[PATCH v3 0/2] iio:adc:ad7476: Regulator support and binding doc

[PATCH v3 0/2] iio:adc:ad7476: Regulator support and binding doc

[Jonathan Cameron]

From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

This driver supports a whole load of devices with a range of different
power supply connections.

Lars-Peter Clausen pointed out v1 did not handle the the ad7091r which
an internal voltage reference, but that can be over-driven on the vref_in /
vref_out pin.  The v2 handles that device properly.  I also realized that
I'd the binding was more restrictive for devices with internal references
than it needed to be (required vcc-supply) so I've relaxed that in
the updated bindings.  Also reorganized the big allOf block in the
binding doc to put all the constraints on reference voltage first.

v3 incorporates Lars' suggestion to set the regulator pointer to null
as a way to indicate that we should definitely use the internal reference.

Jonathan Cameron (2):
  iio:adc:ad7476: Handle the different regulators used by various parts.
  dt-bindings:iio:adc:adi,ad7474: Add missing binding document

 .../bindings/iio/adc/adi,ad7476.yaml          | 174 ++++++++++++++++++
 drivers/iio/adc/ad7476.c                      | 116 ++++++++++--
 2 files changed, 275 insertions(+), 15 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml

-- 
2.31.1

[PATCH v3 1/2] iio:adc:ad7476: Handle the different regulators used by various parts.

[Jonathan Cameron]

From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Not all of the parts supported by this driver use single supply.
Hence we add chip_info fields to say what additional supplies exist
and in the case of vref, ensure that is used for the reference voltage
rather than vcc.

One corner case is the ad7091r which has an internal reference that
can be over-driven by an external reference connected on the vref pin.
To handle that force_ext_vref is introduced and set if an optional
vref regulator is present.

Tested using really simple QEMU model and some fixed regulators.

The devm_add_action_or_reset() callback is changed to take the
regulator as it's parameter so we can use one callback for all the
different regulators without having to store pointers to them in
the iio_priv() structure.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Michael Hennerich <michael.hennerich@analog.com>
Reported-by: kernel test robot <lkp@intel.com>
---
 drivers/iio/adc/ad7476.c | 116 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 101 insertions(+), 15 deletions(-)

diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
index 9e9ff07cf972..22991cda932a 100644
--- a/drivers/iio/adc/ad7476.c
+++ b/drivers/iio/adc/ad7476.c
@@ -32,12 +32,14 @@ struct ad7476_chip_info {
 	/* channels used when convst gpio is defined */
 	struct iio_chan_spec		convst_channel[2];
 	void (*reset)(struct ad7476_state *);
+	bool				has_vref;
+	bool				has_vdrive;
 };
 
 struct ad7476_state {
 	struct spi_device		*spi;
 	const struct ad7476_chip_info	*chip_info;
-	struct regulator		*reg;
+	struct regulator		*ref_reg;
 	struct gpio_desc		*convst_gpio;
 	struct spi_transfer		xfer;
 	struct spi_message		msg;
@@ -52,13 +54,17 @@ struct ad7476_state {
 };
 
 enum ad7476_supported_device_ids {
+	ID_AD7091,
 	ID_AD7091R,
+	ID_AD7273,
+	ID_AD7274,
 	ID_AD7276,
 	ID_AD7277,
 	ID_AD7278,
 	ID_AD7466,
 	ID_AD7467,
 	ID_AD7468,
+	ID_AD7475,
 	ID_AD7495,
 	ID_AD7940,
 	ID_ADC081S,
@@ -145,8 +151,8 @@ static int ad7476_read_raw(struct iio_dev *indio_dev,
 			GENMASK(st->chip_info->channel[0].scan_type.realbits - 1, 0);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
-		if (!st->chip_info->int_vref_uv) {
-			scale_uv = regulator_get_voltage(st->reg);
+		if (st->ref_reg) {
+			scale_uv = regulator_get_voltage(st->ref_reg);
 			if (scale_uv < 0)
 				return scale_uv;
 		} else {
@@ -187,13 +193,32 @@ static int ad7476_read_raw(struct iio_dev *indio_dev,
 		BIT(IIO_CHAN_INFO_RAW))
 
