfwP\n",
+					     ch_func, child);
+		}
+
+		st->iio_chans[i++] = (struct iio_chan_spec) {
+			.output = 1,
+			.indexed = 1,
+			.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+					      BIT(IIO_CHAN_INFO_SCALE),
+			.ext_info = max22007_ext_info,
+			.channel = reg,
+			.type = chan_type,
+		};
+
+		ret = regmap_update_bits(st->regmap, MAX22007_CHANNEL_MODE_REG,
+					 MAX22007_CH_MODE_CH_MASK(reg),
+					 MAX22007_CH_MODE_VAL(reg, ch_func - 1));
+		if (ret)
+			return ret;
+
+		/* Set DAC to transparent mode (immediate update) */
+		ret = regmap_update_bits(st->regmap, MAX22007_CONFIG_REG,
+					 MAX22007_DAC_LATCH_MODE_MASK(reg),
+					 MAX22007_DAC_LATCH_MODE_VAL(reg, 1));
+		if (ret)
+			return ret;
+	}
+
+	*num_channels = num_chan;
+
+	return 0;
+}
+
+static int max22007_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct gpio_desc *reset_gpio;
+	struct max22007_state *st;
+	struct iio_dev *indio_dev;
+	u8 num_channels;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	st->spi = spi;
+
+	crc8_populate_lsb(max22007_crc8_table, MAX22007_CRC8_POLYNOMIAL);
+
+	st->regmap = devm_regmap_init(dev, &max22007_regmap_bus, st,
+					 &max22007_regmap_config);
+	if (IS_ERR(st->regmap))
+		return dev_err_probe(dev, PTR_ERR(st->regmap),
+				     "Failed to initialize regmap\n");
+
+	ret = devm_regulator_bulk_get_enable(dev, MAX22007_NUM_SUPPLIES,
+					     max22007_supply_names);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to get and enable regulators\n");
+
+	reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(reset_gpio),
+				     "Failed to get reset GPIO\n");
+
+	if (reset_gpio) {
+		gpiod_set_value_cansleep(reset_gpio, 1);
+		usleep_range(1000, 5000);
+		gpiod_set_value_cansleep(reset_gpio, 0);
+		usleep_range(1000, 5000);
+	} else {
+		ret = regmap_write(st->regmap, MAX22007_SOFT_RESET_REG,
+				   MAX22007_SOFT_RESET_BITS_MASK);
+		if (ret)
+			return ret;
+	}
+
+	ret = regmap_set_bits(st->regmap, MAX22007_CONFIG_REG,
+			      MAX22007_CRC_EN_MASK);
+	if (ret)
+		return ret;
+
+	ret = max22007_parse_channel_cfg(st, &num_channels);
+	if (ret)
+		return ret;
+
+	indio_dev->info = &max22007_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = st->iio_chans;
+	indio_dev->num_channels = num_channels;
+	indio_dev->name = "max22007";
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct spi_device_id max22007_id[] = {
+	{ "max22007" },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, max22007_id);
+
+static const struct of_device_id max22007_of_match[] = {
+	{ .compatible = "adi,max22007" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max22007_of_match);
+
+static struct spi_driver max22007_driver = {
+	.driver = {
+		.name = "max22007",
+		.of_match_table = max22007_of_match,
+	},
+	.probe = max22007_probe,
+	.id_table = max22007_id,
+};
+module_spi_driver(max22007_driver);
+
+MODULE_AUTHOR("Janani Sunil <janani.sunil@analog.com>");
+MODULE_DESCRIPTION("Analog Devices MAX22007 DAC");
+MODULE_LICENSE("GPL");

-- 
2.43.0

Re: [PATCH v4 2/2] iio: dac: Add MAX22007 DAC driver support

[Jonathan Cameron]

On Mon, 19 Jan 2026 12:24:24 +0100
Janani Sunil <janani.sunil@analog.com> wrote:

> Add support for the MAX22007 4 channel DAC that drives a voltage or
> current output on each channel.
> 
> Signed-off-by: Janani Sunil <janani.sunil@analog.com>

I'm going to move a little quicker on this one than I normally would
(so if for instance anyone still wants to take a look I might drop it again).
Code looks good to me.

