Add implementation for Maxim Integrated 5481, 5482, 5483, and 5484 digital potentiometer devices. Datasheet: http://datasheets.maximintegrated.com/en/ds/MAX5481-MAX5484.pdf Signed-off-by: Maury Anderson <maury.anderson@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Matthew Weber <matthew.weber@xxxxxxxxxxxxxxxxxxx> --- This patch is a proposed implementation which compiles and is based on the 5487 part. The integration of the component was cancelled but we wanted to still share this work hoping that others might pick it up. --- .../bindings/iio/potentiometer/max5481.txt | 23 +++ drivers/iio/potentiometer/Kconfig | 12 ++ drivers/iio/potentiometer/Makefile | 1 + drivers/iio/potentiometer/max5481.c | 212 +++++++++++++++++++++ 4 files changed, 248 insertions(+) create mode 100644 Documentation/devicetree/bindings/iio/potentiometer/max5481.txt create mode 100644 drivers/iio/potentiometer/max5481.c diff --git a/Documentation/devicetree/bindings/iio/potentiometer/max5481.txt b/Documentation/devicetree/bindings/iio/potentiometer/max5481.txt new file mode 100644 index 0000000..3bc59b4 --- /dev/null +++ b/Documentation/devicetree/bindings/iio/potentiometer/max5481.txt @@ -0,0 +1,23 @@ +* Maxim Linear-Taper Digital Potentiometer MAX5481-MAX5484 + +The node for this driver must be a child node of a SPI controller, hence +all mandatory properties described in + + Documentation/devicetree/bindings/spi/spi-bus.txt + +must be specified. + +Required properties: + - compatible: Must be one of the following, depending on the + model: + "maxim,max5481" + "maxim,max5482" + "maxim,max5483" + "maxim,max5484" + +Example: +max548x: max548x@0 { + compatible = "maxim,max5482"; + spi-max-frequency = <7000000``>; + reg = <0>; /* chip-select */ +}; diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig index 2e9da1c..872b25b 100644 --- a/drivers/iio/potentiometer/Kconfig +++ b/drivers/iio/potentiometer/Kconfig @@ -15,6 +15,18 @@ config DS1803 To compile this driver as a module, choose M here: the module will be called ds1803. +config MAX5481 + tristate "Maxim MAX5481-MAX5484 Digital Potentiometer driver" + depends on SPI + help + Say yes here to build support for the Maxim + MAX5481, MAX5482, MAX5483, MAX5484 digital potentiometer + chips. + + To compile this driver as a module, choose M here: the + module will be called max5481. + +c config MAX5487 tristate "Maxim MAX5487/MAX5488/MAX5489 Digital Potentiometer driver" depends on SPI diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile index 8adb58f..2260d40 100644 --- a/drivers/iio/potentiometer/Makefile +++ b/drivers/iio/potentiometer/Makefile @@ -4,6 +4,7 @@ # When adding new entries keep the list in alphabetical order obj-$(CONFIG_DS1803) += ds1803.o +obj-$(CONFIG_MAX5481) += max5481.o obj-$(CONFIG_MAX5487) += max5487.o obj-$(CONFIG_MCP4131) += mcp4131.o obj-$(CONFIG_MCP4531) += mcp4531.o diff --git a/drivers/iio/potentiometer/max5481.c b/drivers/iio/potentiometer/max5481.c new file mode 100644 index 0000000..f3feefc --- /dev/null +++ b/drivers/iio/potentiometer/max5481.c @@ -0,0 +1,212 @@ +/* + * Maxim Integrated MAX5481-MAX5484 digital potentiometer driver + * Copyright 2016 Rockwell Collins + * + * Datasheet: + * http://datasheets.maximintegrated.com/en/ds/MAX5481-MAX5484.pdf + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the gnu general public license version 2 as + * published by the free software foundation. + * + */ + +#include <linux/module.h> +#include <linux/spi/spi.h> +#include <linux/of.h> +#include <linux/acpi.h> + +#include <linux/iio/sysfs.h> +#include <linux/iio/iio.h> + +/* write wiper reg */ +#define MAX5481_WRITE_WIPER (0 << 4) +/* copy wiper reg to NV reg */ +#define MAX5481_COPY_AB_TO_NV (2 << 4) +/* copy NV reg to wiper reg */ +#define MAX5481_COPY_NV_TO_AB (3 << 4) + +#define MAX5481_MAX_POS 1023 + +enum max5481_variant { + max5481, + max5482, + max5483, + max5484 +}; + +struct max5481_cfg { + int kohms; + int maxpos; +}; + +static const struct max5481_cfg max5481_cfg[] = { + [max5481] = { .kohms = 10, .maxpos = MAX5481_MAX_POS }, + [max5482] = { .kohms = 50, .maxpos = MAX5481_MAX_POS }, + [max5483] = { .kohms = 10, .maxpos = MAX5481_MAX_POS }, + [max5484] = { .kohms = 50, .maxpos = MAX5481_MAX_POS }, +}; + +struct max5481_data { + struct spi_device *spi; + const struct max5481_cfg *cfg; +}; + +#define max5481_CHANNEL(ch) { \ + .type = IIO_RESISTANCE, \ + .indexed = 1, \ + .output = 1, \ + .channel = (ch), \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ +} + +static const struct iio_chan_spec max5481_channels[] = { + max5481_CHANNEL(0), +}; + +static int max5481_write_cmd(struct spi_device *spi, int cmd, int val) +{ + /* SPI Format from MAX5481-MAX5484 (19-3708; Rev 5; 4/10) pg 15 */ + u8 msg[3] = { + (u8)cmd, + (u8)((u16)val >> 2), + (u8)(val & 0x3) << 6 + }; + + return spi_write(spi, msg, (cmd == MAX5481_WRITE_WIPER) ? sizeof(msg) : sizeof(u8)); +} + +static int max5481_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct max5481_data *data = iio_priv(indio_dev); + + if (mask != IIO_CHAN_INFO_SCALE) + return -EINVAL; + + *val = 1000 * data->cfg->kohms; + *val2 = data->cfg->maxpos; + + return IIO_VAL_FRACTIONAL; +} + +static int max5481_write_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int val, int val2, long mask) +{ + struct max5481_data *data = iio_priv(indio_dev); + + if (mask != IIO_CHAN_INFO_RAW) + return -EINVAL; + + if (val < 0 || val > data->cfg->maxpos) + return -EINVAL; + + return max5481_write_cmd(data->spi, MAX5481_WRITE_WIPER, val); +} + +static const struct iio_info max5481_info = { + .read_raw = max5481_read_raw, + .write_raw = max5481_write_raw, + .driver_module = THIS_MODULE, +}; + +static int max5481_probe(struct spi_device *spi) +{ + struct iio_dev *indio_dev; + struct max5481_data *data; + const struct spi_device_id *id = spi_get_device_id(spi); + int ret; + + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data)); + if (!indio_dev) + return -ENOMEM; + + dev_set_drvdata(&spi->dev, indio_dev); + data = iio_priv(indio_dev); + + data->spi = spi; + data->cfg = &max5481_cfg[id->driver_data]; + + indio_dev->name = id->name; + indio_dev->dev.parent = &spi->dev; + indio_dev->modes = INDIO_DIRECT_MODE; + + /* variant specific configuration */ + indio_dev->info = &max5481_info; + indio_dev->channels = max5481_channels; + indio_dev->num_channels = ARRAY_SIZE(max5481_channels); + + /* restore wiper from NV */ + ret = max5481_write_cmd(data->spi, MAX5481_COPY_NV_TO_AB, 0); + if (ret < 0) + return ret; + + return iio_device_register(indio_dev); +} + +static int max5481_remove(struct spi_device *spi) +{ + struct iio_dev *indio_dev = dev_get_drvdata(&spi->dev); + int ret; + + /* save wiper reg to NV reg */ + ret = max5481_write_cmd(spi, MAX5481_COPY_AB_TO_NV, 0); + + iio_device_unregister(indio_dev); + + return ret; +} + +static const struct spi_device_id max5481_id_table[] = { + { "MAX5481", max5481 }, + { "MAX5482", max5482 }, + { "MAX5483", max5483 }, + { "MAX5484", max5484 }, + { } +}; +MODULE_DEVICE_TABLE(spi, max5481_id_table); + +#if defined(CONFIG_OF) +static const struct of_device_id max5481_match[] = { + { .compatible = "maxim,max5481", .data = &max5481_cfg[max5481] }, + { .compatible = "maxim,max5482", .data = &max5481_cfg[max5482] }, + { .compatible = "maxim,max5483", .data = &max5481_cfg[max5483] }, + { .compatible = "maxim,max5484", .data = &max5481_cfg[max5484] }, + { } +}; +MODULE_DEVICE_TABLE(of, max5481_match); +#endif + +#if defined(CONFIG_ACPI) +static const struct acpi_device_id max5481_acpi_match[] = { + { "MAX5481", max5481 }, + { "MAX5482", max5482 }, + { "MAX5483", max5483 }, + { "MAX5484", max5484 }, + { } +}; +MODULE_DEVICE_TABLE(acpi, max5481_acpi_match); +#endif + +static struct spi_driver max5481_driver = +{ + .driver = + { + .name = "max5481", + .owner = THIS_MODULE, + .of_match_table = of_match_ptr(max5481_match), + .acpi_match_table = ACPI_PTR(max5481_acpi_match), + }, + .probe = max5481_probe, + .remove = max5481_remove, + .id_table = max5481_id_table, +}; + +module_spi_driver(max5481_driver); + +MODULE_AUTHOR("Maury Anderson <maury.anderson@xxxxxxxxxxxxxxxxxxx>"); +MODULE_DESCRIPTION("max5481 SPI driver"); +MODULE_LICENSE("GPL v2"); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
