[PATCH v3 0/8] Support ROHM BD79104 ADC

[PATCH v3 0/8] Support ROHM BD79104 ADC

[Matti Vaittinen]

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The ROHM BD79104 ADC is a 12 bit, 8-channel ADC controlled via SPI.

The communication over SPI uses similar protocol as the ti-adc128s052.
In order to avoid code duplication, the support for the ROHM IC is
added in the same driver.

The driver side differencies between the ti-adc128s052 and the ROHM
BD79104 are related to the supply regulator handling. The BD79104
requires supplies for the VDD and IOVDD. The ti-adc128s052 driver
handles only the reference voltage supply, even though the TI data-sheet
indicates it can also have separate supplies.

Hardware vise the ROHM BD79104 requires SPI MODE 3, and has also some SPI
frequency limitations.

I decided to add own binding document for the ROHM BD79104 so it is
easier to document the SPI limitations. It also allows using the supply
names from the data sheet. And finally, it gives users of this IC a
better hint that it is supported.

I added myself as a maintainer for the driver, so I can stay on track of
the changes to it. If anyone with experience with (and acces to) the
TI's ICs has the energy ... feel free to add more maintainers.

This series was based on the v6.15-rc1

Revision history:

v2 = v3:
 - Rebase on v6.15-rc1
 - Minor improvements to the Vref handling
 - Add MAINTAINERS entry
v1 => v2:
 - Drop the claim that original driver is broken for BE and rename the
   patch 0001 accordingly
 - Fix race when filling the SPI message
 - Check return value for the devm_mutex_init()
 - Add a RFC patch for dropping the support for variable Vref.

---

Matti Vaittinen (8):
  dt-bindings: ROHM BD79104 ADC
  iio: adc: ti-adc128s052: Simplify using be16_to_cpu()
  iio: adc: ti-adc128s052: Be consistent with arrays
  iio: adc: ti-adc128s052: Use devm_mutex_init()
  iio: adc: ti-adc128s052: Simplify using guard(mutex)
  iio: adc: ti-adc128s052: Support ROHM BD79104
  MAINTAINERS: A driver for TI/ROHM ADCs
  iio: ti-adc128s052: Drop variable vref

 .../bindings/iio/adc/rohm,bd79104.yaml        | 69 +++++++++++++
 MAINTAINERS                                   |  6 ++
 drivers/iio/adc/Kconfig                       |  2 +-
 drivers/iio/adc/ti-adc128s052.c               | 96 ++++++++++++-------
 4 files changed, 135 insertions(+), 38 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/rohm,bd79104.yaml

-- 
2.49.0


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[PATCH v3 1/8] dt-bindings: ROHM BD79104 ADC

[Matti Vaittinen]

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The ROHM BD79104 is a 12-bit, 8-channel ADC with two power supply pins,
connected to SPI. It's worth noting the IC requires SPI MODE 3, (CPHA =
1, CPOL = 1).

I used an evaluation board "BD79104FV-EVK-001" from ROHM. With this
board I had problems to have things working correctly with higher SPI
clock frequencies. I didn't do thorough testing for maximum frequency
though. First attempt was 40M, then 20M and finally 4M. With 20M it
seemed as if the read values were shifted by 1 bit. With 4M it worked
fine.

The component data-sheet is not exact what comes to the maximum SPI
frequency. It says SPI frequency is 20M - "unless othervice specified".
Additionally, it says that maximum sampling rate is 1Mhz, and since
reading a sample requires writing the channel (16 bits) and reading
data (16 bits) - we get some upper limit from this.

From the "frequency is 20M, unless othervice specified" I picked the
maximum frequency 20M - and did assumption that my problems with 20M
weren't related to the BD79104 - but to the evaluation board
"BD79104FV-EVK-001".