I remembered to run my config for iwyu on this one (I dropped device.h
by hand to see what was actually in use).

Note I ignored a few of them as they are considered standard as included
from types.h which you have (need to tweak my config on that).

Ignored the errno.h thing as that's because I have a rule to say err.h
is enough, but I'm currently taking the view that one is a bit flexible.

drivers/iio/dac/max22007.c should add these lines:                                
#include <linux/compiler.h>                      // for __aligned                 
#include <linux/delay.h>                         // for usleep_range              
#include <linux/device/devres.h>                 // for devm_kcalloc              
#include <linux/minmax.h>                        // for __cmp_op_max
#include <linux/stddef.h>                        // for true, false               
struct device;                        
                                                                                  
drivers/iio/dac/max22007.c should remove these lines:                             
- #include <linux/errno.h>  // lines 15-15   

Applied with this diff to make the headers a little more directly relevant:

diff --git a/drivers/iio/dac/max22007.c b/drivers/iio/dac/max22007.c
index e95036a10991..182ac7155a89 100644
--- a/drivers/iio/dac/max22007.c
+++ b/drivers/iio/dac/max22007.c
@@ -10,13 +10,15 @@
 #include <linux/bitfield.h>
 #include <linux/bits.h>
 #include <linux/crc8.h>
+#include <linux/delay.h>
 #include <linux/dev_printk.h>
-#include <linux/device.h>
+#include <linux/device/devres.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/gpio/consumer.h>
 #include <linux/iio/iio.h>
 #include <linux/kstrtox.h>
+#include <linux/minmax.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/property.h>
@@ -29,6 +31,7 @@
 #include <linux/types.h>
 
 #include <dt-bindings/iio/addac/adi,ad74413r.h>
+struct device;
 
 #define MAX22007_NUM_CHANNELS                          4
 #define MAX22007_REV_ID_REG                            0x00

