[PATCH v3 0/2] Add maxim max34408/34409 ADC driver and yaml

[PATCH v3 0/2] Add maxim max34408/34409 ADC driver and yaml

[Ivan Mikhaylov]

Add Maxim max34408/34409 ADC driver and yaml for it. Until now it
supports only current monitioring function without overcurrent
threshold/delay, shutdown delay configuration, alert interrupt.

Changes from v1:
   - minor changes from Rob's comments for yaml
   - add ena, shtdn and make 4 inputs for R sense from Jonathan's comments for yaml
   - add _REG suffix and make prefix for bitmasks and statuses
   - add SCALE/OFFSET instead of AVG/PROCESSED from Jonathan and
     Lars-Peter comments
   - add chip data from Jonathan and Lars-Peter comments
   - minor changes from Lars-Peter and Jonathan comments for driver

Changes from v2:
   - add channels into hardware description into yaml
   - add rsense property per channel
   - rename pins for shtdn and ena pins
   - make one array for input_rsense values

Ivan Mikhaylov (2):
  dt-bindings: adc: provide max34408/9 device tree binding document
  iio: adc: Add driver support for MAX34408/9

 .../bindings/iio/adc/maxim,max34408.yaml      | 137 +++++++++
 drivers/iio/adc/Kconfig                       |  11 +
 drivers/iio/adc/Makefile                      |   1 +
 drivers/iio/adc/max34408.c                    | 270 ++++++++++++++++++
 4 files changed, 419 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml
 create mode 100644 drivers/iio/adc/max34408.c

-- 
2.42.0

[PATCH v3 1/2] dt-bindings: adc: provide max34408/9 device tree binding document

[Ivan Mikhaylov]

The hardware binding for i2c current monitoring device with overcurrent
control.

Signed-off-by: Ivan Mikhaylov <fr0st61te@gmail.com>
---
 .../bindings/iio/adc/maxim,max34408.yaml      | 137 ++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml b/Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml
new file mode 100644
index 000000000000..4262bedb4bfa
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml
@@ -0,0 +1,137 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/maxim,max34408.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Two- and four-channel current monitors with overcurrent control
+
+maintainers:
+  - Ivan Mikhaylov <fr0st61te@gmail.com>
+
+description: |
+  The MAX34408/MAX34409 are two- and four-channel current monitors that are
+  configured and monitored with a standard I2C/SMBus serial interface. Each
+  unidirectional current sensor offers precision high-side operation with a
+  low full-scale sense voltage. The devices automatically sequence through
+  two or four channels and collect the current-sense samples and average them
+  to reduce the effect of impulse noise. The raw ADC samples are compared to
+  user-programmable digital thresholds to indicate overcurrent conditions.
+  Overcurrent conditions trigger a hardware output to provide an immediate
+  indication to shut down any necessary external circuitry.
+
+  Specifications about the devices can be found at:
+  https://www.analog.com/media/en/technical-documentation/data-sheets/MAX34408-MAX34409.pdf
+
+properties:
+  compatible:
+    enum:
+      - maxim,max34408
+      - maxim,max34409
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  isshutdown-gpios:
+    description:
+      Shutdown Output. Open-drain output. This output transitions to high impedance
+      when any of the digital comparator thresholds are exceeded as long as the ENA
+      pin is high.
+    maxItems: 1
+
+  shtdn-enable-gpios:
+    description:
+      SHTDN Enable Input. CMOS digital input. Connect to GND to clear the latch and
+      unconditionally deassert (force low) the SHTDN output and reset the shutdown
+      delay. Connect to VDD to enable normal latch operation of the SHTDN output.
+    maxItems: 1
+
+  vdd-supply: true
+
+required:
+  - compatible
+  - reg
+
+patternProperties:
+  "^channel@[0-3]$":
+    $ref: adc.yaml
+    type: object
+    description:
+      Represents the internal channels of the ADC.
+
+    properties:
+      reg:
+        items:
+          minimum: 0
+          maximum: 3
+
+      maxim,rsense-val-micro-ohms:
+        description:
+          Adjust the Rsense value to monitor higher or lower current levels for
+          input.
+        enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+        default: 1000
+
+    required:
+      - reg
+      - maxim,rsense-val-micro-ohms
+
+    unevaluatedProperties: false
+
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: maxim,max34408
+    then:
+      patternProperties:
+        "^channel@[2-3]$": false
+        "^channel@[0-1]$":
+          properties:
+            reg:
+              minimum: 0
+              maximum: 1
+    else:
+      patternProperties:
+        "^channel@[0-3]$":
+          properties:
+            reg:
+              minimum: 0
+              maximum: 3
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@1e {
+              compatible = "maxim,max34409";
+              reg = <0x1e>;
+
+              #address-cells = <1>;
+              #size-cells = <0>;
+              channel@0 {
+                  reg = <0x0>;
+                  maxim,rsense-val-micro-ohms = <5000>;
+              };
+
+              channel@1 {
+                  reg = <0x1>;
+                  maxim,rsense-val-micro-ohms = <10000>;
+             };
+        };
+    };
-- 
2.42.0

