Add a driver for the Maxim Integrated MAX5432-MAX5435 family of digital potentiometers. These potentiometers are connected via I2C and have 32 wiper positions. Supported functionality - set the volatile wiper position - read the potentiometer scale Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX5432-MAX5435.pdf Signed-off-by: Martin Kaiser <martin@xxxxxxxxx> --- changes in v4 - fix the dt bindings - replace ic20 with i2c - document the reg property - add additionalProperties and required changes in v3 - split dt bindings and driver code into separate patches - use yaml format for dt bindings - fix formatting of parameter lists changes in v2 - use MAX5432_ prefix for all defines - fix indentation - convert void * to unsigned long, not to u32 (warning from kbuild test robot) drivers/iio/potentiometer/Kconfig | 11 +++ drivers/iio/potentiometer/Makefile | 1 + drivers/iio/potentiometer/max5432.c | 135 ++++++++++++++++++++++++++++++++++++ 3 files changed, 147 insertions(+) create mode 100644 drivers/iio/potentiometer/max5432.c diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig index ebc7c72a5e36..4cac0173db8b 100644 --- a/drivers/iio/potentiometer/Kconfig +++ b/drivers/iio/potentiometer/Kconfig @@ -26,6 +26,17 @@ config DS1803 To compile this driver as a module, choose M here: the module will be called ds1803. +config MAX5432 + tristate "Maxim MAX5432-MAX5435 Digital Potentiometer driver" + depends on I2C + help + Say yes here to build support for the Maxim + MAX5432, MAX5433, MAX5434 and MAX5435 digital + potentiometer chips. + + To compile this driver as a module, choose M here: the + module will be called max5432. + config MAX5481 tristate "Maxim MAX5481-MAX5484 Digital Potentiometer driver" depends on SPI diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile index 8ff55138cf12..091adf3cdd0b 100644 --- a/drivers/iio/potentiometer/Makefile +++ b/drivers/iio/potentiometer/Makefile @@ -6,6 +6,7 @@ # When adding new entries keep the list in alphabetical order obj-$(CONFIG_AD5272) += ad5272.o obj-$(CONFIG_DS1803) += ds1803.o +obj-$(CONFIG_MAX5432) += max5432.o obj-$(CONFIG_MAX5481) += max5481.o obj-$(CONFIG_MAX5487) += max5487.o obj-$(CONFIG_MCP4018) += mcp4018.o diff --git a/drivers/iio/potentiometer/max5432.c b/drivers/iio/potentiometer/max5432.c new file mode 100644 index 000000000000..641b1821fdf6 --- /dev/null +++ b/drivers/iio/potentiometer/max5432.c @@ -0,0 +1,135 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Maxim Integrated MAX5432-MAX5435 digital potentiometer driver + * Copyright (C) 2019 Martin Kaiser <martin@xxxxxxxxx> + * + * Datasheet: + * https://datasheets.maximintegrated.com/en/ds/MAX5432-MAX5435.pdf + */ + +#include <linux/i2c.h> +#include <linux/iio/iio.h> +#include <linux/limits.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_device.h> + +/* All chip variants have 32 wiper positions. */ +#define MAX5432_MAX_POS 31 + +#define MAX5432_OHM_50K (50 * 1000) +#define MAX5432_OHM_100K (100 * 1000) + +/* Update the volatile (currently active) setting. */ +#define MAX5432_CMD_VREG 0x11 + +struct max5432_data { + struct i2c_client *client; + unsigned long ohm; +}; + +static const struct iio_chan_spec max5432_channels[] = { + { + .type = IIO_RESISTANCE, + .indexed = 1, + .output = 1, + .channel = 0, + .address = MAX5432_CMD_VREG, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), + } +}; + +static int max5432_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct max5432_data *data = iio_priv(indio_dev); + + if (mask != IIO_CHAN_INFO_SCALE) + return -EINVAL; + + if (unlikely(data->ohm > INT_MAX)) + return -ERANGE; + + *val = data->ohm; + *val2 = MAX5432_MAX_POS; + + return IIO_VAL_FRACTIONAL; +} + +static int max5432_write_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int val, int val2, long mask) +{ + struct max5432_data *data = iio_priv(indio_dev); + u8 data_byte; + + if (mask != IIO_CHAN_INFO_RAW) + return -EINVAL; + + if (val < 0 || val > MAX5432_MAX_POS) + return -EINVAL; + + if (val2 != 0) + return -EINVAL; + + /* Wiper position is in bits D7-D3. (D2-D0 are don't care bits.) */ + data_byte = val << 3; + return i2c_smbus_write_byte_data(data->client, chan->address, + data_byte); +} + +static const struct iio_info max5432_info = { + .read_raw = max5432_read_raw, + .write_raw = max5432_write_raw, +}; + +static int max5432_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct device *dev = &client->dev; + struct iio_dev *indio_dev; + struct max5432_data *data; + + indio_dev = devm_iio_device_alloc(dev, sizeof(struct max5432_data)); + if (!indio_dev) + return -ENOMEM; + + i2c_set_clientdata(client, indio_dev); + + data = iio_priv(indio_dev); + data->client = client; + data->ohm = (unsigned long)of_device_get_match_data(dev); + + indio_dev->dev.parent = dev; + indio_dev->info = &max5432_info; + indio_dev->channels = max5432_channels; + indio_dev->num_channels = ARRAY_SIZE(max5432_channels); + indio_dev->name = client->name; + + return devm_iio_device_register(dev, indio_dev); +} + +static const struct of_device_id max5432_dt_ids[] = { + { .compatible = "maxim,max5432", .data = (void *)MAX5432_OHM_50K }, + { .compatible = "maxim,max5433", .data = (void *)MAX5432_OHM_100K }, + { .compatible = "maxim,max5434", .data = (void *)MAX5432_OHM_50K }, + { .compatible = "maxim,max5435", .data = (void *)MAX5432_OHM_100K }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, max5432_dt_ids); + +static struct i2c_driver max5432_driver = { + .driver = { + .name = "max5432", + .of_match_table = of_match_ptr(max5432_dt_ids), + }, + .probe = max5432_probe, +}; + +module_i2c_driver(max5432_driver); + +MODULE_AUTHOR("Martin Kaiser <martin@xxxxxxxxx>"); +MODULE_DESCRIPTION("max5432-max5435 digital potentiometers"); +MODULE_LICENSE("GPL v2"); -- 2.11.0
