// SPDX-License-Identifier: GPL-2.0+
/*
 * Watchdog driver for the A21 VME CPU Boards
 *
 * Copyright (C) 2013 MEN Mikro Elektronik Nuernberg GmbH
 *
 */
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/uaccess.h>
#include <linux/gpio/consumer.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#include <linux/of.h>

#define NUM_GPIOS 6

enum a21_wdt_gpios {
        GPIO_WD_ENAB,
        GPIO_WD_FAST,
        GPIO_WD_TRIG,
        GPIO_WD_RST0,
        GPIO_WD_RST1,
        GPIO_WD_RST2,
};

struct a21_wdt_drv {
        struct watchdog_device wdt;
        struct gpio_desc *gpios[NUM_GPIOS];
};

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
                            __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

static unsigned int a21_wdt_get_bootstatus(struct a21_wdt_drv *drv)
{
        int reset = 0;

        reset |= gpiod_get_value(drv->gpios[GPIO_WD_RST0]) ? (1 << 0) : 0;
        reset |= gpiod_get_value(drv->gpios[GPIO_WD_RST1]) ? (1 << 1) : 0;
        reset |= gpiod_get_value(drv->gpios[GPIO_WD_RST2]) ? (1 << 2) : 0;

        return reset;
}

static int a21_wdt_start(struct watchdog_device *wdt)
{
        struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);

        gpiod_set_value(drv->gpios[GPIO_WD_ENAB], 1);

        return 0;
}

static int a21_wdt_stop(struct watchdog_device *wdt)
{
        struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);

        gpiod_set_value(drv->gpios[GPIO_WD_ENAB], 0);

        return 0;
}

static int a21_wdt_ping(struct watchdog_device *wdt)
{
        struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);

        gpiod_set_value(drv->gpios[GPIO_WD_TRIG], 0);
        ndelay(10);
        gpiod_set_value(drv->gpios[GPIO_WD_TRIG], 1);

        return 0;
}

static int a21_wdt_set_timeout(struct watchdog_device *wdt,
                               unsigned int timeout)
{
        struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);

        if (timeout != 1 && timeout != 30) {
                dev_err(wdt->parent, "Only 1 and 30 allowed as timeout\n");
                return -EINVAL;
        }

        if (timeout == 30 && wdt->timeout == 1) {
                dev_err(wdt->parent,
                        "Transition from fast to slow mode not allowed\n");
                return -EINVAL;
        }

        if (timeout == 1)
                gpiod_set_value(drv->gpios[GPIO_WD_FAST], 1);
        else
                gpiod_set_value(drv->gpios[GPIO_WD_FAST], 0);

        wdt->timeout = timeout;

        return 0;
}

static const struct watchdog_info a21_wdt_info = {
        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
        .identity = "MEN A21 Watchdog",
};

static const struct watchdog_ops a21_wdt_ops = {
        .owner = THIS_MODULE,
        .start = a21_wdt_start,
        .stop = a21_wdt_stop,
        .ping = a21_wdt_ping,
        .set_timeout = a21_wdt_set_timeout,
};

static struct watchdog_device a21_wdt = {
        .info = &a21_wdt_info,
        .ops = &a21_wdt_ops,
        .min_timeout = 1,
        .max_timeout = 30,
};

static int a21_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct a21_wdt_drv *drv;
        unsigned int reset = 0;
        int num_gpios;
        int ret;
        int i;

        drv = devm_kzalloc(dev, sizeof(struct a21_wdt_drv), GFP_KERNEL);
        if (!drv)
                return -ENOMEM;

        num_gpios = gpiod_count(dev, NULL);
        if (num_gpios != NUM_GPIOS) {
                dev_err(dev, "gpios DT property wrong, got %d want %d",
                        num_gpios, NUM_GPIOS);
                return -ENODEV;
        }

        /* Request the used GPIOs */
        for (i = 0; i < num_gpios; i++) {
                enum gpiod_flags gflags;

                if (i < GPIO_WD_RST0)
                        gflags = GPIOD_ASIS;
                else
                        gflags = GPIOD_IN;
                drv->gpios[i] = devm_gpiod_get_index(dev, NULL, i, gflags);
                if (IS_ERR(drv->gpios[i]))
                        return PTR_ERR(drv->gpios[i]);

                gpiod_set_consumer_name(drv->gpios[i], "MEN A21 Watchdog");

                /*
                 * Retrieve the initial value from the GPIOs that should be
                 * output, then set up the line as output with that value.
                 */
                if (i < GPIO_WD_RST0) {
                        int val;

                        val = gpiod_get_value(drv->gpios[i]);
                        gpiod_direction_output(drv->gpios[i], val);
                }
        }

        watchdog_init_timeout(&a21_wdt, 30, dev);
        watchdog_set_nowayout(&a21_wdt, nowayout);
        watchdog_set_drvdata(&a21_wdt, drv);
        a21_wdt.parent = dev;

        reset = a21_wdt_get_bootstatus(drv);
        if (reset == 2)
                a21_wdt.bootstatus |= WDIOF_EXTERN1;
        else if (reset == 4)
                a21_wdt.bootstatus |= WDIOF_CARDRESET;
        else if (reset == 5)
                a21_wdt.bootstatus |= WDIOF_POWERUNDER;
        else if (reset == 7)
                a21_wdt.bootstatus |= WDIOF_EXTERN2;

        drv->wdt = a21_wdt;
        dev_set_drvdata(dev, drv);

        ret = devm_watchdog_register_device(dev, &a21_wdt);
        if (ret)
                return ret;

        dev_info(dev, "MEN A21 watchdog timer driver enabled\n");

        return 0;
}

static void a21_wdt_shutdown(struct platform_device *pdev)
{
        struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);

        gpiod_set_value(drv->gpios[GPIO_WD_ENAB], 0);
}

static const struct of_device_id a21_wdt_ids[] = {
        { .compatible = "men,a021-wdt" },
        { },
};
MODULE_DEVICE_TABLE(of, a21_wdt_ids);

static struct platform_driver a21_wdt_driver = {
        .probe = a21_wdt_probe,
        .shutdown = a21_wdt_shutdown,
        .driver = {
                .name = "a21-watchdog",
                .of_match_table = a21_wdt_ids,
        },
};

module_platform_driver(a21_wdt_driver);

MODULE_AUTHOR("MEN Mikro Elektronik");
MODULE_DESCRIPTION("MEN A21 Watchdog");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:a21-watchdog");