iio: max5481: Add support for Maxim digital potentiometers (df1fd2de) · Commits · 戴 / test

Documentation/devicetree/bindings/iio/potentiometer/max5481.txt

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		* 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 */
		};

drivers/iio/potentiometer/Kconfig

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		@@ -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

drivers/iio/potentiometer/Makefile

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		@@ -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

drivers/iio/potentiometer/max5481.c

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		/*
		* 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/of_device.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, 3);

		case MAX5481_COPY_AB_TO_NV:
		case MAX5481_COPY_NV_TO_AB:
		return spi_write(spi, data->msg, 1);

		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,
		};

		#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

		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);
		const struct of_device_id *match;
		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;

		match = of_match_device(of_match_ptr(max5481_match), &spi->dev);
		if (match)
		data->cfg = of_device_get_match_data(&spi->dev);
		else
		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_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@rockwellcollins.com>");
		MODULE_DESCRIPTION("max5481 SPI driver");
		MODULE_LICENSE("GPL v2");

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