/*
 * Watchdog driver for the wm8350
 *
 * Copyright (C) 2007, 2008 Wolfson Microelectronics <linux@wolfsonmicro.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/uaccess.h>
#include <linux/mfd/wm8350/core.h>

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

static unsigned long wm8350_wdt_users;
static struct miscdevice wm8350_wdt_miscdev;
static int wm8350_wdt_expect_close;
static DEFINE_MUTEX(wdt_mutex);

static struct {
        int time;  /* Seconds */
        u16 val;   /* To be set in WM8350_SYSTEM_CONTROL_2 */
} wm8350_wdt_cfgs[] = {
        { 1, 0x02 },
        { 2, 0x04 },
        { 4, 0x05 },
};

static struct wm8350 *get_wm8350(void)
{
        return dev_get_drvdata(wm8350_wdt_miscdev.parent);
}

static int wm8350_wdt_set_timeout(struct wm8350 *wm8350, u16 value)
{
        int ret;
        u16 reg;

        mutex_lock(&wdt_mutex);
        wm8350_reg_unlock(wm8350);

        reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
        reg &= ~WM8350_WDOG_TO_MASK;
        reg |= value;
        ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);

        wm8350_reg_lock(wm8350);
        mutex_unlock(&wdt_mutex);

        return ret;
}

static int wm8350_wdt_start(struct wm8350 *wm8350)
{
        int ret;
        u16 reg;

        mutex_lock(&wdt_mutex);
        wm8350_reg_unlock(wm8350);

        reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
        reg &= ~WM8350_WDOG_MODE_MASK;
        reg |= 0x20;
        ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);

        wm8350_reg_lock(wm8350);
        mutex_unlock(&wdt_mutex);

        return ret;
}

static int wm8350_wdt_stop(struct wm8350 *wm8350)
{
        int ret;
        u16 reg;

        mutex_lock(&wdt_mutex);
        wm8350_reg_unlock(wm8350);

        reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
        reg &= ~WM8350_WDOG_MODE_MASK;
        ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);

        wm8350_reg_lock(wm8350);
        mutex_unlock(&wdt_mutex);

        return ret;
}

static int wm8350_wdt_kick(struct wm8350 *wm8350)
{
        int ret;
        u16 reg;

        mutex_lock(&wdt_mutex);

        reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
        ret = wm8350_reg_write(wm8350, WM8350_SYSTEM_CONTROL_2, reg);

        mutex_unlock(&wdt_mutex);

        return ret;
}

static int wm8350_wdt_open(struct inode *inode, struct file *file)
{
        struct wm8350 *wm8350 = get_wm8350();
        int ret;

        if (!wm8350)
                return -ENODEV;

        if (test_and_set_bit(0, &wm8350_wdt_users))
                return -EBUSY;

        ret = wm8350_wdt_start(wm8350);
        if (ret != 0)
                return ret;

        return nonseekable_open(inode, file);
}

static int wm8350_wdt_release(struct inode *inode, struct file *file)
{
        struct wm8350 *wm8350 = get_wm8350();

        if (wm8350_wdt_expect_close)
                wm8350_wdt_stop(wm8350);
        else {
                dev_warn(wm8350->dev, "Watchdog device closed uncleanly\n");
                wm8350_wdt_kick(wm8350);
        }

        clear_bit(0, &wm8350_wdt_users);

        return 0;
}

static ssize_t wm8350_wdt_write(struct file *file,
                                const char __user *data, size_t count,
                                loff_t *ppos)
{
        struct wm8350 *wm8350 = get_wm8350();
        size_t i;

        if (count) {
                wm8350_wdt_kick(wm8350);

                if (!nowayout) {
                        /* In case it was set long ago */
                        wm8350_wdt_expect_close = 0;

