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
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 | 101 ++++++
drivers/iio/adc/Kconfig | 11 +
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/max34408.c | 334 ++++++++++++++++++
4 files changed, 447 insertions(+)
create mode 100644 Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml
create mode 100644 drivers/iio/adc/max34408.c
--
2.42.0
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 <[email protected]>
---
drivers/iio/adc/Kconfig | 11 ++
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/max34408.c | 334 +++++++++++++++++++++++++++++++++++++
3 files changed, 346 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..f576c65e3900
--- /dev/null
+++ b/drivers/iio/adc/max34408.c
@@ -0,0 +1,334 @@
+// 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)
+
+/* 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.
+ * @rsense: Rsense value in uOhm.
+ */
+struct max34408_data {
+ struct regmap *regmap;
+ struct device *dev;
+ struct mutex lock;
+ u32 input1_rsense;
+ u32 input2_rsense;
+ u32 input3_rsense;
+ u32 input4_rsense;
+};
+
+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) \
+ { \
+ .type = IIO_CURRENT, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
+ BIT(IIO_CHAN_INFO_SCALE) | \
+ BIT(IIO_CHAN_INFO_OFFSET), \
+ .channel = (_index), \
+ .indexed = 1, \
+ }
+
+static const struct iio_chan_spec max34408_channels[] = {
+ MAX34008_CHANNEL(0),
+ MAX34008_CHANNEL(1),
+};
+
+static const struct iio_chan_spec max34409_channels[] = {
+ MAX34008_CHANNEL(0),
+ MAX34008_CHANNEL(1),
+ MAX34008_CHANNEL(2),
+ MAX34008_CHANNEL(3),
+};
+
+static int max34408_read_adc(struct max34408_data *max34408, int channel,
+ int *val)
+{
+ u32 adc_reg;
+
+ switch (channel) {
+ case 0:
+ adc_reg = MAX34408_ADC1_REG;
+ break;
+ case 1:
+ adc_reg = MAX34408_ADC2_REG;
+ break;
+ case 2:
+ adc_reg = MAX34409_ADC3_REG;
+ break;
+ case 3:
+ adc_reg = MAX34409_ADC4_REG;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return regmap_read(max34408->regmap, adc_reg, val);
+}
+
+static int max34408_read_adc_avg(struct max34408_data *max34408, int channel, int *val)
+{
+ unsigned int ctrl;
+ int rc;
+ u8 tmp;
+
+ guard(mutex)(&max34408->lock);
+ rc = regmap_read(max34408->regmap, MAX34408_CONTROL_REG, (u32 *)&ctrl);
+ if (rc)
+ return rc;
+
+ /* set averaging (0b100) default values*/
+ tmp = ctrl;
+ ctrl |= MAX34408_CONTROL_AVG2;
+ ctrl &= ~MAX34408_CONTROL_AVG1;
+ ctrl &= ~MAX34408_CONTROL_AVG0;
+ rc = regmap_write(max34408->regmap, MAX34408_CONTROL_REG, ctrl);
+ if (rc) {
+ dev_err(max34408->dev,
+ "Error (%d) writing control register\n", rc);
+ return rc;
+ }
+
+ rc = max34408_read_adc(max34408, channel, val);
+ if (rc)
+ return rc;
+
+ /* back to old values */
+ rc = regmap_write(max34408->regmap, MAX34408_CONTROL_REG, tmp);
+ 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 input_rsense;
+ int rc;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ rc = max34408_read_adc_avg(max34408, chan->channel,
+ 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
+ */
+ switch (chan->channel) {
+ case 0:
+ input_rsense = max34408->input1_rsense;
+ break;
+ case 1:
+ input_rsense = max34408->input2_rsense;
+ break;
+ case 2:
+ input_rsense = max34408->input3_rsense;
+ break;
+ case 3:
+ input_rsense = max34408->input4_rsense;
+ break;
+ default:
+ return -EINVAL;
+ }
+ *val = 10000 / input_rsense;
