ath79: add gpio-latch driver for MikroTik RouterBOARDs

[openwrt/staging/xback.git] / target / linux / ath79 / files / drivers / gpio / gpio-latch.c

diff --git a/target/linux/ath79/files/drivers/gpio/gpio-latch.c b/target/linux/ath79/files/drivers/gpio/gpio-latch.c
new file mode 100644 (file)
index 0000000..f3545a6
--- /dev/null
+++ b/target/linux/ath79/files/drivers/gpio/gpio-latch.c
@@ -0,0 +1,203 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  GPIO latch driver
+ *
+ *  Copyright (C) 2014 Gabor Juhos <juhosg@openwrt.org>
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/platform_device.h>
+#include <linux/of_platform.h>
+#include <linux/of_gpio.h>
+
+#define GPIO_LATCH_DRIVER_NAME  "gpio-latch"
+#define GPIO_LATCH_LINES 9
+
+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;
+       struct gpio_desc *gpios[GPIO_LATCH_LINES];
+};
+
+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 = gpiod_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;
+
+       if (offset == glc->le_gpio) {
+               enable_latch = value ^ glc->le_active_low;
+               disable_latch = !enable_latch;
+       }
+
+       gpio_latch_lock(glc, enable_latch);
+       gpiod_set_raw_value(glc->gpios[offset], value);
+       gpio_latch_unlock(glc, disable_latch);
+}
+
+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 ret;
+
+       if (offset == glc->le_gpio) {
+               enable_latch = value ^ glc->le_active_low;
+               disable_latch = !enable_latch;
+       }
+
+       gpio_latch_lock(glc, enable_latch);
+       ret = gpiod_direction_output_raw(glc->gpios[offset], 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_chip *gc;
+       struct device *dev = &pdev->dev;
+       struct device_node *of_node = dev->of_node;
+       int i, n;
+
+       glc = devm_kzalloc(dev, sizeof(*glc), GFP_KERNEL);
+       if (!glc)
+               return -ENOMEM;
+
+       mutex_init(&glc->mutex);
+       mutex_init(&glc->latch_mutex);
+
+       n = gpiod_count(dev, NULL);
+       if (n <= 0) {
+               dev_err(dev, "failed to get gpios: %d\n", n);
+               return n;
+       } else if (n != GPIO_LATCH_LINES) {
+               dev_err(dev, "expected %d gpios\n", GPIO_LATCH_LINES);
+               return -EINVAL;
+       }
+
+       for (i = 0; i < n; i++) {
+               glc->gpios[i] = devm_gpiod_get_index_optional(dev, NULL, i,
+                       GPIOD_OUT_LOW);
+               if (IS_ERR(glc->gpios[i])) {
+                       dev_err(dev, "failed to get gpio %d: %d\n", i,
+                               PTR_ERR(glc->gpios[i]));
+                       return PTR_ERR(glc->gpios[i]);
+               }
+       }
+
+       glc->le_gpio = 8;
+       glc->le_active_low = gpiod_is_active_low(glc->gpios[glc->le_gpio]);
+
+       if (!glc->gpios[glc->le_gpio]) {
+               dev_err(dev, "missing required latch-enable gpio %d\n",
+                       glc->le_gpio);
+               return -EINVAL;
+       }
+
+       gc = &glc->gc;
+       gc->label = GPIO_LATCH_DRIVER_NAME;
+       gc->can_sleep = true;
+       gc->base = -1;
+       gc->ngpio = GPIO_LATCH_LINES;
+       gc->get = gpio_latch_get;
+       gc->set = gpio_latch_set;
+       gc->direction_output = gpio_latch_direction_output;
+       gc->of_node = of_node;
+
+       platform_set_drvdata(pdev, glc);
+
+       i = gpiochip_add(&glc->gc);
+       if (i) {
+               dev_err(dev, "gpiochip_add() failed: %d\n", i);
+               return i;
+       }
+
+       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 const struct of_device_id gpio_latch_match[] = {
+       { .compatible = GPIO_LATCH_DRIVER_NAME },
+       {},
+};
+
+MODULE_DEVICE_TABLE(of, gpio_latch_match);
+
+static struct platform_driver gpio_latch_driver = {
+       .probe = gpio_latch_probe,
+       .remove = gpio_latch_remove,
+       .driver = {
+               .name = GPIO_LATCH_DRIVER_NAME,
+               .owner = THIS_MODULE,
+               .of_match_table = gpio_latch_match,
+       },
+};
+
+module_platform_driver(gpio_latch_driver);
+
+MODULE_DESCRIPTION("GPIO latch driver");
+MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
+MODULE_AUTHOR("Denis Kalashnikov <denis281089@gmail.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" GPIO_LATCH_DRIVER_NAME);