> ---
>  MAINTAINERS                |   1 +
>  drivers/iio/dac/Kconfig    |  13 ++
>  drivers/iio/dac/Makefile   |   1 +
>  drivers/iio/dac/max22007.c | 488 +++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 503 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 48559d2625b3..f54150e81fe8 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1600,6 +1600,7 @@ L:	linux-iio@vger.kernel.org
>  S:	Supported
>  W:	https://ez.analog.com/linux-software-drivers
>  F:	Documentation/devicetree/bindings/iio/dac/adi,max22007.yaml
> +F:	drivers/iio/dac/max22007.c
>  
>  ANALOG DEVICES INC ADA4250 DRIVER
>  M:	Antoniu Miclaus <antoniu.miclaus@analog.com>
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index 7cd3caec1262..4a31993f5b14 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -482,6 +482,19 @@ config MAX517
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called max517.
>  
> +config MAX22007
> +	tristate "Analog Devices MAX22007 DAC Driver"
> +	depends on SPI
> +	select REGMAP_SPI
> +	select CRC8
> +	help
> +	  Say Y here if you want to build a driver for Analog Devices MAX22007.
> +
> +	  MAX22007 is a quad-channel, 12-bit, voltage-output digital to
> +	  analog converter (DAC) with SPI interface.
> +
> +	  If compiled as a module, it will be called max22007.
> +
>  config MAX5522
>  	tristate "Maxim MAX5522 DAC driver"
>  	depends on SPI_MASTER
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index e6ac4c67e337..0bbc6d09d22c 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -48,6 +48,7 @@ obj-$(CONFIG_LTC2664) += ltc2664.o
>  obj-$(CONFIG_LTC2688) += ltc2688.o
>  obj-$(CONFIG_M62332) += m62332.o
>  obj-$(CONFIG_MAX517) += max517.o
> +obj-$(CONFIG_MAX22007) += max22007.o
>  obj-$(CONFIG_MAX5522) += max5522.o
>  obj-$(CONFIG_MAX5821) += max5821.o
>  obj-$(CONFIG_MCP4725) += mcp4725.o
> diff --git a/drivers/iio/dac/max22007.c b/drivers/iio/dac/max22007.c
> new file mode 100644
> index 000000000000..e95036a10991
> --- /dev/null
> +++ b/drivers/iio/dac/max22007.c
> @@ -0,0 +1,488 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * max22007.c - MAX22007 DAC driver
> + *
> + * Driver for Analog Devices MAX22007 Digital to Analog Converter.
> + *
> + * Copyright (c) 2026 Analog Devices Inc.
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/bits.h>
> +#include <linux/crc8.h>
> +#include <linux/dev_printk.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/errno.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/kstrtox.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/property.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +#include <linux/spi/spi.h>
> +#include <linux/string.h>
> +#include <linux/sysfs.h>
> +#include <linux/types.h>
> +
> +#include <dt-bindings/iio/addac/adi,ad74413r.h>
> +
> +#define MAX22007_NUM_CHANNELS				4
> +#define MAX22007_REV_ID_REG				0x00
> +#define MAX22007_STAT_INTR_REG				0x01
> +#define MAX22007_INTERRUPT_EN_REG			0x02
> +#define MAX22007_CONFIG_REG				0x03
> +#define MAX22007_CONTROL_REG				0x04
> +#define MAX22007_CHANNEL_MODE_REG			0x05
> +#define MAX22007_SOFT_RESET_REG				0x06
> +#define MAX22007_DAC_CHANNEL_REG(ch)			(0x07 + (ch))
> +#define MAX22007_GPIO_CTRL_REG				0x0B
> +#define MAX22007_GPIO_DATA_REG				0x0C
> +#define MAX22007_GPI_EDGE_INT_CTRL_REG			0x0D
> +#define MAX22007_GPI_INT_STATUS_REG			0x0E
> +
> +/* Channel mask definitions */
> +#define     MAX22007_CH_MODE_CH_MASK(ch)		BIT(12 + (ch))
> +#define     MAX22007_CH_PWRON_CH_MASK(ch)		BIT(8 + (ch))
> +#define     MAX22007_DAC_LATCH_MODE_MASK(ch)		BIT(12 + (ch))
> +#define     MAX22007_LDAC_UPDATE_MASK(ch)		BIT(12 + (ch))
> +#define     MAX22007_SW_RST_MASK			BIT(8)
> +#define     MAX22007_SW_CLR_MASK			BIT(12)
> +#define     MAX22007_SOFT_RESET_BITS_MASK		(MAX22007_SW_RST_MASK | \
> +							 MAX22007_SW_CLR_MASK)
> +#define     MAX22007_DAC_DATA_MASK			GENMASK(15, 4)
> +#define     MAX22007_DAC_MAX_RAW			GENMASK(11, 0)
> +#define     MAX22007_CRC8_POLYNOMIAL			0x8C