+ *val2 = 8;
+ return IIO_VAL_FRACTIONAL_LOG2;
+ case IIO_CHAN_INFO_OFFSET:
+ *val = 0;
+ return IIO_VAL_INT;
+ 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;
+ const struct of_device_id *match;
+ struct max34408_data *max34408;
+ struct iio_dev *indio_dev;
+ struct regmap *regmap;
+ int rc;
+
+ match = of_match_device(max34408_of_match, &client->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(&client->dev, PTR_ERR(regmap),
+ "regmap_init failed\n");
+ return PTR_ERR(regmap);
+ }
+
+ indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*max34408));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ max34408 = iio_priv(indio_dev);
+ max34408->regmap = regmap;
+ max34408->dev = &client->dev;
+ mutex_init(&max34408->lock);
+
+ rc = device_property_read_u32(&client->dev,
+ "maxim,input1-rsense-val-micro-ohms",
+ &max34408->input1_rsense);
+ if (rc)
+ max34408->input1_rsense = MAX34408_DEFAULT_RSENSE;
+
+ rc = device_property_read_u32(&client->dev,
+ "maxim,input2-rsense-val-micro-ohms",
+ &max34408->input2_rsense);
+ if (rc)
+ max34408->input2_rsense = MAX34408_DEFAULT_RSENSE;
+
+ rc = device_property_read_u32(&client->dev,
+ "maxim,input3-rsense-val-micro-ohms",
+ &max34408->input3_rsense);
+ if (rc)
+ max34408->input3_rsense = MAX34408_DEFAULT_RSENSE;
+
+ rc = device_property_read_u32(&client->dev,
+ "maxim,input4-rsense-val-micro-ohms",
+ &max34408->input4_rsense);
+ if (rc)
+ max34408->input4_rsense = MAX34408_DEFAULT_RSENSE;
+
+ /* 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(&client->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 <[email protected]>");
+MODULE_DESCRIPTION("Maxim MAX34408/34409 ADC driver");
+MODULE_LICENSE("GPL");
--
2.42.0
Hi Ivan,
kernel test robot noticed the following build warnings:
[auto build test WARNING on jic23-iio/togreg]
[also build test WARNING on robh/for-next linus/master v6.6-rc3 next-20230929]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Ivan-Mikhaylov/dt-bindings-adc-provide-max34408-9-device-tree-binding-document/20230930-043842
base: https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git togreg
patch link: https://lore.kernel.org/r/20230929200844.23316-3-fr0st61te%40gmail.com
patch subject: [PATCH v2 2/2] iio: adc: Add driver support for MAX34408/9
config: sparc-allyesconfig (https://download.01.org/0day-ci/archive/20230930/[email protected]/config)
compiler: sparc64-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230930/[email protected]/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
All warnings (new ones prefixed by >>):
>> drivers/iio/adc/max34408.c:79: warning: Function parameter or member 'input1_rsense' not described in 'max34408_data'
>> drivers/iio/adc/max34408.c:79: warning: Function parameter or member 'input2_rsense' not described in 'max34408_data'
>> drivers/iio/adc/max34408.c:79: warning: Function parameter or member 'input3_rsense' not described in 'max34408_data'
>> drivers/iio/adc/max34408.c:79: warning: Function parameter or member 'input4_rsense' not described in 'max34408_data'
vim +79 drivers/iio/adc/max34408.c
62
63 /**
64 * struct max34408_data - max34408/max34409 specific data.
65 * @regmap: device register map.
66 * @dev: max34408 device.
67 * @lock: lock for protecting access to device hardware registers, mostly
68 * for read modify write cycles for control registers.
69 * @rsense: Rsense value in uOhm.