 static const struct ad7476_chip_info ad7476_chip_info_tbl[] = {
+	[ID_AD7091] = {
+		.channel[0] = AD7091R_CHAN(12),
+		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+		.convst_channel[0] = AD7091R_CONVST_CHAN(12),
+		.convst_channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+		.reset = ad7091_reset,
+	},
 	[ID_AD7091R] = {
 		.channel[0] = AD7091R_CHAN(12),
 		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
 		.convst_channel[0] = AD7091R_CONVST_CHAN(12),
 		.convst_channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+		.int_vref_uv = 2500000,
+		.has_vref = true,
 		.reset = ad7091_reset,
 	},
+	[ID_AD7273] = {
+		.channel[0] = AD7940_CHAN(10),
+		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+		.has_vref = true,
+	},
+	[ID_AD7274] = {
+		.channel[0] = AD7940_CHAN(12),
+		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+		.has_vref = true,
+	},
 	[ID_AD7276] = {
 		.channel[0] = AD7940_CHAN(12),
 		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
@@ -218,10 +243,17 @@ static const struct ad7476_chip_info ad7476_chip_info_tbl[] = {
 		.channel[0] = AD7476_CHAN(8),
 		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
 	},
+	[ID_AD7475] = {
+		.channel[0] = AD7476_CHAN(12),
+		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+		.has_vref = true,
+		.has_vdrive = true,
+	},
 	[ID_AD7495] = {
 		.channel[0] = AD7476_CHAN(12),
 		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
 		.int_vref_uv = 2500000,
+		.has_vdrive = true,
 	},
 	[ID_AD7940] = {
 		.channel[0] = AD7940_CHAN(14),
@@ -254,6 +286,7 @@ static const struct ad7476_chip_info ad7476_chip_info_tbl[] = {
 	[ID_LTC2314_14] = {
 		.channel[0] = AD7940_CHAN(14),
 		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+		.has_vref = true,
 	},
 };
 
@@ -263,15 +296,16 @@ static const struct iio_info ad7476_info = {
 
 static void ad7476_reg_disable(void *data)
 {
-	struct ad7476_state *st = data;
+	struct regulator *reg = data;
 
-	regulator_disable(st->reg);
+	regulator_disable(reg);
 }
 
 static int ad7476_probe(struct spi_device *spi)
 {
 	struct ad7476_state *st;
 	struct iio_dev *indio_dev;
+	struct regulator *reg;
 	int ret;
 
 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
@@ -282,19 +316,71 @@ static int ad7476_probe(struct spi_device *spi)
 	st->chip_info =
 		&ad7476_chip_info_tbl[spi_get_device_id(spi)->driver_data];
 
-	st->reg = devm_regulator_get(&spi->dev, "vcc");
-	if (IS_ERR(st->reg))
-		return PTR_ERR(st->reg);
+	reg = devm_regulator_get(&spi->dev, "vcc");
+	if (IS_ERR(reg))
+		return PTR_ERR(reg);
 
-	ret = regulator_enable(st->reg);
+	ret = regulator_enable(reg);
 	if (ret)
 		return ret;
 
-	ret = devm_add_action_or_reset(&spi->dev, ad7476_reg_disable,
-				       st);
+	ret = devm_add_action_or_reset(&spi->dev, ad7476_reg_disable, reg);
 	if (ret)
 		return ret;
 
