[PATCH 0/2] Maxim MAX1241 driver, v2

[PATCH 0/2] Maxim MAX1241 driver, v2

[Alexandru Lazar]

Hello again,

Here's version 2 of a patch series which adds support for the Maxim
MAX1241, a 12-bit, single-channel, SPI-connected ADC. The previous
version is here:

https://lore.kernel.org/linux-iio/20200317201710.23180-1-alazar@startmail.com/

I've integrated pretty much all of the suggestions I got here, and fixed
the issues that you all pointed out (thanks again! Did I say thanks
lately? Thanks!!!). A short list of the changes is at the end of this
message. checkpatch.pl is happy, it just warns me about the MAINTAINERS
file, where I don't think an entry is necessary. dt_bindings_check is
happy, too.

The only suggestion that I haven't incorporated is adding max1240 to the
list of compatible devices. I've thought about it, but there are
timing-related differences between the two devices, so simply validating
what my machine sends wouldn't be definitive. I think it would be
disingenious to claim compatibility under these circumstances. I do plan
to get a 1240 asap, anyway, and with any luck my patch would just update
the compat string.

Now, here's what I changed:

* Removed useeless header includes

* Dropped needlessly verbose stuff in _read and _probe functions

* Dropped useless GPL notice

* Lowered log level of shdn pin status in probe function, now it's
  dev_dbg
  
* Added proper error checking for the GPIO shutdown pin

* remove now always returns zero (man, I've been wrong about this for
  *years* now...)
  
* Added regulator disable action, cleanup is now handled via devm

* Drop delay_usecs, use delay.value, delay.unit

* Drop config_of, of_match_ptr call

* Dropped IIO_BUFFER, IIO_TRIGGERED_BUFFER dependencies, set SPI_MASTER
  as dependency, fix indenting.
  
* DT binding: use correct id, add reg description (looks pretty
  standard), dropped spi-max-frequency, fixed dt_binding_check
  complaints (oops!)

Thanks!

Alex

Alexandru Lazar (2):
  iio: adc: Add MAX1241 driver
  dt-bindings: iio: adc: Add MAX1241 device tree bindings in
    documentation

 .../bindings/iio/adc/maxim,max1241.yaml       |  62 ++++++
 drivers/iio/adc/Kconfig                       |  10 +
 drivers/iio/adc/Makefile                      |   1 +
 drivers/iio/adc/max1241.c                     | 206 ++++++++++++++++++
 4 files changed, 279 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/maxim,max1241.yaml
 create mode 100644 drivers/iio/adc/max1241.c

-- 
2.25.1

[PATCH 1/2] iio: adc: Add MAX1241 driver

[Alexandru Lazar]

Add driver for the Maxim MAX1241 12-bit, single-channel ADC. The driver
includes support for this device's low-power operation mode.

Signed-off-by: Alexandru Lazar <alazar@startmail.com>
---
 drivers/iio/adc/Kconfig   |  10 ++
 drivers/iio/adc/Makefile  |   1 +
 drivers/iio/adc/max1241.c | 206 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 217 insertions(+)
 create mode 100644 drivers/iio/adc/max1241.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 5d8540b7b427..4254633147af 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -566,6 +566,16 @@ config MAX1118
 	  To compile this driver as a module, choose M here: the module will be
 	  called max1118.
 
