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// 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);
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