+	/* Either vcc or vref (below) as appropriate */
+	if (!st->chip_info->int_vref_uv)
+		st->ref_reg = reg;
+
+	if (st->chip_info->has_vref) {
+
+		/* If a device has an internal reference vref is optional */
+		if (st->chip_info->int_vref_uv) {
+			reg = devm_regulator_get_optional(&spi->dev, "vref");
+		} else {
+			reg = devm_regulator_get(&spi->dev, "vref");
+			if (IS_ERR(reg))
+				return PTR_ERR(reg);
+		}
+
+		if (!IS_ERR(reg)) {
+			ret = regulator_enable(reg);
+			if (ret)
+				return ret;
+
+			ret = devm_add_action_or_reset(&spi->dev,
+						       ad7476_reg_disable,
+						       reg);
+			if (ret)
+				return ret;
+			st->ref_reg = reg;
+		} else {
+			/*
+			 * Can only get here if device supports both internal
+			 * and external reference, but the regulator connected
+			 * to the external reference is not connected.
+			 * Set the reference regulator pointer to NULL to
+			 * indicate this.
+			 */
+			st->ref_reg = NULL;
+		}
+	}
+
+	if (st->chip_info->has_vdrive) {
+		reg = devm_regulator_get(&spi->dev, "vdrive");
+		if (IS_ERR(reg))
+			return PTR_ERR(reg);
+
+		ret = regulator_enable(reg);
+		if (ret)
+			return ret;
+
+		ret = devm_add_action_or_reset(&spi->dev, ad7476_reg_disable,
+					       reg);
+		if (ret)
+			return ret;
+	}
+
 	st->convst_gpio = devm_gpiod_get_optional(&spi->dev,
 						  "adi,conversion-start",
 						  GPIOD_OUT_LOW);
@@ -333,17 +419,17 @@ static int ad7476_probe(struct spi_device *spi)
 }
 
 static const struct spi_device_id ad7476_id[] = {
-	{"ad7091", ID_AD7091R},
+	{"ad7091", ID_AD7091},
 	{"ad7091r", ID_AD7091R},
-	{"ad7273", ID_AD7277},
-	{"ad7274", ID_AD7276},
+	{"ad7273", ID_AD7273},
+	{"ad7274", ID_AD7274},
 	{"ad7276", ID_AD7276},
 	{"ad7277", ID_AD7277},
 	{"ad7278", ID_AD7278},
 	{"ad7466", ID_AD7466},
 	{"ad7467", ID_AD7467},
 	{"ad7468", ID_AD7468},
-	{"ad7475", ID_AD7466},
+	{"ad7475", ID_AD7475},
 	{"ad7476", ID_AD7466},
 	{"ad7476a", ID_AD7466},
 	{"ad7477", ID_AD7467},
-- 
2.31.1

Re: [PATCH v3 1/2] iio:adc:ad7476: Handle the different regulators used by various parts.

[Lars-Peter Clausen]

On 4/24/21 7:03 PM, Jonathan Cameron wrote:
> [...]
>   
> +	/* Either vcc or vref (below) as appropriate */
> +	if (!st->chip_info->int_vref_uv)
> +		st->ref_reg = reg;
> +
> +	if (st->chip_info->has_vref) {
> +
> +		/* If a device has an internal reference vref is optional */
> +		if (st->chip_info->int_vref_uv) {
> +			reg = devm_regulator_get_optional(&spi->dev, "vref");
> +		} else {
> +			reg = devm_regulator_get(&spi->dev, "vref");
> +			if (IS_ERR(reg))
> +				return PTR_ERR(reg);
> +		}
> +
> +		if (!IS_ERR(reg)) {
> +			ret = regulator_enable(reg);
> +			if (ret)
> +				return ret;
> +
> +			ret = devm_add_action_or_reset(&spi->dev,
> +						       ad7476_reg_disable,
> +						       reg);
> +			if (ret)
> +				return ret;
> +			st->ref_reg = reg;
> +		} else {
We still need to check for errors, e.g. to support EPROBE_DEFER. The 
only error that can be ignored is ENOENT, which means no regulator is 
specified.
> +			/*
> +			 * Can only get here if device supports both internal
> +			 * and external reference, but the regulator connected
> +			 * to the external reference is not connected.
> +			 * Set the reference regulator pointer to NULL to
> +			 * indicate this.
> +			 */
> +			st->ref_reg = NULL;
> +		}
> +	}

Re: [PATCH v3 1/2] iio:adc:ad7476: Handle the different regulators used by various parts.

