ar71xx: add a generic GPIO latch driver

[openwrt.git] / target / linux / ar71xx / files / drivers / gpio / gpio-latch.c

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 (file)
index 0000000..1efa1a1
--- /dev/null
+++ b/target/linux/ar71xx/files/drivers/gpio/gpio-latch.c
@@ -0,0 +1,219 @@
+/*
+ *  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);