Merge tag 'iio-for-6.8b' of https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into char-misc-next

Jonathan writes:

IIO: 2nd set of new device support, features and cleanup for 6.8

A late/optimistic second pull request. The bots have been poking them
since Wednesday without any issues. There are a few fixes in the
ad7091r5 driver as part of rework to enable the ad7091r8 parts that
are included at start of that series.

Includes pre-work for major changes to the DMA buffers that should
land in 6.9 and will greatly improve performance and flexibility for
high performance devices by enabling DMABUF based zero copy transfers
when we don't need to bounce the data via user space.

New device support
------------------
adi,ad7091r8
- Major refactor of existing adi,ad7091r5 driver to separate out useful
shared library code that can be used by I2C and SPI parts.
- Use that library from a new driver supporting the AD7091R-2, AD7091R-4
and AD7091R-8 12-Bit SPI ADCs.
- Series includes some late breaking fixes for the ad7091r5.

microchip,mcp4821
- New driver for MCP4801, MCP4802, MCP4811, MCP4812, MCP4821 and MCP4822
I2C single / dual channel DACs.

Cleanup
-------
buffers:
- Use IIO_SEPARATE in place of some hard-coded 0 values.
dma-buffers:
- Simplify things to not use an outgoing queue given it only ever has
up to two elements and we only need to track which is first.
- Split the iio_dma_buffer_fileio_free() function up to make it easier
to read and enable reuse in a series lining up for 6.9
iio.h
- Drop some stale documentation of struct fields that don't exist.

* tag 'iio-for-6.8b' of https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio:
iio: linux/iio.h: fix Excess kernel-doc description warning
MAINTAINERS: Add MAINTAINERS entry for AD7091R
iio: adc: Add support for AD7091R-8
dt-bindings: iio: Add AD7091R-8
iio: adc: Split AD7091R-5 config symbol
iio: adc: ad7091r: Add chip_info callback to get conversion result channel
iio: adc: ad7091r: Set device mode through chip_info callback
iio: adc: ad7091r: Remove unneeded probe parameters
iio: adc: ad7091r: Move chip init data to container struct
iio: adc: ad7091r: Move generic AD7091R code to base driver and header file
iio: adc: ad7091r: Enable internal vref if external vref is not supplied
iio: adc: ad7091r: Allow users to configure device events
iio: dac: driver for MCP4821
dt-bindings: iio: dac: add MCP4821
iio: buffer-dma: split iio_dma_buffer_fileio_free() function
iio: buffer-dma: Get rid of outgoing queue
iio: buffer: Use IIO_SEPARATE instead of a hard-coded 0

Documentation/devicetree/bindings/iio/adc/adi,ad7091r5.yaml

···
 $id: http://devicetree.org/schemas/iio/adc/adi,ad7091r5.yaml#
 $schema: http://devicetree.org/meta-schemas/core.yaml#
 
-title: Analog Devices AD7091R5 4-Channel 12-Bit ADC
+title: Analog Devices AD7091R-2/-4/-5/-8 Multi-Channel 12-Bit ADCs
 
 maintainers:
   - Michael Hennerich <[e-mail]>
+  - Marcelo Schmitt <[e-mail]>
 
 description: |
-  Analog Devices AD7091R5 4-Channel 12-Bit ADC
+  Analog Devices AD7091R5 4-Channel 12-Bit ADC supporting I2C interface
   https://www.analog.com/media/en/technical-documentation/data-sheets/ad7091r-5.pdf
+  Analog Devices AD7091R-2/AD7091R-4/AD7091R-8 2-/4-/8-Channel 12-Bit ADCs
+  supporting SPI interface
+  https://www.analog.com/media/en/technical-documentation/data-sheets/AD7091R-2_7091R-4_7091R-8.pdf
 
 properties:
   compatible:
     enum:
+      - adi,ad7091r2
+      - adi,ad7091r4
       - adi,ad7091r5
+      - adi,ad7091r8
 
   reg:
     maxItems: 1
+
+  vdd-supply:
+    description:
+      Provide VDD power to the sensor (VDD range is from 2.7V to 5.25V).
+
+  vdrive-supply:
+    description:
+      Determines the voltage level at which the interface logic will operate.
+      The V_drive voltage range is from 1.8V to 5.25V and must not exceed VDD by
+      more than 0.3V.
 
   vref-supply:
     description:
       Phandle to the vref power supply
 
-  interrupts:
+  convst-gpios:
+    description:
+      GPIO connected to the CONVST pin.
+      This logic input is used to initiate conversions on the analog
+      input channels.
     maxItems: 1
 
+  reset-gpios:
+    maxItems: 1
+
+  interrupts:
+    description:
+      Interrupt for signaling when conversion results exceed the high limit for
+      ADC readings or fall below the low limit for them. Interrupt source must
+      be attached to ALERT/BUSY/GPO0 pin.
+    maxItems: 1
 
 required:
   - compatible
   - reg
 
-additionalProperties: false
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+  # AD7091R-2 does not have ALERT/BUSY/GPO pin
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - adi,ad7091r2
+    then:
+      properties:
+        interrupts: false
+
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - adi,ad7091r2
+              - adi,ad7091r4
+              - adi,ad7091r8
+    then:
+      required:
+        - convst-gpios
+
+unevaluatedProperties: false
 
 examples:
   - |
···
             reg = <0x2f>;
 
             interrupts = <25 IRQ_TYPE_EDGE_FALLING>;
+            interrupt-parent = <&gpio>;
+        };
+    };
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@0 {
+            compatible = "adi,ad7091r8";
+            reg = <0x0>;
+            spi-max-frequency = <1000000>;
+            vref-supply = <&adc_vref>;
+            convst-gpios = <&gpio 25 GPIO_ACTIVE_LOW>;
+            reset-gpios = <&gpio 27 GPIO_ACTIVE_LOW>;
+            interrupts = <22 IRQ_TYPE_EDGE_FALLING>;
             interrupt-parent = <&gpio>;
         };
     };

Documentation/devicetree/bindings/iio/dac/microchip,mcp4821.yaml

···
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/dac/microchip,mcp4821.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip MCP4821 and similar DACs
+
+description: |
+  Supports MCP48x1 (single channel) and MCP48x2 (dual channel) series of DACs.
+  Device supports simplex communication over SPI in Mode 0 and Mode 3.
+
+  +---------+--------------+-------------+
+  | Device  |  Resolution  |   Channels  |
+  |---------|--------------|-------------|
+  | MCP4801 |     8-bit    |      1      |
+  | MCP4802 |     8-bit    |      2      |
+  | MCP4811 |    10-bit    |      1      |
+  | MCP4812 |    10-bit    |      2      |
+  | MCP4821 |    12-bit    |      1      |
+  | MCP4822 |    12-bit    |      2      |
+  +---------+--------------+-------------+
+
+  Datasheet:
+    MCP48x1: https://ww1.microchip.com/downloads/en/DeviceDoc/22244B.pdf
+    MCP48x2: https://ww1.microchip.com/downloads/en/DeviceDoc/20002249B.pdf
+
+maintainers:
+  - Anshul Dalal <[e-mail]>
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+properties:
+  compatible:
+    enum:
+      - microchip,mcp4801
+      - microchip,mcp4802
+      - microchip,mcp4811
+      - microchip,mcp4812
+      - microchip,mcp4821
+      - microchip,mcp4822
+
+  reg:
+    maxItems: 1
+
+  vdd-supply: true
+
+  ldac-gpios:
+    description: |
+      Active Low LDAC (Latch DAC Input) pin used to update the DAC output.
+    maxItems: 1
+
+  powerdown-gpios:
+    description: |
+      Active Low SHDN pin used to enter the shutdown mode.
+    maxItems: 1
+
+  spi-cpha: true
+  spi-cpol: true
+
+required:
+  - compatible
+  - reg
+  - vdd-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        dac@0 {
+            compatible = "microchip,mcp4821";
+            reg = <0>;
+            vdd-supply = <&vdd_regulator>;
+            ldac-gpios = <&gpio0 1 GPIO_ACTIVE_HIGH>;
+            powerdown-gpios = <&gpio0 2 GPIO_ACTIVE_HIGH>;
+            spi-cpha;
+            spi-cpol;
+        };
+    };