[PATCH v3 2/2] iio: adc: Add driver support for MAX34408/9

[Ivan Mikhaylov]

The MAX34408/MAX34409 are two- and four-channel current monitors that are
configured and monitored with a standard I2C/SMBus serial interface. Each
unidirectional current sensor offers precision high-side operation with a
low full-scale sense voltage. The devices automatically sequence through
two or four channels and collect the current-sense samples and average them
to reduce the effect of impulse noise. The raw ADC samples are compared to
user-programmable digital thresholds to indicate overcurrent conditions.
Overcurrent conditions trigger a hardware output to provide an immediate
indication to shut down any necessary external circuitry.

Add as ADC driver which only supports current monitoring for now.

Link: https://www.analog.com/media/en/technical-documentation/data-sheets/MAX34408-MAX34409.pdf

Signed-off-by: Ivan Mikhaylov <fr0st61te@gmail.com>
---
 drivers/iio/adc/Kconfig    |  11 ++
 drivers/iio/adc/Makefile   |   1 +
 drivers/iio/adc/max34408.c | 270 +++++++++++++++++++++++++++++++++++++
 3 files changed, 282 insertions(+)
 create mode 100644 drivers/iio/adc/max34408.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 517b3db114b8..c215a2861350 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -735,6 +735,17 @@ config MAX1363
 	  To compile this driver as a module, choose M here: the module will be
 	  called max1363.
 
