[PATCH v5 1/3] dt-bindings: iio: dac: AD5766 yaml documentation

[PATCH v5 1/3] dt-bindings: iio: dac: AD5766 yaml documentation

[Cristian Pop]

This adds device tree bindings for the AD5766 DAC.

Signed-off-by: Cristian Pop <cristian.pop@analog.com>
---
Changelog v5:                                                              
        -rename to property to "output-range-voltage"
 .../bindings/iio/dac/adi,ad5766.yaml          | 64 +++++++++++++++++++
 1 file changed, 64 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/dac/adi,ad5766.yaml

diff --git a/Documentation/devicetree/bindings/iio/dac/adi,ad5766.yaml b/Documentation/devicetree/bindings/iio/dac/adi,ad5766.yaml
new file mode 100644
index 000000000000..1deace7c48b2
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/dac/adi,ad5766.yaml
@@ -0,0 +1,64 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+# Copyright 2020 Analog Devices Inc.
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/dac/adi,ad5766.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices AD5766 DAC device driver
+
+maintainers:
+  - Cristian Pop <cristian.pop@analog.com>
+
+description: |
+  Bindings for the Analog Devices AD5766 current DAC device. Datasheet can be
+  found here:
+    https://www.analog.com/media/en/technical-documentation/data-sheets/ad5766-5767.pdf
+
+properties:
+  compatible:
+    enum:
+      - adi,ad5766
+      - adi,ad5767
+
+  output-range-volts:
+    description: Select converter output range.
+
+  reg:
+    maxItems: 1
+
+  spi-max-frequency:
+    maximum: 1000000
+
+  spi-cpol: true
+
+  reset-gpios:
+    description: GPIO spec for the RESET pin. If specified, it will be asserted
+      during driver probe. As the line is active low, it should be marked
+      GPIO_ACTIVE_LOW.
+    maxItems: 1
+
+required:
+  - compatible
+  - output-range-volts
+  - reg
+  - spi-max-frequency
+  - spi-cpol
+
+additionalProperties: false
+
+examples:
+  - |
+    spi {
+          #address-cells = <1>;
+          #size-cells = <0>;
+          
+          ad5766@0 {
+              compatible = "adi,ad5766";
+              output-range-volts = <(-5) 5>;
+              reg = <0>;
+              spi-cpol;
+              spi-max-frequency = <1000000>;
+              reset-gpios = <&gpio 22 0>;
+            };
+      };
-- 
2.17.1

[PATCH v5 2/3] Documentation/ABI/testing: Add documentation for AD5766 new ABI

[Cristian Pop]

New interface is proposed for dither functionality. This future allows
composing  an external signals to the selected output channel.
The dither signal can be turned on/off, scaled, inverted, or it can be
selected from different sources.

Signed-off-by: Cristian Pop <cristian.pop@analog.com>
---
Changelog v5:                                                              
        - Rename property to: "in_voltageY_dither_enable"                  
        - Change scale values to: "1 0.75 0.5 0.25"                        
        - Specify KernelVersion
 .../ABI/testing/sysfs-bus-iio-dac-ad5766      | 31 +++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-dac-ad5766

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-dac-ad5766 b/Documentation/ABI/testing/sysfs-bus-iio-dac-ad5766
new file mode 100644
index 000000000000..6e5e383b2c53
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-dac-ad5766
@@ -0,0 +1,31 @@
+What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY_dither_ennable
+KernelVersion:	5.12
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Dither enable. Write 1 to enable dither or 0 to disable it.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY_dither_invert
+KernelVersion:	5.12
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Inverts the dither applied to the selected DAC channel. Dither is not
+		inverted by default. Write "1" to invert dither.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY_dither_scale_available
+KernelVersion:	5.12
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Returns possible scalings available for the current channel.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY_dither_scale
+KernelVersion:	5.12
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Scales the dither before it is applied to the selected channel.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY_dither_source
+KernelVersion:	5.12
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Selects dither source applied to the selected channel. Write "0" to
+		select N0 source, write "1" to select N1 source.
-- 
2.17.1

Re: [PATCH v5 2/3] Documentation/ABI/testing: Add documentation for AD5766 new ABI

[Jonathan Cameron]

On Fri, 8 Jan 2021 20:37:38 +0200
Cristian Pop <cristian.pop@analog.com> wrote:

> New interface is proposed for dither functionality. This future allows
> composing  an external signals to the selected output channel.
> The dither signal can be turned on/off, scaled, inverted, or it can be
> selected from different sources.
> 
> Signed-off-by: Cristian Pop <cristian.pop@analog.com>
Hi Cristian,

One trivial inline to fix if you need to respin. Otherwise I can tidy up whilst
applying.

Jonathan


> ---
> Changelog v5:                                                              
>         - Rename property to: "in_voltageY_dither_enable"                  
>         - Change scale values to: "1 0.75 0.5 0.25"                        
>         - Specify KernelVersion
>  .../ABI/testing/sysfs-bus-iio-dac-ad5766      | 31 +++++++++++++++++++
>  1 file changed, 31 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-dac-ad5766
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-dac-ad5766 b/Documentation/ABI/testing/sysfs-bus-iio-dac-ad5766
> new file mode 100644
> index 000000000000..6e5e383b2c53
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-bus-iio-dac-ad5766
> @@ -0,0 +1,31 @@
> +What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY_dither_ennable
Typo, enable but I can fix that whilst applying if there is nothing else.

Jonathan

> +KernelVersion:	5.12
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Dither enable. Write 1 to enable dither or 0 to disable it.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY_dither_invert
> +KernelVersion:	5.12
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Inverts the dither applied to the selected DAC channel. Dither is not
> +		inverted by default. Write "1" to invert dither.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY_dither_scale_available
> +KernelVersion:	5.12
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Returns possible scalings available for the current channel.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY_dither_scale
> +KernelVersion:	5.12
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Scales the dither before it is applied to the selected channel.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY_dither_source
> +KernelVersion:	5.12
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Selects dither source applied to the selected channel. Write "0" to
> +		select N0 source, write "1" to select N1 source.

[PATCH v5 3/3] iio: dac: ad5766: add driver support for AD5766

[Cristian Pop]

The AD5766/AD5767 are 16-channel, 16-bit/12-bit, voltage output dense DACs
Digital-to-Analog converters.

This change adds support for these DACs.

Signed-off-by: Cristian Pop <cristian.pop@analog.com>
---
Changelog v5:
	- Remove explicit init in "ad5766_span_tbl"
	- Check the return value of "devm_gpiod_get_optional()" call
	- Remove unreachable code in "ad5766_read_ext"
 drivers/iio/dac/Kconfig  |  10 +
 drivers/iio/dac/Makefile |   1 +
 drivers/iio/dac/ad5766.c | 643 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 654 insertions(+)
 create mode 100644 drivers/iio/dac/ad5766.c

diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 6f6074a5d3db..cea07b4cced1 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -189,6 +189,16 @@ config AD5764
 	  To compile this driver as a module, choose M here: the
 	  module will be called ad5764.
 