+config MAX1241
+	tristate "Maxim max1241 ADC driver"
+	depends on SPI_MASTER
+	help
+	  Say yes here to build support for Maxim max1241 12-bit, single-channel
+	  ADC.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called max1118.
+
 config MAX1363
 	tristate "Maxim max1363 ADC driver"
 	depends on I2C
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index a1f1fbec0f87..37d6f17559dc 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -54,6 +54,7 @@ obj-$(CONFIG_LTC2497) += ltc2497.o
 obj-$(CONFIG_MAX1027) += max1027.o
 obj-$(CONFIG_MAX11100) += max11100.o
 obj-$(CONFIG_MAX1118) += max1118.o
+obj-$(CONFIG_MAX1241) += max1241.o
 obj-$(CONFIG_MAX1363) += max1363.o
 obj-$(CONFIG_MAX9611) += max9611.o
 obj-$(CONFIG_MCP320X) += mcp320x.o
diff --git a/drivers/iio/adc/max1241.c b/drivers/iio/adc/max1241.c
new file mode 100644
index 000000000000..0278510ec346
--- /dev/null
+++ b/drivers/iio/adc/max1241.c
@@ -0,0 +1,206 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MAX1241 low-power, 12-bit serial ADC
+ *
+ * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1240-MAX1241.pdf
+ */
+
+#include <linux/regulator/consumer.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+
+#define MAX1241_VAL_MASK 0xFFF
+#define MAX1241_SHDN_DELAY_USEC 4
+
+enum max1241_id {
+	max1241,
+};
+
+struct max1241 {
+	struct spi_device *spi;
+	struct mutex lock;
+	struct regulator *reg;
+	struct gpio_desc *shdn;
+
+	__be16 data ____cacheline_aligned;
+};
+
+static const struct iio_chan_spec max1241_channels[] = {
+	{
+		.type = IIO_VOLTAGE,
+		.indexed = 1,
+		.channel = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 12,
+			.storagebits = 16,
+		},
+	},
+};
+
+static int max1241_read(struct max1241 *adc)
+{
+	struct spi_transfer xfers[] = {
+		/*
+		 * Begin conversion by bringing /CS low for at least
+		 * tconv us.
+		 */
+		{
+			.len = 0,
+			.delay.value = 8,
+			.delay.unit = SPI_DELAY_UNIT_USECS,
+		},
+		/*
+		 * Then read two bytes of data in our RX buffer.
+		 */
+		{
+			.rx_buf = &adc->data,
+			.len = 2,
+		},
+	};
+
+	return spi_sync_transfer(adc->spi, xfers, ARRAY_SIZE(xfers));
+}
+
+static int max1241_read_raw(struct iio_dev *indio_dev,
+			struct iio_chan_spec const *chan,
+			int *val, int *val2, long mask)
+{
+	int ret, vref_uV;
+	struct max1241 *adc = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&adc->lock);
+
+		if (adc->shdn) {
+			gpiod_set_value(adc->shdn, 0);
+			udelay(MAX1241_SHDN_DELAY_USEC);
+		}
+
+		ret = max1241_read(adc);
+
+		if (adc->shdn)
+			gpiod_set_value(adc->shdn, 1);
+
+		if (ret) {
+			mutex_unlock(&adc->lock);
+			return ret;
+		}
+
+		*val = (be16_to_cpu(adc->data) >> 3) & MAX1241_VAL_MASK;
+
+		mutex_unlock(&adc->lock);
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		vref_uV = regulator_get_voltage(adc->reg);
+
+		if (vref_uV < 0)
+			return vref_uV;
+
+		*val = vref_uV / 1000;
+		*val2 = 12;
+
+		return IIO_VAL_FRACTIONAL_LOG2;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info max1241_info = {
+	.read_raw = max1241_read_raw,
+};
+
+static void max1241_disable_reg_action(void *data)
+{
+	struct max1241 *adc = data;
+	int err;
+
+	err = regulator_disable(adc->reg);
+	if (err)
+		dev_err(&adc->spi->dev, "could not disable reference regulator.\n");
+}
+
+static int max1241_probe(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev;
+	struct max1241 *adc;
+	int ret = 0;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	adc = iio_priv(indio_dev);
+	adc->spi = spi;
+	mutex_init(&adc->lock);
+
+	spi_set_drvdata(spi, indio_dev);
+
+	adc->reg = devm_regulator_get(&spi->dev, "vref");
+	if (IS_ERR(adc->reg)) {
+		dev_err(&spi->dev, "failed to get vref regulator\n");
+		return PTR_ERR(adc->reg);
+	}
+
+	ret = regulator_enable(adc->reg);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action_or_reset(&spi->dev, max1241_disable_reg_action,
+					adc);
+	if (ret) {
+		dev_err(&spi->dev, "could not set up regulator cleanup action!\n");
+		return ret;
+	}
+
+	adc->shdn = devm_gpiod_get_optional(&spi->dev, "shdn", GPIOD_OUT_HIGH);
+
+	if (IS_ERR(adc->shdn))
+		return PTR_ERR(adc->shdn);
+
+	if (!adc->shdn)
+		dev_dbg(&spi->dev, "no shdn pin passed, low-power mode disabled");
+	else
+		dev_dbg(&spi->dev, "shdn pin passed, low-power mode enabled");
+
+	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->info = &max1241_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = max1241_channels;
+	indio_dev->num_channels = ARRAY_SIZE(max1241_channels);
+
+	return devm_iio_device_register(&spi->dev, indio_dev);
+}
+
+static const struct spi_device_id max1241_id[] = {
+	{ "max1241", max1241 },
+	{},
+};
+
+static const struct of_device_id max1241_dt_ids[] = {
+	{ .compatible = "maxim,max1241" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, max1241_dt_ids);
+
+static struct spi_driver max1241_spi_driver = {
+	.driver = {
+		.name = "max1241",
+		.of_match_table = max1241_dt_ids,
+	},
+	.probe = max1241_probe,
+	.id_table = max1241_id,
+};
+module_spi_driver(max1241_spi_driver);
+
+MODULE_AUTHOR("Alexandru Lazar <alazar@startmail.com>");
+MODULE_DESCRIPTION("MAX1241 ADC driver");
+MODULE_LICENSE("GPL v2");
-- 
2.25.1