> +#define     MAX22007_CRC_EN_MASK			BIT(0)
> +#define     MAX22007_RW_MASK				BIT(0)
> +#define     MAX22007_CRC_OVERHEAD			1
> +#define     MAX22007_NUM_SUPPLIES			3
> +#define     MAX22007_REF_MV				2500
> +
> +/* Field value preparation macros with masking */
> +#define     MAX22007_CH_PWR_VAL(ch, val)		(((val) & 0x1) << (8 + (ch)))
> +#define     MAX22007_CH_MODE_VAL(ch, val)		(((val) & 0x1) << (12 + (ch)))
> +#define     MAX22007_DAC_LATCH_MODE_VAL(ch, val)	(((val) & 0x1) << (12 + (ch)))
> +
> +static u8 max22007_crc8_table[CRC8_TABLE_SIZE];
> +
> +static const char * const max22007_supply_names[MAX22007_NUM_SUPPLIES] = {
> +	"vdd",
> +	"hvdd",
> +	"hvss",
> +};
> +
> +struct max22007_state {
> +	struct spi_device *spi;
> +	struct regmap *regmap;
> +	struct iio_chan_spec *iio_chans;
> +	u8 tx_buf[4] __aligned(IIO_DMA_MINALIGN);
> +	u8 rx_buf[4];
> +};
> +
> +static int max22007_spi_read(void *context, const void *reg, size_t reg_size,
> +			     void *val, size_t val_size)
> +{
> +	struct max22007_state *st = context;
> +	u8 calculated_crc, received_crc;
> +	u8 rx_buf[4];
> +	u8 reg_byte;
> +	int ret;
> +
> +	if (reg_size != 1)
> +		return -EINVAL;
> +
> +	if (val_size == 0 || val_size > 3)
> +		return -EINVAL;
> +
> +	memcpy(&reg_byte, reg, 1);
> +
> +	ret = spi_write_then_read(st->spi, &reg_byte, 1, rx_buf,
> +				  val_size + MAX22007_CRC_OVERHEAD);
> +	if (ret) {
> +		dev_err(&st->spi->dev, "SPI transfer failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	calculated_crc = crc8(max22007_crc8_table, &reg_byte, 1, 0x00);
> +	calculated_crc = crc8(max22007_crc8_table, rx_buf, 2, calculated_crc);
> +	received_crc = rx_buf[val_size];
> +
> +	if (calculated_crc != received_crc) {
> +		dev_err(&st->spi->dev, "CRC mismatch on read register %02x\n", reg_byte);
> +		return -EIO;
> +	}
> +
> +	memcpy(val, rx_buf, val_size);
> +
> +	return 0;
> +}
> +
> +static int max22007_spi_write(void *context, const void *data, size_t count)
> +{
> +	struct max22007_state *st = context;
> +	struct spi_transfer xfer = {
> +		.tx_buf = st->tx_buf,
> +		.rx_buf = st->rx_buf,
> +	};
> +
> +	if (count + MAX22007_CRC_OVERHEAD > sizeof(st->tx_buf))
> +		return -EINVAL;
> +
> +	memset(st->tx_buf, 0, sizeof(st->tx_buf));
> +
> +	xfer.len = count + MAX22007_CRC_OVERHEAD;
> +
> +	memcpy(st->tx_buf, data, count);
> +	st->tx_buf[count] = crc8(max22007_crc8_table, st->tx_buf,
> +				 sizeof(st->tx_buf) - 1, 0x00);
> +
> +	return spi_sync_transfer(st->spi, &xfer, 1);
> +}
> +
> +static bool max22007_reg_readable(struct device *dev, unsigned int reg)
> +{
> +	switch (reg) {
> +	case MAX22007_REV_ID_REG:
> +	case MAX22007_STAT_INTR_REG:
> +	case MAX22007_CONFIG_REG:
> +	case MAX22007_CONTROL_REG:
> +	case MAX22007_CHANNEL_MODE_REG:
> +	case MAX22007_SOFT_RESET_REG:
> +	case MAX22007_GPIO_CTRL_REG:
> +	case MAX22007_GPIO_DATA_REG:
> +	case MAX22007_GPI_EDGE_INT_CTRL_REG:
> +	case MAX22007_GPI_INT_STATUS_REG:
> +		return true;
> +	case MAX22007_DAC_CHANNEL_REG(0) ... MAX22007_DAC_CHANNEL_REG(MAX22007_NUM_CHANNELS - 1):
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +static bool max22007_reg_writable(struct device *dev, unsigned int reg)
> +{
> +	switch (reg) {
> +	case MAX22007_CONFIG_REG:
> +	case MAX22007_CONTROL_REG:
> +	case MAX22007_CHANNEL_MODE_REG:
> +	case MAX22007_SOFT_RESET_REG:
> +	case MAX22007_GPIO_CTRL_REG:
> +	case MAX22007_GPIO_DATA_REG:
> +	case MAX22007_GPI_EDGE_INT_CTRL_REG:
> +		return true;
> +	case MAX22007_DAC_CHANNEL_REG(0) ... MAX22007_DAC_CHANNEL_REG(MAX22007_NUM_CHANNELS - 1):
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +static const struct regmap_bus max22007_regmap_bus = {
> +	.read = max22007_spi_read,
> +	.write = max22007_spi_write,
> +	.read_flag_mask = MAX22007_RW_MASK,
> +	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
> +	.val_format_endian_default = REGMAP_ENDIAN_BIG,
> +};
> +
> +static const struct regmap_config max22007_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 16,
> +	.reg_shift = -1,