+config AD5766
+	tristate "Analog Devices AD5766/AD5767 DAC driver"
+	depends on SPI_MASTER
+	help
+	  Say yes here to build support for Analog Devices AD5766, AD5767
+	  Digital to Analog Converter.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ad5766.
+
 config AD5770R
 	tristate "Analog Devices AD5770R IDAC driver"
 	depends on SPI_MASTER
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 2fc481167724..33e16f14902a 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_AD5755) += ad5755.o
 obj-$(CONFIG_AD5755) += ad5758.o
 obj-$(CONFIG_AD5761) += ad5761.o
 obj-$(CONFIG_AD5764) += ad5764.o
+obj-$(CONFIG_AD5766) += ad5766.o
 obj-$(CONFIG_AD5770R) += ad5770r.o
 obj-$(CONFIG_AD5791) += ad5791.o
 obj-$(CONFIG_AD5686) += ad5686.o
diff --git a/drivers/iio/dac/ad5766.c b/drivers/iio/dac/ad5766.c
new file mode 100644
index 000000000000..dac35711771e
--- /dev/null
+++ b/drivers/iio/dac/ad5766.c
@@ -0,0 +1,643 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Analog Devices AD5766, AD5767
+ * Digital to Analog Converters driver
+ * Copyright 2019-2020 Analog Devices Inc.
+ */
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+#include <linux/unaligned/be_byteshift.h>
+
+#define AD5766_UPPER_WORD_SPI_MASK		GENMASK(31, 16)
+#define AD5766_LOWER_WORD_SPI_MASK		GENMASK(15, 0)
+#define AD5766_DITHER_SOURCE_MASK(ch)		GENMASK(((2 * ch) + 1), (2 * ch))
+#define AD5766_DITHER_SOURCE(ch, source)	BIT((ch * 2) + source)
+#define AD5766_DITHER_SCALE_MASK(x)		AD5766_DITHER_SOURCE_MASK(x)
+#define AD5766_DITHER_SCALE(ch, scale)		(scale << (ch * 2))
+#define AD5766_DITHER_ENABLE_MASK(ch)		BIT(ch)
+#define AD5766_DITHER_ENABLE(ch, state)		((!state) << ch)
+#define AD5766_DITHER_INVERT_MASK(ch)		BIT(ch)
+#define AD5766_DITHER_INVERT(ch, state)		(state << ch)
+
+#define AD5766_CMD_NOP_MUX_OUT			0x00
+#define AD5766_CMD_SDO_CNTRL			0x01
+#define AD5766_CMD_WR_IN_REG(x)			(0x10 | ((x) & GENMASK(3, 0)))
+#define AD5766_CMD_WR_DAC_REG(x)		(0x20 | ((x) & GENMASK(3, 0)))
+#define AD5766_CMD_SW_LDAC			0x30
+#define AD5766_CMD_SPAN_REG			0x40
+#define AD5766_CMD_WR_PWR_DITHER		0x51
+#define AD5766_CMD_WR_DAC_REG_ALL		0x60
+#define AD5766_CMD_SW_FULL_RESET		0x70
+#define AD5766_CMD_READBACK_REG(x)		(0x80 | ((x) & GENMASK(3, 0)))
+#define AD5766_CMD_DITHER_SIG_1			0x90
+#define AD5766_CMD_DITHER_SIG_2			0xA0
+#define AD5766_CMD_INV_DITHER			0xB0
+#define AD5766_CMD_DITHER_SCALE_1		0xC0
+#define AD5766_CMD_DITHER_SCALE_2		0xD0
+
+#define AD5766_FULL_RESET_CODE			0x1234
+
+enum ad5766_type {
+	ID_AD5766,
+	ID_AD5767,
+};
+
+enum ad5766_voltage_range {
+	AD5766_VOLTAGE_RANGE_M20V_0V,
+	AD5766_VOLTAGE_RANGE_M16V_to_0V,
+	AD5766_VOLTAGE_RANGE_M10V_to_0V,
+	AD5766_VOLTAGE_RANGE_M12V_to_14V,
+	AD5766_VOLTAGE_RANGE_M16V_to_10V,
+	AD5766_VOLTAGE_RANGE_M10V_to_6V,
+	AD5766_VOLTAGE_RANGE_M5V_to_5V,
+	AD5766_VOLTAGE_RANGE_M10V_to_10V,
+};
+
+/**
+ * struct ad5766_chip_info - chip specific information
+ * @num_channels:	number of channels
+ * @channel:	        channel specification
+ */
+struct ad5766_chip_info {
+	unsigned int			num_channels;
+	const struct iio_chan_spec	*channels;
+};
+
+enum {
+	AD5766_DITHER_ENABLE,
+	AD5766_DITHER_INVERT,
+	AD5766_DITHER_SOURCE,
+};
+
+/*
+ * Dither signal can also be scaled.
+ * Available dither scale strings corresponding to "dither_scale" field in
+ * "struct ad5766_state".
+ */
+static const char * const ad5766_dither_scales[] = {
+	"1",
+	"0.75",
+	"0.5",
+	"0.25",
+};
+
+/**
+ * struct ad5766_state - driver instance specific data
+ * @spi:		SPI device
+ * @lock:		Lock used to restrict concurent access to SPI device
+ * @chip_info:		Chip model specific constants
+ * @gpio_reset:		Reset GPIO, used to reset the device
+ * @crt_range:		Current selected output range
+ * @dither_enable:	Power enable bit for each channel dither block (for
+ *			example, D15 = DAC 15,D8 = DAC 8, and D0 = DAC 0)
+ *			0 - Normal operation, 1 - Power down
+ * @dither_invert:	Inverts the dither signal applied to the selected DAC
+ *			outputs
+ * @dither_source:	Selects between 2 possible sources:
+ *			1: N0, 2: N1
+ *			Two bits are used for each channel
+ * @dither_scale:	Two bits are used for each of the 16 channels:
+ *			0: 1 SCALING, 1: 0.75 SCALING, 2: 0.5 SCALING,
+ *			3: 0.25 SCALING.
+ * @data:		SPI transfer buffers
+ */
+struct ad5766_state {
+	struct spi_device		*spi;
+	struct mutex			lock;
+	const struct ad5766_chip_info	*chip_info;
+	struct gpio_desc		*gpio_reset;
+	enum ad5766_voltage_range	crt_range;
+	u16		dither_enable;
+	u16		dither_invert;
+	u32		dither_source;
+	u32		dither_scale;
+	union {
+		u32	d32;
+		u16	w16[2];
+		u8	b8[4];
+	} data[3] ____cacheline_aligned;
+};
+
+struct ad5766_span_tbl {
+	int		min;
+	int		max;
+};
+
+static const struct ad5766_span_tbl ad5766_span_tbl[] = {
+	[AD5766_VOLTAGE_RANGE_M20V_0V] =	{-20, 0},
+	[AD5766_VOLTAGE_RANGE_M16V_to_0V] =	{-16, 0},
+	[AD5766_VOLTAGE_RANGE_M10V_to_0V] =	{-10, 0},
+	[AD5766_VOLTAGE_RANGE_M12V_to_14V] =	{-12, 14},
+	[AD5766_VOLTAGE_RANGE_M16V_to_10V] =	{-16, 10},
+	[AD5766_VOLTAGE_RANGE_M10V_to_6V] =	{-10, 6},
+	[AD5766_VOLTAGE_RANGE_M5V_to_5V] =	{-5, 5},
+	[AD5766_VOLTAGE_RANGE_M10V_to_10V] =	{-10, 10},
+};
+
+static int __ad5766_spi_read(struct ad5766_state *st, u8 dac, int *val)
+{
+	int ret;
+	struct spi_transfer xfers[] = {
+		{
+			.tx_buf = &st->data[0].d32,
+			.bits_per_word = 8,
+			.len = 3,
+			.cs_change = 1,
+		}, {
+			.tx_buf = &st->data[1].d32,
+			.rx_buf = &st->data[2].d32,
+			.bits_per_word = 8,
+			.len = 3,
+		},
+	};
+
+	st->data[0].d32 = AD5766_CMD_READBACK_REG(dac);
+	st->data[1].d32 = AD5766_CMD_NOP_MUX_OUT;
+
+	ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
+	if (ret)
+		return ret;
+
+	*val = st->data[2].w16[1];
+
+	return ret;
+}
+
+static int __ad5766_spi_write(struct ad5766_state *st, u8 command, u16 data)
+{
+	st->data[0].b8[0] = command;
+	put_unaligned_be16(data, &st->data[0].b8[1]);
+
+	return spi_write(st->spi, &st->data[0].b8[0], 3);
+}
+