MAINTAINERS

···
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad4130.yaml
 F:	drivers/iio/adc/ad4130.c
 
+ANALOG DEVICES INC AD7091R DRIVER
+M:	Marcelo Schmitt <[e-mail]>
+L:	[e-mail]
+S:	Supported
+W:	http://ez.analog.com/community/linux-device-drivers
+F:	Documentation/devicetree/bindings/iio/adc/adi,ad7091r*
+F:	drivers/iio/adc/drivers/iio/adc/ad7091r*
+
 ANALOG DEVICES INC AD7192 DRIVER
 M:	Alexandru Tachici <[e-mail]>
 L:	[e-mail]
···
 F:	Documentation/ABI/testing/sysfs-bus-iio-potentiometer-mcp4531
 F:	drivers/iio/potentiometer/mcp4018.c
 F:	drivers/iio/potentiometer/mcp4531.c
+
+MCP4821 DAC DRIVER
+M:	Anshul Dalal <[e-mail]>
+L:	[e-mail]
+S:	Maintained
+F:	Documentation/devicetree/bindings/iio/dac/microchip,mcp4821.yaml
+F:	drivers/iio/dac/mcp4821.c
 
 MCR20A IEEE-802.15.4 RADIO DRIVER
 M:	Stefan Schmidt <[e-mail]>

drivers/iio/adc/Kconfig

···
 	  To compile this driver as a module, choose M here: the module will be
 	  called ad4130.
 
+config AD7091R
+	tristate
+
 config AD7091R5
 	tristate "Analog Devices AD7091R5 ADC Driver"
 	depends on I2C
+	select AD7091R
 	select REGMAP_I2C
 	help
 	  Say yes here to build support for Analog Devices AD7091R-5 ADC.
+
+config AD7091R8
+	tristate "Analog Devices AD7091R8 ADC Driver"
+	depends on SPI
+	select AD7091R
+	select REGMAP_SPI
+	help
+	  Say yes here to build support for Analog Devices AD7091R-2, AD7091R-4,
+	  and AD7091R-8 ADC.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called ad7091r8.
 
 config AD7124
 	tristate "Analog Devices AD7124 and similar sigma-delta ADCs driver"

drivers/iio/adc/Makefile

···
 obj-$(CONFIG_AB8500_GPADC) += ab8500-gpadc.o
 obj-$(CONFIG_AD_SIGMA_DELTA) += ad_sigma_delta.o
 obj-$(CONFIG_AD4130) += ad4130.o
-obj-$(CONFIG_AD7091R5) += ad7091r5.o ad7091r-base.o
+obj-$(CONFIG_AD7091R) += ad7091r-base.o
+obj-$(CONFIG_AD7091R5) += ad7091r5.o
+obj-$(CONFIG_AD7091R8) += ad7091r8.o
 obj-$(CONFIG_AD7124) += ad7124.o
 obj-$(CONFIG_AD7192) += ad7192.o
 obj-$(CONFIG_AD7266) += ad7266.o

drivers/iio/adc/ad7091r-base.c

···
  */
 
 #include <linux/bitops.h>
+#include <linux/bitfield.h>
 #include <linux/iio/events.h>
 #include <linux/iio/iio.h>
 #include <linux/interrupt.h>
···
 
 #include "ad7091r-base.h"
 
-#define AD7091R_REG_RESULT  0
-#define AD7091R_REG_CHANNEL 1
-#define AD7091R_REG_CONF    2
-#define AD7091R_REG_ALERT   3
-#define AD7091R_REG_CH_LOW_LIMIT(ch) ((ch) * 3 + 4)
-#define AD7091R_REG_CH_HIGH_LIMIT(ch) ((ch) * 3 + 5)
-#define AD7091R_REG_CH_HYSTERESIS(ch) ((ch) * 3 + 6)
-
-/* AD7091R_REG_RESULT */
-#define AD7091R_REG_RESULT_CH_ID(x)	    (((x) >> 13) & 0x3)
-#define AD7091R_REG_RESULT_CONV_RESULT(x)   ((x) & 0xfff)
-
-/* AD7091R_REG_CONF */
-#define AD7091R_REG_CONF_ALERT_EN   BIT(4)
-#define AD7091R_REG_CONF_AUTO   BIT(8)
-#define AD7091R_REG_CONF_CMD    BIT(10)
-
-#define AD7091R_REG_CONF_MODE_MASK  \
-	(AD7091R_REG_CONF_AUTO | AD7091R_REG_CONF_CMD)
-
-enum ad7091r_mode {
-	AD7091R_MODE_SAMPLE,
-	AD7091R_MODE_COMMAND,
-	AD7091R_MODE_AUTOCYCLE,
+const struct iio_event_spec ad7091r_events[] = {
+	{
+		.type = IIO_EV_TYPE_THRESH,
+		.dir = IIO_EV_DIR_RISING,
+		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
+				 BIT(IIO_EV_INFO_ENABLE),
+	},
+	{
+		.type = IIO_EV_TYPE_THRESH,
+		.dir = IIO_EV_DIR_FALLING,
+		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
+				 BIT(IIO_EV_INFO_ENABLE),
+	},
+	{
+		.type = IIO_EV_TYPE_THRESH,
+		.dir = IIO_EV_DIR_EITHER,
+		.mask_separate = BIT(IIO_EV_INFO_HYSTERESIS),
+	},
 };
-
-struct ad7091r_state {
-	struct device *dev;
-	struct regmap *map;
-	struct regulator *vref;
-	const struct ad7091r_chip_info *chip_info;
-	enum ad7091r_mode mode;
-	struct mutex lock; /*lock to prevent concurent reads */
-};
-
-static int ad7091r_set_mode(struct ad7091r_state *st, enum ad7091r_mode mode)
-{
-	int ret, conf;
-
-	switch (mode) {
-	case AD7091R_MODE_SAMPLE:
-		conf = 0;
-		break;
-	case AD7091R_MODE_COMMAND:
-		conf = AD7091R_REG_CONF_CMD;
-		break;
-	case AD7091R_MODE_AUTOCYCLE:
-		conf = AD7091R_REG_CONF_AUTO;
-		break;
-	default:
-		return -EINVAL;
-	}
-
-	ret = regmap_update_bits(st->map, AD7091R_REG_CONF,
-				 AD7091R_REG_CONF_MODE_MASK, conf);
-	if (ret)
-		return ret;
-
-	st->mode = mode;
-
-	return 0;
-}
+EXPORT_SYMBOL_NS_GPL(ad7091r_events, IIO_AD7091R);
 
 static int ad7091r_set_channel(struct ad7091r_state *st, unsigned int channel)
 {
···
 	if (ret)
 		return ret;
 
-	if (AD7091R_REG_RESULT_CH_ID(val) != channel)
+	if (st->chip_info->reg_result_chan_id(val) != channel)
 		return -EIO;
 
