diff options
Diffstat (limited to 'target/linux/ar71xx/files/drivers/gpio/gpio-latch.c')
| -rw-r--r-- | target/linux/ar71xx/files/drivers/gpio/gpio-latch.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/target/linux/ar71xx/files/drivers/gpio/gpio-latch.c b/target/linux/ar71xx/files/drivers/gpio/gpio-latch.c new file mode 100644 index 0000000..d911f6a --- /dev/null +++ b/target/linux/ar71xx/files/drivers/gpio/gpio-latch.c @@ -0,0 +1,220 @@ +/* + * 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); + + gpiochip_remove(&glc->gc); + return 0; +} + + +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); |