[Jonathan Cameron]

On Sat, 24 Apr 2021 20:20:41 +0200
Lars-Peter Clausen <lars@metafoo.de> wrote:

> On 4/24/21 7:03 PM, Jonathan Cameron wrote:
> > [...]
> >   
> > +	/* Either vcc or vref (below) as appropriate */
> > +	if (!st->chip_info->int_vref_uv)
> > +		st->ref_reg = reg;
> > +
> > +	if (st->chip_info->has_vref) {
> > +
> > +		/* If a device has an internal reference vref is optional */
> > +		if (st->chip_info->int_vref_uv) {
> > +			reg = devm_regulator_get_optional(&spi->dev, "vref");
> > +		} else {
> > +			reg = devm_regulator_get(&spi->dev, "vref");
> > +			if (IS_ERR(reg))
> > +				return PTR_ERR(reg);
> > +		}
> > +
> > +		if (!IS_ERR(reg)) {
> > +			ret = regulator_enable(reg);
> > +			if (ret)
> > +				return ret;
> > +
> > +			ret = devm_add_action_or_reset(&spi->dev,
> > +						       ad7476_reg_disable,
> > +						       reg);
> > +			if (ret)
> > +				return ret;
> > +			st->ref_reg = reg;
> > +		} else {  
> We still need to check for errors, e.g. to support EPROBE_DEFER. The 
> only error that can be ignored is ENOENT, which means no regulator is 
> specified.
Good point.  I got fixated on all the different combinations and forgot the
simple 'error' case :)

V4 coming up.

Jonathan

> > +			/*
> > +			 * Can only get here if device supports both internal
> > +			 * and external reference, but the regulator connected
> > +			 * to the external reference is not connected.
> > +			 * Set the reference regulator pointer to NULL to
> > +			 * indicate this.
> > +			 */
> > +			st->ref_reg = NULL;
> > +		}
> > +	}  
> 

Re: [PATCH v3 1/2] iio:adc:ad7476: Handle the different regulators used by various parts.

[Jonathan Cameron]

On Sun, 25 Apr 2021 16:18:02 +0100
Jonathan Cameron <jic23@kernel.org> wrote:

> On Sat, 24 Apr 2021 20:20:41 +0200
> Lars-Peter Clausen <lars@metafoo.de> wrote:
> 
> > On 4/24/21 7:03 PM, Jonathan Cameron wrote:  
> > > [...]
> > >   
> > > +	/* Either vcc or vref (below) as appropriate */
> > > +	if (!st->chip_info->int_vref_uv)
> > > +		st->ref_reg = reg;
> > > +
> > > +	if (st->chip_info->has_vref) {
> > > +
> > > +		/* If a device has an internal reference vref is optional */
> > > +		if (st->chip_info->int_vref_uv) {
> > > +			reg = devm_regulator_get_optional(&spi->dev, "vref");
> > > +		} else {
> > > +			reg = devm_regulator_get(&spi->dev, "vref");
> > > +			if (IS_ERR(reg))
> > > +				return PTR_ERR(reg);
> > > +		}
> > > +
> > > +		if (!IS_ERR(reg)) {
> > > +			ret = regulator_enable(reg);
> > > +			if (ret)
> > > +				return ret;
> > > +
> > > +			ret = devm_add_action_or_reset(&spi->dev,
> > > +						       ad7476_reg_disable,
> > > +						       reg);
> > > +			if (ret)
> > > +				return ret;
> > > +			st->ref_reg = reg;
> > > +		} else {    
> > We still need to check for errors, e.g. to support EPROBE_DEFER. The 
> > only error that can be ignored is ENOENT, which means no regulator is 
> > specified.  
> Good point.  I got fixated on all the different combinations and forgot the
> simple 'error' case :)

As far as I can tell -ENODEV is the return for no regulator specified.