 	*read_val = AD7091R_REG_RESULT_CONV_RESULT(val);
···
 	return ret;
 }
 
+static int ad7091r_read_event_config(struct iio_dev *indio_dev,
+				     const struct iio_chan_spec *chan,
+				     enum iio_event_type type,
+				     enum iio_event_direction dir)
+{
+	struct ad7091r_state *st = iio_priv(indio_dev);
+	int val, ret;
+
+	switch (dir) {
+	case IIO_EV_DIR_RISING:
+		ret = regmap_read(st->map,
+				  AD7091R_REG_CH_HIGH_LIMIT(chan->channel),
+				  &val);
+		if (ret)
+			return ret;
+		return val != AD7091R_HIGH_LIMIT;
+	case IIO_EV_DIR_FALLING:
+		ret = regmap_read(st->map,
+				  AD7091R_REG_CH_LOW_LIMIT(chan->channel),
+				  &val);
+		if (ret)
+			return ret;
+		return val != AD7091R_LOW_LIMIT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad7091r_write_event_config(struct iio_dev *indio_dev,
+				      const struct iio_chan_spec *chan,
+				      enum iio_event_type type,
+				      enum iio_event_direction dir, int state)
+{
+	struct ad7091r_state *st = iio_priv(indio_dev);
+
+	if (state) {
+		return regmap_set_bits(st->map, AD7091R_REG_CONF,
+				       AD7091R_REG_CONF_ALERT_EN);
+	} else {
+		/*
+		 * Set thresholds either to 0 or to 2^12 - 1 as appropriate to
+		 * prevent alerts and thus disable event generation.
+		 */
+		switch (dir) {
+		case IIO_EV_DIR_RISING:
+			return regmap_write(st->map,
+					    AD7091R_REG_CH_HIGH_LIMIT(chan->channel),
+					    AD7091R_HIGH_LIMIT);
+		case IIO_EV_DIR_FALLING:
+			return regmap_write(st->map,
+					    AD7091R_REG_CH_LOW_LIMIT(chan->channel),
+					    AD7091R_LOW_LIMIT);
+		default:
+			return -EINVAL;
+		}
+	}
+}
+
+static int ad7091r_read_event_value(struct iio_dev *indio_dev,
+				    const struct iio_chan_spec *chan,
+				    enum iio_event_type type,
+				    enum iio_event_direction dir,
+				    enum iio_event_info info, int *val, int *val2)
+{
+	struct ad7091r_state *st = iio_priv(indio_dev);
+	int ret;
+
+	switch (info) {
+	case IIO_EV_INFO_VALUE:
+		switch (dir) {
+		case IIO_EV_DIR_RISING:
+			ret = regmap_read(st->map,
+					  AD7091R_REG_CH_HIGH_LIMIT(chan->channel),
+					  val);
+			if (ret)
+				return ret;
+			return IIO_VAL_INT;
+		case IIO_EV_DIR_FALLING:
+			ret = regmap_read(st->map,
+					  AD7091R_REG_CH_LOW_LIMIT(chan->channel),
+					  val);
+			if (ret)
+				return ret;
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	case IIO_EV_INFO_HYSTERESIS:
+		ret = regmap_read(st->map,
+				  AD7091R_REG_CH_HYSTERESIS(chan->channel),
+				  val);
+		if (ret)
+			return ret;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad7091r_write_event_value(struct iio_dev *indio_dev,
+				     const struct iio_chan_spec *chan,
+				     enum iio_event_type type,
+				     enum iio_event_direction dir,
+				     enum iio_event_info info, int val, int val2)
+{
+	struct ad7091r_state *st = iio_priv(indio_dev);
+
+	switch (info) {
+	case IIO_EV_INFO_VALUE:
+		switch (dir) {
+		case IIO_EV_DIR_RISING:
+			return regmap_write(st->map,
+					    AD7091R_REG_CH_HIGH_LIMIT(chan->channel),
+					    val);
+		case IIO_EV_DIR_FALLING:
+			return regmap_write(st->map,
+					    AD7091R_REG_CH_LOW_LIMIT(chan->channel),
+					    val);
+		default:
+			return -EINVAL;
+		}
+	case IIO_EV_INFO_HYSTERESIS:
+		return regmap_write(st->map,
+				    AD7091R_REG_CH_HYSTERESIS(chan->channel),
+				    val);
+	default:
+		return -EINVAL;
+	}
+}
+
 static const struct iio_info ad7091r_info = {
 	.read_raw = ad7091r_read_raw,
+	.read_event_config = &ad7091r_read_event_config,
+	.write_event_config = &ad7091r_write_event_config,
+	.read_event_value = &ad7091r_read_event_value,
+	.write_event_value = &ad7091r_write_event_value,
 };
 
 static irqreturn_t ad7091r_event_handler(int irq, void *private)
···
 	regulator_disable(st->vref);
 }
 
-int ad7091r_probe(struct device *dev, const char *name,
-		const struct ad7091r_chip_info *chip_info,
-		struct regmap *map, int irq)
+int ad7091r_probe(struct device *dev, const struct ad7091r_init_info *init_info,
+		  int irq)
 {
 	struct iio_dev *iio_dev;
 	struct ad7091r_state *st;
···
 
 	st = iio_priv(iio_dev);
 	st->dev = dev;
-	st->chip_info = chip_info;
-	st->map = map;
+	init_info->init_adc_regmap(st, init_info->regmap_config);
+	if (IS_ERR(st->map))
+		return dev_err_probe(st->dev, PTR_ERR(st->map),
+				     "Error initializing regmap\n");
 
-	iio_dev->name = name;
 	iio_dev->info = &ad7091r_info;
 	iio_dev->modes = INDIO_DIRECT_MODE;
 
-	iio_dev->num_channels = chip_info->num_channels;
-	iio_dev->channels = chip_info->channels;
+	if (init_info->setup) {
+		ret = init_info->setup(st);
+		if (ret < 0)
+			return ret;
+	}
 
 	if (irq) {
+		st->chip_info = init_info->info_irq;
 		ret = regmap_update_bits(st->map, AD7091R_REG_CONF,
 					 AD7091R_REG_CONF_ALERT_EN, BIT(4));
 		if (ret)
···
 		ret = devm_request_threaded_irq(dev, irq, NULL,
 						ad7091r_event_handler,
 						IRQF_TRIGGER_FALLING |
-						IRQF_ONESHOT, name, iio_dev);
+						IRQF_ONESHOT,
+						st->chip_info->name, iio_dev);
 		if (ret)
 			return ret;
+	} else {
+		st->chip_info = init_info->info_no_irq;
 	}
+
+	iio_dev->name = st->chip_info->name;
+	iio_dev->num_channels = st->chip_info->num_channels;
+	iio_dev->channels = st->chip_info->channels;
 
 	st->vref = devm_regulator_get_optional(dev, "vref");
 	if (IS_ERR(st->vref)) {
 		if (PTR_ERR(st->vref) == -EPROBE_DEFER)
 			return -EPROBE_DEFER;
+
 		st->vref = NULL;
+		/* Enable internal vref */
+		ret = regmap_set_bits(st->map, AD7091R_REG_CONF,
+				      AD7091R_REG_CONF_INT_VREF);
+		if (ret)
+			return dev_err_probe(st->dev, ret,
+					     "Error on enable internal reference\n");
 	} else {
 		ret = regulator_enable(st->vref);
 		if (ret)
···
 	}
 
 	/* Use command mode by default to convert only desired channels*/
-	ret = ad7091r_set_mode(st, AD7091R_MODE_COMMAND);
+	ret = st->chip_info->set_mode(st, AD7091R_MODE_COMMAND);
 	if (ret)
 		return ret;
 
···
 }
 EXPORT_SYMBOL_NS_GPL(ad7091r_probe, IIO_AD7091R);
 
-static bool ad7091r_writeable_reg(struct device *dev, unsigned int reg)
+bool ad7091r_writeable_reg(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case AD7091R_REG_RESULT:
···
 		return true;
 	}
 }
+EXPORT_SYMBOL_NS_GPL(ad7091r_writeable_reg, IIO_AD7091R);
 
-static bool ad7091r_volatile_reg(struct device *dev, unsigned int reg)
+bool ad7091r_volatile_reg(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case AD7091R_REG_RESULT:
···
 		return false;
 	}
 }
-
-const struct regmap_config ad7091r_regmap_config = {
-	.reg_bits = 8,
-	.val_bits = 16,
-	.writeable_reg = ad7091r_writeable_reg,
-	.volatile_reg = ad7091r_volatile_reg,
-};
-EXPORT_SYMBOL_NS_GPL(ad7091r_regmap_config, IIO_AD7091R);
+EXPORT_SYMBOL_NS_GPL(ad7091r_volatile_reg, IIO_AD7091R);
 