> +	.readable_reg = max22007_reg_readable,
> +	.writeable_reg = max22007_reg_writable,
> +	.max_register = 0x0E,
> +};
> +
> +static int max22007_write_channel_data(struct max22007_state *st,
> +				       unsigned int channel, int data)
> +{
> +	unsigned int reg_val;
> +
> +	if (data < 0 || data > MAX22007_DAC_MAX_RAW)
> +		return -EINVAL;
> +
> +	reg_val = FIELD_PREP(MAX22007_DAC_DATA_MASK, data);
> +
> +	return regmap_write(st->regmap, MAX22007_DAC_CHANNEL_REG(channel), reg_val);
> +}
> +
> +static int max22007_read_channel_data(struct max22007_state *st,
> +				      unsigned int channel, int *data)
> +{
> +	unsigned int reg_val;
> +	int ret;
> +
> +	ret = regmap_read(st->regmap, MAX22007_DAC_CHANNEL_REG(channel), &reg_val);
> +	if (ret)
> +		return ret;
> +
> +	*data = FIELD_GET(MAX22007_DAC_DATA_MASK, reg_val);
> +
> +	return 0;
> +}
> +
> +static int max22007_read_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     int *val, int *val2, long mask)
> +{
> +	struct max22007_state *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		ret = max22007_read_channel_data(st, chan->channel, val);
> +		if (ret)
> +			return ret;
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		if (chan->type == IIO_VOLTAGE)
> +			*val = 5 * MAX22007_REF_MV;  /* 5 * Vref in mV */
> +		else
> +			*val = 25;  /* Vref / (2 * Rsense) = MAX22007_REF_MV / 100 */
> +		*val2 = 12;  /* 12-bit DAC resolution */
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int max22007_write_raw(struct iio_dev *indio_dev,
> +			      struct iio_chan_spec const *chan,
> +			      int val, int val2, long mask)
> +{
> +	struct max22007_state *st = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		return max22007_write_channel_data(st, chan->channel, val);
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_info max22007_info = {
> +	.read_raw = max22007_read_raw,
> +	.write_raw = max22007_write_raw,
> +};
> +
> +static ssize_t max22007_read_dac_powerdown(struct iio_dev *indio_dev,
> +					   uintptr_t private,
> +					   const struct iio_chan_spec *chan,
> +					   char *buf)
> +{
> +	struct max22007_state *st = iio_priv(indio_dev);
> +	unsigned int reg_val;
> +	bool powerdown;
> +	int ret;
> +
> +	ret = regmap_read(st->regmap, MAX22007_CHANNEL_MODE_REG, &reg_val);
> +	if (ret)
> +		return ret;
> +
> +	powerdown = !(reg_val & MAX22007_CH_PWRON_CH_MASK(chan->channel));
> +
> +	return sysfs_emit(buf, "%d\n", powerdown);
> +}
> +
> +static ssize_t max22007_write_dac_powerdown(struct iio_dev *indio_dev,
> +					    uintptr_t private,
> +					    const struct iio_chan_spec *chan,
> +					    const char *buf, size_t len)
> +{
> +	struct max22007_state *st = iio_priv(indio_dev);
> +	bool powerdown;
> +	int ret;
> +
> +	ret = kstrtobool(buf, &powerdown);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_update_bits(st->regmap, MAX22007_CHANNEL_MODE_REG,
> +				 MAX22007_CH_PWRON_CH_MASK(chan->channel),
> +				 MAX22007_CH_PWR_VAL(chan->channel, powerdown ? 0 : 1));
> +	if (ret)
> +		return ret;
> +
> +	return len;
> +}
> +
> +static const struct iio_chan_spec_ext_info max22007_ext_info[] = {
> +	{
> +		.name = "powerdown",
> +		.read = max22007_read_dac_powerdown,
> +		.write = max22007_write_dac_powerdown,
> +		.shared = IIO_SEPARATE,
> +	},
> +	{ }
> +};
> +
> +static int max22007_parse_channel_cfg(struct max22007_state *st, u8 *num_channels)
> +{
> +	struct device *dev = &st->spi->dev;
> +	int ret, num_chan;
> +	int i = 0;
> +	u32 reg;
> +
> +	num_chan = device_get_child_node_count(dev);
> +	if (!num_chan)
> +		return dev_err_probe(dev, -ENODEV, "no channels configured\n");
> +
> +	st->iio_chans = devm_kcalloc(dev, num_chan, sizeof(*st->iio_chans), GFP_KERNEL);
> +	if (!st->iio_chans)
> +		return -ENOMEM;
> +
> +	device_for_each_child_node_scoped(dev, child) {
> +		u32 ch_func;
> +		enum iio_chan_type chan_type;
> +
> +		ret = fwnode_property_read_u32(child, "reg", &reg);
> +		if (ret)
> +			return dev_err_probe(dev, ret,