+static int ad5766_read(struct iio_dev *indio_dev, u8 dac, int *val)
+{
+	struct ad5766_state *st = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&st->lock);
+	ret = __ad5766_spi_read(st, dac, val);
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static int ad5766_write(struct iio_dev *indio_dev, u8 dac, u16 data)
+{
+	struct ad5766_state *st = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&st->lock);
+	ret = __ad5766_spi_write(st, AD5766_CMD_WR_DAC_REG(dac), data);
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static int ad5766_reset(struct ad5766_state *st)
+{
+	int ret;
+
+	if (st->gpio_reset) {
+		gpiod_set_value_cansleep(st->gpio_reset, 1);
+		ndelay(100); /* t_reset >= 100ns */
+		gpiod_set_value_cansleep(st->gpio_reset, 0);
+	} else {
+		ret = __ad5766_spi_write(st, AD5766_CMD_SW_FULL_RESET,
+					AD5766_FULL_RESET_CODE);
+		if (ret < 0)
+			return ret;
+	}
+
+	/*
+	 * Minimum time between a reset and the subsequent successful write is
+	 * typically 25 ns
+	 */
+	ndelay(25);
+
+	return 0;
+}
+
+static int ad5766_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val,
+			   int *val2,
+			   long m)
+{
+	struct ad5766_state *st = iio_priv(indio_dev);
+	int ret;
+
+	switch (m) {
+	case IIO_CHAN_INFO_RAW:
+		ret = ad5766_read(indio_dev, chan->address, val);
+		if (ret)
+			return ret;
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_OFFSET:
+		*val = ad5766_span_tbl[st->crt_range].min;
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = ad5766_span_tbl[st->crt_range].max -
+		       ad5766_span_tbl[st->crt_range].min;
+		*val2 = st->chip_info->channels[0].scan_type.realbits;
+
+		return IIO_VAL_FRACTIONAL_LOG2;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad5766_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int val,
+			    int val2,
+			    long info)
+{
+	switch (info) {
+	case IIO_CHAN_INFO_RAW:
+	{
+		const int max_val = GENMASK(chan->scan_type.realbits - 1, 0);
+
+		if (val > max_val || val < 0)
+			return -EINVAL;
+		val <<= chan->scan_type.shift;
+		return ad5766_write(indio_dev, chan->address, val);
+	}
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info ad5766_info = {
+	.read_raw = ad5766_read_raw,
+	.write_raw = ad5766_write_raw,
+};
+
+static int ad5766_get_dither_source(struct iio_dev *dev,
+				    const struct iio_chan_spec *chan)
+{
+	struct ad5766_state *st = iio_priv(dev);
+	u32 source;
+
+	source = st->dither_source & AD5766_DITHER_SOURCE_MASK(chan->channel);
+	source = source >> (chan->channel * 2);
+	source -= 1;
+
+	return source;
+}
+
+static int ad5766_set_dither_source(struct iio_dev *dev,
+			  const struct iio_chan_spec *chan,
+			  unsigned int source)
+{
+	struct ad5766_state *st = iio_priv(dev);
+	uint16_t val;
+	int ret;
+
+	st->dither_source &= ~AD5766_DITHER_SOURCE_MASK(chan->channel);
+	st->dither_source |= AD5766_DITHER_SOURCE(chan->channel, source);
+
+	val = FIELD_GET(AD5766_LOWER_WORD_SPI_MASK, st->dither_source);
+	ret = ad5766_write(dev, AD5766_CMD_DITHER_SIG_1, val);
+	if (ret)
+		return ret;
+
+	val = FIELD_GET(AD5766_UPPER_WORD_SPI_MASK, st->dither_source);
+
+	return ad5766_write(dev, AD5766_CMD_DITHER_SIG_2, val);
+}
+
+static int ad5766_get_dither_scale(struct iio_dev *dev,
+				   const struct iio_chan_spec *chan)
+{
+	struct ad5766_state *st = iio_priv(dev);
+	u32 scale;
+
+	scale = st->dither_scale & AD5766_DITHER_SCALE_MASK(chan->channel);
+
+	return (scale >> (chan->channel * 2));
+}
+
+static int ad5766_set_dither_scale(struct iio_dev *dev,
+			  const struct iio_chan_spec *chan,
+			  unsigned int scale)
+{
+	int ret;
+	struct ad5766_state *st = iio_priv(dev);
+	uint16_t val;
+
+	st->dither_scale &= ~AD5766_DITHER_SCALE_MASK(chan->channel);
+	st->dither_scale |= AD5766_DITHER_SCALE(chan->channel, scale);
+
+	val = FIELD_GET(AD5766_LOWER_WORD_SPI_MASK, st->dither_scale);
+	ret = ad5766_write(dev, AD5766_CMD_DITHER_SCALE_1, val);
+	if (ret)
+		return ret;
+	val = FIELD_GET(AD5766_UPPER_WORD_SPI_MASK, st->dither_scale);
+
+	return ad5766_write(dev, AD5766_CMD_DITHER_SCALE_2, val);
+}
+
+static const struct iio_enum ad5766_dither_scale_enum = {
+	.items = ad5766_dither_scales,
+	.num_items = ARRAY_SIZE(ad5766_dither_scales),
+	.set = ad5766_set_dither_scale,
+	.get = ad5766_get_dither_scale,
+};
+
+static ssize_t ad5766_read_ext(struct iio_dev *indio_dev,
+			       uintptr_t private,
+			       const struct iio_chan_spec *chan,
+			       char *buf)
+{
+	struct ad5766_state *st = iio_priv(indio_dev);
+
+	switch (private) {
+	case AD5766_DITHER_ENABLE:
+		return sprintf(buf, "%u\n",
+			       !(st->dither_enable & BIT(chan->channel)));
+		break;
+	case AD5766_DITHER_INVERT:
+		return sprintf(buf, "%u\n",
+			       !!(st->dither_invert & BIT(chan->channel)));
+		break;
+	case AD5766_DITHER_SOURCE:
+		return sprintf(buf, "%u\n",
+			       ad5766_get_dither_source(indio_dev, chan));
+	default:
+		return -EINVAL;
+	}
+}
+
+static ssize_t ad5766_write_ext(struct iio_dev *indio_dev,
+				 uintptr_t private,
+				 const struct iio_chan_spec *chan,
+				 const char *buf, size_t len)
+{
+	struct ad5766_state *st = iio_priv(indio_dev);
+	bool readin;
+	int ret;
+
+	ret = kstrtobool(buf, &readin);
+	if (ret)
+		return ret;
+
+	switch (private) {
+	case AD5766_DITHER_ENABLE:
+		st->dither_enable &= ~AD5766_DITHER_ENABLE_MASK(chan->channel);
+		st->dither_enable |= AD5766_DITHER_ENABLE(chan->channel,
+							  readin);
+		ret = ad5766_write(indio_dev, AD5766_CMD_WR_PWR_DITHER,
+				   st->dither_enable);
+		break;
+	case AD5766_DITHER_INVERT:
+		st->dither_invert &= ~AD5766_DITHER_INVERT_MASK(chan->channel);
+		st->dither_invert |= AD5766_DITHER_INVERT(chan->channel,
+							  readin);
+		ret = ad5766_write(indio_dev, AD5766_CMD_INV_DITHER,
+				   st->dither_invert);
+		break;
+	case AD5766_DITHER_SOURCE:
+		ret = ad5766_set_dither_source(indio_dev, chan, readin);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return ret ? ret : len;
+}
+