 MODULE_AUTHOR("Beniamin Bia <[e-mail]>");
 MODULE_DESCRIPTION("Analog Devices AD7091Rx multi-channel converters");

drivers/iio/adc/ad7091r-base.h

···
 #ifndef __DRIVERS_IIO_ADC_AD7091R_BASE_H__
 #define __DRIVERS_IIO_ADC_AD7091R_BASE_H__
 
+#include <linux/regmap.h>
+
+#define AD7091R_REG_RESULT  0
+#define AD7091R_REG_CHANNEL 1
+#define AD7091R_REG_CONF    2
+#define AD7091R_REG_ALERT   3
+#define AD7091R_REG_CH_LOW_LIMIT(ch) ((ch) * 3 + 4)
+#define AD7091R_REG_CH_HIGH_LIMIT(ch) ((ch) * 3 + 5)
+#define AD7091R_REG_CH_HYSTERESIS(ch) ((ch) * 3 + 6)
+
+/* AD7091R_REG_RESULT */
+#define AD7091R5_REG_RESULT_CH_ID(x)	    (((x) >> 13) & 0x3)
+#define AD7091R8_REG_RESULT_CH_ID(x)	    (((x) >> 13) & 0x7)
+#define AD7091R_REG_RESULT_CONV_RESULT(x)   ((x) & 0xfff)
+
+/* AD7091R_REG_CONF */
+#define AD7091R_REG_CONF_INT_VREF	BIT(0)
+#define AD7091R_REG_CONF_ALERT_EN	BIT(4)
+#define AD7091R_REG_CONF_AUTO		BIT(8)
+#define AD7091R_REG_CONF_CMD		BIT(10)
+
+#define AD7091R_REG_CONF_MODE_MASK  \
+	(AD7091R_REG_CONF_AUTO | AD7091R_REG_CONF_CMD)
+
+/* AD7091R_REG_CH_LIMIT */
+#define AD7091R_HIGH_LIMIT		0xFFF
+#define AD7091R_LOW_LIMIT		0x0
+
+#define AD7091R_CHANNEL(idx, bits, ev, num_ev) {			\
+	.type = IIO_VOLTAGE,						\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),		\
+	.indexed = 1,							\
+	.channel = idx,							\
+	.event_spec = ev,						\
+	.num_event_specs = num_ev,					\
+	.scan_type.storagebits = 16,					\
+	.scan_type.realbits = bits,					\
+}
+
 struct device;
-struct ad7091r_state;
+struct gpio_desc;
+
+enum ad7091r_mode {
+	AD7091R_MODE_SAMPLE,
+	AD7091R_MODE_COMMAND,
+	AD7091R_MODE_AUTOCYCLE,
+};
+
+struct ad7091r_state {
+	struct device *dev;
+	struct regmap *map;
+	struct gpio_desc *convst_gpio;
+	struct gpio_desc *reset_gpio;
+	struct regulator *vref;
+	const struct ad7091r_chip_info *chip_info;
+	enum ad7091r_mode mode;
+	struct mutex lock; /*lock to prevent concurent reads */
+	__be16 tx_buf __aligned(IIO_DMA_MINALIGN);
+	__be16 rx_buf;
+};
 
 struct ad7091r_chip_info {
+	const char *name;
 	unsigned int num_channels;
 	const struct iio_chan_spec *channels;
 	unsigned int vref_mV;
+	unsigned int (*reg_result_chan_id)(unsigned int val);
+	int (*set_mode)(struct ad7091r_state *st, enum ad7091r_mode mode);
 };
 
-extern const struct regmap_config ad7091r_regmap_config;
+struct ad7091r_init_info {
+	const struct ad7091r_chip_info *info_irq;
+	const struct ad7091r_chip_info *info_no_irq;
+	const struct regmap_config *regmap_config;
+	void (*init_adc_regmap)(struct ad7091r_state *st,
+				const struct regmap_config *regmap_conf);
+	int (*setup)(struct ad7091r_state *st);
+};
 
-int ad7091r_probe(struct device *dev, const char *name,
-		const struct ad7091r_chip_info *chip_info,
-		struct regmap *map, int irq);
+extern const struct iio_event_spec ad7091r_events[3];
+
+int ad7091r_probe(struct device *dev, const struct ad7091r_init_info *init_info,
+		  int irq);
+
+bool ad7091r_volatile_reg(struct device *dev, unsigned int reg);
+bool ad7091r_writeable_reg(struct device *dev, unsigned int reg);
 
 #endif /* __DRIVERS_IIO_ADC_AD7091R_BASE_H__ */

drivers/iio/adc/ad7091r5.c

···
 
 #include "ad7091r-base.h"
 
-static const struct iio_event_spec ad7091r5_events[] = {
-	{
-		.type = IIO_EV_TYPE_THRESH,
-		.dir = IIO_EV_DIR_RISING,
-		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
-				 BIT(IIO_EV_INFO_ENABLE),
-	},
-	{
-		.type = IIO_EV_TYPE_THRESH,
-		.dir = IIO_EV_DIR_FALLING,
-		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
-				 BIT(IIO_EV_INFO_ENABLE),
-	},
-	{
-		.type = IIO_EV_TYPE_THRESH,
-		.dir = IIO_EV_DIR_EITHER,
-		.mask_separate = BIT(IIO_EV_INFO_HYSTERESIS),
-	},
-};
-
-#define AD7091R_CHANNEL(idx, bits, ev, num_ev) { \
-	.type = IIO_VOLTAGE, \
-	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
-	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
-	.indexed = 1, \
-	.channel = idx, \
-	.event_spec = ev, \
-	.num_event_specs = num_ev, \
-	.scan_type.storagebits = 16, \
-	.scan_type.realbits = bits, \
-}
 static const struct iio_chan_spec ad7091r5_channels_irq[] = {
-	AD7091R_CHANNEL(0, 12, ad7091r5_events, ARRAY_SIZE(ad7091r5_events)),
-	AD7091R_CHANNEL(1, 12, ad7091r5_events, ARRAY_SIZE(ad7091r5_events)),
-	AD7091R_CHANNEL(2, 12, ad7091r5_events, ARRAY_SIZE(ad7091r5_events)),
-	AD7091R_CHANNEL(3, 12, ad7091r5_events, ARRAY_SIZE(ad7091r5_events)),
+	AD7091R_CHANNEL(0, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
+	AD7091R_CHANNEL(1, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
+	AD7091R_CHANNEL(2, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
+	AD7091R_CHANNEL(3, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
 };
 
 static const struct iio_chan_spec ad7091r5_channels_noirq[] = {
···
 	AD7091R_CHANNEL(3, 12, NULL, 0),
 };
 
+static int ad7091r5_set_mode(struct ad7091r_state *st, enum ad7091r_mode mode)
+{
+	int ret, conf;
+
+	switch (mode) {
+	case AD7091R_MODE_SAMPLE:
+		conf = 0;
+		break;
+	case AD7091R_MODE_COMMAND:
+		conf = AD7091R_REG_CONF_CMD;
+		break;
+	case AD7091R_MODE_AUTOCYCLE:
+		conf = AD7091R_REG_CONF_AUTO;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = regmap_update_bits(st->map, AD7091R_REG_CONF,
+				 AD7091R_REG_CONF_MODE_MASK, conf);
+	if (ret)
+		return ret;
+
+	st->mode = mode;
+
+	return 0;
+}
+
+static unsigned int ad7091r5_reg_result_chan_id(unsigned int val)
+{
+	return AD7091R5_REG_RESULT_CH_ID(val);
+}
+
 static const struct ad7091r_chip_info ad7091r5_chip_info_irq = {
+	.name = "ad7091r-5",
 	.channels = ad7091r5_channels_irq,
 	.num_channels = ARRAY_SIZE(ad7091r5_channels_irq),
 	.vref_mV = 2500,
+	.reg_result_chan_id = &ad7091r5_reg_result_chan_id,
+	.set_mode = &ad7091r5_set_mode,
 };
 