                        /* scan to see whether or not we got the magic
                           character */
                        for (i = 0; i != count; i++) {
                                char c;
                                if (get_user(c, data + i))
                                        return -EFAULT;
                                if (c == 'V')
                                        wm8350_wdt_expect_close = 42;
                        }
                }
        }
        return count;
}

static struct watchdog_info ident = {
        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
        .identity = "WM8350 Watchdog",
};

static long wm8350_wdt_ioctl(struct file *file, unsigned int cmd,
                             unsigned long arg)
{
        struct wm8350 *wm8350 = get_wm8350();
        int ret = -ENOTTY, time, i;
        void __user *argp = (void __user *)arg;
        int __user *p = argp;
        u16 reg;

        switch (cmd) {
        case WDIOC_GETSUPPORT:
                ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
                break;

        case WDIOC_GETSTATUS:
        case WDIOC_GETBOOTSTATUS:
                ret = put_user(0, p);
                break;

        case WDIOC_SETOPTIONS:
        {
                int options;

                if (get_user(options, p))
                        return -EFAULT;

                ret = -EINVAL;

                /* Setting both simultaneously means at least one must fail */
                if (options == WDIOS_DISABLECARD)
                        ret = wm8350_wdt_start(wm8350);

                if (options == WDIOS_ENABLECARD)
                        ret = wm8350_wdt_stop(wm8350);
                break;
        }

        case WDIOC_KEEPALIVE:
                ret = wm8350_wdt_kick(wm8350);
                break;

        case WDIOC_SETTIMEOUT:
                ret = get_user(time, p);
                if (ret)
                        break;

                if (time == 0) {
                        if (nowayout)
                                ret = -EINVAL;
                        else
                                wm8350_wdt_stop(wm8350);
                        break;
                }

                for (i = 0; i < ARRAY_SIZE(wm8350_wdt_cfgs); i++)
                        if (wm8350_wdt_cfgs[i].time == time)
                                break;
                if (i == ARRAY_SIZE(wm8350_wdt_cfgs))
                        ret = -EINVAL;
                else
                        ret = wm8350_wdt_set_timeout(wm8350,
                                                     wm8350_wdt_cfgs[i].val);
                break;

        case WDIOC_GETTIMEOUT:
                reg = wm8350_reg_read(wm8350, WM8350_SYSTEM_CONTROL_2);
                reg &= WM8350_WDOG_TO_MASK;
                for (i = 0; i < ARRAY_SIZE(wm8350_wdt_cfgs); i++)
                        if (wm8350_wdt_cfgs[i].val == reg)
                                break;
                if (i == ARRAY_SIZE(wm8350_wdt_cfgs)) {
                        dev_warn(wm8350->dev,
                                 "Unknown watchdog configuration: %x\n", reg);
                        ret = -EINVAL;
                } else
                        ret = put_user(wm8350_wdt_cfgs[i].time, p);

        }

        return ret;
}

static const struct file_operations wm8350_wdt_fops = {
        .owner = THIS_MODULE,
        .llseek = no_llseek,
        .write = wm8350_wdt_write,
        .unlocked_ioctl = wm8350_wdt_ioctl,
        .open = wm8350_wdt_open,
        .release = wm8350_wdt_release,
};

static struct miscdevice wm8350_wdt_miscdev = {
        .minor = WATCHDOG_MINOR,
        .name = "watchdog",
        .fops = &wm8350_wdt_fops,
};

static int __devinit wm8350_wdt_probe(struct platform_device *pdev)
{
        struct wm8350 *wm8350 = platform_get_drvdata(pdev);

        if (!wm8350) {
                dev_err(wm8350->dev, "No driver data supplied\n");
                return -ENODEV;
        }

        /* Default to 4s timeout */
        wm8350_wdt_set_timeout(wm8350, 0x05);

        wm8350_wdt_miscdev.parent = &pdev->dev;

        return misc_register(&wm8350_wdt_miscdev);
}

static int __devexit wm8350_wdt_remove(struct platform_device *pdev)
{
        misc_deregister(&wm8350_wdt_miscdev);

        return 0;
}

static struct platform_driver wm8350_wdt_driver = {
        .probe = wm8350_wdt_probe,
        .remove = __devexit_p(wm8350_wdt_remove),
        .driver = {
                .name = "wm8350-wdt",
        },
};

static int __init wm8350_wdt_init(void)
{
        return platform_driver_register(&wm8350_wdt_driver);
}
module_init(wm8350_wdt_init);

static void __exit wm8350_wdt_exit(void)
{
        platform_driver_unregister(&wm8350_wdt_driver);
}
module_exit(wm8350_wdt_exit);

MODULE_AUTHOR("Mark Brown");
MODULE_DESCRIPTION("WM8350 Watchdog");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:wm8350-wdt");