gpio: Add driver for SPI serializers (df6df93c) · Commits · e / devices / android_kernel_fairphone_FP4

drivers/gpio/Kconfig

+6 −0

Original line number	Original line	Diff line number	Diff line
	@@ -1048,6 +1048,12 @@ config GPIO_MC33880
	SPI driver for Freescale MC33880 high-side/low-side switch.		SPI driver for Freescale MC33880 high-side/low-side switch.
	This provides GPIO interface supporting inputs and outputs.		This provides GPIO interface supporting inputs and outputs.

			config GPIO_PISOSR
			tristate "Generic parallel-in/serial-out shift register"
			help
			GPIO driver for SPI compatible parallel-in/serial-out shift
			registers. These are input only devices.

	endmenu		endmenu

	menu "SPI or I2C GPIO expanders"		menu "SPI or I2C GPIO expanders"

drivers/gpio/Makefile

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -76,6 +76,7 @@ obj-$(CONFIG_GPIO_OMAP) += gpio-omap.o
	obj-$(CONFIG_GPIO_PCA953X) += gpio-pca953x.o		obj-$(CONFIG_GPIO_PCA953X) += gpio-pca953x.o
	obj-$(CONFIG_GPIO_PCF857X) += gpio-pcf857x.o		obj-$(CONFIG_GPIO_PCF857X) += gpio-pcf857x.o
	obj-$(CONFIG_GPIO_PCH) += gpio-pch.o		obj-$(CONFIG_GPIO_PCH) += gpio-pch.o
			obj-$(CONFIG_GPIO_PISOSR) += gpio-pisosr.o
	obj-$(CONFIG_GPIO_PL061) += gpio-pl061.o		obj-$(CONFIG_GPIO_PL061) += gpio-pl061.o
	obj-$(CONFIG_GPIO_PXA) += gpio-pxa.o		obj-$(CONFIG_GPIO_PXA) += gpio-pxa.o
	obj-$(CONFIG_GPIO_RC5T583) += gpio-rc5t583.o		obj-$(CONFIG_GPIO_RC5T583) += gpio-rc5t583.o

drivers/gpio/gpio-pisosr.c

0 → 100644

+188 −0

Original line number	Original line	Diff line number	Diff line
			/*
			* Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com/
			* Andrew F. Davis <afd@ti.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.
			*
			* This program is distributed "as is" WITHOUT ANY WARRANTY of any
			* kind, whether expressed or implied; without even the implied warranty
			* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
			* GNU General Public License version 2 for more details.
			*/

			#include <linux/delay.h>
			#include <linux/gpio/consumer.h>
			#include <linux/gpio/driver.h>
			#include <linux/module.h>
			#include <linux/mutex.h>
			#include <linux/spi/spi.h>

			#define DEFAULT_NGPIO 8

			/**
			* struct pisosr_gpio - GPIO driver data
			* @chip: GPIO controller chip
			* @spi: SPI device pointer
			* @buffer: Buffer for device reads
			* @buffer_size: Size of buffer
			* @load_gpio: GPIO pin used to load input into device
			* @lock: Protects read sequences
			*/
			struct pisosr_gpio {
			struct gpio_chip chip;
			struct spi_device *spi;
			u8 *buffer;
			size_t buffer_size;
			struct gpio_desc *load_gpio;
			struct mutex lock;
			};

			static int pisosr_gpio_refresh(struct pisosr_gpio *gpio)
			{
			int ret;

			mutex_lock(&gpio->lock);

			if (gpio->load_gpio) {
			gpiod_set_value(gpio->load_gpio, 1);
			udelay(1); /* registers load time (~10ns) */
			gpiod_set_value(gpio->load_gpio, 0);
			udelay(1); /* registers recovery time (~5ns) */
			}

			ret = spi_read(gpio->spi, gpio->buffer, gpio->buffer_size);
			if (ret)
			return ret;

			mutex_unlock(&gpio->lock);

			return 0;
			}

			static int pisosr_gpio_get_direction(struct gpio_chip *chip,
			unsigned offset)
			{
			/* This device always input */
			return 1;
			}

			static int pisosr_gpio_direction_input(struct gpio_chip *chip,
			unsigned offset)
			{
			/* This device always input */
			return 0;
			}

			static int pisosr_gpio_direction_output(struct gpio_chip *chip,
			unsigned offset, int value)
			{
			/* This device is input only */
			return -EINVAL;
			}

			static int pisosr_gpio_get(struct gpio_chip *chip, unsigned offset)
			{
			struct pisosr_gpio *gpio = gpiochip_get_data(chip);

			/* Refresh may not always be needed */
			pisosr_gpio_refresh(gpio);

			return (gpio->buffer[offset / 8] >> (offset % 8)) & 0x1;
			}

			static struct gpio_chip template_chip = {
			.label = "pisosr-gpio",
			.owner = THIS_MODULE,
			.get_direction = pisosr_gpio_get_direction,
			.direction_input = pisosr_gpio_direction_input,
			.direction_output = pisosr_gpio_direction_output,
			.get = pisosr_gpio_get,
			.base = -1,
			.ngpio = DEFAULT_NGPIO,
			.can_sleep = true,
			};

			static int pisosr_gpio_probe(struct spi_device *spi)
			{
			struct device *dev = &spi->dev;
			struct pisosr_gpio *gpio;
			int ret;

			gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
			if (!gpio)
			return -ENOMEM;

			spi_set_drvdata(spi, gpio);

			gpio->chip = template_chip;
			gpio->chip.parent = dev;
			of_property_read_u16(dev->of_node, "ngpios", &gpio->chip.ngpio);

			gpio->spi = spi;

			gpio->buffer_size = DIV_ROUND_UP(gpio->chip.ngpio, 8);
			gpio->buffer = devm_kzalloc(dev, gpio->buffer_size, GFP_KERNEL);
			if (!gpio->buffer)
			return -ENOMEM;

			gpio->load_gpio = devm_gpiod_get(dev, "load", GPIOD_OUT_LOW);
			if (IS_ERR(gpio->load_gpio)) {
			ret = PTR_ERR(gpio->load_gpio);
			if (ret != -ENOENT && ret != -ENOSYS) {
			if (ret != -EPROBE_DEFER)
			dev_err(dev, "Unable to allocate load GPIO\n");
			return ret;
			}
			gpio->load_gpio = NULL;
			}

			mutex_init(&gpio->lock);

			ret = gpiochip_add_data(&gpio->chip, gpio);
			if (ret < 0) {
			dev_err(dev, "Unable to register gpiochip\n");
			return ret;
			}

			return 0;
			}

			static int pisosr_gpio_remove(struct spi_device *spi)
			{
			struct pisosr_gpio *gpio = spi_get_drvdata(spi);

			gpiochip_remove(&gpio->chip);

			mutex_destroy(&gpio->lock);

			return 0;
			}

			static const struct spi_device_id pisosr_gpio_id_table[] = {
			{ "pisosr-gpio", },
			{ /* sentinel */ }
			};
			MODULE_DEVICE_TABLE(spi, pisosr_gpio_id_table);

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

			static struct spi_driver pisosr_gpio_driver = {
			.driver = {
			.name = "pisosr-gpio",
			.of_match_table = pisosr_gpio_of_match_table,
			},
			.probe = pisosr_gpio_probe,
			.remove = pisosr_gpio_remove,
			.id_table = pisosr_gpio_id_table,
			};
			module_spi_driver(pisosr_gpio_driver);

			MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
			MODULE_DESCRIPTION("SPI Compatible PISO Shift Register GPIO Driver");
			MODULE_LICENSE("GPL v2");