 static const struct ad7091r_chip_info ad7091r5_chip_info_noirq = {
+	.name = "ad7091r-5",
 	.channels = ad7091r5_channels_noirq,
 	.num_channels = ARRAY_SIZE(ad7091r5_channels_noirq),
 	.vref_mV = 2500,
+	.reg_result_chan_id = &ad7091r5_reg_result_chan_id,
+	.set_mode = &ad7091r5_set_mode,
+};
+
+static const struct regmap_config ad7091r_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 16,
+	.writeable_reg = ad7091r_writeable_reg,
+	.volatile_reg = ad7091r_volatile_reg,
+};
+
+static void ad7091r5_regmap_init(struct ad7091r_state *st,
+				 const struct regmap_config *regmap_conf)
+{
+	struct i2c_client *i2c = container_of(st->dev, struct i2c_client, dev);
+
+	st->map = devm_regmap_init_i2c(i2c, regmap_conf);
+}
+
+static struct ad7091r_init_info ad7091r5_init_info = {
+	.info_irq = &ad7091r5_chip_info_irq,
+	.info_no_irq = &ad7091r5_chip_info_noirq,
+	.regmap_config = &ad7091r_regmap_config,
+	.init_adc_regmap = &ad7091r5_regmap_init
 };
 
 static int ad7091r5_i2c_probe(struct i2c_client *i2c)
 {
-	const struct i2c_device_id *id = i2c_client_get_device_id(i2c);
-	const struct ad7091r_chip_info *chip_info;
-	struct regmap *map = devm_regmap_init_i2c(i2c, &ad7091r_regmap_config);
+	const struct ad7091r_init_info *init_info;
 
-	if (IS_ERR(map))
-		return PTR_ERR(map);
+	init_info = i2c_get_match_data(i2c);
+	if (!init_info)
+		return -EINVAL;
 
-	if (i2c->irq)
-		chip_info = &ad7091r5_chip_info_irq;
-	else
-		chip_info = &ad7091r5_chip_info_noirq;
-
-	return ad7091r_probe(&i2c->dev, id->name, chip_info, map, i2c->irq);
+	return ad7091r_probe(&i2c->dev, init_info, i2c->irq);
 }
 
 static const struct of_device_id ad7091r5_dt_ids[] = {
-	{ .compatible = "adi,ad7091r5" },
+	{ .compatible = "adi,ad7091r5", .data = &ad7091r5_init_info },
 	{},
 };
 MODULE_DEVICE_TABLE(of, ad7091r5_dt_ids);
 
 static const struct i2c_device_id ad7091r5_i2c_ids[] = {
-	{"ad7091r5", 0},
+	{"ad7091r5", (kernel_ulong_t)&ad7091r5_init_info },
 	{}
 };
 MODULE_DEVICE_TABLE(i2c, ad7091r5_i2c_ids);

