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Release 4.14 drivers/gpio/gpio-pisosr.c

Directory: drivers/gpio
/*
 * 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_cansleep(gpio->load_gpio, 1); udelay(1); /* registers load time (~10ns) */ gpiod_set_value_cansleep(gpio->load_gpio, 0); udelay(1); /* registers recovery time (~5ns) */ } ret = spi_read(gpio->spi, gpio->buffer, gpio->buffer_size); mutex_unlock(&gpio->lock); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Andrew F. Davis8596.59%133.33%
Axel Lin22.27%133.33%
Sudip Mukherjee11.14%133.33%
Total88100.00%3100.00%


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

Contributors

PersonTokensPropCommitsCommitProp
Andrew F. Davis18100.00%1100.00%
Total18100.00%1100.00%


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

Contributors

PersonTokensPropCommitsCommitProp
Andrew F. Davis18100.00%1100.00%
Total18100.00%1100.00%


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

Contributors

PersonTokensPropCommitsCommitProp
Andrew F. Davis22100.00%1100.00%
Total22100.00%1100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Andrew F. Davis50100.00%1100.00%
Total50100.00%1100.00%

static const 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_optional(dev, "load", GPIOD_OUT_LOW); if (IS_ERR(gpio->load_gpio)) { ret = PTR_ERR(gpio->load_gpio); if (ret != -EPROBE_DEFER) dev_err(dev, "Unable to allocate load GPIO\n"); return ret; } 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; }

Contributors

PersonTokensPropCommitsCommitProp
Andrew F. Davis22799.56%150.00%
Axel Lin10.44%150.00%
Total228100.00%2100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Andrew F. Davis40100.00%1100.00%
Total40100.00%1100.00%

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");

Overall Contributors

PersonTokensPropCommitsCommitProp
Andrew F. Davis67599.26%120.00%
Axel Lin30.44%240.00%
Julia Lawall10.15%120.00%
Sudip Mukherjee10.15%120.00%
Total680100.00%5100.00%
Directory: drivers/gpio
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