+#define _AD5766_CHAN_EXT_INFO(_name, _what, _shared) { \
+	.name = _name, \
+	.read = ad5766_read_ext, \
+	.write = ad5766_write_ext, \
+	.private = _what, \
+	.shared = _shared, \
+}
+
+#define IIO_ENUM_AVAILABLE_SHARED(_name, _shared, _e) \
+{ \
+	.name = (_name "_available"), \
+	.shared = _shared, \
+	.read = iio_enum_available_read, \
+	.private = (uintptr_t)(_e), \
+}
+
+static const struct iio_chan_spec_ext_info ad5766_ext_info[] = {
+
+	_AD5766_CHAN_EXT_INFO("dither_enable", AD5766_DITHER_ENABLE,
+			      IIO_SEPARATE),
+	_AD5766_CHAN_EXT_INFO("dither_invert", AD5766_DITHER_INVERT,
+			      IIO_SEPARATE),
+	_AD5766_CHAN_EXT_INFO("dither_source", AD5766_DITHER_SOURCE,
+			      IIO_SEPARATE),
+	IIO_ENUM("dither_scale", IIO_SEPARATE, &ad5766_dither_scale_enum),
+	IIO_ENUM_AVAILABLE_SHARED("dither_scale",
+				  IIO_SEPARATE,
+				  &ad5766_dither_scale_enum),
+	{}
+};
+
+#define AD576x_CHANNEL(_chan, _bits) {					\
+	.type = IIO_VOLTAGE,						\
+	.indexed = 1,							\
+	.output = 1,							\
+	.channel = (_chan),						\
+	.address = (_chan),						\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |		\
+		BIT(IIO_CHAN_INFO_SCALE),				\
+	.scan_type = {							\
+		.sign = 'u',						\
+		.realbits = (_bits),					\
+		.storagebits = 16,					\
+		.shift = 16 - (_bits),					\
+	},								\
+	.ext_info = ad5766_ext_info,					\
+}
+
+#define DECLARE_AD576x_CHANNELS(_name, _bits)			\
+const struct iio_chan_spec _name[] = {				\
+	AD576x_CHANNEL(0, (_bits)),				\
+	AD576x_CHANNEL(1, (_bits)),				\
+	AD576x_CHANNEL(2, (_bits)),				\
+	AD576x_CHANNEL(3, (_bits)),				\
+	AD576x_CHANNEL(4, (_bits)),				\
+	AD576x_CHANNEL(5, (_bits)),				\
+	AD576x_CHANNEL(6, (_bits)),				\
+	AD576x_CHANNEL(7, (_bits)),				\
+	AD576x_CHANNEL(8, (_bits)),				\
+	AD576x_CHANNEL(9, (_bits)),				\
+	AD576x_CHANNEL(10, (_bits)),				\
+	AD576x_CHANNEL(11, (_bits)),				\
+	AD576x_CHANNEL(12, (_bits)),				\
+	AD576x_CHANNEL(13, (_bits)),				\
+	AD576x_CHANNEL(14, (_bits)),				\
+	AD576x_CHANNEL(15, (_bits)),				\
+}
+
+static DECLARE_AD576x_CHANNELS(ad5766_channels, 16);
+static DECLARE_AD576x_CHANNELS(ad5767_channels, 12);
+
+static const struct ad5766_chip_info ad5766_chip_infos[] = {
+	[ID_AD5766] = {
+		.num_channels = ARRAY_SIZE(ad5766_channels),
+		.channels = ad5766_channels,
+	},
+	[ID_AD5767] = {
+		.num_channels = ARRAY_SIZE(ad5767_channels),
+		.channels = ad5767_channels,
+	},
+};
+
+static int ad5766_get_output_range(struct ad5766_state *st)
+{
+	int i, ret, min, max, tmp[2];
+
+	ret = device_property_read_u32_array(&st->spi->dev,
+					     "output-range-voltage",
+					     tmp, 2);
+	if (ret)
+		return ret;
+
+	min = tmp[0];
+	max = tmp[1];
+	for (i = 0; i < ARRAY_SIZE(ad5766_span_tbl); i++) {
+		if (ad5766_span_tbl[i].min != min ||
+		    ad5766_span_tbl[i].max != max)
+			continue;
+
+		st->crt_range = i;
+
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static int ad5766_default_setup(struct ad5766_state *st)
+{
+	uint16_t val;
+	int ret, i;
+
+	/* Always issue a reset before writing to the span register. */
+	ret = ad5766_reset(st);
+	if (ret)
+		return ret;
+
+	ret = ad5766_get_output_range(st);
+	if (ret)
+		return ret;
+
+	/* Dither power down */
+	st->dither_enable = GENMASK(15, 0);
+	ret = __ad5766_spi_write(st, AD5766_CMD_WR_PWR_DITHER,
+			     st->dither_enable);
+	if (ret)
+		return ret;
+
+	st->dither_source = 0;
+	for (i = 0; i < ARRAY_SIZE(ad5766_channels); i++)
+		st->dither_source |= AD5766_DITHER_SOURCE(i, 0);
+	val = FIELD_GET(AD5766_LOWER_WORD_SPI_MASK, st->dither_source);
+	ret = __ad5766_spi_write(st, AD5766_CMD_DITHER_SIG_1, val);
+	if (ret)
+		return ret;
+
+	val = FIELD_GET(AD5766_UPPER_WORD_SPI_MASK, st->dither_source);
+	ret = __ad5766_spi_write(st, AD5766_CMD_DITHER_SIG_2, val);
+	if (ret)
+		return ret;
+
+	st->dither_scale = 0;
+	val = FIELD_GET(AD5766_LOWER_WORD_SPI_MASK, st->dither_scale);
+	ret = __ad5766_spi_write(st, AD5766_CMD_DITHER_SCALE_1, val);
+	if (ret)
+		return ret;
+
+	val = FIELD_GET(AD5766_UPPER_WORD_SPI_MASK, st->dither_scale);
+	ret = __ad5766_spi_write(st, AD5766_CMD_DITHER_SCALE_2, val);
+	if (ret)
+		return ret;
+
+	st->dither_invert = 0;
+	ret = __ad5766_spi_write(st, AD5766_CMD_INV_DITHER, st->dither_invert);
+	if (ret)
+		return ret;
+
+	return  __ad5766_spi_write(st, AD5766_CMD_SPAN_REG, st->crt_range);
+}
+
+static int ad5766_probe(struct spi_device *spi)
+{
+	enum ad5766_type type;
+	struct iio_dev *indio_dev;
+	struct ad5766_state *st;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	mutex_init(&st->lock);
+
+	st->spi = spi;
+	type = spi_get_device_id(spi)->driver_data;
+	st->chip_info = &ad5766_chip_infos[type];
+
+	indio_dev->channels = st->chip_info->channels;
+	indio_dev->num_channels = st->chip_info->num_channels;
+	indio_dev->info = &ad5766_info;
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->dev.of_node = spi->dev.of_node;
+	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	st->gpio_reset = devm_gpiod_get_optional(&st->spi->dev, "reset",
+						GPIOD_OUT_LOW);
+	if (IS_ERR(st->gpio_reset))
+		return PTR_ERR(st->gpio_reset);
+
+	ret = ad5766_default_setup(st);
+	if (ret)
+		return ret;
+
+	return devm_iio_device_register(&spi->dev, indio_dev);
+}
+
+static const struct of_device_id ad5766_dt_match[] = {
+	{ .compatible = "adi,ad5766" },
+	{ .compatible = "adi,ad5767" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, ad5766_dt_match);
+
+static const struct spi_device_id ad5766_spi_ids[] = {
+	{ "ad5766", ID_AD5766 },
+	{ "ad5767", ID_AD5767 },
+	{}
+};
+MODULE_DEVICE_TABLE(spi, ad5766_spi_ids);
+
+static struct spi_driver ad5766_driver = {
+	.driver = {
+		.name = "ad5766",
+		.of_match_table = ad5766_dt_match,
+	},
+	.probe = ad5766_probe,
+	.id_table = ad5766_spi_ids,
+};
+module_spi_driver(ad5766_driver);
+
+MODULE_AUTHOR("Denis-Gabriel Gheorghescu <denis.gheorghescu@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD5766/AD5767 DACs");
+MODULE_LICENSE("GPL v2");
-- 
2.17.1