drivers/iio/adc/ad7091r8.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Analog Devices AD7091R8 12-bit SAR ADC driver
+ *
+ * Copyright 2023 Analog Devices Inc.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/gpio/consumer.h>
+#include <linux/spi/spi.h>
+
+#include "ad7091r-base.h"
+
+#define AD7091R8_REG_ADDR_MSK				GENMASK(15, 11)
+#define AD7091R8_RD_WR_FLAG_MSK				BIT(10)
+#define AD7091R8_REG_DATA_MSK				GENMASK(9, 0)
+
+#define AD7091R_SPI_REGMAP_CONFIG(n) {					\
+	.reg_bits = 8,							\
+	.val_bits = 16,							\
+	.volatile_reg = ad7091r_volatile_reg,				\
+	.writeable_reg = ad7091r_writeable_reg,				\
+	.max_register = AD7091R_REG_CH_HYSTERESIS(n),			\
+}
+
+static int ad7091r8_set_mode(struct ad7091r_state *st, enum ad7091r_mode mode)
+{
+	/* AD7091R-2/-4/-8 don't set sample/command/autocycle mode in conf reg */
+	st->mode = mode;
+	return 0;
+}
+
+static unsigned int ad7091r8_reg_result_chan_id(unsigned int val)
+{
+	return AD7091R8_REG_RESULT_CH_ID(val);
+}
+
+#define AD7091R_SPI_CHIP_INFO(_n, _name) {				\
+	.name = _name,							\
+	.channels = ad7091r##_n##_channels,				\
+	.num_channels = ARRAY_SIZE(ad7091r##_n##_channels),		\
+	.vref_mV = 2500,						\
+	.reg_result_chan_id = &ad7091r8_reg_result_chan_id,	\
+	.set_mode = &ad7091r8_set_mode,				\
+}
+
+#define AD7091R_SPI_CHIP_INFO_IRQ(_n, _name) {				\
+	.name = _name,							\
+	.channels = ad7091r##_n##_channels_irq,				\
+	.num_channels = ARRAY_SIZE(ad7091r##_n##_channels_irq),		\
+	.vref_mV = 2500,						\
+	.reg_result_chan_id = &ad7091r8_reg_result_chan_id,	\
+	.set_mode = &ad7091r8_set_mode,				\
+}
+
+enum ad7091r8_info_ids {
+	AD7091R2_INFO,
+	AD7091R4_INFO,
+	AD7091R4_INFO_IRQ,
+	AD7091R8_INFO,
+	AD7091R8_INFO_IRQ,
+};
+
+static const struct iio_chan_spec ad7091r2_channels[] = {
+	AD7091R_CHANNEL(0, 12, NULL, 0),
+	AD7091R_CHANNEL(1, 12, NULL, 0),
+};
+
+static const struct iio_chan_spec ad7091r4_channels[] = {
+	AD7091R_CHANNEL(0, 12, NULL, 0),
+	AD7091R_CHANNEL(1, 12, NULL, 0),
+	AD7091R_CHANNEL(2, 12, NULL, 0),
+	AD7091R_CHANNEL(3, 12, NULL, 0),
+};
+
+static const struct iio_chan_spec ad7091r4_channels_irq[] = {
+	AD7091R_CHANNEL(0, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
+	AD7091R_CHANNEL(1, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
+	AD7091R_CHANNEL(2, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
+	AD7091R_CHANNEL(3, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
+};
+
+static const struct iio_chan_spec ad7091r8_channels[] = {
+	AD7091R_CHANNEL(0, 12, NULL, 0),
+	AD7091R_CHANNEL(1, 12, NULL, 0),
+	AD7091R_CHANNEL(2, 12, NULL, 0),
+	AD7091R_CHANNEL(3, 12, NULL, 0),
+	AD7091R_CHANNEL(4, 12, NULL, 0),
+	AD7091R_CHANNEL(5, 12, NULL, 0),
+	AD7091R_CHANNEL(6, 12, NULL, 0),
+	AD7091R_CHANNEL(7, 12, NULL, 0),
+};
+
+static const struct iio_chan_spec ad7091r8_channels_irq[] = {
+	AD7091R_CHANNEL(0, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
+	AD7091R_CHANNEL(1, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
+	AD7091R_CHANNEL(2, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
+	AD7091R_CHANNEL(3, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
+	AD7091R_CHANNEL(4, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
+	AD7091R_CHANNEL(5, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
+	AD7091R_CHANNEL(6, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
+	AD7091R_CHANNEL(7, 12, ad7091r_events, ARRAY_SIZE(ad7091r_events)),
+};
+
+static void ad7091r_pulse_convst(struct ad7091r_state *st)
+{
+	gpiod_set_value_cansleep(st->convst_gpio, 1);
+	gpiod_set_value_cansleep(st->convst_gpio, 0);
+}
+
+static int ad7091r_regmap_bus_reg_read(void *context, unsigned int reg,
+				       unsigned int *val)
+{
+	struct ad7091r_state *st = context;
+	struct spi_device *spi = container_of(st->dev, struct spi_device, dev);
+	int ret;
+
+	struct spi_transfer t[] = {
+		{
+			.tx_buf = &st->tx_buf,
+			.len = 2,
+			.cs_change = 1,
+		}, {
+			.rx_buf = &st->rx_buf,
+			.len = 2,
+		}
+	};
+
+	if (reg == AD7091R_REG_RESULT)
+		ad7091r_pulse_convst(st);
+
+	st->tx_buf = cpu_to_be16(reg << 11);
+
+	ret = spi_sync_transfer(spi, t, ARRAY_SIZE(t));
+	if (ret < 0)
+		return ret;
+
+	*val = be16_to_cpu(st->rx_buf);
+	return 0;
+}
+
+static int ad7091r_regmap_bus_reg_write(void *context, unsigned int reg,
+					unsigned int val)
+{
+	struct ad7091r_state *st = context;
+	struct spi_device *spi = container_of(st->dev, struct spi_device, dev);
+
+	/*
+	 * AD7091R-2/-4/-8 protocol (datasheet page 31) is to do a single SPI
+	 * transfer with reg address set in bits B15:B11 and value set in B9:B0.
+	 */
+	st->tx_buf = cpu_to_be16(FIELD_PREP(AD7091R8_REG_DATA_MSK, val) |
+				 FIELD_PREP(AD7091R8_RD_WR_FLAG_MSK, 1) |
+				 FIELD_PREP(AD7091R8_REG_ADDR_MSK, reg));
+
+	return spi_write(spi, &st->tx_buf, 2);
+}
+
+static struct regmap_bus ad7091r8_regmap_bus = {
+	.reg_read = ad7091r_regmap_bus_reg_read,
+	.reg_write = ad7091r_regmap_bus_reg_write,
+	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
+	.val_format_endian_default = REGMAP_ENDIAN_BIG,
+};
+
+static const struct ad7091r_chip_info ad7091r8_infos[] = {
+	[AD7091R2_INFO] = AD7091R_SPI_CHIP_INFO(2, "ad7091r-2"),
+	[AD7091R4_INFO] = AD7091R_SPI_CHIP_INFO(4, "ad7091r-4"),
+	[AD7091R4_INFO_IRQ] = AD7091R_SPI_CHIP_INFO_IRQ(4, "ad7091r-4"),
+	[AD7091R8_INFO] = AD7091R_SPI_CHIP_INFO(8, "ad7091r-8"),
+	[AD7091R8_INFO_IRQ] = AD7091R_SPI_CHIP_INFO_IRQ(8, "ad7091r-8")
+};
+
+static const struct regmap_config ad7091r2_reg_conf = AD7091R_SPI_REGMAP_CONFIG(2);
+static const struct regmap_config ad7091r4_reg_conf = AD7091R_SPI_REGMAP_CONFIG(4);
+static const struct regmap_config ad7091r8_reg_conf = AD7091R_SPI_REGMAP_CONFIG(8);
+
+static void ad7091r8_regmap_init(struct ad7091r_state *st,
+				 const struct regmap_config *regmap_conf)
+{
+	st->map = devm_regmap_init(st->dev, &ad7091r8_regmap_bus, st,
+				   regmap_conf);
+}
+
+static int ad7091r8_gpio_setup(struct ad7091r_state *st)
+{
+	st->convst_gpio = devm_gpiod_get(st->dev, "convst", GPIOD_OUT_LOW);
+	if (IS_ERR(st->convst_gpio))
+		return dev_err_probe(st->dev, PTR_ERR(st->convst_gpio),
+				     "Error getting convst GPIO\n");
+
+	st->reset_gpio = devm_gpiod_get_optional(st->dev, "reset",
+						 GPIOD_OUT_HIGH);
+	if (IS_ERR(st->reset_gpio))
+		return dev_err_probe(st->dev, PTR_ERR(st->convst_gpio),
+				     "Error on requesting reset GPIO\n");
+
+	if (st->reset_gpio) {
+		fsleep(20);
+		gpiod_set_value_cansleep(st->reset_gpio, 0);
+	}
+
+	return 0;
+}
+
+static struct ad7091r_init_info ad7091r2_init_info = {
+	.info_no_irq = &ad7091r8_infos[AD7091R2_INFO],
+	.regmap_config = &ad7091r2_reg_conf,
+	.init_adc_regmap = &ad7091r8_regmap_init,
+	.setup = &ad7091r8_gpio_setup
+};
+
+static struct ad7091r_init_info ad7091r4_init_info = {
+	.info_no_irq = &ad7091r8_infos[AD7091R4_INFO],
+	.info_irq = &ad7091r8_infos[AD7091R4_INFO_IRQ],
+	.regmap_config = &ad7091r4_reg_conf,
+	.init_adc_regmap = &ad7091r8_regmap_init,
+	.setup = &ad7091r8_gpio_setup
+};
+
+static struct ad7091r_init_info ad7091r8_init_info = {
+	.info_no_irq = &ad7091r8_infos[AD7091R8_INFO],
+	.info_irq = &ad7091r8_infos[AD7091R8_INFO_IRQ],
+	.regmap_config = &ad7091r8_reg_conf,
+	.init_adc_regmap = &ad7091r8_regmap_init,
+	.setup = &ad7091r8_gpio_setup
+};
+
+static int ad7091r8_spi_probe(struct spi_device *spi)
+{
+	const struct ad7091r_init_info *init_info;
+
+	init_info = spi_get_device_match_data(spi);
+	if (!init_info)
+		return -EINVAL;
+
+	return ad7091r_probe(&spi->dev, init_info, spi->irq);
+}
+
+static const struct of_device_id ad7091r8_of_match[] = {
+	{ .compatible = "adi,ad7091r2", .data = &ad7091r2_init_info },
+	{ .compatible = "adi,ad7091r4", .data = &ad7091r4_init_info },
+	{ .compatible = "adi,ad7091r8", .data = &ad7091r8_init_info },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ad7091r8_of_match);
+
+static const struct spi_device_id ad7091r8_spi_id[] = {
+	{ "ad7091r2", (kernel_ulong_t)&ad7091r2_init_info },
+	{ "ad7091r4", (kernel_ulong_t)&ad7091r4_init_info },
+	{ "ad7091r8", (kernel_ulong_t)&ad7091r8_init_info },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, ad7091r8_spi_id);
+
+static struct spi_driver ad7091r8_driver = {
+	.driver = {
+		.name = "ad7091r8",
+		.of_match_table = ad7091r8_of_match,
+	},
+	.probe = ad7091r8_spi_probe,
+	.id_table = ad7091r8_spi_id,
+};
+module_spi_driver(ad7091r8_driver);
+
+MODULE_AUTHOR("Marcelo Schmitt <[e-mail]>");
+MODULE_DESCRIPTION("Analog Devices AD7091R8 ADC driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(IIO_AD7091R);

drivers/iio/buffer/industrialio-buffer-dma.c

···
 	}
 
 	block->size = size;
-	block->state = IIO_BLOCK_STATE_DEQUEUED;
+	block->state = IIO_BLOCK_STATE_DONE;
 	block->queue = queue;
 	INIT_LIST_HEAD(&block->head);
 	kref_init(&block->kref);
···
 
 static void _iio_dma_buffer_block_done(struct iio_dma_buffer_block *block)
 {
-	struct iio_dma_buffer_queue *queue = block->queue;
-
-	/*
-	 * The buffer has already been freed by the application, just drop the
-	 * reference.
-	 */
-	if (block->state != IIO_BLOCK_STATE_DEAD) {
+	if (block->state != IIO_BLOCK_STATE_DEAD)
 		block->state = IIO_BLOCK_STATE_DONE;
-		list_add_tail(&block->head, &queue->outgoing);
-	}
 }
 
 /**
···
 	 * not support abort and has not given back the block yet.
 	 */
 	switch (block->state) {
-	case IIO_BLOCK_STATE_DEQUEUED:
 	case IIO_BLOCK_STATE_QUEUED:
 	case IIO_BLOCK_STATE_DONE:
 		return true;
···
 	 * dead. This means we can reset the lists without having to fear
 	 * corrution.
 	 */
-	INIT_LIST_HEAD(&queue->outgoing);
 	spin_unlock_irq(&queue->list_lock);
 