Add bindings for the ROHM BD79104 ADC.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

---
Revision history:
v1 =>
 - No changes
---
 .../bindings/iio/adc/rohm,bd79104.yaml        | 69 +++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/rohm,bd79104.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/rohm,bd79104.yaml b/Documentation/devicetree/bindings/iio/adc/rohm,bd79104.yaml
new file mode 100644
index 000000000000..2a8ad4fdfc6b
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/rohm,bd79104.yaml
@@ -0,0 +1,69 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/rohm,bd79104.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ROHM Semiconductor BD79104 ADC
+
+maintainers:
+  - Matti Vaittinen <mazziesaccount@gmail.com>
+
+description: |
+  12 bit SPI ADC with 8 channels.
+
+properties:
+  compatible:
+    const: rohm,bd79104
+
+  reg:
+    maxItems: 1
+
+  vdd-supply: true
+  iovdd-supply: true
+
+# The component data-sheet says the frequency is 20M. I, however, found
+# that the ROHM evaluation board BD79104FV-EVK-001 had problems with 20M.
+# I have successfully used it with 4M. My _assumption_ is that this is not
+# the limitation of the component itself, but a limitation of the EVK.
+  spi-max-frequency:
+    maximum: 20000000
+
+  "#io-channel-cells":
+    const: 1
+
+  spi-cpha: true
+  spi-cpol: true
+
+required:
+  - compatible
+  - reg
+  - vdd-supply
+  - iovdd-supply
+  - spi-cpha
+  - spi-cpol
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@0 {
+            compatible = "rohm,bd79104";
+            reg = <0>;
+            vdd-supply = <&vdd_supply>;
+            iovdd-supply = <&iovdd_supply>;
+            spi-max-frequency = <4000000>;
+            spi-cpha;
+            spi-cpol;
+            #io-channel-cells = <1>;
+        };
+    };
+...
-- 
2.49.0


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[PATCH v3 2/8] iio: adc: ti-adc128s052: Simplify using be16_to_cpu()

[Matti Vaittinen]

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The register data is 12-bit big-endian data. Use be16_to_cpu() to do
the conversion, and simple bitwise AND for masking to make it more
obvious.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
---
Revision history:
v2 => v3:
 - Decrease amount of changed lines by keeping the old buffer name.
v1 => v2:
 - Fix commit msg to reflect the fact there was no bug
 - Drop Fixes tag
 - Use union for rx / tx buffer to avoid casting
 - Keep the shared message protected by the mutex
---
 drivers/iio/adc/ti-adc128s052.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/adc/ti-adc128s052.c b/drivers/iio/adc/ti-adc128s052.c
index a456ea78462f..c5b2374322e4 100644
--- a/drivers/iio/adc/ti-adc128s052.c
+++ b/drivers/iio/adc/ti-adc128s052.c
@@ -28,7 +28,10 @@ struct adc128 {
 	struct regulator *reg;
 	struct mutex lock;
 
-	u8 buffer[2] __aligned(IIO_DMA_MINALIGN);
+	union {
+		__be16 buffer16;
+		u8 buffer[2];
+	} __aligned(IIO_DMA_MINALIGN);
 };
 
 static int adc128_adc_conversion(struct adc128 *adc, u8 channel)
@@ -40,20 +43,18 @@ static int adc128_adc_conversion(struct adc128 *adc, u8 channel)
 	adc->buffer[0] = channel << 3;
 	adc->buffer[1] = 0;
 
-	ret = spi_write(adc->spi, &adc->buffer, 2);
+	ret = spi_write(adc->spi, &adc->buffer, sizeof(adc->buffer));
 	if (ret < 0) {
 		mutex_unlock(&adc->lock);
 		return ret;
 	}
 
-	ret = spi_read(adc->spi, &adc->buffer, 2);
-
+	ret = spi_read(adc->spi, &adc->buffer16, sizeof(adc->buffer16));
 	mutex_unlock(&adc->lock);
-
 	if (ret < 0)
 		return ret;
 
-	return ((adc->buffer[0] << 8 | adc->buffer[1]) & 0xFFF);
+	return be16_to_cpu(adc->buffer16) & 0xFFF;
 }
 
 static int adc128_read_raw(struct iio_dev *indio_dev,
-- 
2.49.0


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[PATCH v3 3/8] iio: adc: ti-adc128s052: Be consistent with arrays

[Matti Vaittinen]

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The ti-adc128s052 driver has NULL terminated ID arrays for the
of_device_id, spi_device_id and acpi_device_id. All of these are
terminated by having an empty string as the last member of an array.
Only the of_device_id array uses the /* sentinel */ comment.

It's better to be consistent.

This /* sentinel */ comment serves no real purpose these days as people
are used to seeing these ID lists terminated with an empty array
element.