Jonathan

> 
> V4 coming up.
> 
> Jonathan
> 
> > > +			/*
> > > +			 * Can only get here if device supports both internal
> > > +			 * and external reference, but the regulator connected
> > > +			 * to the external reference is not connected.
> > > +			 * Set the reference regulator pointer to NULL to
> > > +			 * indicate this.
> > > +			 */
> > > +			st->ref_reg = NULL;
> > > +		}
> > > +	}    
> >   
> 

Re: [PATCH v3 1/2] iio:adc:ad7476: Handle the different regulators used by various parts.

[Lars-Peter Clausen]

On 4/25/21 6:02 PM, Jonathan Cameron wrote:
> On Sun, 25 Apr 2021 16:18:02 +0100
> Jonathan Cameron <jic23@kernel.org> wrote:
>
>> On Sat, 24 Apr 2021 20:20:41 +0200
>> Lars-Peter Clausen <lars@metafoo.de> wrote:
>>
>>> On 4/24/21 7:03 PM, Jonathan Cameron wrote:
>>>> [...]
>>>>    
>>>> +	/* Either vcc or vref (below) as appropriate */
>>>> +	if (!st->chip_info->int_vref_uv)
>>>> +		st->ref_reg = reg;
>>>> +
>>>> +	if (st->chip_info->has_vref) {
>>>> +
>>>> +		/* If a device has an internal reference vref is optional */
>>>> +		if (st->chip_info->int_vref_uv) {
>>>> +			reg = devm_regulator_get_optional(&spi->dev, "vref");
>>>> +		} else {
>>>> +			reg = devm_regulator_get(&spi->dev, "vref");
>>>> +			if (IS_ERR(reg))
>>>> +				return PTR_ERR(reg);
>>>> +		}
>>>> +
>>>> +		if (!IS_ERR(reg)) {
>>>> +			ret = regulator_enable(reg);
>>>> +			if (ret)
>>>> +				return ret;
>>>> +
>>>> +			ret = devm_add_action_or_reset(&spi->dev,
>>>> +						       ad7476_reg_disable,
>>>> +						       reg);
>>>> +			if (ret)
>>>> +				return ret;
>>>> +			st->ref_reg = reg;
>>>> +		} else {
>>> We still need to check for errors, e.g. to support EPROBE_DEFER. The
>>> only error that can be ignored is ENOENT, which means no regulator is
>>> specified.
>> Good point.  I got fixated on all the different combinations and forgot the
>> simple 'error' case :)
> As far as I can tell -ENODEV is the return for no regulator specified.

Yes. We even have a few examples like the ad7124 driver.

[PATCH v3 2/2] dt-bindings:iio:adc:adi,ad7474: Add missing binding document

[Jonathan Cameron]

From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

This binding covers class of simple SPI ADCs which only provide
data output - they don't have MOSI pin.

The only real variation between them is over how many supplies they
use and which one is used for the reference.