 	INIT_LIST_HEAD(&queue->incoming);
···
 	return ret;
 }
 EXPORT_SYMBOL_GPL(iio_dma_buffer_request_update);
+
+static void iio_dma_buffer_fileio_free(struct iio_dma_buffer_queue *queue)
+{
+	unsigned int i;
+
+	spin_lock_irq(&queue->list_lock);
+	for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) {
+		if (!queue->fileio.blocks[i])
+			continue;
+		queue->fileio.blocks[i]->state = IIO_BLOCK_STATE_DEAD;
+	}
+	spin_unlock_irq(&queue->list_lock);
+
+	INIT_LIST_HEAD(&queue->incoming);
+
+	for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) {
+		if (!queue->fileio.blocks[i])
+			continue;
+		iio_buffer_block_put(queue->fileio.blocks[i]);
+		queue->fileio.blocks[i] = NULL;
+	}
+	queue->fileio.active_block = NULL;
+}
 
 static void iio_dma_buffer_submit_block(struct iio_dma_buffer_queue *queue,
 	struct iio_dma_buffer_block *block)
···
 	struct iio_dma_buffer_queue *queue)
 {
 	struct iio_dma_buffer_block *block;
+	unsigned int idx;
 
 	spin_lock_irq(&queue->list_lock);
-	block = list_first_entry_or_null(&queue->outgoing, struct
-		iio_dma_buffer_block, head);
-	if (block != NULL) {
-		list_del(&block->head);
-		block->state = IIO_BLOCK_STATE_DEQUEUED;
+
+	idx = queue->fileio.next_dequeue;
+	block = queue->fileio.blocks[idx];
+
+	if (block->state == IIO_BLOCK_STATE_DONE) {
+		idx = (idx + 1) % ARRAY_SIZE(queue->fileio.blocks);
+		queue->fileio.next_dequeue = idx;
+	} else {
+		block = NULL;
 	}
+
 	spin_unlock_irq(&queue->list_lock);
 
 	return block;
···
 	struct iio_dma_buffer_queue *queue = iio_buffer_to_queue(buf);
 	struct iio_dma_buffer_block *block;
 	size_t data_available = 0;
+	unsigned int i;
 
 	/*
 	 * For counting the available bytes we'll use the size of the block not
···
 		data_available += queue->fileio.active_block->size;
 
 	spin_lock_irq(&queue->list_lock);
-	list_for_each_entry(block, &queue->outgoing, head)
-		data_available += block->size;
+
+	for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) {
+		block = queue->fileio.blocks[i];
+
+		if (block != queue->fileio.active_block
+		    && block->state == IIO_BLOCK_STATE_DONE)
+			data_available += block->size;
+	}
+
 	spin_unlock_irq(&queue->list_lock);
 	mutex_unlock(&queue->lock);
 
···
 	queue->ops = ops;
 
 	INIT_LIST_HEAD(&queue->incoming);
-	INIT_LIST_HEAD(&queue->outgoing);
 
 	mutex_init(&queue->lock);
 	spin_lock_init(&queue->list_lock);
···
  */
 void iio_dma_buffer_exit(struct iio_dma_buffer_queue *queue)
 {
-	unsigned int i;
-
 	mutex_lock(&queue->lock);
 
-	spin_lock_irq(&queue->list_lock);
-	for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) {
-		if (!queue->fileio.blocks[i])
-			continue;
-		queue->fileio.blocks[i]->state = IIO_BLOCK_STATE_DEAD;
-	}
-	INIT_LIST_HEAD(&queue->outgoing);
-	spin_unlock_irq(&queue->list_lock);
-
-	INIT_LIST_HEAD(&queue->incoming);
-
-	for (i = 0; i < ARRAY_SIZE(queue->fileio.blocks); i++) {
-		if (!queue->fileio.blocks[i])
-			continue;
-		iio_buffer_block_put(queue->fileio.blocks[i]);
-		queue->fileio.blocks[i] = NULL;
-	}
-	queue->fileio.active_block = NULL;
+	iio_dma_buffer_fileio_free(queue);
 	queue->ops = NULL;
 
 	mutex_unlock(&queue->lock);

drivers/iio/dac/Kconfig

···
 	  To compile this driver as a module, choose M here: the module
 	  will be called mcp4728.
 
+config MCP4821
+	tristate "MCP4801/02/11/12/21/22 DAC driver"
+	depends on SPI
+	help
+	  Say yes here to build the driver for the Microchip MCP4801
+	  MCP4802, MCP4811, MCP4812, MCP4821 and MCP4822 DAC devices.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called mcp4821.
+
 config MCP4922
 	tristate "MCP4902, MCP4912, MCP4922 DAC driver"
 	depends on SPI

drivers/iio/dac/Makefile

···
 obj-$(CONFIG_MAX5821) += max5821.o
 obj-$(CONFIG_MCP4725) += mcp4725.o
 obj-$(CONFIG_MCP4728) += mcp4728.o
+obj-$(CONFIG_MCP4821) += mcp4821.o
 obj-$(CONFIG_MCP4922) += mcp4922.o
 obj-$(CONFIG_STM32_DAC_CORE) += stm32-dac-core.o
 obj-$(CONFIG_STM32_DAC) += stm32-dac.o