Re: [PATCH 1/2] iio: adc: Add MAX1241 driver

[Ardelean, Alexandru]

On Wed, 2020-03-18 at 22:28 +0200, Alexandru Lazar wrote:
> Add driver for the Maxim MAX1241 12-bit, single-channel ADC. The driver
> includes support for this device's low-power operation mode.

Just one minor typo I see.


> 
> Signed-off-by: Alexandru Lazar <alazar@startmail.com>
> ---
>  drivers/iio/adc/Kconfig   |  10 ++
>  drivers/iio/adc/Makefile  |   1 +
>  drivers/iio/adc/max1241.c | 206 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 217 insertions(+)
>  create mode 100644 drivers/iio/adc/max1241.c
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 5d8540b7b427..4254633147af 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -566,6 +566,16 @@ config MAX1118
>  	  To compile this driver as a module, choose M here: the module will be
>  	  called max1118.
>  
> +config MAX1241
> +	tristate "Maxim max1241 ADC driver"
> +	depends on SPI_MASTER
> +	help
> +	  Say yes here to build support for Maxim max1241 12-bit, single-channel
> +	  ADC.
> +
> +	  To compile this driver as a module, choose M here: the module will be
> +	  called max1118.

Apologies if I did not notice this before.  'called max1118' -> 'called max1241'