Re: [PATCH v5 3/3] iio: dac: ad5766: add driver support for AD5766

[Jonathan Cameron]

On Fri, 8 Jan 2021 20:37:39 +0200
Cristian Pop <cristian.pop@analog.com> wrote:

> The AD5766/AD5767 are 16-channel, 16-bit/12-bit, voltage output dense DACs
> Digital-to-Analog converters.
> 
> This change adds support for these DACs.
> 
> Signed-off-by: Cristian Pop <cristian.pop@analog.com>
One comment inline about including linux/unaligned/be_byteshift.h
that needed a bit of an investigation of the history of that file.

As long as you are happy with it I can switch this over to
asm/unaligned.h whilst applying.

Otherwise I'm happy with this now.

So all that's left is giving Rob time to take another look at the
dt bindings.

thanks,

Jonathan

> ---
> Changelog v5:
> 	- Remove explicit init in "ad5766_span_tbl"
> 	- Check the return value of "devm_gpiod_get_optional()" call
> 	- Remove unreachable code in "ad5766_read_ext"
>  drivers/iio/dac/Kconfig  |  10 +
>  drivers/iio/dac/Makefile |   1 +
>  drivers/iio/dac/ad5766.c | 643 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 654 insertions(+)
>  create mode 100644 drivers/iio/dac/ad5766.c
> 
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index 6f6074a5d3db..cea07b4cced1 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -189,6 +189,16 @@ config AD5764
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called ad5764.
>  
> +config AD5766
> +	tristate "Analog Devices AD5766/AD5767 DAC driver"
> +	depends on SPI_MASTER
> +	help
> +	  Say yes here to build support for Analog Devices AD5766, AD5767
> +	  Digital to Analog Converter.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called ad5766.
> +
>  config AD5770R
>  	tristate "Analog Devices AD5770R IDAC driver"
>  	depends on SPI_MASTER
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index 2fc481167724..33e16f14902a 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -19,6 +19,7 @@ obj-$(CONFIG_AD5755) += ad5755.o
>  obj-$(CONFIG_AD5755) += ad5758.o
>  obj-$(CONFIG_AD5761) += ad5761.o
>  obj-$(CONFIG_AD5764) += ad5764.o
> +obj-$(CONFIG_AD5766) += ad5766.o
>  obj-$(CONFIG_AD5770R) += ad5770r.o
>  obj-$(CONFIG_AD5791) += ad5791.o
>  obj-$(CONFIG_AD5686) += ad5686.o
> diff --git a/drivers/iio/dac/ad5766.c b/drivers/iio/dac/ad5766.c
> new file mode 100644
> index 000000000000..dac35711771e
> --- /dev/null
> +++ b/drivers/iio/dac/ad5766.c
> @@ -0,0 +1,643 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Analog Devices AD5766, AD5767
> + * Digital to Analog Converters driver
> + * Copyright 2019-2020 Analog Devices Inc.
> + */
> +#include <linux/bitfield.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +#include <linux/spi/spi.h>
> +#include <linux/unaligned/be_byteshift.h>

Strangely I hadn't noticed the direct include of this either of the other drivers
in IIO that do it.   Looking back at the history of that file, it is documented
as being safe, but then intension is that you include asm/unaligned.h as there
may be a better option for a given architecture. Particularly likely if it is a big
endian architecture.

If I haven't missed anything I'd rather we make that change here and probably
also clear up the few that have snuck in already.