> +					     "failed to read reg property of %pfwP\n", child);
> +
> +		if (reg >= MAX22007_NUM_CHANNELS)
> +			return dev_err_probe(dev, -EINVAL,
> +					     "reg out of range in %pfwP\n", child);
> +
> +		ret = fwnode_property_read_u32(child, "adi,ch-func", &ch_func);
> +		if (ret)
> +			return dev_err_probe(dev, ret,
> +					     "missing adi,ch-func property for %pfwP\n", child);
> +
> +		switch (ch_func) {
> +		case CH_FUNC_VOLTAGE_OUTPUT:
> +			chan_type = IIO_VOLTAGE;
> +			break;
> +		case CH_FUNC_CURRENT_OUTPUT:
> +			chan_type = IIO_CURRENT;
> +			break;
> +		default:
> +			return dev_err_probe(dev, -EINVAL,
> +					     "invalid adi,ch-func %u for %pfwP\n",
> +					     ch_func, child);
> +		}
> +
> +		st->iio_chans[i++] = (struct iio_chan_spec) {
> +			.output = 1,
> +			.indexed = 1,
> +			.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +					      BIT(IIO_CHAN_INFO_SCALE),
> +			.ext_info = max22007_ext_info,
> +			.channel = reg,
> +			.type = chan_type,
> +		};
> +
> +		ret = regmap_update_bits(st->regmap, MAX22007_CHANNEL_MODE_REG,
> +					 MAX22007_CH_MODE_CH_MASK(reg),
> +					 MAX22007_CH_MODE_VAL(reg, ch_func - 1));
> +		if (ret)
> +			return ret;
> +
> +		/* Set DAC to transparent mode (immediate update) */
> +		ret = regmap_update_bits(st->regmap, MAX22007_CONFIG_REG,
> +					 MAX22007_DAC_LATCH_MODE_MASK(reg),
> +					 MAX22007_DAC_LATCH_MODE_VAL(reg, 1));
> +		if (ret)
> +			return ret;
> +	}
> +
> +	*num_channels = num_chan;
> +
> +	return 0;
> +}
> +
> +static int max22007_probe(struct spi_device *spi)
> +{
> +	struct device *dev = &spi->dev;
> +	struct gpio_desc *reset_gpio;
> +	struct max22007_state *st;
> +	struct iio_dev *indio_dev;
> +	u8 num_channels;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +	st->spi = spi;
> +
> +	crc8_populate_lsb(max22007_crc8_table, MAX22007_CRC8_POLYNOMIAL);
> +
> +	st->regmap = devm_regmap_init(dev, &max22007_regmap_bus, st,
> +					 &max22007_regmap_config);
> +	if (IS_ERR(st->regmap))
> +		return dev_err_probe(dev, PTR_ERR(st->regmap),
> +				     "Failed to initialize regmap\n");
> +
> +	ret = devm_regulator_bulk_get_enable(dev, MAX22007_NUM_SUPPLIES,
> +					     max22007_supply_names);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to get and enable regulators\n");
> +
> +	reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
> +	if (IS_ERR(reset_gpio))
> +		return dev_err_probe(dev, PTR_ERR(reset_gpio),
> +				     "Failed to get reset GPIO\n");
> +
> +	if (reset_gpio) {
> +		gpiod_set_value_cansleep(reset_gpio, 1);
> +		usleep_range(1000, 5000);
> +		gpiod_set_value_cansleep(reset_gpio, 0);
> +		usleep_range(1000, 5000);
> +	} else {
> +		ret = regmap_write(st->regmap, MAX22007_SOFT_RESET_REG,
> +				   MAX22007_SOFT_RESET_BITS_MASK);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	ret = regmap_set_bits(st->regmap, MAX22007_CONFIG_REG,
> +			      MAX22007_CRC_EN_MASK);
> +	if (ret)
> +		return ret;
> +
> +	ret = max22007_parse_channel_cfg(st, &num_channels);
> +	if (ret)
> +		return ret;
> +
> +	indio_dev->info = &max22007_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = st->iio_chans;
> +	indio_dev->num_channels = num_channels;
> +	indio_dev->name = "max22007";
> +
> +	return devm_iio_device_register(dev, indio_dev);
> +}
> +
> +static const struct spi_device_id max22007_id[] = {
> +	{ "max22007" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(spi, max22007_id);
> +
> +static const struct of_device_id max22007_of_match[] = {
> +	{ .compatible = "adi,max22007" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, max22007_of_match);
> +
> +static struct spi_driver max22007_driver = {
> +	.driver = {
> +		.name = "max22007",
> +		.of_match_table = max22007_of_match,
> +	},
> +	.probe = max22007_probe,
> +	.id_table = max22007_id,
> +};
> +module_spi_driver(max22007_driver);
> +
> +MODULE_AUTHOR("Janani Sunil <janani.sunil@analog.com>");
> +MODULE_DESCRIPTION("Analog Devices MAX22007 DAC");
> +MODULE_LICENSE("GPL");
> 