> +
>  config MAX1363
>  	tristate "Maxim max1363 ADC driver"
>  	depends on I2C
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index a1f1fbec0f87..37d6f17559dc 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -54,6 +54,7 @@ obj-$(CONFIG_LTC2497) += ltc2497.o
>  obj-$(CONFIG_MAX1027) += max1027.o
>  obj-$(CONFIG_MAX11100) += max11100.o
>  obj-$(CONFIG_MAX1118) += max1118.o
> +obj-$(CONFIG_MAX1241) += max1241.o
>  obj-$(CONFIG_MAX1363) += max1363.o
>  obj-$(CONFIG_MAX9611) += max9611.o
>  obj-$(CONFIG_MCP320X) += mcp320x.o
> diff --git a/drivers/iio/adc/max1241.c b/drivers/iio/adc/max1241.c
> new file mode 100644
> index 000000000000..0278510ec346
> --- /dev/null
> +++ b/drivers/iio/adc/max1241.c
> @@ -0,0 +1,206 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * MAX1241 low-power, 12-bit serial ADC
> + *
> + * Datasheet: 
> https://datasheets.maximintegrated.com/en/ds/MAX1240-MAX1241.pdf
> + */
> +
> +#include <linux/regulator/consumer.h>
> +#include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +#include <linux/spi/spi.h>
> +
> +#define MAX1241_VAL_MASK 0xFFF
> +#define MAX1241_SHDN_DELAY_USEC 4
> +
> +enum max1241_id {
> +	max1241,
> +};
> +
> +struct max1241 {
> +	struct spi_device *spi;
> +	struct mutex lock;
> +	struct regulator *reg;
> +	struct gpio_desc *shdn;
> +
> +	__be16 data ____cacheline_aligned;
> +};
> +
> +static const struct iio_chan_spec max1241_channels[] = {
> +	{
> +		.type = IIO_VOLTAGE,
> +		.indexed = 1,
> +		.channel = 0,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				BIT(IIO_CHAN_INFO_SCALE),
> +		.scan_index = 0,
> +		.scan_type = {
> +			.sign = 'u',
> +			.realbits = 12,
> +			.storagebits = 16,
> +		},
> +	},
> +};
> +
> +static int max1241_read(struct max1241 *adc)
> +{
> +	struct spi_transfer xfers[] = {
> +		/*
> +		 * Begin conversion by bringing /CS low for at least
> +		 * tconv us.
> +		 */
> +		{
> +			.len = 0,
> +			.delay.value = 8,
> +			.delay.unit = SPI_DELAY_UNIT_USECS,
> +		},
> +		/*
> +		 * Then read two bytes of data in our RX buffer.
> +		 */
> +		{
> +			.rx_buf = &adc->data,
> +			.len = 2,
> +		},
> +	};
> +
> +	return spi_sync_transfer(adc->spi, xfers, ARRAY_SIZE(xfers));
> +}
> +
> +static int max1241_read_raw(struct iio_dev *indio_dev,
> +			struct iio_chan_spec const *chan,
> +			int *val, int *val2, long mask)
> +{
> +	int ret, vref_uV;
> +	struct max1241 *adc = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&adc->lock);
> +
> +		if (adc->shdn) {
> +			gpiod_set_value(adc->shdn, 0);
> +			udelay(MAX1241_SHDN_DELAY_USEC);
> +		}
> +
> +		ret = max1241_read(adc);
> +
> +		if (adc->shdn)
> +			gpiod_set_value(adc->shdn, 1);
> +
> +		if (ret) {
> +			mutex_unlock(&adc->lock);
> +			return ret;
> +		}
> +
> +		*val = (be16_to_cpu(adc->data) >> 3) & MAX1241_VAL_MASK;
> +
> +		mutex_unlock(&adc->lock);
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		vref_uV = regulator_get_voltage(adc->reg);
> +
> +		if (vref_uV < 0)
> +			return vref_uV;
> +
> +		*val = vref_uV / 1000;
> +		*val2 = 12;
> +
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_info max1241_info = {
> +	.read_raw = max1241_read_raw,
> +};
> +
> +static void max1241_disable_reg_action(void *data)
> +{
> +	struct max1241 *adc = data;
> +	int err;
> +
> +	err = regulator_disable(adc->reg);
> +	if (err)
> +		dev_err(&adc->spi->dev, "could not disable reference
> regulator.\n");
> +}
> +
> +static int max1241_probe(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev;
> +	struct max1241 *adc;
> +	int ret = 0;
> +
> +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	adc = iio_priv(indio_dev);
> +	adc->spi = spi;
> +	mutex_init(&adc->lock);
> +
> +	spi_set_drvdata(spi, indio_dev);
> +
> +	adc->reg = devm_regulator_get(&spi->dev, "vref");
> +	if (IS_ERR(adc->reg)) {
> +		dev_err(&spi->dev, "failed to get vref regulator\n");
> +		return PTR_ERR(adc->reg);
> +	}
> +
> +	ret = regulator_enable(adc->reg);
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_add_action_or_reset(&spi->dev, max1241_disable_reg_action,
> +					adc);
> +	if (ret) {
> +		dev_err(&spi->dev, "could not set up regulator cleanup
> action!\n");
> +		return ret;
> +	}
> +
> +	adc->shdn = devm_gpiod_get_optional(&spi->dev, "shdn", GPIOD_OUT_HIGH);
> +
> +	if (IS_ERR(adc->shdn))
> +		return PTR_ERR(adc->shdn);
> +
> +	if (!adc->shdn)
> +		dev_dbg(&spi->dev, "no shdn pin passed, low-power mode
> disabled");
> +	else
> +		dev_dbg(&spi->dev, "shdn pin passed, low-power mode enabled");
> +
> +	indio_dev->name = spi_get_device_id(spi)->name;
> +	indio_dev->dev.parent = &spi->dev;
> +	indio_dev->info = &max1241_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = max1241_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(max1241_channels);
> +
> +	return devm_iio_device_register(&spi->dev, indio_dev);
> +}
> +
> +static const struct spi_device_id max1241_id[] = {
> +	{ "max1241", max1241 },
> +	{},
> +};
> +
> +static const struct of_device_id max1241_dt_ids[] = {
> +	{ .compatible = "maxim,max1241" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, max1241_dt_ids);
> +
> +static struct spi_driver max1241_spi_driver = {
> +	.driver = {
> +		.name = "max1241",
> +		.of_match_table = max1241_dt_ids,
> +	},
> +	.probe = max1241_probe,
> +	.id_table = max1241_id,
> +};
> +module_spi_driver(max1241_spi_driver);
> +
> +MODULE_AUTHOR("Alexandru Lazar <alazar@startmail.com>");
> +MODULE_DESCRIPTION("MAX1241 ADC driver");
> +MODULE_LICENSE("GPL v2");

[PATCH 2/2] dt-bindings: iio: adc: Add MAX1241 device tree bindings in documentation

[Alexandru Lazar]

Add device-tree bindings documentation for the MAX1241 device driver.