drivers/iio/dac/mcp4821.c

···
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2023 Anshul Dalal <[e-mail]>
+ *
+ * Driver for Microchip MCP4801, MCP4802, MCP4811, MCP4812, MCP4821 and MCP4822
+ *
+ * Based on the work of:
+ *	Michael Welling (MCP4922 Driver)
+ *
+ * Datasheet:
+ *	MCP48x1: https://ww1.microchip.com/downloads/en/DeviceDoc/22244B.pdf
+ *	MCP48x2: https://ww1.microchip.com/downloads/en/DeviceDoc/20002249B.pdf
+ *
+ * TODO:
+ *	- Configurable gain
+ *	- Regulator control
+ */
+
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/spi/spi.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/types.h>
+
+#include <asm/unaligned.h>
+
+#define MCP4821_ACTIVE_MODE BIT(12)
+#define MCP4802_SECOND_CHAN BIT(15)
+
+/* DAC uses an internal Voltage reference of 4.096V at a gain of 2x */
+#define MCP4821_2X_GAIN_VREF_MV 4096
+
+enum mcp4821_supported_drvice_ids {
+	ID_MCP4801,
+	ID_MCP4802,
+	ID_MCP4811,
+	ID_MCP4812,
+	ID_MCP4821,
+	ID_MCP4822,
+};
+
+struct mcp4821_state {
+	struct spi_device *spi;
+	u16 dac_value[2];
+};
+
+struct mcp4821_chip_info {
+	const char *name;
+	int num_channels;
+	const struct iio_chan_spec channels[2];
+};
+
+#define MCP4821_CHAN(channel_id, resolution)                          \
+	{                                                             \
+		.type = IIO_VOLTAGE, .output = 1, .indexed = 1,       \
+		.channel = (channel_id),                              \
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),         \
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+		.scan_type = {                                        \
+			.realbits = (resolution),                     \
+			.shift = 12 - (resolution),                   \
+		},                                                    \
+	}
+
+static const struct mcp4821_chip_info mcp4821_chip_info_table[6] = {
+	[ID_MCP4801] = {
+			.name = "mcp4801",
+			.num_channels = 1,
+			.channels = {
+				MCP4821_CHAN(0, 8),
+			},
+	},
+	[ID_MCP4802] = {
+			.name = "mcp4802",
+			.num_channels = 2,
+			.channels = {
+				MCP4821_CHAN(0, 8),
+				MCP4821_CHAN(1, 8),
+			},
+	},
+	[ID_MCP4811] = {
+			.name = "mcp4811",
+			.num_channels = 1,
+			.channels = {
+				MCP4821_CHAN(0, 10),
+			},
+	},
+	[ID_MCP4812] = {
+			.name = "mcp4812",
+			.num_channels = 2,
+			.channels = {
+				MCP4821_CHAN(0, 10),
+				MCP4821_CHAN(1, 10),
+			},
+	},
+	[ID_MCP4821] = {
+			.name = "mcp4821",
+			.num_channels = 1,
+			.channels = {
+				MCP4821_CHAN(0, 12),
+			},
+	},
+	[ID_MCP4822] = {
+			.name = "mcp4822",
+			.num_channels = 2,
+			.channels = {
+				MCP4821_CHAN(0, 12),
+				MCP4821_CHAN(1, 12),
+			},
+	},
+};
+
+static int mcp4821_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan, int *val,
+			    int *val2, long mask)
+{
+	struct mcp4821_state *state;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		state = iio_priv(indio_dev);
+		*val = state->dac_value[chan->channel];
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = MCP4821_2X_GAIN_VREF_MV;
+		*val2 = chan->scan_type.realbits;
+		return IIO_VAL_FRACTIONAL_LOG2;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int mcp4821_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, int val,
+			     int val2, long mask)
+{
+	struct mcp4821_state *state = iio_priv(indio_dev);
+	u16 write_val;
+	__be16 write_buffer;
+	int ret;
+
+	if (val2 != 0)
+		return -EINVAL;
+
+	if (val < 0 || val >= BIT(chan->scan_type.realbits))
+		return -EINVAL;
+
+	if (mask != IIO_CHAN_INFO_RAW)
+		return -EINVAL;
+
+	write_val = MCP4821_ACTIVE_MODE | val << chan->scan_type.shift;
+	if (chan->channel)
+		write_val |= MCP4802_SECOND_CHAN;
+
+	write_buffer = cpu_to_be16(write_val);
+	ret = spi_write(state->spi, &write_buffer, sizeof(write_buffer));
+	if (ret) {
+		dev_err(&state->spi->dev, "Failed to write to device: %d", ret);
+		return ret;
+	}
+
+	state->dac_value[chan->channel] = val;
+
+	return 0;
+}
+
+static const struct iio_info mcp4821_info = {
+	.read_raw = &mcp4821_read_raw,
+	.write_raw = &mcp4821_write_raw,
+};
+
+static int mcp4821_probe(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev;
+	struct mcp4821_state *state;
+	const struct mcp4821_chip_info *info;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
+	if (indio_dev == NULL)
+		return -ENOMEM;
+
+	state = iio_priv(indio_dev);
+	state->spi = spi;
+
+	info = spi_get_device_match_data(spi);
+	indio_dev->name = info->name;
+	indio_dev->info = &mcp4821_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = info->channels;
+	indio_dev->num_channels = info->num_channels;
+
+	return devm_iio_device_register(&spi->dev, indio_dev);
+}
+
+#define MCP4821_COMPATIBLE(of_compatible, id)        \
+	{                                            \
+		.compatible = of_compatible,         \
+		.data = &mcp4821_chip_info_table[id] \
+	}
+
+static const struct of_device_id mcp4821_of_table[] = {
+	MCP4821_COMPATIBLE("microchip,mcp4801", ID_MCP4801),
+	MCP4821_COMPATIBLE("microchip,mcp4802", ID_MCP4802),
+	MCP4821_COMPATIBLE("microchip,mcp4811", ID_MCP4811),
+	MCP4821_COMPATIBLE("microchip,mcp4812", ID_MCP4812),
+	MCP4821_COMPATIBLE("microchip,mcp4821", ID_MCP4821),
+	MCP4821_COMPATIBLE("microchip,mcp4822", ID_MCP4822),
+	{ /* Sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mcp4821_of_table);
+
+static const struct spi_device_id mcp4821_id_table[] = {
+	{ "mcp4801", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4801]},
+	{ "mcp4802", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4802]},
+	{ "mcp4811", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4811]},
+	{ "mcp4812", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4812]},
+	{ "mcp4821", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4821]},
+	{ "mcp4822", (kernel_ulong_t)&mcp4821_chip_info_table[ID_MCP4822]},
+	{ /* Sentinel */ }
+};
+MODULE_DEVICE_TABLE(spi, mcp4821_id_table);
+
+static struct spi_driver mcp4821_driver = {
+	.driver = {
+		.name = "mcp4821",
+		.of_match_table = mcp4821_of_table,
+	},
+	.probe = mcp4821_probe,
+	.id_table = mcp4821_id_table,
+};
+module_spi_driver(mcp4821_driver);
+
+MODULE_AUTHOR("Anshul Dalal <[e-mail]>");
+MODULE_DESCRIPTION("Microchip MCP4821 DAC Driver");
+MODULE_LICENSE("GPL");

drivers/iio/industrialio-buffer.c

···
 				     &iio_show_fixed_type,
 				     NULL,
 				     0,
-				     0,
+				     IIO_SEPARATE,
 				     &indio_dev->dev,
 				     buffer,
 				     &buffer->buffer_attr_list);
···
 					     &iio_scan_el_show,
 					     &iio_scan_el_store,
 					     chan->scan_index,
-					     0,
+					     IIO_SEPARATE,
 					     &indio_dev->dev,
 					     buffer,
 					     &buffer->buffer_attr_list);
···
 					     &iio_scan_el_ts_show,
 					     &iio_scan_el_ts_store,
 					     chan->scan_index,
-					     0,
+					     IIO_SEPARATE,
 					     &indio_dev->dev,
 					     buffer,
 					     &buffer->buffer_attr_list);

include/linux/iio/buffer-dma.h

···
 
 /**
  * enum iio_block_state - State of a struct iio_dma_buffer_block
- * @IIO_BLOCK_STATE_DEQUEUED: Block is not queued
  * @IIO_BLOCK_STATE_QUEUED: Block is on the incoming queue
  * @IIO_BLOCK_STATE_ACTIVE: Block is currently being processed by the DMA
  * @IIO_BLOCK_STATE_DONE: Block is on the outgoing queue
  * @IIO_BLOCK_STATE_DEAD: Block has been marked as to be freed
  */
 enum iio_block_state {
-	IIO_BLOCK_STATE_DEQUEUED,
 	IIO_BLOCK_STATE_QUEUED,
 	IIO_BLOCK_STATE_ACTIVE,
 	IIO_BLOCK_STATE_DONE,
···
  * @active_block: Block being used in read()
  * @pos: Read offset in the active block
  * @block_size: Size of each block
+ * @next_dequeue: index of next block that will be dequeued
  */
 struct iio_dma_buffer_queue_fileio {
 	struct iio_dma_buffer_block *blocks[2];
 	struct iio_dma_buffer_block *active_block;
 	size_t pos;
 	size_t block_size;
+
+	unsigned int next_dequeue;
 };
 
 /**
···
  *   list and typically also a list of active blocks in the part that handles
  *   the DMA controller
  * @incoming: List of buffers on the incoming queue
- * @outgoing: List of buffers on the outgoing queue
  * @active: Whether the buffer is currently active
  * @fileio: FileIO state
  */
···
 	struct mutex lock;
 	spinlock_t list_lock;
 	struct list_head incoming;
-	struct list_head outgoing;
 
 	bool active;
 

include/linux/iio/iio.h

···
  * @update_scan_mode:	function to configure device and scan buffer when
  *			channels have changed
  * @debugfs_reg_access:	function to read or write register value of device
- * @of_xlate:		function pointer to obtain channel specifier index.
- *			When #iio-cells is greater than '0', the driver could
- *			provide a custom of_xlate function that reads the
- *			*args* and returns the appropriate index in registered
- *			IIO channels array.
  * @fwnode_xlate:	fwnode based function pointer to obtain channel specifier index.
- *			Functionally the same as @of_xlate.
  * @hwfifo_set_watermark: function pointer to set the current hardware
  *			fifo watermark level; see hwfifo_* entries in
  *			Documentation/ABI/testing/sysfs-bus-iio for details on