From: Matt Weber <matthew.weber@xxxxxxxxxxxxxxxxxxx> 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> Signed-off-by: Slawomir Stepien <sst@xxxxxxxxx> --- This is my resubmission of this patch after original authors decided not to pursuit it inclusion into kernel. Tested using signal analyzer. Changes since v2: * spi write buffer moved to struct max5481_data and ____cacheline_aligned. * max5481_write_cmd now uses pointer to struct max5481_data as a first argument. Changes since v1: * removed not needed '``' and 'c' chars * includes are now sorted * added coma to last item in enum max5481_variant * removed maxpos from struct max5481_cfg * max5481_CHANNEL is no MAX5481_CHANNEL and it does not have 'ch' argument * max5481_write_cmd is now based around switch * removed not needed cast in max5481_write_cmd * wpier state is saved after iio_device_unregister * changed names in spi_device_id and acpi_device_id to be equal to names in of_device_id --- .../bindings/iio/potentiometer/max5481.txt | 23 +++ drivers/iio/potentiometer/Kconfig | 11 ++ drivers/iio/potentiometer/Makefile | 1 + drivers/iio/potentiometer/max5481.c | 216 +++++++++++++++++++++ 4 files changed, 251 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 000000000000..6a91b106e076 --- /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 2e9da1cf3297..8bf282510be6 100644 --- a/drivers/iio/potentiometer/Kconfig +++ b/drivers/iio/potentiometer/Kconfig @@ -15,6 +15,17 @@ 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. + 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 8adb58f38c0b..2260d40e0936 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 000000000000..559f1635be0a --- /dev/null +++ b/drivers/iio/potentiometer/max5481.c @@ -0,0 +1,216 @@ +/* + * 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/acpi.h> +#include <linux/iio/iio.h> +#include <linux/iio/sysfs.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/spi/spi.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; +}; + +static const struct max5481_cfg max5481_cfg[] = { + [max5481] = { .kohms = 10, }, + [max5482] = { .kohms = 50, }, + [max5483] = { .kohms = 10, }, + [max5484] = { .kohms = 50, }, +}; + +struct max5481_data { + struct spi_device *spi; + const struct max5481_cfg *cfg; + u8 msg[3] ____cacheline_aligned; +}; + +#define MAX5481_CHANNEL { \ + .type = IIO_RESISTANCE, \ + .indexed = 1, \ + .output = 1, \ + .channel = 0, \ + .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, +}; + +static int max5481_write_cmd(struct max5481_data *data, u8 cmd, u16 val) +{ + struct spi_device *spi = data->spi; + + data->msg[0] = cmd; + + switch (cmd) { + case MAX5481_WRITE_WIPER: + data->msg[1] = val >> 2; + data->msg[2] = (val & 0x3) << 6; + return spi_write(spi, data->msg, ARRAY_SIZE(data->msg)); + + case MAX5481_COPY_AB_TO_NV: + case MAX5481_COPY_NV_TO_AB: + return spi_write(spi, data->msg, sizeof(data->msg[0])); + + default: + return -EIO; + } +} + +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 = MAX5481_MAX_POS; + + 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 > MAX5481_MAX_POS) + return -EINVAL; + + return max5481_write_cmd(data, 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, 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); + struct max5481_data *data = iio_priv(indio_dev); + + iio_device_unregister(indio_dev); + + /* save wiper reg to NV reg */ + return max5481_write_cmd(data, MAX5481_COPY_AB_TO_NV, 0); +} + +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"); -- 2.11.0 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
