gpio: Add driver for SPI serializers (df6df93c) · Commits · 戴 / test

drivers/gpio/Kconfig

+6 −0

Original line number	Diff line number	Diff line
		@@ -1048,6 +1048,12 @@ config GPIO_MC33880
		SPI driver for Freescale MC33880 high-side/low-side switch.
		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

		menu "SPI or I2C GPIO expanders"

drivers/gpio/Makefile

+1 −0

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

drivers/gpio/gpio-pisosr.c

0 → 100644

+188 −0

Original line number	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");

Admin message