mux: gpio: add mux controller driver for gpio based multiplexers (2c089f08) · Commits · e / devices / android_kernel_oneplus_sm8150

drivers/mux/Kconfig

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		@@ -14,3 +14,21 @@ menuconfig MULTIPLEXER

		To compile the subsystem as a module, choose M here: the module will
		be called mux-core.

		if MULTIPLEXER

		config MUX_GPIO
		tristate "GPIO-controlled Multiplexer"
		depends on GPIOLIB \|\| COMPILE_TEST
		help
		GPIO-controlled Multiplexer controller.

		The driver builds a single multiplexer controller using a number
		of gpio pins. For N pins, there will be 2^N possible multiplexer
		states. The GPIO pins can be connected (by the hardware) to several
		multiplexers, which in that case will be operated in parallel.

		To compile the driver as a module, choose M here: the module will
		be called mux-gpio.

		endif

drivers/mux/Makefile

+1 −0

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		@@ -3,3 +3,4 @@
		#

		obj-$(CONFIG_MULTIPLEXER) += mux-core.o
		obj-$(CONFIG_MUX_GPIO) += mux-gpio.o

drivers/mux/mux-gpio.c

0 → 100644

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		/*
		* GPIO-controlled multiplexer driver
		*
		* Copyright (C) 2017 Axentia Technologies AB
		*
		* Author: Peter Rosin <peda@axentia.se>
		*
		* 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/err.h>
		#include <linux/gpio/consumer.h>
		#include <linux/module.h>
		#include <linux/mux/driver.h>
		#include <linux/of_platform.h>
		#include <linux/platform_device.h>
		#include <linux/property.h>

		struct mux_gpio {
		struct gpio_descs *gpios;
		int *val;
		};

		static int mux_gpio_set(struct mux_control *mux, int state)
		{
		struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip);
		int i;

		for (i = 0; i < mux_gpio->gpios->ndescs; i++)
		mux_gpio->val[i] = (state >> i) & 1;

		gpiod_set_array_value_cansleep(mux_gpio->gpios->ndescs,
		mux_gpio->gpios->desc,
		mux_gpio->val);

		return 0;
		}

		static const struct mux_control_ops mux_gpio_ops = {
		.set = mux_gpio_set,
		};

		static const struct of_device_id mux_gpio_dt_ids[] = {
		{ .compatible = "gpio-mux", },
		{ /* sentinel */ }
		};
		MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids);

		static int mux_gpio_probe(struct platform_device *pdev)
		{
		struct device *dev = &pdev->dev;
		struct mux_chip *mux_chip;
		struct mux_gpio *mux_gpio;
		int pins;
		s32 idle_state;
		int ret;

		pins = gpiod_count(dev, "mux");
		if (pins < 0)
		return pins;

		mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio) +
		pins * sizeof(*mux_gpio->val));
		if (IS_ERR(mux_chip))
		return PTR_ERR(mux_chip);

		mux_gpio = mux_chip_priv(mux_chip);
		mux_gpio->val = (int *)(mux_gpio + 1);
		mux_chip->ops = &mux_gpio_ops;

		mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW);
		if (IS_ERR(mux_gpio->gpios)) {
		ret = PTR_ERR(mux_gpio->gpios);
		if (ret != -EPROBE_DEFER)
		dev_err(dev, "failed to get gpios\n");
		return ret;
		}
		WARN_ON(pins != mux_gpio->gpios->ndescs);
		mux_chip->mux->states = 1 << pins;

		ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state);
		if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) {
		if (idle_state < 0 \|\| idle_state >= mux_chip->mux->states) {
		dev_err(dev, "invalid idle-state %u\n", idle_state);
		return -EINVAL;
		}

		mux_chip->mux->idle_state = idle_state;
		}

		ret = devm_mux_chip_register(dev, mux_chip);
		if (ret < 0)
		return ret;

		dev_info(dev, "%u-way mux-controller registered\n",
		mux_chip->mux->states);

		return 0;
		}

		static struct platform_driver mux_gpio_driver = {
		.driver = {
		.name = "gpio-mux",
		.of_match_table = of_match_ptr(mux_gpio_dt_ids),
		},
		.probe = mux_gpio_probe,
		};
		module_platform_driver(mux_gpio_driver);

		MODULE_DESCRIPTION("GPIO-controlled multiplexer driver");
		MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
		MODULE_LICENSE("GPL v2");