--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for reset key gpio line on MikroTik RB91x board series.
+ * This line is shared between NAND ALE (goes through a latch),
+ * NAND IO7 and reset key. We make 3 virtual gpio lines from the
+ * single physical one:
+ * 1) Capable output one for NAND,
+ * 2) Capable input one for reset key,
+ * 3) And capable output one, aka "key-poll-disable",
+ * for NAND -- to syncronise NAND operation and key polling.
+ *
+ * Copyright (C) 2021 Denis Kalashnikov <denis281089@gmail.com>
+ */
+
+#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>
+#include <linux/delay.h>
+
+#define GPIO_RB91X_KEY_DRIVER_NAME "gpio-rb91x-key"
+
+enum gpio_rb91x_key_gpios {
+ GPIO_RB91X_KEY_NAND,
+ GPIO_RB91X_KEY_POLL,
+ GPIO_RB91X_KEY_PDIS,
+
+ GPIO_RB91X_KEY_NGPIOS,
+};
+
+struct gpio_rb91x_key {
+ struct gpio_chip gc;
+ struct mutex mutex;
+ struct mutex poll_mutex;
+ int polling_disabled;
+ struct gpio_desc *gpio;
+};
+
+static inline struct gpio_rb91x_key *to_gpio_rb91x_key(struct gpio_chip *gc)
+{
+ return container_of(gc, struct gpio_rb91x_key, gc);
+}
+
+static int gpio_rb91x_key_get(struct gpio_chip *gc, unsigned offset)
+{
+ struct gpio_rb91x_key *drvdata = to_gpio_rb91x_key(gc);
+ struct gpio_desc *gpio = drvdata->gpio;
+ int val, bak_val;
+
+ switch (offset) {
+ case GPIO_RB91X_KEY_NAND:
+ mutex_lock(&drvdata->mutex);
+ val = gpiod_get_value_cansleep(gpio);
+ mutex_unlock(&drvdata->mutex);
+ break;
+ case GPIO_RB91X_KEY_PDIS:
+ mutex_lock(&drvdata->mutex);
+ val = drvdata->polling_disabled;
+ mutex_unlock(&drvdata->mutex);
+ break;
+ case GPIO_RB91X_KEY_POLL:
+ mutex_lock(&drvdata->poll_mutex);
+ mutex_lock(&drvdata->mutex);
+ bak_val = gpiod_get_raw_value_cansleep(gpio);
+ gpiod_direction_input(gpio);
+ /*
+ * Without this delay nothing works. Get it
+ * from mikrotik RouterOS linux kernel patches.
+ */
+ udelay(200);
+ val = gpiod_get_raw_value_cansleep(gpio);
+ gpiod_direction_output_raw(gpio, bak_val);
+ mutex_unlock(&drvdata->mutex);
+ mutex_unlock(&drvdata->poll_mutex);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return val;
+}
+
+static int gpio_rb91x_key_direction_input(struct gpio_chip *gc, unsigned offset)
+{
+ switch (offset) {
+ case GPIO_RB91X_KEY_POLL:
+ return 0;
+ default:
+ return -EINVAL;
+ }
+}
+
+static void gpio_rb91x_key_set(struct gpio_chip *gc, unsigned offset, int value)
+{
+ struct gpio_rb91x_key *drvdata = to_gpio_rb91x_key(gc);
+ struct gpio_desc *gpio = drvdata->gpio;
+
+ mutex_lock(&drvdata->mutex);
+
+ switch (offset) {
+ case GPIO_RB91X_KEY_NAND:
+ gpiod_set_raw_value_cansleep(gpio, value);
+ break;
+ case GPIO_RB91X_KEY_PDIS:
+ if (value) {
+ if (!drvdata->polling_disabled) {
+ mutex_lock(&drvdata->poll_mutex);
+ drvdata->polling_disabled = 1;
+ }
+ } else {
+ if (drvdata->polling_disabled) {
+ mutex_unlock(&drvdata->poll_mutex);
+ drvdata->polling_disabled = 0;
+ }
+ }
+ break;
+ default:
+ break;
+ }
+
+ mutex_unlock(&drvdata->mutex);
+}
+
+static int gpio_rb91x_key_direction_output(struct gpio_chip *gc, unsigned offset,
+ int value)
+{
+ switch (offset) {
+ case GPIO_RB91X_KEY_NAND:
+ case GPIO_RB91X_KEY_PDIS:
+ gpio_rb91x_key_set(gc, offset, value);
+ return 0;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int gpio_rb91x_key_probe(struct platform_device *pdev)
+{
+ struct gpio_rb91x_key *drvdata;
+ struct gpio_chip *gc;
+ struct device *dev = &pdev->dev;
+ struct device_node *of_node = dev->of_node;
+ int r;
+
+ drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
+ if (!drvdata)
+ return -ENOMEM;
+
+ mutex_init(&drvdata->mutex);
+ mutex_init(&drvdata->poll_mutex);
+
+ drvdata->gpio = devm_gpiod_get(dev, NULL, GPIOD_OUT_LOW);
+ if (IS_ERR(drvdata->gpio)) {
+ if (PTR_ERR(drvdata->gpio) != -EPROBE_DEFER) {
+ dev_err(dev, "failed to get gpio: %ld\n",
+ PTR_ERR(drvdata->gpio));
+ }
+ return PTR_ERR(drvdata->gpio);
+ }
+
+ gc = &drvdata->gc;
+ gc->label = GPIO_RB91X_KEY_DRIVER_NAME;
+ gc->can_sleep = 1;
+ gc->base = -1;
+ gc->ngpio = GPIO_RB91X_KEY_NGPIOS;
+ gc->get = gpio_rb91x_key_get;
+ gc->set = gpio_rb91x_key_set;
+ gc->direction_output = gpio_rb91x_key_direction_output;
+ gc->direction_input = gpio_rb91x_key_direction_input;
+ gc->of_node = of_node;
+
+ platform_set_drvdata(pdev, drvdata);
+
+ r = gpiochip_add(&drvdata->gc);
+ if (r) {
+ dev_err(dev, "gpiochip_add() failed: %d\n", r);
+ return r;
+ }
+
+ return 0;
+}
+
+static int gpio_rb91x_key_remove(struct platform_device *pdev)
+{
+ struct gpio_rb91x_key *drvdata = platform_get_drvdata(pdev);
+
+ gpiochip_remove(&drvdata->gc);
+ return 0;
+}
+
+static const struct of_device_id gpio_rb91x_key_match[] = {
+ { .compatible = "mikrotik,"GPIO_RB91X_KEY_DRIVER_NAME },
+ {},
+};
+
+MODULE_DEVICE_TABLE(of, gpio_rb91x_key_match);
+
+static struct platform_driver gpio_rb91x_key_driver = {
+ .probe = gpio_rb91x_key_probe,
+ .remove = gpio_rb91x_key_remove,
+ .driver = {
+ .name = GPIO_RB91X_KEY_DRIVER_NAME,
+ .owner = THIS_MODULE,
+ .of_match_table = gpio_rb91x_key_match,
+ },
+};
+
+module_platform_driver(gpio_rb91x_key_driver);
+
+MODULE_DESCRIPTION("Driver for reset key gpio line shared with NAND for MikroTik RB91x board series.");
+MODULE_AUTHOR("Denis Kalashnikov <denis281089@gmail.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" GPIO_RB91X_KEY_DRIVER_NAME);
projects / openwrt / openwrt.git / blobdiff