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authorGabor Juhos <juhosg@openwrt.org>2014-02-22 18:05:29 +0000
committerGabor Juhos <juhosg@openwrt.org>2014-02-22 18:05:29 +0000
commitab08c4048738cba717aa3dd33f3c75f94f5948a3 (patch)
tree9907347b9858bbe5991b9a7afc80c6eb28ca06bc /target/linux/ar71xx/files/drivers
parentbe18a3849b613d956edd0d3d83b11de26b83e6ab (diff)
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ar71xx: add a generic GPIO latch driver
It will be used for the Mikrotik boards. Signed-off-by: Gabor Juhos <juhosg@openwrt.org> SVN-Revision: 39697
Diffstat (limited to 'target/linux/ar71xx/files/drivers')
-rw-r--r--target/linux/ar71xx/files/drivers/gpio/gpio-latch.c219
1 files changed, 219 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 0000000000..1efa1a1e13
--- /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);