[PATCH 0/7] Introduce max12xx ADC support

[PATCH 0/7] Introduce max12xx ADC support

[Miquel Raynal]

Hello, here is a patchset updating the existing max1027.c driver (for
10-bit max1027/29/31 ADCs) with a few corrections/improvements and
then introducing their 12-bit cousins named max1227/29/31.

As on my hardware setup the "start conversion" and "end of conversion"
pin are not wired (which is absolutely fine for this chip), I also
updated the driver and the bindings to support optional interrupts. In
this case, triggered buffers are not available and the user must poll
the value from sysfs.

Thanks,
Miquèl


Miquel Raynal (7):
  iio: adc: max1027: Add debugfs register read support
  iio: adc: max1027: Make it optional to use interrupts
  iio: adc: max1027: Reset the device at probe time
  iio: adc: max1027: Prepare the introduction of different resolutions
  iio: adc: max1027: Introduce 12-bit devices support
  dt-bindings: iio: adc: max1027: Mark interrupts as optional
  dt-bindings: iio: adc: max1027: Document max12xx series compatibles

 .../bindings/iio/adc/max1027-adc.txt          |  12 +-
 drivers/iio/adc/Kconfig                       |   4 +-
 drivers/iio/adc/max1027.c                     | 190 +++++++++++-------
 3 files changed, 133 insertions(+), 73 deletions(-)

-- 
2.20.1

[PATCH 1/7] iio: adc: max1027: Add debugfs register read support

[Miquel Raynal]

Until now, only write operations were supported. Force two bytes read
operation when reading from this register (might be wrong when reading
the temperature, but will work with any other value).

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/iio/adc/max1027.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
index 214883458582..6cdfe9ef73fc 100644
--- a/drivers/iio/adc/max1027.c
+++ b/drivers/iio/adc/max1027.c
@@ -309,8 +309,11 @@ static int max1027_debugfs_reg_access(struct iio_dev *indio_dev,
 	struct max1027_state *st = iio_priv(indio_dev);
 	u8 *val = (u8 *)st->buffer;
 
-	if (readval != NULL)
-		return -EINVAL;
+	if (readval) {
+		int ret = spi_read(st->spi, val, 2);
+		*readval = be16_to_cpu(st->buffer[0]);
+		return ret;
+	}
 
 	*val = (u8)writeval;
 	return spi_write(st->spi, val, 1);
-- 
2.20.1

[PATCH 2/7] iio: adc: max1027: Make it optional to use interrupts

[Miquel Raynal]

The chip has a 'start conversion' and a 'end of conversion' pair of
pins. They can be used but this is absolutely not mandatory as regular
polling of the value is totally fine with the current internal
clocking setup. Turn the interrupts optional and do not error out if
they are not inquired in the device tree. This has the effect to
prevent triggered buffers use though.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/iio/adc/max1027.c | 57 +++++++++++++++++++++------------------
 1 file changed, 31 insertions(+), 26 deletions(-)

diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
index 6cdfe9ef73fc..823223b77a70 100644
--- a/drivers/iio/adc/max1027.c
+++ b/drivers/iio/adc/max1027.c
@@ -430,35 +430,40 @@ static int max1027_probe(struct spi_device *spi)
 		return -ENOMEM;
 	}
 
-	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
-					&iio_pollfunc_store_time,
-					&max1027_trigger_handler, NULL);
-	if (ret < 0) {
-		dev_err(&indio_dev->dev, "Failed to setup buffer\n");
-		return ret;
-	}
+	if (spi->irq) {
+		ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
+						      &iio_pollfunc_store_time,
+						      &max1027_trigger_handler,
+						      NULL);
+		if (ret < 0) {
+			dev_err(&indio_dev->dev, "Failed to setup buffer\n");
+			return ret;
+		}
 
-	st->trig = devm_iio_trigger_alloc(&spi->dev, "%s-trigger",
-							indio_dev->name);
-	if (st->trig == NULL) {
-		ret = -ENOMEM;
-		dev_err(&indio_dev->dev, "Failed to allocate iio trigger\n");
-		return ret;
-	}
+		st->trig = devm_iio_trigger_alloc(&spi->dev, "%s-trigger",
+						  indio_dev->name);
+		if (st->trig == NULL) {
+			ret = -ENOMEM;
+			dev_err(&indio_dev->dev,
+				"Failed to allocate iio trigger\n");
+			return ret;
+		}
 
