// SPDX-License-Identifier: GPL-2.0+
/*
 * Retu watchdog driver
 *
 * Copyright (C) 2004, 2005 Nokia Corporation
 *
 * Based on code written by Amit Kucheria and Michael Buesch.
 * Rewritten by Aaro Koskinen.
 */

#include <linux/devm-helpers.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mfd/retu.h>
#include <linux/watchdog.h>
#include <linux/platform_device.h>

/* Watchdog timer values in seconds */
#define RETU_WDT_MAX_TIMER 63

struct retu_wdt_dev {
 struct retu_dev  *rdev;
 struct device  *dev;
 struct delayed_work ping_work;
};

/*
 * Since Retu watchdog cannot be disabled in hardware, we must kick it
 * with a timer until userspace watchdog software takes over. If
 * CONFIG_WATCHDOG_NOWAYOUT is set, we never start the feeding.
 */
static void retu_wdt_ping_enable(struct retu_wdt_dev *wdev)
{
 retu_write(wdev->rdev, RETU_REG_WATCHDOG, RETU_WDT_MAX_TIMER);
 schedule_delayed_work(&wdev->ping_work,
   round_jiffies_relative(RETU_WDT_MAX_TIMER * HZ / 2));
}

static void retu_wdt_ping_disable(struct retu_wdt_dev *wdev)
{
 retu_write(wdev->rdev, RETU_REG_WATCHDOG, RETU_WDT_MAX_TIMER);
 cancel_delayed_work_sync(&wdev->ping_work);
}

static void retu_wdt_ping_work(struct work_struct *work)
{
 struct retu_wdt_dev *wdev = container_of(to_delayed_work(work),
      struct retu_wdt_dev, ping_work);
 retu_wdt_ping_enable(wdev);
}

static int retu_wdt_start(struct watchdog_device *wdog)
{
 struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);

 retu_wdt_ping_disable(wdev);

 return retu_write(wdev->rdev, RETU_REG_WATCHDOG, wdog->timeout);
}

static int retu_wdt_stop(struct watchdog_device *wdog)
{
 struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);

 retu_wdt_ping_enable(wdev);

 return 0;
}

static int retu_wdt_ping(struct watchdog_device *wdog)
{
 struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);

 return retu_write(wdev->rdev, RETU_REG_WATCHDOG, wdog->timeout);
}

static int retu_wdt_set_timeout(struct watchdog_device *wdog,
    unsigned int timeout)
{
 struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);

 wdog->timeout = timeout;
 return retu_write(wdev->rdev, RETU_REG_WATCHDOG, wdog->timeout);
}

static const struct watchdog_info retu_wdt_info = {
 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 .identity = "Retu watchdog",
};

static const struct watchdog_ops retu_wdt_ops = {
 .owner  = THIS_MODULE,
 .start  = retu_wdt_start,
 .stop  = retu_wdt_stop,
 .ping  = retu_wdt_ping,
 .set_timeout = retu_wdt_set_timeout,
};

static int retu_wdt_probe(struct platform_device *pdev)
{
 struct retu_dev *rdev = dev_get_drvdata(pdev->dev.parent);
 bool nowayout = WATCHDOG_NOWAYOUT;
 struct watchdog_device *retu_wdt;
 struct retu_wdt_dev *wdev;
 int ret;

 retu_wdt = devm_kzalloc(&pdev->dev, sizeof(*retu_wdt), GFP_KERNEL);
 if (!retu_wdt)
  return -ENOMEM;

 wdev = devm_kzalloc(&pdev->dev, sizeof(*wdev), GFP_KERNEL);
 if (!wdev)
  return -ENOMEM;

 retu_wdt->info  = &retu_wdt_info;
 retu_wdt->ops  = &retu_wdt_ops;
 retu_wdt->timeout = RETU_WDT_MAX_TIMER;
 retu_wdt->min_timeout = 0;
 retu_wdt->max_timeout = RETU_WDT_MAX_TIMER;
 retu_wdt->parent = &pdev->dev;

 watchdog_set_drvdata(retu_wdt, wdev);
 watchdog_set_nowayout(retu_wdt, nowayout);

 wdev->rdev  = rdev;
 wdev->dev  = &pdev->dev;

 ret = devm_delayed_work_autocancel(&pdev->dev, &wdev->ping_work,
        retu_wdt_ping_work);
 if (ret)
  return ret;

 ret = devm_watchdog_register_device(&pdev->dev, retu_wdt);
 if (ret < 0)
  return ret;

 if (nowayout)
  retu_wdt_ping(retu_wdt);
 else
  retu_wdt_ping_enable(wdev);

 return 0;
}

static struct platform_driver retu_wdt_driver = {
 .probe  = retu_wdt_probe,
 .driver  = {
  .name = "retu-wdt",
 },
};
module_platform_driver(retu_wdt_driver);

MODULE_ALIAS("platform:retu-wdt");
MODULE_DESCRIPTION("Retu watchdog");
MODULE_AUTHOR("Amit Kucheria");
MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
MODULE_LICENSE("GPL");