> +
> +#define AD5766_UPPER_WORD_SPI_MASK		GENMASK(31, 16)
> +#define AD5766_LOWER_WORD_SPI_MASK		GENMASK(15, 0)
> +#define AD5766_DITHER_SOURCE_MASK(ch)		GENMASK(((2 * ch) + 1), (2 * ch))
> +#define AD5766_DITHER_SOURCE(ch, source)	BIT((ch * 2) + source)
> +#define AD5766_DITHER_SCALE_MASK(x)		AD5766_DITHER_SOURCE_MASK(x)
> +#define AD5766_DITHER_SCALE(ch, scale)		(scale << (ch * 2))
> +#define AD5766_DITHER_ENABLE_MASK(ch)		BIT(ch)
> +#define AD5766_DITHER_ENABLE(ch, state)		((!state) << ch)
> +#define AD5766_DITHER_INVERT_MASK(ch)		BIT(ch)
> +#define AD5766_DITHER_INVERT(ch, state)		(state << ch)
> +
> +#define AD5766_CMD_NOP_MUX_OUT			0x00
> +#define AD5766_CMD_SDO_CNTRL			0x01
> +#define AD5766_CMD_WR_IN_REG(x)			(0x10 | ((x) & GENMASK(3, 0)))
> +#define AD5766_CMD_WR_DAC_REG(x)		(0x20 | ((x) & GENMASK(3, 0)))
> +#define AD5766_CMD_SW_LDAC			0x30
> +#define AD5766_CMD_SPAN_REG			0x40
> +#define AD5766_CMD_WR_PWR_DITHER		0x51
> +#define AD5766_CMD_WR_DAC_REG_ALL		0x60
> +#define AD5766_CMD_SW_FULL_RESET		0x70
> +#define AD5766_CMD_READBACK_REG(x)		(0x80 | ((x) & GENMASK(3, 0)))
> +#define AD5766_CMD_DITHER_SIG_1			0x90
> +#define AD5766_CMD_DITHER_SIG_2			0xA0
> +#define AD5766_CMD_INV_DITHER			0xB0
> +#define AD5766_CMD_DITHER_SCALE_1		0xC0
> +#define AD5766_CMD_DITHER_SCALE_2		0xD0
> +
> +#define AD5766_FULL_RESET_CODE			0x1234
> +
> +enum ad5766_type {
> +	ID_AD5766,
> +	ID_AD5767,
> +};
> +
> +enum ad5766_voltage_range {
> +	AD5766_VOLTAGE_RANGE_M20V_0V,
> +	AD5766_VOLTAGE_RANGE_M16V_to_0V,
> +	AD5766_VOLTAGE_RANGE_M10V_to_0V,
> +	AD5766_VOLTAGE_RANGE_M12V_to_14V,
> +	AD5766_VOLTAGE_RANGE_M16V_to_10V,
> +	AD5766_VOLTAGE_RANGE_M10V_to_6V,
> +	AD5766_VOLTAGE_RANGE_M5V_to_5V,
> +	AD5766_VOLTAGE_RANGE_M10V_to_10V,
> +};
> +
> +/**
> + * struct ad5766_chip_info - chip specific information
> + * @num_channels:	number of channels
> + * @channel:	        channel specification
> + */
> +struct ad5766_chip_info {
> +	unsigned int			num_channels;
> +	const struct iio_chan_spec	*channels;
> +};
> +
> +enum {
> +	AD5766_DITHER_ENABLE,
> +	AD5766_DITHER_INVERT,
> +	AD5766_DITHER_SOURCE,
> +};
> +
> +/*
> + * Dither signal can also be scaled.
> + * Available dither scale strings corresponding to "dither_scale" field in
> + * "struct ad5766_state".
> + */
> +static const char * const ad5766_dither_scales[] = {
> +	"1",
> +	"0.75",
> +	"0.5",
> +	"0.25",
> +};
> +
> +/**
> + * struct ad5766_state - driver instance specific data
> + * @spi:		SPI device
> + * @lock:		Lock used to restrict concurent access to SPI device
> + * @chip_info:		Chip model specific constants
> + * @gpio_reset:		Reset GPIO, used to reset the device
> + * @crt_range:		Current selected output range
> + * @dither_enable:	Power enable bit for each channel dither block (for
> + *			example, D15 = DAC 15,D8 = DAC 8, and D0 = DAC 0)
> + *			0 - Normal operation, 1 - Power down
> + * @dither_invert:	Inverts the dither signal applied to the selected DAC
> + *			outputs
> + * @dither_source:	Selects between 2 possible sources:
> + *			1: N0, 2: N1
> + *			Two bits are used for each channel
> + * @dither_scale:	Two bits are used for each of the 16 channels:
> + *			0: 1 SCALING, 1: 0.75 SCALING, 2: 0.5 SCALING,
> + *			3: 0.25 SCALING.
> + * @data:		SPI transfer buffers
> + */
> +struct ad5766_state {
> +	struct spi_device		*spi;
> +	struct mutex			lock;
> +	const struct ad5766_chip_info	*chip_info;
> +	struct gpio_desc		*gpio_reset;
> +	enum ad5766_voltage_range	crt_range;
> +	u16		dither_enable;
> +	u16		dither_invert;
> +	u32		dither_source;
> +	u32		dither_scale;
> +	union {
> +		u32	d32;
> +		u16	w16[2];
> +		u8	b8[4];
> +	} data[3] ____cacheline_aligned;
> +};
> +
> +struct ad5766_span_tbl {
> +	int		min;
> +	int		max;
> +};
> +
> +static const struct ad5766_span_tbl ad5766_span_tbl[] = {
> +	[AD5766_VOLTAGE_RANGE_M20V_0V] =	{-20, 0},
> +	[AD5766_VOLTAGE_RANGE_M16V_to_0V] =	{-16, 0},
> +	[AD5766_VOLTAGE_RANGE_M10V_to_0V] =	{-10, 0},
> +	[AD5766_VOLTAGE_RANGE_M12V_to_14V] =	{-12, 14},
> +	[AD5766_VOLTAGE_RANGE_M16V_to_10V] =	{-16, 10},
> +	[AD5766_VOLTAGE_RANGE_M10V_to_6V] =	{-10, 6},
> +	[AD5766_VOLTAGE_RANGE_M5V_to_5V] =	{-5, 5},
> +	[AD5766_VOLTAGE_RANGE_M10V_to_10V] =	{-10, 10},
> +};
> +
> +static int __ad5766_spi_read(struct ad5766_state *st, u8 dac, int *val)
> +{
> +	int ret;
> +	struct spi_transfer xfers[] = {
> +		{
> +			.tx_buf = &st->data[0].d32,
> +			.bits_per_word = 8,
> +			.len = 3,
> +			.cs_change = 1,
> +		}, {
> +			.tx_buf = &st->data[1].d32,
> +			.rx_buf = &st->data[2].d32,
> +			.bits_per_word = 8,
> +			.len = 3,
> +		},
> +	};
> +
> +	st->data[0].d32 = AD5766_CMD_READBACK_REG(dac);
> +	st->data[1].d32 = AD5766_CMD_NOP_MUX_OUT;
> +
> +	ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
> +	if (ret)
> +		return ret;
> +
> +	*val = st->data[2].w16[1];
> +
> +	return ret;
> +}
> +
> +static int __ad5766_spi_write(struct ad5766_state *st, u8 command, u16 data)
> +{
> +	st->data[0].b8[0] = command;
> +	put_unaligned_be16(data, &st->data[0].b8[1]);
> +
> +	return spi_write(st->spi, &st->data[0].b8[0], 3);
> +}
> +
> +static int ad5766_read(struct iio_dev *indio_dev, u8 dac, int *val)
> +{
> +	struct ad5766_state *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	mutex_lock(&st->lock);
> +	ret = __ad5766_spi_read(st, dac, val);
> +	mutex_unlock(&st->lock);
> +
> +	return ret;
> +}
> +
> +static int ad5766_write(struct iio_dev *indio_dev, u8 dac, u16 data)
> +{