Michael listed as maintainer for this one as it is his driver and
falls under the catch all MAINTAINERS entry for ADI devices.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Michael Hennerich <michael.hennerich@analog.com>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 .../bindings/iio/adc/adi,ad7476.yaml          | 174 ++++++++++++++++++
 1 file changed, 174 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
new file mode 100644
index 000000000000..cf711082ad7d
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
@@ -0,0 +1,174 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+# Copyright 2019 Analog Devices Inc.
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/adi,ad7476.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: AD7476 and similar simple SPI ADCs from multiple manufacturers.
+
+maintainers:
+  - Michael Hennerich <michael.hennerich@analog.com>
+
+description: |
+  A lot of simple SPI ADCs have very straight forward interfaces.
+  They typically don't provide a MOSI pin, simply reading out data
+  on MISO when the clock toggles.
+
+properties:
+  compatible:
+    enum:
+      - adi,ad7091
+      - adi,ad7091r
+      - adi,ad7273
+      - adi,ad7274
+      - adi,ad7276
+      - adi,ad7277
+      - adi,ad7278
+      - adi,ad7466
+      - adi,ad7467
+      - adi,ad7468
+      - adi,ad7475
+      - adi,ad7476
+      - adi,ad7476a
+      - adi,ad7477
+      - adi,ad7477a
+      - adi,ad7478
+      - adi,ad7478a
+      - adi,ad7495
+      - adi,ad7910
+      - adi,ad7920
+      - adi,ad7940
+      - ti,adc081s
+      - ti,adc101s
+      - ti,adc121s
+      - ti,ads7866
+      - ti,ads7867
+      - ti,ads7868
+      - lltc,ltc2314-14
+
+  reg:
+    maxItems: 1
+
+  vcc-supply:
+    description:
+      Main powersupply voltage for the chips, sometimes referred to as VDD on
+      datasheets.  If there is no separate vref-supply, then this is needed
+      to establish channel scaling.
+
+  vdrive-supply:
+    description:
+      Some devices have separate supply for their digital control side.
+
+  vref-supply:
+    description:
+      Some devices have a specific reference voltage supplied on a different pin
+      to the other supplies. Needed to be able to establish channel scaling
+      unless there is also an internal reference available (e.g. ad7091r)
+
+  spi-max-frequency: true
+
+  adi,conversion-start-gpios:
+    description: A GPIO used to trigger the start of a conversion
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+allOf:
+  # Devices where reference is vcc
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - adi,ad7091
+              - adi,ad7276
+              - adi,ad7277
+              - adi,ad7278
+              - adi,ad7466
+              - adi,ad7467
+              - adi,ad7468
+              - adi,ad7940
+              - ti,adc081s
+              - ti,adc101s
+              - ti,adc121s
+              - ti,ads7866
+              - ti,ads7868
+      required:
+        - vcc-supply
+  # Devices with a vref
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - adi,ad7091r
+              - adi,ad7273
+              - adi,ad7274
+              - adi,ad7475
+              - lltc,ltc2314-14
+    then:
+      properties:
+        vref-supply: true
+    else:
+      properties:
+        vref-supply: false
+  # Devices with a vref where it is not optional
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - adi,ad7273
+              - adi,ad7274
+              - adi,ad7475
+              - lltc,ltc2314-14
+    then:
+      required:
+        - vref-supply
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - adi,ad7475
+              - adi,ad7495
+    then:
+      properties:
+        vdrive-supply: true
+    else:
+      properties:
+        vdrive-supply: false
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - adi,ad7091
+              - adi,ad7091r
+    then:
+      properties:
+        adi,conversion-start-gpios: true
+    else:
+      properties:
+        adi,conversion-start-gpios: false
+
+examples:
+  - |
+    spi {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      adc@0 {
+        compatible = "adi,ad7091r";
+        reg = <0>;
+        spi-max-frequency = <5000000>;
+        vcc-supply = <&adc_vcc>;
+        vref-supply = <&adc_vref>;
+      };
+    };
+...
-- 
2.31.1

Re: [PATCH v3 2/2] dt-bindings:iio:adc:adi,ad7474: Add missing binding document

[Jonathan Cameron]

On Sat, 24 Apr 2021 18:03:46 +0100
Jonathan Cameron <jic23@kernel.org> wrote:

> From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Let's just pretend that it says ad7476 in the patch title
(I'll fix it whilst applying).

Oops.