Drop the /* sentinel */ from the of_device_id.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>

---
Revision history:
v2 =>
 - No changes
v1 => v2:
 - Drop the comma from the end of the of_device_id list.
---
 drivers/iio/adc/ti-adc128s052.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ti-adc128s052.c b/drivers/iio/adc/ti-adc128s052.c
index c5b2374322e4..d0702d403fbe 100644
--- a/drivers/iio/adc/ti-adc128s052.c
+++ b/drivers/iio/adc/ti-adc128s052.c
@@ -185,7 +185,7 @@ static const struct of_device_id adc128_of_match[] = {
 	{ .compatible = "ti,adc124s021", .data = &adc128_config[2] },
 	{ .compatible = "ti,adc124s051", .data = &adc128_config[2] },
 	{ .compatible = "ti,adc124s101", .data = &adc128_config[2] },
-	{ /* sentinel */ },
+	{ }
 };
 MODULE_DEVICE_TABLE(of, adc128_of_match);
 
-- 
2.49.0


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[PATCH v3 4/8] iio: adc: ti-adc128s052: Use devm_mutex_init()

[Matti Vaittinen]

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Quoting Jonathan:
"Whilst it doesn't bring huge advantage, now we have devm_mutex_init()
it seems reasonable to use it and maybe catch a use after free for the
lock"

Switch to use devm_mutex_init() while working on this file.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>

---
v2 =>
 - No changes
v1 => v2:
 - Check the return value for the devm_mutex_init()
---
 drivers/iio/adc/ti-adc128s052.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ti-adc128s052.c b/drivers/iio/adc/ti-adc128s052.c
index d0702d403fbe..d90a5caa028f 100644
--- a/drivers/iio/adc/ti-adc128s052.c
+++ b/drivers/iio/adc/ti-adc128s052.c
@@ -172,7 +172,9 @@ static int adc128_probe(struct spi_device *spi)
 	if (ret)
 		return ret;
 
-	mutex_init(&adc->lock);
+	ret = devm_mutex_init(&spi->dev, &adc->lock);
+	if (ret)
+		return ret;
 
 	return devm_iio_device_register(&spi->dev, indio_dev);
 }
-- 
2.49.0


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[PATCH v3 5/8] iio: adc: ti-adc128s052: Simplify using guard(mutex)

[Matti Vaittinen]

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Error path in ADC reading function can be slighly simplified using the
guard(mutex).

Use guard(mutex) and document the mutex purpose.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>

---
Revision history:
v2 =>
 - No changes
v1 => v2:
 - Protect the shared message data
 - Add message data protection to the mutex doc
 - Reword the commit message
---
 drivers/iio/adc/ti-adc128s052.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/ti-adc128s052.c b/drivers/iio/adc/ti-adc128s052.c
index d90a5caa028f..fa0099356be7 100644
--- a/drivers/iio/adc/ti-adc128s052.c
+++ b/drivers/iio/adc/ti-adc128s052.c
@@ -9,6 +9,7 @@
  * https://www.ti.com/lit/ds/symlink/adc124s021.pdf
  */
 
+#include <linux/cleanup.h>
 #include <linux/err.h>
 #include <linux/iio/iio.h>
 #include <linux/mod_devicetable.h>
@@ -26,6 +27,10 @@ struct adc128 {
 	struct spi_device *spi;
 
 	struct regulator *reg;
+	/*
+	 * Serialize the SPI 'write-channel + read data' accesses and protect
+	 * the shared buffer.
+	 */
 	struct mutex lock;
 
 	union {
@@ -38,19 +43,16 @@ static int adc128_adc_conversion(struct adc128 *adc, u8 channel)
 {
 	int ret;
 
-	mutex_lock(&adc->lock);
+	guard(mutex)(&adc->lock);
 
 	adc->buffer[0] = channel << 3;
 	adc->buffer[1] = 0;
 
 	ret = spi_write(adc->spi, &adc->buffer, sizeof(adc->buffer));
-	if (ret < 0) {
-		mutex_unlock(&adc->lock);
+	if (ret < 0)
 		return ret;
-	}
 
 	ret = spi_read(adc->spi, &adc->buffer16, sizeof(adc->buffer16));
-	mutex_unlock(&adc->lock);
 	if (ret < 0)
 		return ret;
 
-- 
2.49.0


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[PATCH v3 6/8] iio: adc: ti-adc128s052: Support ROHM BD79104

[Matti Vaittinen]

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The ROHM BD79104 ADC has identical SPI communication logic as the
ti-adc128s052. Eg, SPI transfer should be 16 clk cycles, conversion is
started when the CS is pulled low, and channel selection is done by
writing the channel ID after two zero bits. Data is contained in
big-endian format in the last 12 bits.