Re: [PATCH v4 0/2] iio: dac: Add support for MAX22007 DAC

[Jonathan Cameron]

On Mon, 19 Jan 2026 12:24:22 +0100
Janani Sunil <janani.sunil@analog.com> wrote:

> This patch series introduces support for the Analog Devices MAX22007, a
> quad-channel, 12-bit digital-to-analog converter (DAC) with integrated
> precision output amplifiers and configurable voltage/current output capability.
> 
> **Device Overview:**
> The MAX22007 features four independent DAC channels that can each be configured
> for either voltage output (0-12.5V) or current output (0-25mA) mode. The device
> communicates via SPI interface with built-in CRC8 error checking for data integrity.
> 
> **Features Implemented:**
> - Support for all 4 DAC channels with 12-bit resolution
> - Per-channel voltage/current mode configuration via device tree
>   property `adi,ch-func = [voltage, current]`
> - Independent power control for each channel (attribute)
> - Hardware reset support via GPIO (during probe)
> - CRC8 error checking for SPI communication
> 
> **Patch Summary:**
> 1. dt-bindings: Binding documentation with channel configuration
> 2. driver: Implement IIO DAC driver
> 
> **Testing:**
> The driver was hardware tested on a Raspberry Pi4 on top of v6.12.y
> kernel using the MAX22007EVKIT evaluation board.
> 
> Janani Sunil (3):
> 
> dt-bindings: iio: dac: Add max22007
> iio: dac: Add MAX22007 DAC driver support
> ---
> To: Lars-Peter Clausen <lars@metafoo.de>
> To: Michael Hennerich <Michael.Hennerich@analog.com>
> To: Jonathan Cameron <jic23@kernel.org>
> To: Rob Herring <robh@kernel.org>
> To: Krzysztof Kozlowski <krzk+dt@kernel.org>
> To: Conor Dooley <conor+dt@kernel.org>
> To: Jonathan Corbet <corbet@lwn.net>
> Cc: linux-iio@vger.kernel.org
> Cc: devicetree@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-doc@vger.kernel.org
> Cc: jan.sun97@gmail.com
> Cc: gastmaier@gmail.com
> Signed-off-by: Janani Sunil <janani.sunil@analog.com>
As noted in patch 2 comments I am rushing this a bit given point in cycle
so if anyone else wants to take a final look (e.g. Marcelo who looked at
v2) then that is fine.