> +	struct ad5766_state *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	mutex_lock(&st->lock);
> +	ret = __ad5766_spi_write(st, AD5766_CMD_WR_DAC_REG(dac), data);
> +	mutex_unlock(&st->lock);
> +
> +	return ret;
> +}
> +
> +static int ad5766_reset(struct ad5766_state *st)
> +{
> +	int ret;
> +
> +	if (st->gpio_reset) {
> +		gpiod_set_value_cansleep(st->gpio_reset, 1);
> +		ndelay(100); /* t_reset >= 100ns */
> +		gpiod_set_value_cansleep(st->gpio_reset, 0);
> +	} else {
> +		ret = __ad5766_spi_write(st, AD5766_CMD_SW_FULL_RESET,
> +					AD5766_FULL_RESET_CODE);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	/*
> +	 * Minimum time between a reset and the subsequent successful write is
> +	 * typically 25 ns
> +	 */
> +	ndelay(25);
> +
> +	return 0;
> +}
> +
> +static int ad5766_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan,
> +			   int *val,
> +			   int *val2,
> +			   long m)
> +{
> +	struct ad5766_state *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (m) {
> +	case IIO_CHAN_INFO_RAW:
> +		ret = ad5766_read(indio_dev, chan->address, val);
> +		if (ret)
> +			return ret;
> +
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_OFFSET:
> +		*val = ad5766_span_tbl[st->crt_range].min;
> +
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = ad5766_span_tbl[st->crt_range].max -
> +		       ad5766_span_tbl[st->crt_range].min;
> +		*val2 = st->chip_info->channels[0].scan_type.realbits;
> +
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int ad5766_write_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int val,
> +			    int val2,
> +			    long info)
> +{
> +	switch (info) {
> +	case IIO_CHAN_INFO_RAW:
> +	{
> +		const int max_val = GENMASK(chan->scan_type.realbits - 1, 0);
> +
> +		if (val > max_val || val < 0)
> +			return -EINVAL;
> +		val <<= chan->scan_type.shift;
> +		return ad5766_write(indio_dev, chan->address, val);
> +	}
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_info ad5766_info = {
> +	.read_raw = ad5766_read_raw,
> +	.write_raw = ad5766_write_raw,
> +};
> +
> +static int ad5766_get_dither_source(struct iio_dev *dev,
> +				    const struct iio_chan_spec *chan)
> +{
> +	struct ad5766_state *st = iio_priv(dev);
> +	u32 source;
> +
> +	source = st->dither_source & AD5766_DITHER_SOURCE_MASK(chan->channel);
> +	source = source >> (chan->channel * 2);
> +	source -= 1;
> +
> +	return source;
> +}
> +
> +static int ad5766_set_dither_source(struct iio_dev *dev,
> +			  const struct iio_chan_spec *chan,
> +			  unsigned int source)
> +{
> +	struct ad5766_state *st = iio_priv(dev);
> +	uint16_t val;
> +	int ret;
> +
> +	st->dither_source &= ~AD5766_DITHER_SOURCE_MASK(chan->channel);
> +	st->dither_source |= AD5766_DITHER_SOURCE(chan->channel, source);
> +
> +	val = FIELD_GET(AD5766_LOWER_WORD_SPI_MASK, st->dither_source);
> +	ret = ad5766_write(dev, AD5766_CMD_DITHER_SIG_1, val);
> +	if (ret)
> +		return ret;
> +
> +	val = FIELD_GET(AD5766_UPPER_WORD_SPI_MASK, st->dither_source);
> +
> +	return ad5766_write(dev, AD5766_CMD_DITHER_SIG_2, val);
> +}
> +
> +static int ad5766_get_dither_scale(struct iio_dev *dev,
> +				   const struct iio_chan_spec *chan)
> +{
> +	struct ad5766_state *st = iio_priv(dev);
> +	u32 scale;
> +
> +	scale = st->dither_scale & AD5766_DITHER_SCALE_MASK(chan->channel);
> +
> +	return (scale >> (chan->channel * 2));
> +}
> +
> +static int ad5766_set_dither_scale(struct iio_dev *dev,
> +			  const struct iio_chan_spec *chan,
> +			  unsigned int scale)
> +{
> +	int ret;
> +	struct ad5766_state *st = iio_priv(dev);
> +	uint16_t val;
> +
> +	st->dither_scale &= ~AD5766_DITHER_SCALE_MASK(chan->channel);
> +	st->dither_scale |= AD5766_DITHER_SCALE(chan->channel, scale);
> +
> +	val = FIELD_GET(AD5766_LOWER_WORD_SPI_MASK, st->dither_scale);
> +	ret = ad5766_write(dev, AD5766_CMD_DITHER_SCALE_1, val);
> +	if (ret)
> +		return ret;
> +	val = FIELD_GET(AD5766_UPPER_WORD_SPI_MASK, st->dither_scale);
> +
> +	return ad5766_write(dev, AD5766_CMD_DITHER_SCALE_2, val);
> +}
> +
> +static const struct iio_enum ad5766_dither_scale_enum = {
> +	.items = ad5766_dither_scales,
> +	.num_items = ARRAY_SIZE(ad5766_dither_scales),
> +	.set = ad5766_set_dither_scale,
> +	.get = ad5766_get_dither_scale,
> +};
> +
> +static ssize_t ad5766_read_ext(struct iio_dev *indio_dev,
> +			       uintptr_t private,
> +			       const struct iio_chan_spec *chan,
> +			       char *buf)
> +{
> +	struct ad5766_state *st = iio_priv(indio_dev);
> +
> +	switch (private) {
> +	case AD5766_DITHER_ENABLE:
> +		return sprintf(buf, "%u\n",
> +			       !(st->dither_enable & BIT(chan->channel)));
> +		break;
> +	case AD5766_DITHER_INVERT:
> +		return sprintf(buf, "%u\n",
> +			       !!(st->dither_invert & BIT(chan->channel)));
> +		break;
> +	case AD5766_DITHER_SOURCE:
> +		return sprintf(buf, "%u\n",
> +			       ad5766_get_dither_source(indio_dev, chan));
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static ssize_t ad5766_write_ext(struct iio_dev *indio_dev,
> +				 uintptr_t private,
> +				 const struct iio_chan_spec *chan,
> +				 const char *buf, size_t len)
> +{
> +	struct ad5766_state *st = iio_priv(indio_dev);
> +	bool readin;
> +	int ret;
> +
> +	ret = kstrtobool(buf, &readin);
> +	if (ret)
> +		return ret;
> +
> +	switch (private) {
> +	case AD5766_DITHER_ENABLE:
> +		st->dither_enable &= ~AD5766_DITHER_ENABLE_MASK(chan->channel);
> +		st->dither_enable |= AD5766_DITHER_ENABLE(chan->channel,
> +							  readin);