The BD79104 has two input voltage pins. Data sheet uses terms "vdd" and
"iovdd". The "vdd" is used also as an analog reference voltage. Hence
the driver expects finding these from the device-tree, instead of having
the "vref" only as TI's driver.

NOTE: The TI's data sheet[1] does show that the TI's IC does actually
have two voltage inputs as well. Pins are called Va (analog reference)
and Vd (digital supply pin) - but I keep the existing driver behaviour
for the TI's IC "as is", because I have no HW to test changes, and
because I have no real need to touch it.

NOTE II: The BD79104 requires SPI MODE 3.

NOTE III: I used evaluation board "BD79104FV-EVK-001" made by ROHM. With
this board I had to drop the SPI speed below the 20M which is mentioned
in the data-sheet [2]. This, however, may be a limitation of the EVK
board, not the component itself.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Datasheet: https://www.ti.com/lit/ds/symlink/adc128s052.pdf # [1]
Datasheet: https://fscdn.rohm.com/en/products/databook/datasheet/ic/data_converter/dac/bd79104fv-la-e.pdf # [2]

---
Revision history:
v2 =>
 - No changes
 v1 => v2:
  - Use Datasheet tags in commit message.
---
 drivers/iio/adc/Kconfig         |  2 +-
 drivers/iio/adc/ti-adc128s052.c | 40 +++++++++++++++++++++++++++++----
 2 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 6529df1a498c..bbad7b3d41bf 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1469,7 +1469,7 @@ config TI_ADC128S052
 	depends on SPI
 	help
 	  If you say yes here you get support for Texas Instruments ADC128S052,
-	  ADC122S021 and ADC124S021 chips.
+	  ADC122S021, ADC124S021 and ROHM Semiconductor BD79104 chips.
 
 	  This driver can also be built as a module. If so, the module will be
 	  called ti-adc128s052.
diff --git a/drivers/iio/adc/ti-adc128s052.c b/drivers/iio/adc/ti-adc128s052.c
index fa0099356be7..d4721ad90f2c 100644
--- a/drivers/iio/adc/ti-adc128s052.c
+++ b/drivers/iio/adc/ti-adc128s052.c
@@ -21,6 +21,9 @@
 struct adc128_configuration {
 	const struct iio_chan_spec	*channels;
 	u8				num_channels;
+	const char			*refname;
+	int				num_other_regulators;
+	const char * const		(*other_regulators)[];
 };
 
 struct adc128 {
@@ -124,10 +127,28 @@ static const struct iio_chan_spec adc124s021_channels[] = {
 	ADC128_VOLTAGE_CHANNEL(3),
 };
 
+static const char * const bd79104_regulators[] = { "iovdd" };
+
 static const struct adc128_configuration adc128_config[] = {
-	{ adc128s052_channels, ARRAY_SIZE(adc128s052_channels) },
-	{ adc122s021_channels, ARRAY_SIZE(adc122s021_channels) },
-	{ adc124s021_channels, ARRAY_SIZE(adc124s021_channels) },
+	{
+		.channels = adc128s052_channels,
+		.num_channels = ARRAY_SIZE(adc128s052_channels),
+		.refname = "vref",
+	}, {
+		.channels = adc122s021_channels,
+		.num_channels = ARRAY_SIZE(adc122s021_channels),
+		.refname = "vref",
+	}, {
+		.channels = adc124s021_channels,
+		.num_channels = ARRAY_SIZE(adc124s021_channels),
+		.refname = "vref",
+	}, {
+		.channels = adc128s052_channels,
+		.num_channels = ARRAY_SIZE(adc128s052_channels),
+		.refname = "vdd",
+		.other_regulators = &bd79104_regulators,
+		.num_other_regulators = 1,
+	},
 };
 
 static const struct iio_info adc128_info = {
@@ -162,7 +183,7 @@ static int adc128_probe(struct spi_device *spi)
 	indio_dev->channels = config->channels;
 	indio_dev->num_channels = config->num_channels;
 