Jonathan

> 
> This binding covers class of simple SPI ADCs which only provide
> data output - they don't have MOSI pin.
> 
> The only real variation between them is over how many supplies they
> use and which one is used for the reference.
> 
> Michael listed as maintainer for this one as it is his driver and
> falls under the catch all MAINTAINERS entry for ADI devices.
> 
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Cc: Michael Hennerich <michael.hennerich@analog.com>
> Reviewed-by: Rob Herring <robh@kernel.org>
> ---
>  .../bindings/iio/adc/adi,ad7476.yaml          | 174 ++++++++++++++++++
>  1 file changed, 174 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
> new file mode 100644
> index 000000000000..cf711082ad7d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
> @@ -0,0 +1,174 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +# Copyright 2019 Analog Devices Inc.
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/adc/adi,ad7476.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: AD7476 and similar simple SPI ADCs from multiple manufacturers.
> +
> +maintainers:
> +  - Michael Hennerich <michael.hennerich@analog.com>
> +
> +description: |
> +  A lot of simple SPI ADCs have very straight forward interfaces.
> +  They typically don't provide a MOSI pin, simply reading out data
> +  on MISO when the clock toggles.
> +
> +properties:
> +  compatible:
> +    enum:
> +      - adi,ad7091
> +      - adi,ad7091r
> +      - adi,ad7273
> +      - adi,ad7274
> +      - adi,ad7276
> +      - adi,ad7277
> +      - adi,ad7278
> +      - adi,ad7466
> +      - adi,ad7467
> +      - adi,ad7468
> +      - adi,ad7475
> +      - adi,ad7476
> +      - adi,ad7476a
> +      - adi,ad7477
> +      - adi,ad7477a
> +      - adi,ad7478
> +      - adi,ad7478a
> +      - adi,ad7495
> +      - adi,ad7910
> +      - adi,ad7920
> +      - adi,ad7940
> +      - ti,adc081s
> +      - ti,adc101s
> +      - ti,adc121s
> +      - ti,ads7866
> +      - ti,ads7867
> +      - ti,ads7868
> +      - lltc,ltc2314-14
> +
> +  reg:
> +    maxItems: 1
> +
> +  vcc-supply:
> +    description:
> +      Main powersupply voltage for the chips, sometimes referred to as VDD on
> +      datasheets.  If there is no separate vref-supply, then this is needed
> +      to establish channel scaling.
> +
> +  vdrive-supply:
> +    description:
> +      Some devices have separate supply for their digital control side.
> +
> +  vref-supply:
> +    description:
> +      Some devices have a specific reference voltage supplied on a different pin
> +      to the other supplies. Needed to be able to establish channel scaling
> +      unless there is also an internal reference available (e.g. ad7091r)
> +
> +  spi-max-frequency: true
> +
> +  adi,conversion-start-gpios:
> +    description: A GPIO used to trigger the start of a conversion
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +allOf:
> +  # Devices where reference is vcc
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - adi,ad7091
> +              - adi,ad7276
> +              - adi,ad7277
> +              - adi,ad7278
> +              - adi,ad7466
> +              - adi,ad7467
> +              - adi,ad7468
> +              - adi,ad7940
> +              - ti,adc081s
> +              - ti,adc101s
> +              - ti,adc121s
> +              - ti,ads7866
> +              - ti,ads7868
> +      required:
> +        - vcc-supply
> +  # Devices with a vref
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - adi,ad7091r
> +              - adi,ad7273
> +              - adi,ad7274
> +              - adi,ad7475
> +              - lltc,ltc2314-14
> +    then:
> +      properties:
> +        vref-supply: true
> +    else:
> +      properties:
> +        vref-supply: false
> +  # Devices with a vref where it is not optional
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - adi,ad7273
> +              - adi,ad7274
> +              - adi,ad7475
> +              - lltc,ltc2314-14
> +    then:
> +      required:
> +        - vref-supply
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - adi,ad7475
> +              - adi,ad7495
> +    then:
> +      properties:
> +        vdrive-supply: true
> +    else:
> +      properties:
> +        vdrive-supply: false
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - adi,ad7091
> +              - adi,ad7091r
> +    then:
> +      properties:
> +        adi,conversion-start-gpios: true
> +    else:
> +      properties:
> +        adi,conversion-start-gpios: false
> +
> +examples:
> +  - |
> +    spi {
> +      #address-cells = <1>;
> +      #size-cells = <0>;
> +
> +      adc@0 {
> +        compatible = "adi,ad7091r";
> +        reg = <0>;
> +        spi-max-frequency = <5000000>;
> +        vcc-supply = <&adc_vcc>;
> +        vref-supply = <&adc_vref>;
> +      };
> +    };
> +...