+config MAX34408
+	tristate "Maxim max34408/max344089 ADC driver"
+	depends on I2C
+	help
+	  Say yes here to build support for Maxim max34408/max34409 current sense
+	  monitor with 8-bits ADC interface with overcurrent delay/threshold and
+	  shutdown delay.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called max34408.
+
 config MAX77541_ADC
 	tristate "Analog Devices MAX77541 ADC driver"
 	depends on MFD_MAX77541
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 2facf979327d..46dceab85e9a 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -67,6 +67,7 @@ obj-$(CONFIG_MAX11205) += max11205.o
 obj-$(CONFIG_MAX11410) += max11410.o
 obj-$(CONFIG_MAX1241) += max1241.o
 obj-$(CONFIG_MAX1363) += max1363.o
+obj-$(CONFIG_MAX34408) += max34408.o
 obj-$(CONFIG_MAX77541_ADC) += max77541-adc.o
 obj-$(CONFIG_MAX9611) += max9611.o
 obj-$(CONFIG_MCP320X) += mcp320x.o
diff --git a/drivers/iio/adc/max34408.c b/drivers/iio/adc/max34408.c
new file mode 100644
index 000000000000..f743bf6338dc
--- /dev/null
+++ b/drivers/iio/adc/max34408.c
@@ -0,0 +1,270 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * IIO driver for Maxim MAX34409/34408 ADC, 4-Channels/2-Channels, 8bits, I2C
+ *
+ * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/MAX34408-MAX34409.pdf
+ *
+ * TODO: ALERT interrupt, Overcurrent delay, Shutdown delay
+ */
+
+#include <linux/bitfield.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/types.h>
+
+#define MAX34408_STATUS_REG		0x0
+#define MAX34408_CONTROL_REG		0x1
+#define MAX34408_OCDELAY_REG		0x2
+#define MAX34408_SDDELAY_REG		0x3
+
+#define MAX34408_ADC1_REG		0x4
+#define MAX34408_ADC2_REG		0x5
+/* ADC3 & ADC4 always returns 0x0 on 34408 */
+#define MAX34409_ADC3_REG		0x6
+#define MAX34409_ADC4_REG		0x7
+
+#define MAX34408_OCT1_REG		0x8
+#define MAX34408_OCT2_REG		0x9
+#define MAX34408_OCT3_REG		0xA
+#define MAX34408_OCT4_REG		0xB
+
+#define MAX34408_DID_REG		0xC
+#define MAX34408_DCYY_REG		0xD
+#define MAX34408_DCWW_REG		0xE
+
+/* Bit masks for status register */
+#define MAX34408_STATUS_OC_MSK		GENMASK(1, 0)
+#define MAX34409_STATUS_OC_MSK		GENMASK(3, 0)
+#define MAX34408_STATUS_SHTDN		BIT(4)
+#define MAX34408_STATUS_ENA		BIT(5)
+
+/* Bit masks for control register */
+#define MAX34408_CONTROL_AVG0		BIT(0)
+#define MAX34408_CONTROL_AVG1		BIT(1)
+#define MAX34408_CONTROL_AVG2		BIT(2)
+#define MAX34408_CONTROL_ALERT		BIT(3)
+
+#define MAX34408_DEFAULT_AVG		0x4
+
+/* Bit masks for over current delay */
+#define MAX34408_OCDELAY_OCD_MSK	GENMASK(6, 0)
+#define MAX34408_OCDELAY_RESET		BIT(7)
+
+/* Bit masks for shutdown delay */
+#define MAX34408_SDDELAY_SHD_MSK	GENMASK(6, 0)
+#define MAX34408_SDDELAY_RESET		BIT(7)
+
+#define MAX34408_DEFAULT_RSENSE	1000
+
+/**
+ * struct max34408_data - max34408/max34409 specific data.
+ * @regmap:	device register map.
+ * @dev:	max34408 device.
+ * @lock:	lock for protecting access to device hardware registers, mostly
+ *		for read modify write cycles for control registers.
+ * @input_rsense:	Rsense values in uOhm, will be overwritten by
+ *			values from channel nodes.
+ */
+struct max34408_data {
+	struct regmap *regmap;
+	struct device *dev;
+	struct mutex lock;
+	u32 input_rsense[4];
+};
+
+static const struct regmap_config max34408_regmap_config = {
+	.reg_bits	= 8,
+	.val_bits	= 8,
+	.max_register	= MAX34408_DCWW_REG,
+};
+
+struct max34408_adc_model_data {
+	const char *model_name;
+	const struct iio_chan_spec *channels;
+	const int num_channels;
+};
+
+#define MAX34008_CHANNEL(_index, _address)			\
+	{							\
+		.type = IIO_CURRENT,				\
+		.info_mask_separate	= BIT(IIO_CHAN_INFO_RAW) | \
+					  BIT(IIO_CHAN_INFO_SCALE) | \
+					  BIT(IIO_CHAN_INFO_OFFSET), \
+		.channel = (_index),				\
+		.address = (_address),				\
+		.indexed = 1,					\
+	}
+
+static const struct iio_chan_spec max34408_channels[] = {
+	MAX34008_CHANNEL(0, MAX34408_ADC1_REG),
+	MAX34008_CHANNEL(1, MAX34408_ADC2_REG),
+};
+
+static const struct iio_chan_spec max34409_channels[] = {
+	MAX34008_CHANNEL(0, MAX34408_ADC1_REG),