Trivial but the above is under 80 chars on one line so better to not wrap it.

> +		ret = ad5766_write(indio_dev, AD5766_CMD_WR_PWR_DITHER,
> +				   st->dither_enable);
> +		break;
> +	case AD5766_DITHER_INVERT:
> +		st->dither_invert &= ~AD5766_DITHER_INVERT_MASK(chan->channel);
> +		st->dither_invert |= AD5766_DITHER_INVERT(chan->channel,
> +							  readin);
> +		ret = ad5766_write(indio_dev, AD5766_CMD_INV_DITHER,
> +				   st->dither_invert);
> +		break;
> +	case AD5766_DITHER_SOURCE:
> +		ret = ad5766_set_dither_source(indio_dev, chan, readin);
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return ret ? ret : len;
> +}
> +
> +#define _AD5766_CHAN_EXT_INFO(_name, _what, _shared) { \
> +	.name = _name, \
> +	.read = ad5766_read_ext, \
> +	.write = ad5766_write_ext, \
> +	.private = _what, \
> +	.shared = _shared, \
> +}
> +
> +#define IIO_ENUM_AVAILABLE_SHARED(_name, _shared, _e) \
> +{ \
> +	.name = (_name "_available"), \
> +	.shared = _shared, \
> +	.read = iio_enum_available_read, \
> +	.private = (uintptr_t)(_e), \
> +}
> +
> +static const struct iio_chan_spec_ext_info ad5766_ext_info[] = {
> +
> +	_AD5766_CHAN_EXT_INFO("dither_enable", AD5766_DITHER_ENABLE,
> +			      IIO_SEPARATE),
> +	_AD5766_CHAN_EXT_INFO("dither_invert", AD5766_DITHER_INVERT,
> +			      IIO_SEPARATE),
> +	_AD5766_CHAN_EXT_INFO("dither_source", AD5766_DITHER_SOURCE,
> +			      IIO_SEPARATE),
> +	IIO_ENUM("dither_scale", IIO_SEPARATE, &ad5766_dither_scale_enum),
> +	IIO_ENUM_AVAILABLE_SHARED("dither_scale",
> +				  IIO_SEPARATE,
> +				  &ad5766_dither_scale_enum),
> +	{}
> +};
> +
> +#define AD576x_CHANNEL(_chan, _bits) {					\
> +	.type = IIO_VOLTAGE,						\
> +	.indexed = 1,							\
> +	.output = 1,							\
> +	.channel = (_chan),						\
> +	.address = (_chan),						\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			\
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |		\
> +		BIT(IIO_CHAN_INFO_SCALE),				\
> +	.scan_type = {							\
> +		.sign = 'u',						\
> +		.realbits = (_bits),					\
> +		.storagebits = 16,					\
> +		.shift = 16 - (_bits),					\
> +	},								\
> +	.ext_info = ad5766_ext_info,					\
> +}
> +
> +#define DECLARE_AD576x_CHANNELS(_name, _bits)			\
> +const struct iio_chan_spec _name[] = {				\
> +	AD576x_CHANNEL(0, (_bits)),				\
> +	AD576x_CHANNEL(1, (_bits)),				\
> +	AD576x_CHANNEL(2, (_bits)),				\
> +	AD576x_CHANNEL(3, (_bits)),				\
> +	AD576x_CHANNEL(4, (_bits)),				\
> +	AD576x_CHANNEL(5, (_bits)),				\
> +	AD576x_CHANNEL(6, (_bits)),				\
> +	AD576x_CHANNEL(7, (_bits)),				\
> +	AD576x_CHANNEL(8, (_bits)),				\
> +	AD576x_CHANNEL(9, (_bits)),				\
> +	AD576x_CHANNEL(10, (_bits)),				\
> +	AD576x_CHANNEL(11, (_bits)),				\
> +	AD576x_CHANNEL(12, (_bits)),				\
> +	AD576x_CHANNEL(13, (_bits)),				\
> +	AD576x_CHANNEL(14, (_bits)),				\
> +	AD576x_CHANNEL(15, (_bits)),				\
> +}
> +
> +static DECLARE_AD576x_CHANNELS(ad5766_channels, 16);
> +static DECLARE_AD576x_CHANNELS(ad5767_channels, 12);
> +
> +static const struct ad5766_chip_info ad5766_chip_infos[] = {
> +	[ID_AD5766] = {
> +		.num_channels = ARRAY_SIZE(ad5766_channels),
> +		.channels = ad5766_channels,
> +	},
> +	[ID_AD5767] = {
> +		.num_channels = ARRAY_SIZE(ad5767_channels),
> +		.channels = ad5767_channels,
> +	},
> +};
> +
> +static int ad5766_get_output_range(struct ad5766_state *st)
> +{
> +	int i, ret, min, max, tmp[2];
> +
> +	ret = device_property_read_u32_array(&st->spi->dev,
> +					     "output-range-voltage",
> +					     tmp, 2);
> +	if (ret)
> +		return ret;
> +
> +	min = tmp[0];
> +	max = tmp[1];
> +	for (i = 0; i < ARRAY_SIZE(ad5766_span_tbl); i++) {
> +		if (ad5766_span_tbl[i].min != min ||
> +		    ad5766_span_tbl[i].max != max)
> +			continue;
> +
> +		st->crt_range = i;
> +
> +		return 0;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int ad5766_default_setup(struct ad5766_state *st)
> +{
> +	uint16_t val;
> +	int ret, i;
> +
> +	/* Always issue a reset before writing to the span register. */
> +	ret = ad5766_reset(st);
> +	if (ret)
> +		return ret;
> +
> +	ret = ad5766_get_output_range(st);
> +	if (ret)
> +		return ret;
> +
> +	/* Dither power down */
> +	st->dither_enable = GENMASK(15, 0);
> +	ret = __ad5766_spi_write(st, AD5766_CMD_WR_PWR_DITHER,
> +			     st->dither_enable);
> +	if (ret)
> +		return ret;
> +
> +	st->dither_source = 0;
> +	for (i = 0; i < ARRAY_SIZE(ad5766_channels); i++)
> +		st->dither_source |= AD5766_DITHER_SOURCE(i, 0);
> +	val = FIELD_GET(AD5766_LOWER_WORD_SPI_MASK, st->dither_source);
> +	ret = __ad5766_spi_write(st, AD5766_CMD_DITHER_SIG_1, val);
> +	if (ret)
> +		return ret;
> +
> +	val = FIELD_GET(AD5766_UPPER_WORD_SPI_MASK, st->dither_source);
> +	ret = __ad5766_spi_write(st, AD5766_CMD_DITHER_SIG_2, val);
> +	if (ret)
> +		return ret;
> +
> +	st->dither_scale = 0;
> +	val = FIELD_GET(AD5766_LOWER_WORD_SPI_MASK, st->dither_scale);
> +	ret = __ad5766_spi_write(st, AD5766_CMD_DITHER_SCALE_1, val);
> +	if (ret)
> +		return ret;
> +
> +	val = FIELD_GET(AD5766_UPPER_WORD_SPI_MASK, st->dither_scale);
> +	ret = __ad5766_spi_write(st, AD5766_CMD_DITHER_SCALE_2, val);
> +	if (ret)
> +		return ret;
> +
> +	st->dither_invert = 0;
> +	ret = __ad5766_spi_write(st, AD5766_CMD_INV_DITHER, st->dither_invert);
> +	if (ret)
> +		return ret;
> +
> +	return  __ad5766_spi_write(st, AD5766_CMD_SPAN_REG, st->crt_range);
> +}
> +
> +static int ad5766_probe(struct spi_device *spi)
> +{
> +	enum ad5766_type type;
> +	struct iio_dev *indio_dev;
> +	struct ad5766_state *st;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +	mutex_init(&st->lock);
> +
> +	st->spi = spi;
> +	type = spi_get_device_id(spi)->driver_data;
> +	st->chip_info = &ad5766_chip_infos[type];
> +
> +	indio_dev->channels = st->chip_info->channels;
> +	indio_dev->num_channels = st->chip_info->num_channels;
> +	indio_dev->info = &ad5766_info;
> +	indio_dev->dev.parent = &spi->dev;
> +	indio_dev->dev.of_node = spi->dev.of_node;
> +	indio_dev->name = spi_get_device_id(spi)->name;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	st->gpio_reset = devm_gpiod_get_optional(&st->spi->dev, "reset",
> +						GPIOD_OUT_LOW);
> +	if (IS_ERR(st->gpio_reset))
> +		return PTR_ERR(st->gpio_reset);
> +
> +	ret = ad5766_default_setup(st);
> +	if (ret)
> +		return ret;
> +
> +	return devm_iio_device_register(&spi->dev, indio_dev);
> +}
> +
> +static const struct of_device_id ad5766_dt_match[] = {
> +	{ .compatible = "adi,ad5766" },
> +	{ .compatible = "adi,ad5767" },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, ad5766_dt_match);
> +
> +static const struct spi_device_id ad5766_spi_ids[] = {
> +	{ "ad5766", ID_AD5766 },
> +	{ "ad5767", ID_AD5767 },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(spi, ad5766_spi_ids);
> +
> +static struct spi_driver ad5766_driver = {
> +	.driver = {
> +		.name = "ad5766",
> +		.of_match_table = ad5766_dt_match,
> +	},
> +	.probe = ad5766_probe,
> +	.id_table = ad5766_spi_ids,
> +};
> +module_spi_driver(ad5766_driver);
> +
> +MODULE_AUTHOR("Denis-Gabriel Gheorghescu <denis.gheorghescu@analog.com>");
> +MODULE_DESCRIPTION("Analog Devices AD5766/AD5767 DACs");
> +MODULE_LICENSE("GPL v2");

Re: [PATCH v5 1/3] dt-bindings: iio: dac: AD5766 yaml documentation

[Rob Herring]

On Fri, Jan 08, 2021 at 08:37:37PM +0200, Cristian Pop wrote:
> This adds device tree bindings for the AD5766 DAC.
> 
> Signed-off-by: Cristian Pop <cristian.pop@analog.com>
> ---
> Changelog v5:                                                              
>         -rename to property to "output-range-voltage"
>  .../bindings/iio/dac/adi,ad5766.yaml          | 64 +++++++++++++++++++
>  1 file changed, 64 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/dac/adi,ad5766.yaml
> 
> diff --git a/Documentation/devicetree/bindings/iio/dac/adi,ad5766.yaml b/Documentation/devicetree/bindings/iio/dac/adi,ad5766.yaml
> new file mode 100644
> index 000000000000..1deace7c48b2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/dac/adi,ad5766.yaml
> @@ -0,0 +1,64 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +# Copyright 2020 Analog Devices Inc.
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/dac/adi,ad5766.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Analog Devices AD5766 DAC device driver
> +
> +maintainers:
> +  - Cristian Pop <cristian.pop@analog.com>
> +
> +description: |
> +  Bindings for the Analog Devices AD5766 current DAC device. Datasheet can be
> +  found here:
> +    https://www.analog.com/media/en/technical-documentation/data-sheets/ad5766-5767.pdf
> +
> +properties:
> +  compatible:
> +    enum:
> +      - adi,ad5766
> +      - adi,ad5767
> +
> +  output-range-volts:

Use a unit defined in property-units.txt (-microvolt).

> +    description: Select converter output range.
> +
> +  reg:
> +    maxItems: 1
> +
> +  spi-max-frequency:
> +    maximum: 1000000
> +
> +  spi-cpol: true
> +
> +  reset-gpios:
> +    description: GPIO spec for the RESET pin. If specified, it will be asserted
> +      during driver probe. As the line is active low, it should be marked
> +      GPIO_ACTIVE_LOW.

'asserted during driver probe' is a Linux implementation detail not 
relevant to the binding.

> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - output-range-volts
> +  - reg
> +  - spi-max-frequency
> +  - spi-cpol
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    spi {
> +          #address-cells = <1>;
> +          #size-cells = <0>;
> +          
> +          ad5766@0 {
> +              compatible = "adi,ad5766";
> +              output-range-volts = <(-5) 5>;
> +              reg = <0>;
> +              spi-cpol;
> +              spi-max-frequency = <1000000>;
> +              reset-gpios = <&gpio 22 0>;
> +            };
> +      };
> -- 
> 2.17.1
>