-	adc->reg = devm_regulator_get(&spi->dev, "vref");
+	adc->reg = devm_regulator_get(&spi->dev, config->refname);
 	if (IS_ERR(adc->reg))
 		return PTR_ERR(adc->reg);
 
@@ -174,6 +195,15 @@ static int adc128_probe(struct spi_device *spi)
 	if (ret)
 		return ret;
 
+	if (config->num_other_regulators) {
+		ret = devm_regulator_bulk_get_enable(&spi->dev,
+						config->num_other_regulators,
+						*config->other_regulators);
+		if (ret)
+			return dev_err_probe(&spi->dev, ret,
+					     "Failed to enable regulators\n");
+	}
+
 	ret = devm_mutex_init(&spi->dev, &adc->lock);
 	if (ret)
 		return ret;
@@ -189,6 +219,7 @@ static const struct of_device_id adc128_of_match[] = {
 	{ .compatible = "ti,adc124s021", .data = &adc128_config[2] },
 	{ .compatible = "ti,adc124s051", .data = &adc128_config[2] },
 	{ .compatible = "ti,adc124s101", .data = &adc128_config[2] },
+	{ .compatible = "rohm,bd79104", .data = &adc128_config[3] },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, adc128_of_match);
@@ -201,6 +232,7 @@ static const struct spi_device_id adc128_id[] = {
 	{ "adc124s021", (kernel_ulong_t)&adc128_config[2] },
 	{ "adc124s051", (kernel_ulong_t)&adc128_config[2] },
 	{ "adc124s101", (kernel_ulong_t)&adc128_config[2] },
+	{ "bd79104", (kernel_ulong_t)&adc128_config[3] },
 	{ }
 };
 MODULE_DEVICE_TABLE(spi, adc128_id);
-- 
2.49.0


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[PATCH v3 7/8] MAINTAINERS: A driver for TI/ROHM ADCs

[Matti Vaittinen]

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Add undersigned as a maintainer for the ti-adc128s052.c which supports a
few TI's ADCs and the ROHM Semiconductor BD79704 ADC.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>

---
Revision history:
v2 => v3:
 - New patch

I only have access to the ROHM BD79704. Maintainers with access to the
TIs ICs (and time, energy and the knowledge) would be welcome :)
---
 MAINTAINERS | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 96b827049501..bb705fac9279 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -24088,6 +24088,12 @@ M:	Robert Richter <rric@kernel.org>
 S:	Odd Fixes
 F:	drivers/gpio/gpio-thunderx.c
 
+TI ADC12xs and ROHM BD79104 ADC driver
+M:	Matti Vaittinen <mazziesaccount@gmail.com>
+S:	Maintained
+F:	drivers/iio/adc/ti-adc128s052.c
+L:	linux-iio@vger.kernel.org
+
 TI ADS1119 ADC DRIVER
 M:	Francesco Dolcini <francesco@dolcini.it>
 M:	João Paulo Gonçalves <jpaulo.silvagoncalves@gmail.com>
-- 
2.49.0


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[PATCH RFC v3 8/8] iio: ti-adc128s052: Drop variable vref

[Matti Vaittinen]

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According to Jonathan, variable reference voltages are very rare. It is
unlikely it is needed, and supporting it makes the code a bit more
complex.

Simplify the driver and drop the variable vref support.

Suggested-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>

---
Revision History:
 v2 => v3:
  - Rename vref => vref_mv to make units visible
  - Divide vref once in the probe to avoid division every time the scale
    is requested
 v2:
  - New patch
---
 drivers/iio/adc/ti-adc128s052.c | 29 +++++++----------------------
 1 file changed, 7 insertions(+), 22 deletions(-)

diff --git a/drivers/iio/adc/ti-adc128s052.c b/drivers/iio/adc/ti-adc128s052.c
index d4721ad90f2c..c38468f299ce 100644
--- a/drivers/iio/adc/ti-adc128s052.c
+++ b/drivers/iio/adc/ti-adc128s052.c
@@ -29,13 +29,12 @@ struct adc128_configuration {
 struct adc128 {
 	struct spi_device *spi;
 