In meantime I've applied this to the testing branch of iio.git which will
become togreg if all looks good in test builds.

Jonathan

> 
> ---
> Changes in v4:
> - Re-sent of improper v3 (at v3 I *accidentaly* reverted the dt-binding
>   commit to v1 after a rebase).
> - Corrected description for reset GPIO in the dt-binding
> - Wrap commit description at 75 columns
> - Link to v3: https://lore.kernel.org/r/20260114-max22007-patch-v3-0-769298f50b8a@analog.com
> 
> Changes in v3:
> - Remove node defined for power supplies in the devicetree documentaiton
> - Made use of CRC8_TABLE_SIZE macro in the crc table definition
> - Corrected casting of reg address in the SPI read function
> - Applied reverse christmas tree variable ordering
> - Added a macro fro the reference voltage and reused the same in the
>   scale factor
> - Removed usage of 'supplies' in enabling bulk regulator and removed
>   unused variable 'i'
> - Added step n the probe function to toggle the reset GPIO
> - Updated spacing in macro definitions
> - Link to v2: https://lore.kernel.org/r/20260108-max22007-dev-v2-0-2506c738784f@analog.com/
> 
> Changes in v2:
> - Wrap commit messages as per coding guidelines
> - Removed all driver references from the hardware
> - Update property description for reset-gpio
> - Removed allOf
> - Added minimum/maximum limits for channel number in the devicetree
>   binding
> - Replaced adi,type with adi,ch-func.
> - Added reference to required supplies in the binding, configured them
>   in the driver
> - Channels are not a required property anymore.
> - Replaced instances of 'channel' in macros to just 'ch'
> - Added trailing commas wherever necessary, removed them as per comments
> - Add explicit values for enum- max22007_channel_power
> - Replace channel spec structure member 'iio_chan' with 'iio_chans'
> - Use spi_write_then_read() API in the max22007_spi_read() API
> - Check for reg_size ==1 and hardcode the size otherwise
> - Wrap lines in the driver to 80 characters
> - Update in-line comment on the resolution
> - Separate declarations with assignment, from the ones that don't
> - Update the usage of channel template
> - Add a local device descriptor to point to the SPI device
> - Add a transition of the Reset GPIO from low to high in the probe
> - Make use of regmap_set_bits() instead of regmap_update_bits during CRC
>   Enable function call.
> - Remove the documentation commit, as it is not needed anymore.
> - Link to v1: https://lore.kernel.org/r/20251219-max22007-dev-v1-0-242da2c2b868@analog.com
> 
> ---
> Janani Sunil (2):
>       dt-bindings: iio: dac: Add max22007
>       iio: dac: Add MAX22007 DAC driver support
> 
>  .../devicetree/bindings/iio/dac/adi,max22007.yaml  | 120 +++++
>  MAINTAINERS                                        |   8 +
>  drivers/iio/dac/Kconfig                            |  13 +
>  drivers/iio/dac/Makefile                           |   1 +
>  drivers/iio/dac/max22007.c                         | 488 +++++++++++++++++++++
>  5 files changed, 630 insertions(+)
> ---
> base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
> change-id: 20260114-max22007-patch-6b5c48e37457
> 
> Best regards,