Signed-off-by: Alexandru Lazar <alazar@startmail.com>
---
 .../bindings/iio/adc/maxim,max1241.yaml       | 62 +++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/maxim,max1241.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/maxim,max1241.yaml b/Documentation/devicetree/bindings/iio/adc/maxim,max1241.yaml
new file mode 100644
index 000000000000..28c73ed795aa
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/maxim,max1241.yaml
@@ -0,0 +1,62 @@
+# SPDX-License-Identifier: GPL-2.0
+# Copyright 2020 Ioan-Alexandru Lazar
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/maxim,max1241.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Maxim MAX1241 12-bit, single-channel analog to digital converter
+
+maintainers:
+  - Ioan-Alexandru Lazar <alazar@startmail.com>
+
+description: |
+  Bindings for the max1241 12-bit, single-channel ADC device. This
+  driver supports voltage reading and can optionally be configured for
+  power-down mode operation. The datasheet can be found at:
+    https://datasheets.maximintegrated.com/en/ds/MAX1240-MAX1241.pdf
+
+properties:
+  compatible:
+    enum:
+      - maxim,max1241
+
+  reg:
+    description: SPI chip select number for this device
+    maxItems: 1
+
+  vref-supply:
+    description:
+      Device tree identifier of the regulator that provides the external
+      reference voltage.
+    maxItems: 1
+
+  shdn-gpios:
+    description:
+      GPIO spec for the GPIO pin connected to the ADC's /SHDN pin. If
+      specified, the /SHDN pin will be asserted between conversions,
+      thus enabling power-down mode.
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - vref-supply
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    spi0 {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+        adc@0 {
+            compatible = "maxim,max1241";
+            reg = <0>;
+            vref-supply = <&vdd_3v3_reg>;
+            spi-max-frequency = <1000000>;
+            shdn-gpios = <&gpio 26 1>;
+        };
+    };
+
+
-- 
2.25.1

Re: [PATCH 0/2] Maxim MAX1241 driver, v2

[Ardelean, Alexandru]

On Wed, 2020-03-18 at 22:28 +0200, Alexandru Lazar wrote:
> Hello again,
> 
> Here's version 2 of a patch series which adds support for the Maxim
> MAX1241, a 12-bit, single-channel, SPI-connected ADC. The previous
> version is here:
> 

as a quick note, when generating patches with V2 it's useful to do:

git format-patch -v2 <commit-range>

that way, the V2 gets appended to all patches;
makes it easier for maintainers to see which is V2,3,4,etc

no need to re-spin V2;
but when going to V3, you can try it


> https://lore.kernel.org/linux-iio/20200317201710.23180-1-alazar@startmail.com/
> 
> I've integrated pretty much all of the suggestions I got here, and fixed
> the issues that you all pointed out (thanks again! Did I say thanks
> lately? Thanks!!!). A short list of the changes is at the end of this
> message. checkpatch.pl is happy, it just warns me about the MAINTAINERS
> file, where I don't think an entry is necessary. dt_bindings_check is
> happy, too.
> 
> The only suggestion that I haven't incorporated is adding max1240 to the
> list of compatible devices. I've thought about it, but there are
> timing-related differences between the two devices, so simply validating
> what my machine sends wouldn't be definitive. I think it would be
> disingenious to claim compatibility under these circumstances. I do plan
> to get a 1240 asap, anyway, and with any luck my patch would just update
> the compat string.
> 
> Now, here's what I changed:
> 
> * Removed useeless header includes
> 
> * Dropped needlessly verbose stuff in _read and _probe functions
> 
> * Dropped useless GPL notice
> 
> * Lowered log level of shdn pin status in probe function, now it's
>   dev_dbg
>   
> * Added proper error checking for the GPIO shutdown pin
> 
> * remove now always returns zero (man, I've been wrong about this for
>   *years* now...)
>   
> * Added regulator disable action, cleanup is now handled via devm
> 
> * Drop delay_usecs, use delay.value, delay.unit
> 
> * Drop config_of, of_match_ptr call
> 
> * Dropped IIO_BUFFER, IIO_TRIGGERED_BUFFER dependencies, set SPI_MASTER
>   as dependency, fix indenting.
>   
> * DT binding: use correct id, add reg description (looks pretty
>   standard), dropped spi-max-frequency, fixed dt_binding_check
>   complaints (oops!)
> 
> Thanks!
> 
> Alex
> 
> Alexandru Lazar (2):
>   iio: adc: Add MAX1241 driver
>   dt-bindings: iio: adc: Add MAX1241 device tree bindings in
>     documentation
> 
>  .../bindings/iio/adc/maxim,max1241.yaml       |  62 ++++++
>  drivers/iio/adc/Kconfig                       |  10 +
>  drivers/iio/adc/Makefile                      |   1 +
>  drivers/iio/adc/max1241.c                     | 206 ++++++++++++++++++
>  4 files changed, 279 insertions(+)
>  create mode 100644
> Documentation/devicetree/bindings/iio/adc/maxim,max1241.yaml
>  create mode 100644 drivers/iio/adc/max1241.c
>