-	struct regulator *reg;
 	/*
 	 * Serialize the SPI 'write-channel + read data' accesses and protect
 	 * the shared buffer.
 	 */
 	struct mutex lock;
-
+	int vref_mv;
 	union {
 		__be16 buffer16;
 		u8 buffer[2];
@@ -81,11 +80,7 @@ static int adc128_read_raw(struct iio_dev *indio_dev,
 
 	case IIO_CHAN_INFO_SCALE:
 
-		ret = regulator_get_voltage(adc->reg);
-		if (ret < 0)
-			return ret;
-
-		*val = ret / 1000;
+		*val = adc->vref_mv;
 		*val2 = 12;
 		return IIO_VAL_FRACTIONAL_LOG2;
 
@@ -155,11 +150,6 @@ static const struct iio_info adc128_info = {
 	.read_raw = adc128_read_raw,
 };
 
-static void adc128_disable_regulator(void *reg)
-{
-	regulator_disable(reg);
-}
-
 static int adc128_probe(struct spi_device *spi)
 {
 	const struct adc128_configuration *config;
@@ -183,17 +173,12 @@ static int adc128_probe(struct spi_device *spi)
 	indio_dev->channels = config->channels;
 	indio_dev->num_channels = config->num_channels;
 
-	adc->reg = devm_regulator_get(&spi->dev, config->refname);
-	if (IS_ERR(adc->reg))
-		return PTR_ERR(adc->reg);
+	adc->vref_mv = devm_regulator_get_enable_read_voltage(&spi->dev,
+							   config->refname);
+	if (adc->vref_mv < 0)
+		return adc->vref_mv;
 
-	ret = regulator_enable(adc->reg);
-	if (ret < 0)
-		return ret;
-	ret = devm_add_action_or_reset(&spi->dev, adc128_disable_regulator,
-				       adc->reg);
-	if (ret)
-		return ret;
+	adc->vref_mv /= 1000;
 
 	if (config->num_other_regulators) {
 		ret = devm_regulator_bulk_get_enable(&spi->dev,
-- 
2.49.0


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Re: [PATCH RFC v3 8/8] iio: ti-adc128s052: Drop variable vref

[David Lechner]

On 4/7/25 6:37 AM, Matti Vaittinen wrote:
> According to Jonathan, variable reference voltages are very rare. It is
> unlikely it is needed, and supporting it makes the code a bit more
> complex.
> 
> Simplify the driver and drop the variable vref support.
> 
> Suggested-by: Jonathan Cameron <jic23@kernel.org>
> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
> 
> ---

...

>  static int adc128_probe(struct spi_device *spi)
>  {
>  	const struct adc128_configuration *config;
> @@ -183,17 +173,12 @@ static int adc128_probe(struct spi_device *spi)
>  	indio_dev->channels = config->channels;
>  	indio_dev->num_channels = config->num_channels;
>  
> -	adc->reg = devm_regulator_get(&spi->dev, config->refname);
> -	if (IS_ERR(adc->reg))
> -		return PTR_ERR(adc->reg);
> +	adc->vref_mv = devm_regulator_get_enable_read_voltage(&spi->dev,
> +							   config->refname);
> +	if (adc->vref_mv < 0)
> +		return adc->vref_mv;
>  
> -	ret = regulator_enable(adc->reg);
> -	if (ret < 0)
> -		return ret;
> -	ret = devm_add_action_or_reset(&spi->dev, adc128_disable_regulator,
> -				       adc->reg);
> -	if (ret)
> -		return ret;
> +	adc->vref_mv /= 1000;

In other drivers, we've been doing:

ret = devm_regulator_get_enable_read_voltage(...);
if (ret < 0)
	return dev_err_probe(dev, ret, "failed to read '%s' voltage, ...);

adc->vref_mv = ret / 1000;

It can be easy to make a typo or forget to specify the voltage when creating
a .dts, so I think the error message is helpful to catch that.

And we use ret to avoid having adc->vref_mv temporarily holding a
value with the wrong units (and can make it have an unsigned type).

