gpio: add support for 74x164 serial-in/parallel-out 8-bit shift register (ead6db08) · Commits · e / devices / android_kernel_fairphone_FP5

drivers/gpio/74x164.c

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		/*
		* 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver
		*
		* Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org>
		* Copyright (C) 2010 Miguel Gaio <miguel.gaio@efixo.com>
		*
		* 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/init.h>
		#include <linux/mutex.h>
		#include <linux/spi/spi.h>
		#include <linux/spi/74x164.h>
		#include <linux/gpio.h>
		#include <linux/slab.h>

		#define GEN_74X164_GPIO_COUNT 8


		struct gen_74x164_chip {
		struct spi_device *spi;
		struct gpio_chip gpio_chip;
		struct mutex lock;
		u8 port_config;
		};

		static void gen_74x164_set_value(struct gpio_chip *, unsigned, int);

		static struct gen_74x164_chip gpio_to_chip(struct gpio_chip gc)
		{
		return container_of(gc, struct gen_74x164_chip, gpio_chip);
		}

		static int __gen_74x164_write_config(struct gen_74x164_chip *chip)
		{
		return spi_write(chip->spi,
		&chip->port_config, sizeof(chip->port_config));
		}

		static int gen_74x164_direction_output(struct gpio_chip *gc,
		unsigned offset, int val)
		{
		gen_74x164_set_value(gc, offset, val);
		return 0;
		}

		static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset)
		{
		struct gen_74x164_chip *chip = gpio_to_chip(gc);
		int ret;

		mutex_lock(&chip->lock);
		ret = (chip->port_config >> offset) & 0x1;
		mutex_unlock(&chip->lock);

		return ret;
		}

		static void gen_74x164_set_value(struct gpio_chip *gc,
		unsigned offset, int val)
		{
		struct gen_74x164_chip *chip = gpio_to_chip(gc);

		mutex_lock(&chip->lock);
		if (val)
		chip->port_config \|= (1 << offset);
		else
		chip->port_config &= ~(1 << offset);

		__gen_74x164_write_config(chip);
		mutex_unlock(&chip->lock);
		}

		static int __devinit gen_74x164_probe(struct spi_device *spi)
		{
		struct gen_74x164_chip *chip;
		struct gen_74x164_chip_platform_data *pdata;
		int ret;

		pdata = spi->dev.platform_data;
		if (!pdata \|\| !pdata->base) {
		dev_dbg(&spi->dev, "incorrect or missing platform data\n");
		return -EINVAL;
		}

		/*
		* bits_per_word cannot be configured in platform data
		*/
		spi->bits_per_word = 8;

		ret = spi_setup(spi);
		if (ret < 0)
		return ret;

		chip = kzalloc(sizeof(*chip), GFP_KERNEL);
		if (!chip)
		return -ENOMEM;

		mutex_init(&chip->lock);

		dev_set_drvdata(&spi->dev, chip);

		chip->spi = spi;

		chip->gpio_chip.label = GEN_74X164_DRIVER_NAME,
		chip->gpio_chip.direction_output = gen_74x164_direction_output;
		chip->gpio_chip.get = gen_74x164_get_value;
		chip->gpio_chip.set = gen_74x164_set_value;
		chip->gpio_chip.base = pdata->base;
		chip->gpio_chip.ngpio = GEN_74X164_GPIO_COUNT;
		chip->gpio_chip.can_sleep = 1;
		chip->gpio_chip.dev = &spi->dev;
		chip->gpio_chip.owner = THIS_MODULE;

		ret = __gen_74x164_write_config(chip);
		if (ret) {
		dev_err(&spi->dev, "Failed writing: %d\n", ret);
		goto exit_destroy;
		}

		ret = gpiochip_add(&chip->gpio_chip);
		if (ret)
		goto exit_destroy;

		return ret;

		exit_destroy:
		dev_set_drvdata(&spi->dev, NULL);
		mutex_destroy(&chip->lock);
		kfree(chip);
		return ret;
		}

		static int gen_74x164_remove(struct spi_device *spi)
		{
		struct gen_74x164_chip *chip;
		int ret;

		chip = dev_get_drvdata(&spi->dev);
		if (chip == NULL)
		return -ENODEV;

		dev_set_drvdata(&spi->dev, NULL);

		ret = gpiochip_remove(&chip->gpio_chip);
		if (!ret) {
		mutex_destroy(&chip->lock);
		kfree(chip);
		} else
		dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n",
		ret);

		return ret;
		}

		static struct spi_driver gen_74x164_driver = {
		.driver = {
		.name = GEN_74X164_DRIVER_NAME,
		.owner = THIS_MODULE,
		},
		.probe = gen_74x164_probe,
		.remove = __devexit_p(gen_74x164_remove),
		};

		static int __init gen_74x164_init(void)
		{
		return spi_register_driver(&gen_74x164_driver);
		}
		subsys_initcall(gen_74x164_init);

		static void __exit gen_74x164_exit(void)
		{
		spi_unregister_driver(&gen_74x164_driver);
		}
		module_exit(gen_74x164_exit);

		MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
		MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>");
		MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register");
		MODULE_LICENSE("GPL v2");

drivers/gpio/Kconfig

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		@@ -344,6 +344,14 @@ config GPIO_MC33880
		SPI driver for Freescale MC33880 high-side/low-side switch.
		This provides GPIO interface supporting inputs and outputs.

		config GPIO_74X164
		tristate "74x164 serial-in/parallel-out 8-bits shift register"
		depends on SPI_MASTER
		help
		Platform driver for 74x164 compatible serial-in/parallel-out
		8-outputs shift registers. This driver can be used to provide access
		to more gpio outputs.

		comment "AC97 GPIO expanders:"

		config GPIO_UCB1400

drivers/gpio/Makefile

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		@@ -18,6 +18,7 @@ obj-$(CONFIG_GPIO_MAX7301) += max7301.o
		obj-$(CONFIG_GPIO_MAX732X) += max732x.o
		obj-$(CONFIG_GPIO_MC33880) += mc33880.o
		obj-$(CONFIG_GPIO_MCP23S08) += mcp23s08.o
		obj-$(CONFIG_GPIO_74X164) += 74x164.o
		obj-$(CONFIG_GPIO_PCA953X) += pca953x.o
		obj-$(CONFIG_GPIO_PCF857X) += pcf857x.o
		obj-$(CONFIG_GPIO_PL061) += pl061.o

include/linux/spi/74x164.h

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		#ifndef LINUX_SPI_74X164_H
		#define LINUX_SPI_74X164_H

		#define GEN_74X164_DRIVER_NAME "74x164"

		struct gen_74x164_chip_platform_data {
		/* number assigned to the first GPIO */
		unsigned base;
		};

		#endif