70 */
71 struct max34408_data {
72 struct regmap *regmap;
73 struct device *dev;
74 struct mutex lock;
75 u32 input1_rsense;
76 u32 input2_rsense;
77 u32 input3_rsense;
78 u32 input4_rsense;
> 79 };
80
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
On Fri, 29 Sep 2023 23:08:44 +0300
Ivan Mikhaylov <[email protected]> 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 <[email protected]>
Hi Ivan,
Various small comments inline. Mostly simplifications to the code.
Thanks,
Jonathan
> diff --git a/drivers/iio/adc/max34408.c b/drivers/iio/adc/max34408.c
> new file mode 100644
> index 000000000000..f576c65e3900
> --- /dev/null
> +++ b/drivers/iio/adc/max34408.c
> @@ -0,0 +1,334 @@
> +// 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)
> +
> +/* 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.
> + * @rsense: Rsense value in uOhm.
Bot complained about this doc being out of date.
As mentioned below, an array seems more appropriate to me than 4
separate struct elements.
> + */
> +struct max34408_data {
> + struct regmap *regmap;
> + struct device *dev;
> + struct mutex lock;
> + u32 input1_rsense;
> + u32 input2_rsense;
> + u32 input3_rsense;
> + u32 input4_rsense;
> +};
> +
> +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) \
> + { \
> + .type = IIO_CURRENT, \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
I'd drop the tab and not force that indent. A space is enough and consistent
with other elements.
> + BIT(IIO_CHAN_INFO_SCALE) | \
> + BIT(IIO_CHAN_INFO_OFFSET), \
> + .channel = (_index), \
> + .indexed = 1, \
> + }
> +
> +static const struct iio_chan_spec max34408_channels[] = {
> + MAX34008_CHANNEL(0),
> + MAX34008_CHANNEL(1),
> +};
> +
> +static const struct iio_chan_spec max34409_channels[] = {
> + MAX34008_CHANNEL(0),
> + MAX34008_CHANNEL(1),
> + MAX34008_CHANNEL(2),
> + MAX34008_CHANNEL(3),
> +};
> +
> +static int max34408_read_adc(struct max34408_data *max34408, int channel,
> + int *val)
> +{
> + u32 adc_reg;
> +
> + switch (channel) {
> + case 0:
> + adc_reg = MAX34408_ADC1_REG;
Channels have an .address field for this purpose.
I would put this in there then this just becomes
return regmap_read(max34408->regmap, chan->address, val);
with no need for the switch statement.
> + break;
> + case 1:
> + adc_reg = MAX34408_ADC2_REG;
> + break;
> + case 2:
> + adc_reg = MAX34409_ADC3_REG;
> + break;
> + case 3:
> + adc_reg = MAX34409_ADC4_REG;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + return regmap_read(max34408->regmap, adc_reg, val);
> +}
> +
> +static int max34408_read_adc_avg(struct max34408_data *max34408, int channel, int *val)
> +{
> + unsigned int ctrl;
> + int rc;
> + u8 tmp;
> +
> + guard(mutex)(&max34408->lock);
> + rc = regmap_read(max34408->regmap, MAX34408_CONTROL_REG, (u32 *)&ctrl);
> + if (rc)
> + return rc;
> +
> + /* set averaging (0b100) default values*/
> + tmp = ctrl;
> + ctrl |= MAX34408_CONTROL_AVG2;
> + ctrl &= ~MAX34408_CONTROL_AVG1;
> + ctrl &= ~MAX34408_CONTROL_AVG0;
It's a 3 bit field. Define a single mask for the field and then either
as set of defines for the values, or (if my maths is write)
#define MAX34408_CONTROL_AVG_FIELD_TO_SAMPLES(x) (1 << x)
#define MAX34408_CONTROL_AVG_SAMPLES_TO_FIELD(x) ffs(x)
to go backwards and forwards from the encoded value which is just powers of 2
> + rc = regmap_write(max34408->regmap, MAX34408_CONTROL_REG, ctrl);
> + if (rc) {
> + dev_err(max34408->dev,
> + "Error (%d) writing control register\n", rc);
> + return rc;
> + }
> +
> + rc = max34408_read_adc(max34408, channel, val);
> + if (rc)
> + return rc;
> +
> + /* back to old values */
> + rc = regmap_write(max34408->regmap, MAX34408_CONTROL_REG, tmp);
> + 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 input_rsense;
> + int rc;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + rc = max34408_read_adc_avg(max34408, chan->channel,
> + val);
Fits on one line under 80 chars. Check for other cases and tidy
those up as well.
