Initial commit

target/linux/ath79/files/drivers/gpio/gpio-rb91x-key.c

@@ -0,0 +1,194 @@
+// 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 int gpio_rb91x_key_get(struct gpio_chip *gc, unsigned offset)
+{
+	struct gpio_rb91x_key *drvdata = gpiochip_get_data(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 = gpiochip_get_data(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;
+	int err;
+
+	drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
+	if (!drvdata)
+		return -ENOMEM;
+
+	err = devm_mutex_init(dev, &drvdata->mutex);
+	if (err)
+		return err;
+
+	err = devm_mutex_init(dev, &drvdata->poll_mutex);
+	if (err)
+		return err;
+
+	drvdata->gpio = devm_gpiod_get(dev, NULL, GPIOD_OUT_LOW);
+	if (IS_ERR(drvdata->gpio))
+		return dev_err_probe(dev, PTR_ERR(drvdata->gpio), "failed to get gpio");
+
+	gc = &drvdata->gc;
+	gc->label = GPIO_RB91X_KEY_DRIVER_NAME;
+	gc->parent = dev;
+	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;
+
+	return devm_gpiochip_add_data(dev, gc, drvdata);
+}
+
+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,
+	.driver = {
+		.name = GPIO_RB91X_KEY_DRIVER_NAME,
+		.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);