-	st->trig->ops = &max1027_trigger_ops;
-	st->trig->dev.parent = &spi->dev;
-	iio_trigger_set_drvdata(st->trig, indio_dev);
-	iio_trigger_register(st->trig);
+		st->trig->ops = &max1027_trigger_ops;
+		st->trig->dev.parent = &spi->dev;
+		iio_trigger_set_drvdata(st->trig, indio_dev);
+		iio_trigger_register(st->trig);
 
-	ret = devm_request_threaded_irq(&spi->dev, spi->irq,
-					iio_trigger_generic_data_rdy_poll,
-					NULL,
-					IRQF_TRIGGER_FALLING,
-					spi->dev.driver->name, st->trig);
-	if (ret < 0) {
-		dev_err(&indio_dev->dev, "Failed to allocate IRQ.\n");
-		return ret;
+		ret = devm_request_threaded_irq(&spi->dev, spi->irq,
+						iio_trigger_generic_data_rdy_poll,
+						NULL,
+						IRQF_TRIGGER_FALLING,
+						spi->dev.driver->name,
+						st->trig);
+		if (ret < 0) {
+			dev_err(&indio_dev->dev, "Failed to allocate IRQ.\n");
+			return ret;
+		}
 	}
 
 	/* Disable averaging */
-- 
2.20.1

[PATCH 3/7] iio: adc: max1027: Reset the device at probe time

[Miquel Raynal]

All the registers are configured by the driver, let's reset the chip
at probe time, avoiding any conflict with a possible earlier
configuration.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/iio/adc/max1027.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
index 823223b77a70..f9b473ee6711 100644
--- a/drivers/iio/adc/max1027.c
+++ b/drivers/iio/adc/max1027.c
@@ -466,6 +466,14 @@ static int max1027_probe(struct spi_device *spi)
 		}
 	}
 
+	/* Internal reset */
+	st->reg = MAX1027_RST_REG;
+	ret = spi_write(st->spi, &st->reg, 1);
+	if (ret < 0) {
+		dev_err(&indio_dev->dev, "Failed to reset the ADC\n");
+		return ret;
+	}
+
 	/* Disable averaging */
 	st->reg = MAX1027_AVG_REG;
 	ret = spi_write(st->spi, &st->reg, 1);
-- 
2.20.1

[PATCH 4/7] iio: adc: max1027: Prepare the introduction of different resolutions

[Miquel Raynal]

Maxim's max1027/29/31 series returns the measured voltages with a
resolution of 10 bits. There is a very similar series, max1227/29/31
which works very similarly but uses a resolution of 12 bits. Prepare
the support for these chips by turning the 'depth' into a macro
parameter instead of hardcoding it everywhere. Also reorganize just a
bit the macros at the top to avoid repeating tens of lines when adding
support for a new chip.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/iio/adc/max1027.c | 81 +++++++++++++++++++--------------------
 1 file changed, 39 insertions(+), 42 deletions(-)

diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
index f9b473ee6711..fc75764a6fd7 100644
--- a/drivers/iio/adc/max1027.c
+++ b/drivers/iio/adc/max1027.c
@@ -78,12 +78,15 @@ static const struct of_device_id max1027_adc_dt_ids[] = {
 	{ .compatible = "maxim,max1027" },
 	{ .compatible = "maxim,max1029" },
 	{ .compatible = "maxim,max1031" },
+	{ .compatible = "maxim,max1227" },
+	{ .compatible = "maxim,max1229" },
+	{ .compatible = "maxim,max1231" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, max1027_adc_dt_ids);
 #endif
 
-#define MAX1027_V_CHAN(index)						\
+#define MAX1027_V_CHAN(index, depth)					\
 	{								\
 		.type = IIO_VOLTAGE,					\
 		.indexed = 1,						\
@@ -93,7 +96,7 @@ MODULE_DEVICE_TABLE(of, max1027_adc_dt_ids);
 		.scan_index = index + 1,				\
 		.scan_type = {						\
 			.sign = 'u',					\
-			.realbits = 10,					\
+			.realbits = depth,				\
 			.storagebits = 16,				\
 			.shift = 2,					\
 			.endianness = IIO_BE,				\
@@ -115,52 +118,42 @@ MODULE_DEVICE_TABLE(of, max1027_adc_dt_ids);
 		},							\
 	}
 