+	MAX34008_CHANNEL(1, MAX34408_ADC2_REG),
+	MAX34008_CHANNEL(2, MAX34409_ADC3_REG),
+	MAX34008_CHANNEL(3, MAX34409_ADC4_REG),
+};
+
+static int max34408_read_adc_avg(struct max34408_data *max34408,
+				 const struct iio_chan_spec *chan, int *val)
+{
+	unsigned int ctrl;
+	int rc;
+
+	guard(mutex)(&max34408->lock);
+	rc = regmap_read(max34408->regmap, MAX34408_CONTROL_REG, (u32 *)&ctrl);
+	if (rc)
+		return rc;
+
+	/* set averaging (0b100) default values*/
+	rc = regmap_write(max34408->regmap, MAX34408_CONTROL_REG,
+			  MAX34408_DEFAULT_AVG);
+	if (rc) {
+		dev_err(max34408->dev,
+			"Error (%d) writing control register\n", rc);
+		return rc;
+	}
+
+	rc = regmap_read(max34408->regmap, chan->address, val);
+	if (rc)
+		return rc;
+
+	/* back to old values */
+	rc = regmap_write(max34408->regmap, MAX34408_CONTROL_REG, ctrl);
+	if (rc)
+		dev_err(max34408->dev,
+			"Error (%d) writing control register\n", rc);
+
+	return rc;
+}
+
+static int max34408_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct max34408_data *max34408 = iio_priv(indio_dev);
+	int rc;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		rc = max34408_read_adc_avg(max34408, chan, val);
+		if (rc)
+			return rc;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		/*
+		 * calcluate current for 8bit ADC with Rsense
+		 * value.
+		 * 10 mV * 1000 / Rsense uOhm = max current
+		 * (max current * adc val * 1000) / (2^8 - 1) mA
+		 */
+		*val = 10000 / max34408->input_rsense[chan->channel];
+		*val2 = 8;
+		return IIO_VAL_FRACTIONAL_LOG2;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info max34408_info = {
+	.read_raw	= max34408_read_raw,
+};
+
+static const struct max34408_adc_model_data max34408_model_data = {
+	.model_name = "max34408",
+	.channels = max34408_channels,
+	.num_channels = 2,
+};
+
+static const struct max34408_adc_model_data max34409_model_data = {
+	.model_name = "max34409",
+	.channels = max34409_channels,
+	.num_channels = 4,
+};
+
+static const struct of_device_id max34408_of_match[] = {
+	{
+		.compatible = "maxim,max34408",
+		.data = &max34408_model_data,
+	},
+	{
+		.compatible = "maxim,max34409",
+		.data = &max34409_model_data,
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(of, max34408_of_match);
+
+static int max34408_probe(struct i2c_client *client)
+{
+	const struct max34408_adc_model_data *model_data;
+	struct device *dev = &client->dev;
+	const struct of_device_id *match;
+	struct max34408_data *max34408;
+	struct device_node *child;
+	struct iio_dev *indio_dev;
+	struct regmap *regmap;
+	int rc, i;
+
+	match = of_match_device(max34408_of_match, dev);
+	if (!match)
+		return -EINVAL;
+	model_data = match->data;
+
+	regmap = devm_regmap_init_i2c(client, &max34408_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err_probe(dev, PTR_ERR(regmap),
+			      "regmap_init failed\n");
+		return PTR_ERR(regmap);
+	}
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*max34408));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	max34408 = iio_priv(indio_dev);
+	max34408->regmap = regmap;
+	max34408->dev = dev;
+	mutex_init(&max34408->lock);
+
+	for_each_available_child_of_node(dev->of_node, child) {
+		of_property_read_u32(child, "maxim,rsense-val-micro-ohms",
+				     &max34408->input_rsense[i]);
+		i++;
+	}
+
+	/* disable ALERT and averaging */
+	rc = regmap_write(max34408->regmap, MAX34408_CONTROL_REG, 0x0);
+	if (rc)
+		return rc;
+
+	indio_dev->channels = model_data->channels;
+	indio_dev->num_channels = model_data->num_channels;
+	indio_dev->name = model_data->model_name;
+
+	indio_dev->info = &max34408_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static struct i2c_driver max34408_driver = {
+	.driver = {
+		.name   = "max34408",
+		.of_match_table = max34408_of_match,
+	},
+	.probe = max34408_probe,
+};
+module_i2c_driver(max34408_driver);
+
+MODULE_AUTHOR("Ivan Mikhaylov <fr0st61te@gmail.com>");
+MODULE_DESCRIPTION("Maxim MAX34408/34409 ADC driver");
+MODULE_LICENSE("GPL");
-- 
2.42.0