>  
>  	if (config->num_other_regulators) {
>  		ret = devm_regulator_bulk_get_enable(&spi->dev,

Re: [PATCH RFC v3 8/8] iio: ti-adc128s052: Drop variable vref

[Jonathan Cameron]

On Fri, 11 Apr 2025 08:34:42 -0500
David Lechner <dlechner@baylibre.com> wrote:

> On 4/7/25 6:37 AM, Matti Vaittinen wrote:
> > According to Jonathan, variable reference voltages are very rare. It is
> > unlikely it is needed, and supporting it makes the code a bit more
> > complex.
> > 
> > Simplify the driver and drop the variable vref support.
> > 
> > Suggested-by: Jonathan Cameron <jic23@kernel.org>
> > Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
> > 
> > ---  
> 
> ...
> 
> >  static int adc128_probe(struct spi_device *spi)
> >  {
> >  	const struct adc128_configuration *config;
> > @@ -183,17 +173,12 @@ static int adc128_probe(struct spi_device *spi)
> >  	indio_dev->channels = config->channels;
> >  	indio_dev->num_channels = config->num_channels;
> >  
> > -	adc->reg = devm_regulator_get(&spi->dev, config->refname);
> > -	if (IS_ERR(adc->reg))
> > -		return PTR_ERR(adc->reg);
> > +	adc->vref_mv = devm_regulator_get_enable_read_voltage(&spi->dev,
> > +							   config->refname);
> > +	if (adc->vref_mv < 0)
> > +		return adc->vref_mv;
> >  
> > -	ret = regulator_enable(adc->reg);
> > -	if (ret < 0)
> > -		return ret;
> > -	ret = devm_add_action_or_reset(&spi->dev, adc128_disable_regulator,
> > -				       adc->reg);
> > -	if (ret)
> > -		return ret;
> > +	adc->vref_mv /= 1000;  
> 
> In other drivers, we've been doing:
> 
> ret = devm_regulator_get_enable_read_voltage(...);
> if (ret < 0)
> 	return dev_err_probe(dev, ret, "failed to read '%s' voltage, ...);
> 
> adc->vref_mv = ret / 1000;
> 
> It can be easy to make a typo or forget to specify the voltage when creating
> a .dts, so I think the error message is helpful to catch that.
> 
> And we use ret to avoid having adc->vref_mv temporarily holding a
> value with the wrong units (and can make it have an unsigned type).

Good idea. 
Applied patches 1-7. I did tweak this one as well but then couldn't make
up my mind on whether to change the type of vref_mv so I'll avoid making
a decision and will leave patch 8 for a v4 from Matti :)

Jonathan



> 
> >  
> >  	if (config->num_other_regulators) {
> >  		ret = devm_regulator_bulk_get_enable(&spi->dev,  
> 

Re: [PATCH RFC v3 8/8] iio: ti-adc128s052: Drop variable vref

[Matti Vaittinen]

On 11/04/2025 16:34, David Lechner wrote:
> On 4/7/25 6:37 AM, Matti Vaittinen wrote:
>> According to Jonathan, variable reference voltages are very rare. It is
>> unlikely it is needed, and supporting it makes the code a bit more
>> complex.
>>
>> Simplify the driver and drop the variable vref support.
>>
>> Suggested-by: Jonathan Cameron <jic23@kernel.org>
>> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
>>
>> ---
> 
> ...
> 
>>   static int adc128_probe(struct spi_device *spi)
>>   {
>>   	const struct adc128_configuration *config;
>> @@ -183,17 +173,12 @@ static int adc128_probe(struct spi_device *spi)
>>   	indio_dev->channels = config->channels;
>>   	indio_dev->num_channels = config->num_channels;
>>   
>> -	adc->reg = devm_regulator_get(&spi->dev, config->refname);
>> -	if (IS_ERR(adc->reg))
>> -		return PTR_ERR(adc->reg);
>> +	adc->vref_mv = devm_regulator_get_enable_read_voltage(&spi->dev,
>> +							   config->refname);
>> +	if (adc->vref_mv < 0)
>> +		return adc->vref_mv;
>>   
>> -	ret = regulator_enable(adc->reg);
>> -	if (ret < 0)
>> -		return ret;
>> -	ret = devm_add_action_or_reset(&spi->dev, adc128_disable_regulator,
>> -				       adc->reg);
>> -	if (ret)
>> -		return ret;
>> +	adc->vref_mv /= 1000;
> 
> In other drivers, we've been doing:
> 
> ret = devm_regulator_get_enable_read_voltage(...);
> if (ret < 0)
> 	return dev_err_probe(dev, ret, "failed to read '%s' voltage, ...);
> 
> adc->vref_mv = ret / 1000;
> 
> It can be easy to make a typo or forget to specify the voltage when creating
> a .dts, so I think the error message is helpful to catch that.