+#define MAX1X27_CHANNELS(depth)			\
+	MAX1027_T_CHAN,				\
+	MAX1027_V_CHAN(0, depth),		\
+	MAX1027_V_CHAN(1, depth),		\
+	MAX1027_V_CHAN(2, depth),		\
+	MAX1027_V_CHAN(3, depth),		\
+	MAX1027_V_CHAN(4, depth),		\
+	MAX1027_V_CHAN(5, depth),		\
+	MAX1027_V_CHAN(6, depth),		\
+	MAX1027_V_CHAN(7, depth)
+
+#define MAX1X29_CHANNELS(depth)			\
+	MAX1027_V_CHAN(8, depth),		\
+	MAX1027_V_CHAN(9, depth),		\
+	MAX1027_V_CHAN(10, depth),		\
+	MAX1027_V_CHAN(11, depth)
+
+#define MAX1X31_CHANNELS(depth)			\
+	MAX1027_V_CHAN(12, depth),		\
+	MAX1027_V_CHAN(13, depth),		\
+	MAX1027_V_CHAN(14, depth),		\
+	MAX1027_V_CHAN(15, depth)
+
 static const struct iio_chan_spec max1027_channels[] = {
-	MAX1027_T_CHAN,
-	MAX1027_V_CHAN(0),
-	MAX1027_V_CHAN(1),
-	MAX1027_V_CHAN(2),
-	MAX1027_V_CHAN(3),
-	MAX1027_V_CHAN(4),
-	MAX1027_V_CHAN(5),
-	MAX1027_V_CHAN(6),
-	MAX1027_V_CHAN(7)
+	MAX1X27_CHANNELS(10)
 };
 
 static const struct iio_chan_spec max1029_channels[] = {
-	MAX1027_T_CHAN,
-	MAX1027_V_CHAN(0),
-	MAX1027_V_CHAN(1),
-	MAX1027_V_CHAN(2),
-	MAX1027_V_CHAN(3),
-	MAX1027_V_CHAN(4),
-	MAX1027_V_CHAN(5),
-	MAX1027_V_CHAN(6),
-	MAX1027_V_CHAN(7),
-	MAX1027_V_CHAN(8),
-	MAX1027_V_CHAN(9),
-	MAX1027_V_CHAN(10),
-	MAX1027_V_CHAN(11)
+	MAX1X27_CHANNELS(10),
+	MAX1X29_CHANNELS(10)
 };
 
 static const struct iio_chan_spec max1031_channels[] = {
-	MAX1027_T_CHAN,
-	MAX1027_V_CHAN(0),
-	MAX1027_V_CHAN(1),
-	MAX1027_V_CHAN(2),
-	MAX1027_V_CHAN(3),
-	MAX1027_V_CHAN(4),
-	MAX1027_V_CHAN(5),
-	MAX1027_V_CHAN(6),
-	MAX1027_V_CHAN(7),
-	MAX1027_V_CHAN(8),
-	MAX1027_V_CHAN(9),
-	MAX1027_V_CHAN(10),
-	MAX1027_V_CHAN(11),
-	MAX1027_V_CHAN(12),
-	MAX1027_V_CHAN(13),
-	MAX1027_V_CHAN(14),
-	MAX1027_V_CHAN(15)
+	MAX1X27_CHANNELS(10),
+	MAX1X29_CHANNELS(10),
+	MAX1X31_CHANNELS(10)
 };
 
 static const unsigned long max1027_available_scan_masks[] = {
@@ -181,6 +174,7 @@ static const unsigned long max1031_available_scan_masks[] = {
 struct max1027_chip_info {
 	const struct iio_chan_spec *channels;
 	unsigned int num_channels;
+	unsigned int depth;
 	const unsigned long *available_scan_masks;
 };
 
