// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  MEN 14F021P00 Board Management Controller (BMC) Watchdog Driver.
 *
 *  Copyright (C) 2014 MEN Mikro Elektronik Nuernberg GmbH
 */

#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/watchdog.h>
#include <linux/platform_device.h>
#include <linux/i2c.h>

#define DEVNAME "menf21bmc_wdt"

#define BMC_CMD_WD_ON           0x11
#define BMC_CMD_WD_OFF          0x12
#define BMC_CMD_WD_TRIG         0x13
#define BMC_CMD_WD_TIME         0x14
#define BMC_CMD_WD_STATE        0x17
#define BMC_WD_OFF_VAL          0x69
#define BMC_CMD_RST_RSN         0x92

#define BMC_WD_TIMEOUT_MIN      1       /* in sec */
#define BMC_WD_TIMEOUT_MAX      6553    /* in sec */

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) ")");

struct menf21bmc_wdt {
        struct watchdog_device wdt;
        struct i2c_client *i2c_client;
};

static int menf21bmc_wdt_set_bootstatus(struct menf21bmc_wdt *data)
{
        int rst_rsn;

        rst_rsn = i2c_smbus_read_byte_data(data->i2c_client, BMC_CMD_RST_RSN);
        if (rst_rsn < 0)
                return rst_rsn;

        if (rst_rsn == 0x02)
                data->wdt.bootstatus |= WDIOF_CARDRESET;
        else if (rst_rsn == 0x05)
                data->wdt.bootstatus |= WDIOF_EXTERN1;
        else if (rst_rsn == 0x06)
                data->wdt.bootstatus |= WDIOF_EXTERN2;
        else if (rst_rsn == 0x0A)
                data->wdt.bootstatus |= WDIOF_POWERUNDER;

        return 0;
}

static int menf21bmc_wdt_start(struct watchdog_device *wdt)
{
        struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);

        return i2c_smbus_write_byte(drv_data->i2c_client, BMC_CMD_WD_ON);
}

static int menf21bmc_wdt_stop(struct watchdog_device *wdt)
{
        struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);

        return i2c_smbus_write_byte_data(drv_data->i2c_client,
                                         BMC_CMD_WD_OFF, BMC_WD_OFF_VAL);
}

static int
menf21bmc_wdt_settimeout(struct watchdog_device *wdt, unsigned int timeout)
{
        int ret;
        struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);

        /*
         *  BMC Watchdog does have a resolution of 100ms.
         *  Watchdog API defines the timeout in seconds, so we have to
         *  multiply the value.
         */
        ret = i2c_smbus_write_word_data(drv_data->i2c_client,
                                        BMC_CMD_WD_TIME, timeout * 10);
        if (ret < 0)
                return ret;

        wdt->timeout = timeout;

        return 0;
}

static int menf21bmc_wdt_ping(struct watchdog_device *wdt)
{
        struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);

        return i2c_smbus_write_byte(drv_data->i2c_client, BMC_CMD_WD_TRIG);
}

static const struct watchdog_info menf21bmc_wdt_info = {
        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
        .identity = DEVNAME,
};

static const struct watchdog_ops menf21bmc_wdt_ops = {
        .owner          = THIS_MODULE,
        .start          = menf21bmc_wdt_start,
        .stop           = menf21bmc_wdt_stop,
        .ping           = menf21bmc_wdt_ping,
        .set_timeout    = menf21bmc_wdt_settimeout,
};

static int menf21bmc_wdt_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        int ret, bmc_timeout;
        struct menf21bmc_wdt *drv_data;
        struct i2c_client *i2c_client = to_i2c_client(dev->parent);

        drv_data = devm_kzalloc(dev, sizeof(struct menf21bmc_wdt), GFP_KERNEL);
        if (!drv_data)
                return -ENOMEM;

        drv_data->wdt.ops = &menf21bmc_wdt_ops;
        drv_data->wdt.info = &menf21bmc_wdt_info;
        drv_data->wdt.min_timeout = BMC_WD_TIMEOUT_MIN;
        drv_data->wdt.max_timeout = BMC_WD_TIMEOUT_MAX;
        drv_data->wdt.parent = dev;
        drv_data->i2c_client = i2c_client;

        /*
         * Get the current wdt timeout value from the BMC because
         * the BMC will save the value set before if the system restarts.
         */
        bmc_timeout = i2c_smbus_read_word_data(drv_data->i2c_client,
                                               BMC_CMD_WD_TIME);
        if (bmc_timeout < 0) {
                dev_err(dev, "failed to get current WDT timeout\n");
                return bmc_timeout;
        }

        watchdog_init_timeout(&drv_data->wdt, bmc_timeout / 10, dev);
        watchdog_set_nowayout(&drv_data->wdt, nowayout);
        watchdog_set_drvdata(&drv_data->wdt, drv_data);
        platform_set_drvdata(pdev, drv_data);

        ret = menf21bmc_wdt_set_bootstatus(drv_data);
        if (ret < 0) {
                dev_err(dev, "failed to set Watchdog bootstatus\n");
                return ret;
        }

        ret = devm_watchdog_register_device(dev, &drv_data->wdt);
        if (ret)
                return ret;

        dev_info(dev, "MEN 14F021P00 BMC Watchdog device enabled\n");

        return 0;
}

static void menf21bmc_wdt_shutdown(struct platform_device *pdev)
{
        struct menf21bmc_wdt *drv_data = platform_get_drvdata(pdev);

        i2c_smbus_write_word_data(drv_data->i2c_client,
                                  BMC_CMD_WD_OFF, BMC_WD_OFF_VAL);
}

static struct  platform_driver menf21bmc_wdt = {
        .driver         = {
                .name   = DEVNAME,
        },
        .probe          = menf21bmc_wdt_probe,
        .shutdown       = menf21bmc_wdt_shutdown,
};

module_platform_driver(menf21bmc_wdt);

MODULE_DESCRIPTION("MEN 14F021P00 BMC Watchdog driver");
MODULE_AUTHOR("Andreas Werner <andreas.werner@men.de>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:menf21bmc_wdt");