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/*
* GPIO latch driver
*
* Copyright (C) 2014 Gabor Juhos <juhosg@openwrt.org>
*
* 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/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/platform_data/gpio-latch.h>
struct gpio_latch_chip {
struct gpio_chip gc;
struct mutex mutex;
struct mutex latch_mutex;
bool latch_enabled;
int le_gpio;
bool le_active_low;
int *gpios;
};
static inline struct gpio_latch_chip *to_gpio_latch_chip(struct gpio_chip *gc)
{
return container_of(gc, struct gpio_latch_chip, gc);
}
static void gpio_latch_lock(struct gpio_latch_chip *glc, bool enable)
{
mutex_lock(&glc->mutex);
if (enable)
glc->latch_enabled = true;
if (glc->latch_enabled)
mutex_lock(&glc->latch_mutex);
}
static void gpio_latch_unlock(struct gpio_latch_chip *glc, bool disable)
{
if (glc->latch_enabled)
mutex_unlock(&glc->latch_mutex);
if (disable)
glc->latch_enabled = true;
mutex_unlock(&glc->mutex);
}
static int
gpio_latch_get(struct gpio_chip *gc, unsigned offset)
{
struct gpio_latch_chip *glc = to_gpio_latch_chip(gc);
int ret;
gpio_latch_lock(glc, false);
ret = gpio_get_value(glc->gpios[offset]);
gpio_latch_unlock(glc, false);
return ret;
}
static void
gpio_latch_set(struct gpio_chip *gc, unsigned offset, int value)
{
struct gpio_latch_chip *glc = to_gpio_latch_chip(gc);
bool enable_latch = false;
bool disable_latch = false;
int gpio;
gpio = glc->gpios[offset];
if (gpio == glc->le_gpio) {
enable_latch = value ^ glc->le_active_low;
disable_latch = !enable_latch;
}
gpio_latch_lock(glc, enable_latch);
gpio_set_value(gpio, value);
gpio_latch_unlock(glc, disable_latch);
}
static int
gpio_latch_direction_input(struct gpio_chip *gc, unsigned offset)
{
struct gpio_latch_chip *glc = to_gpio_latch_chip(gc);
int ret;
gpio_latch_lock(glc, false);
ret = gpio_direction_input(glc->gpios[offset]);
gpio_latch_unlock(glc, false);
return ret;
}
static int
gpio_latch_direction_output(struct gpio_chip *gc, unsigned offset, int value)
{
struct gpio_latch_chip *glc = to_gpio_latch_chip(gc);
bool enable_latch = false;
bool disable_latch = false;
int gpio;
int ret;
gpio = glc->gpios[offset];
if (gpio == glc->le_gpio) {
enable_latch = value ^ glc->le_active_low;
disable_latch = !enable_latch;
}
gpio_latch_lock(glc, enable_latch);
ret = gpio_direction_output(gpio, value);
gpio_latch_unlock(glc, disable_latch);
return ret;
}
static int gpio_latch_probe(struct platform_device *pdev)
{
struct gpio_latch_chip *glc;
struct gpio_latch_platform_data *pdata;
struct gpio_chip *gc;
int size;
int ret;
int i;
pdata = dev_get_platdata(&pdev->dev);
if (!pdata)
return -EINVAL;
if (pdata->le_gpio_index >= pdata->num_gpios ||
!pdata->num_gpios ||
!pdata->gpios)
return -EINVAL;
for (i = 0; i < pdata->num_gpios; i++) {
int gpio = pdata->gpios[i];
ret = devm_gpio_request(&pdev->dev, gpio,
GPIO_LATCH_DRIVER_NAME);
if (ret)
return ret;
}
glc = devm_kzalloc(&pdev->dev, sizeof(*glc), GFP_KERNEL);
if (!glc)
return -ENOMEM;
mutex_init(&glc->mutex);
mutex_init(&glc->latch_mutex);
size = pdata->num_gpios * sizeof(glc->gpios[0]);
glc->gpios = devm_kzalloc(&pdev->dev, size , GFP_KERNEL);
if (!glc->gpios)
return -ENOMEM;
memcpy(glc->gpios, pdata->gpios, size);
glc->le_gpio = glc->gpios[pdata->le_gpio_index];
glc->le_active_low = pdata->le_active_low;
gc = &glc->gc;
gc->label = GPIO_LATCH_DRIVER_NAME;
gc->base = pdata->base;
gc->can_sleep = true;
gc->ngpio = pdata->num_gpios;
gc->get = gpio_latch_get;
gc->set = gpio_latch_set;
gc->direction_input = gpio_latch_direction_input,
gc->direction_output = gpio_latch_direction_output;
platform_set_drvdata(pdev, glc);
ret = gpiochip_add(&glc->gc);
if (ret)
return ret;
return 0;
}
static int gpio_latch_remove(struct platform_device *pdev)
{
struct gpio_latch_chip *glc = platform_get_drvdata(pdev);
return gpiochip_remove(&glc->gc);;
}
static struct platform_driver gpio_latch_driver = {
.probe = gpio_latch_probe,
.remove = gpio_latch_remove,
.driver = {
.name = GPIO_LATCH_DRIVER_NAME,
.owner = THIS_MODULE,
},
};
static int __init gpio_latch_init(void)
{
return platform_driver_register(&gpio_latch_driver);
}
postcore_initcall(gpio_latch_init);
MODULE_DESCRIPTION("GPIO latch driver");
MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" GPIO_LATCH_DRIVER_NAME);
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