> + 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
> + */
> + switch (chan->channel) {
> + case 0:
> + input_rsense = max34408->input1_rsense;
Array?
Then this becomes
input_rsense = max34408->input_rsense[chan->channel];
or skip the local variable and use it directly
*val = 10000 / max34408->input_rsense[chan->chanel];
*val2 = 8;
return IIO_VAL_FRACTION_LOG2;
> + break;
> + case 1:
> + input_rsense = max34408->input2_rsense;
> + break;
> + case 2:
> + input_rsense = max34408->input3_rsense;
> + break;
> + case 3:
> + input_rsense = max34408->input4_rsense;
> + break;
> + default:
> + return -EINVAL;
> + }
> + *val = 10000 / input_rsense;
> + *val2 = 8;
> + return IIO_VAL_FRACTIONAL_LOG2;
> + case IIO_CHAN_INFO_OFFSET:
> + *val = 0;
When the offset is 0, there is no in exposing that interface.
0 is the default if the file isn't there in sysfs.
> + return IIO_VAL_INT;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static const struct iio_info max34408_info = {
> + .read_raw = max34408_read_raw,
> +};
...
> +static int max34408_probe(struct i2c_client *client)
> +{
> + const struct max34408_adc_model_data *model_data;
> + const struct of_device_id *match;
> + struct max34408_data *max34408;
> + struct iio_dev *indio_dev;
> + struct regmap *regmap;
> + int rc;
> +
> + match = of_match_device(max34408_of_match, &client->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(&client->dev, PTR_ERR(regmap),
> + "regmap_init failed\n");
> + return PTR_ERR(regmap);
> + }
> +
> + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*max34408));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + max34408 = iio_priv(indio_dev);
> + max34408->regmap = regmap;
> + max34408->dev = &client->dev;
> + mutex_init(&max34408->lock);
> +
> + rc = device_property_read_u32(&client->dev,
> + "maxim,input1-rsense-val-micro-ohms",
> + &max34408->input1_rsense);
> + if (rc)
> + max34408->input1_rsense = MAX34408_DEFAULT_RSENSE;
> +
> + rc = device_property_read_u32(&client->dev,
> + "maxim,input2-rsense-val-micro-ohms",
> + &max34408->input2_rsense);
> + if (rc)
> + max34408->input2_rsense = MAX34408_DEFAULT_RSENSE;
> +
> + rc = device_property_read_u32(&client->dev,
> + "maxim,input3-rsense-val-micro-ohms",
> + &max34408->input3_rsense);
> + if (rc)
> + max34408->input3_rsense = MAX34408_DEFAULT_RSENSE;
> +
> + rc = device_property_read_u32(&client->dev,
> + "maxim,input4-rsense-val-micro-ohms",
> + &max34408->input4_rsense);
> + if (rc)
> + max34408->input4_rsense = MAX34408_DEFAULT_RSENSE;
> +
So, device_property_read_u32() is guaranteed to have no side effects on the
value being set if there is an error. Hence normal way of doing defaults
for optional parameters is the simpler.
max34408->input4_rsense = MAX34408_DEFAULT_RENSE;
device_property_read_u32(dev, "....", &max34408->input4_rsense);
So deliberately don't check the return value.
Not I would also suggest introducing a
struct device *dev = &client->dev; local variable as you use &client->dev
a lot.
Jonathan