@@ -188,16 +182,19 @@ static const struct max1027_chip_info max1027_chip_info_tbl[] = {
 	[max1027] = {
 		.channels = max1027_channels,
 		.num_channels = ARRAY_SIZE(max1027_channels),
+		.depth = 10,
 		.available_scan_masks = max1027_available_scan_masks,
 	},
 	[max1029] = {
 		.channels = max1029_channels,
 		.num_channels = ARRAY_SIZE(max1029_channels),
+		.depth = 10,
 		.available_scan_masks = max1029_available_scan_masks,
 	},
 	[max1031] = {
 		.channels = max1031_channels,
 		.num_channels = ARRAY_SIZE(max1031_channels),
+		.depth = 10,
 		.available_scan_masks = max1031_available_scan_masks,
 	},
 };
@@ -284,7 +281,7 @@ static int max1027_read_raw(struct iio_dev *indio_dev,
 			break;
 		case IIO_VOLTAGE:
 			*val = 2500;
-			*val2 = 10;
+			*val2 = st->info->depth;
 			ret = IIO_VAL_FRACTIONAL_LOG2;
 			break;
 		default:
-- 
2.20.1

[PATCH 5/7] iio: adc: max1027: Introduce 12-bit devices support

[Miquel Raynal]

Maxim's max12xx series is very similar to the max10xx series, with the
difference of the measurements depth which is upgraded from 10 to 12
bits per channel. Everything else looks the same.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/iio/adc/Kconfig   |  4 ++--
 drivers/iio/adc/max1027.c | 41 ++++++++++++++++++++++++++++++++++++++-
 2 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index f0af3a42f53c..6ac16d738822 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -508,8 +508,8 @@ config MAX1027
 	select IIO_BUFFER
 	select IIO_TRIGGERED_BUFFER
 	help
-	  Say yes here to build support for Maxim SPI ADC models
-	  max1027, max1029 and max1031.
+	  Say yes here to build support for Maxim SPI {10,12}-bit ADC models:
+	  max1027, max1029, max1031, max1227, max1229 and max1231.
 
 	  To compile this driver as a module, choose M here: the module will be
 	  called max1027.
diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
index fc75764a6fd7..0d7116e9a63b 100644
--- a/drivers/iio/adc/max1027.c
+++ b/drivers/iio/adc/max1027.c
@@ -63,12 +63,18 @@ enum max1027_id {
 	max1027,
 	max1029,
 	max1031,
+	max1227,
+	max1229,
+	max1231,
 };
 
 static const struct spi_device_id max1027_id[] = {
 	{"max1027", max1027},
 	{"max1029", max1029},
 	{"max1031", max1031},
+	{"max1227", max1227},
+	{"max1229", max1229},
+	{"max1231", max1231},
 	{}
 };
 MODULE_DEVICE_TABLE(spi, max1027_id);
@@ -156,6 +162,21 @@ static const struct iio_chan_spec max1031_channels[] = {
 	MAX1X31_CHANNELS(10)
 };
 
+static const struct iio_chan_spec max1227_channels[] = {
+	MAX1X27_CHANNELS(12)
+};
+
+static const struct iio_chan_spec max1229_channels[] = {
+	MAX1X27_CHANNELS(12),
+	MAX1X29_CHANNELS(12)
+};
+
+static const struct iio_chan_spec max1231_channels[] = {
+	MAX1X27_CHANNELS(12),
+	MAX1X29_CHANNELS(12),
+	MAX1X31_CHANNELS(12)
+};
+
 static const unsigned long max1027_available_scan_masks[] = {
 	0x000001ff,
 	0x00000000,
@@ -197,6 +218,24 @@ static const struct max1027_chip_info max1027_chip_info_tbl[] = {
 		.depth = 10,
 		.available_scan_masks = max1031_available_scan_masks,
 	},
+	[max1227] = {
+		.channels = max1227_channels,
+		.num_channels = ARRAY_SIZE(max1227_channels),
+		.depth = 12,
+		.available_scan_masks = max1027_available_scan_masks,
+	},
+	[max1229] = {
+		.channels = max1229_channels,
+		.num_channels = ARRAY_SIZE(max1229_channels),
+		.depth = 12,
+		.available_scan_masks = max1029_available_scan_masks,
+	},
+	[max1231] = {
+		.channels = max1231_channels,
+		.num_channels = ARRAY_SIZE(max1231_channels),
+		.depth = 12,
+		.available_scan_masks = max1031_available_scan_masks,
+	},
 };
 
 struct max1027_state {
@@ -493,5 +532,5 @@ static struct spi_driver max1027_driver = {
 module_spi_driver(max1027_driver);
 