Re: [PATCH v3 2/2] iio: adc: Add driver support for MAX34408/9

[Jonathan Cameron]

On Thu,  5 Oct 2023 19:09:30 +0300
Ivan Mikhaylov <fr0st61te@gmail.com> wrote:

> The MAX34408/MAX34409 are two- and four-channel current monitors that are
> configured and monitored with a standard I2C/SMBus serial interface. Each
> unidirectional current sensor offers precision high-side operation with a
> low full-scale sense voltage. The devices automatically sequence through
> two or four channels and collect the current-sense samples and average them
> to reduce the effect of impulse noise. The raw ADC samples are compared to
> user-programmable digital thresholds to indicate overcurrent conditions.
> Overcurrent conditions trigger a hardware output to provide an immediate
> indication to shut down any necessary external circuitry.
> 
> Add as ADC driver which only supports current monitoring for now.
> 
> Link: https://www.analog.com/media/en/technical-documentation/data-sheets/MAX34408-MAX34409.pdf
> 
> Signed-off-by: Ivan Mikhaylov <fr0st61te@gmail.com>
Hi Ivan,

Biggest thing remaining that I noticed on this read through is that for
new drivers in IIO I am asking people to only use generic firmware property
accessors from property.h instead of the of specific ones.
I rarely makes things less readable or more complex, and leaves us
ready for other options in future.

Thanks,

Jonathan

> --- /dev/null
> +++ b/drivers/iio/adc/max34408.c
> @@ -0,0 +1,270 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * IIO driver for Maxim MAX34409/34408 ADC, 4-Channels/2-Channels, 8bits, I2C
> + *
> + * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/MAX34408-MAX34409.pdf
> + *
> + * TODO: ALERT interrupt, Overcurrent delay, Shutdown delay
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/init.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>

mod_devicetable.h for the various firmware match table definitions

> +#include <linux/mutex.h>
> +#include <linux/of_device.h>

Should be include <linux/property.h>
and use the accessors in there instead of of specific ones.


> +
> +static int max34408_probe(struct i2c_client *client)
> +{
> +	const struct max34408_adc_model_data *model_data;
> +	struct device *dev = &client->dev;
> +	const struct of_device_id *match;
> +	struct max34408_data *max34408;
> +	struct device_node *child;
> +	struct iio_dev *indio_dev;
> +	struct regmap *regmap;
> +	int rc, i;
> +
> +	match = of_match_device(max34408_of_match, dev);
> +	if (!match)
> +		return -EINVAL;
> +	model_data = match->data;

	match = i2c_get_match_data() 
as that will cope with all forms of firmware and i2c_device_id tables.


> +
> +	regmap = devm_regmap_init_i2c(client, &max34408_regmap_config);
> +	if (IS_ERR(regmap)) {
> +		dev_err_probe(dev, PTR_ERR(regmap),
> +			      "regmap_init failed\n");
> +		return PTR_ERR(regmap);
> +	}
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*max34408));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	max34408 = iio_priv(indio_dev);
> +	max34408->regmap = regmap;
> +	max34408->dev = dev;
> +	mutex_init(&max34408->lock);
> +
> +	for_each_available_child_of_node(dev->of_node, child) {
> +		of_property_read_u32(child, "maxim,rsense-val-micro-ohms",

Use the stuff in property.h so that we are ready for other firmware
types.  We are still pushing this (slowly) throughout IIO drivers
that are already in tree.


> +				     &max34408->input_rsense[i]);
> +		i++;
> +	}
> +
> +	/* disable ALERT and averaging */
> +	rc = regmap_write(max34408->regmap, MAX34408_CONTROL_REG, 0x0);
> +	if (rc)
> +		return rc;
> +
> +	indio_dev->channels = model_data->channels;
> +	indio_dev->num_channels = model_data->num_channels;
> +	indio_dev->name = model_data->model_name;
> +
> +	indio_dev->info = &max34408_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	return devm_iio_device_register(dev, indio_dev);
> +}
> +
> +static struct i2c_driver max34408_driver = {
> +	.driver = {
> +		.name   = "max34408",
> +		.of_match_table = max34408_of_match,
> +	},
Provide the i2c_device_id table as well as you never know what route
people will use to probe this.

> +	.probe = max34408_probe,
> +};
> +module_i2c_driver(max34408_driver);
> +
> +MODULE_AUTHOR("Ivan Mikhaylov <fr0st61te@gmail.com>");
> +MODULE_DESCRIPTION("Maxim MAX34408/34409 ADC driver");
> +MODULE_LICENSE("GPL");