Good idea. Thanks.

> And we use ret to avoid having adc->vref_mv temporarily holding a
> value with the wrong units (and can make it have an unsigned type).

I'm not convinced about the benefits. The "temporary holding" is not 
really an issue as it is only held unmodified for the duration of the 
error check. Furthermore, converting the voltage unsigned does not add 
much as the regulator framework does any way return the voltage as integer.

Still, even if I am not convinced about the benefits, I don't really see 
any downsides in your suggestions either :)

>>   
>>   	if (config->num_other_regulators) {
>>   		ret = devm_regulator_bulk_get_enable(&spi->dev,
> 

Yours,
	-- Matti

Re: [PATCH RFC v3 8/8] iio: ti-adc128s052: Drop variable vref

[Matti Vaittinen]

On 12/04/2025 14:42, Jonathan Cameron wrote:
> On Fri, 11 Apr 2025 08:34:42 -0500
> David Lechner <dlechner@baylibre.com> wrote:
> 
>> On 4/7/25 6:37 AM, Matti Vaittinen wrote:
>>> According to Jonathan, variable reference voltages are very rare. It is
>>> unlikely it is needed, and supporting it makes the code a bit more
>>> complex.
>>>
>>> Simplify the driver and drop the variable vref support.
>>>
>>> Suggested-by: Jonathan Cameron <jic23@kernel.org>
>>> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
>>>
>>> ---
>>
>> ...
>>
>>>   static int adc128_probe(struct spi_device *spi)
>>>   {
>>>   	const struct adc128_configuration *config;
>>> @@ -183,17 +173,12 @@ static int adc128_probe(struct spi_device *spi)
>>>   	indio_dev->channels = config->channels;
>>>   	indio_dev->num_channels = config->num_channels;
>>>   
>>> -	adc->reg = devm_regulator_get(&spi->dev, config->refname);
>>> -	if (IS_ERR(adc->reg))
>>> -		return PTR_ERR(adc->reg);
>>> +	adc->vref_mv = devm_regulator_get_enable_read_voltage(&spi->dev,
>>> +							   config->refname);
>>> +	if (adc->vref_mv < 0)
>>> +		return adc->vref_mv;
>>>   
>>> -	ret = regulator_enable(adc->reg);
>>> -	if (ret < 0)
>>> -		return ret;
>>> -	ret = devm_add_action_or_reset(&spi->dev, adc128_disable_regulator,
>>> -				       adc->reg);
>>> -	if (ret)
>>> -		return ret;
>>> +	adc->vref_mv /= 1000;
>>
>> In other drivers, we've been doing:
>>
>> ret = devm_regulator_get_enable_read_voltage(...);
>> if (ret < 0)
>> 	return dev_err_probe(dev, ret, "failed to read '%s' voltage, ...);
>>
>> adc->vref_mv = ret / 1000;
>>
>> It can be easy to make a typo or forget to specify the voltage when creating
>> a .dts, so I think the error message is helpful to catch that.
>>
>> And we use ret to avoid having adc->vref_mv temporarily holding a
>> value with the wrong units (and can make it have an unsigned type).
> 
> Good idea.
> Applied patches 1-7. I did tweak this one as well but then couldn't make
> up my mind on whether to change the type of vref_mv so I'll avoid making
> a decision and will leave patch 8 for a v4 from Matti :)

Thanks for handling the 1-7 :) I'll re-spin this, but it's likely to 
take some time. I'm having 2 weeks off from work, and my motorbike and 
boat is requiring some attention ;)

I hope I have regained a lot of energy after 2 weeks ;)

> 
> Jonathan
> 
> 
> 
>>
>>>   
>>>   	if (config->num_other_regulators) {
>>>   		ret = devm_regulator_bulk_get_enable(&spi->dev,
>>
> 


Yours,
	-- Matti