 MODULE_AUTHOR("Philippe Reynes <tremyfr@yahoo.fr>");
-MODULE_DESCRIPTION("MAX1027/MAX1029/MAX1031 ADC");
+MODULE_DESCRIPTION("MAX1X27/MAX1X29/MAX1X31 ADC");
 MODULE_LICENSE("GPL v2");
-- 
2.20.1

[PATCH 6/7] dt-bindings: iio: adc: max1027: Mark interrupts as optional

[Miquel Raynal]

The chips have a 'start conversion' and a 'end of conversion' pair of
pins. They can be used but this is absolutely not mandatory as regular
polling is supported by the chip depending on its internal clocking
setup.

There is no physical reason to force the use of interrupts so turn
them optional.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 Documentation/devicetree/bindings/iio/adc/max1027-adc.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt b/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
index e680c61dfb84..7b23d68f655c 100644
--- a/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
+++ b/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
@@ -3,6 +3,8 @@
 Required properties:
   - compatible: Should be "maxim,max1027" or "maxim,max1029" or "maxim,max1031"
   - reg: SPI chip select number for the device
+
+Optional properties:
   - interrupts: IRQ line for the ADC
   see: Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
 
-- 
2.20.1

[PATCH 7/7] dt-bindings: iio: adc: max1027: Document max12xx series compatibles

[Miquel Raynal]

Update the bindings documentation with new Maxim ADCs compatibles.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 .../devicetree/bindings/iio/adc/max1027-adc.txt        | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt b/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
index 7b23d68f655c..1b703a01d882 100644
--- a/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
+++ b/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
@@ -1,7 +1,13 @@
-* Maxim 1027/1029/1031 Analog to Digital Converter (ADC)
+* Maxim 1027/1029/1031/1227/1229/1231 Analog to Digital Converter (ADC)
 
 Required properties:
-  - compatible: Should be "maxim,max1027" or "maxim,max1029" or "maxim,max1031"
+  - compatible: Should be one of:
+    * "maxim,max1027"
+    * "maxim,max1029"
+    * "maxim,max1031"
+    * "maxim,max1227"
+    * "maxim,max1229"
+    * "maxim,max1231"
   - reg: SPI chip select number for the device
 
 Optional properties:
-- 
2.20.1

Re: [PATCH 4/7] iio: adc: max1027: Prepare the introduction of different resolutions

[Miquel Raynal]

Hello,

Miquel Raynal <miquel.raynal@bootlin.com> wrote on Wed,  2 Oct 2019
14:30:22 +0200:

> Maxim's max1027/29/31 series returns the measured voltages with a
> resolution of 10 bits. There is a very similar series, max1227/29/31
> which works very similarly but uses a resolution of 12 bits. Prepare
> the support for these chips by turning the 'depth' into a macro
> parameter instead of hardcoding it everywhere. Also reorganize just a
> bit the macros at the top to avoid repeating tens of lines when adding
> support for a new chip.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>  drivers/iio/adc/max1027.c | 81 +++++++++++++++++++--------------------
>  1 file changed, 39 insertions(+), 42 deletions(-)
> 
> diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
> index f9b473ee6711..fc75764a6fd7 100644
> --- a/drivers/iio/adc/max1027.c
> +++ b/drivers/iio/adc/max1027.c
> @@ -78,12 +78,15 @@ static const struct of_device_id max1027_adc_dt_ids[] = {
>  	{ .compatible = "maxim,max1027" },
>  	{ .compatible = "maxim,max1029" },
>  	{ .compatible = "maxim,max1031" },
> +	{ .compatible = "maxim,max1227" },
> +	{ .compatible = "maxim,max1229" },
> +	{ .compatible = "maxim,max1231" },

Just spotted a mistake here: the addition of these three lines, while
harmless, should have come in patch 5/7.

Let me respin the series with this corrected.

Thanks and sorry for the noise,
Miquèl