/*
 * omap_wdt.c
 *
 * Watchdog driver for the TI OMAP 16xx & 24xx/34xx 32KHz (non-secure) watchdog
 *
 * Author: MontaVista Software, Inc.
 *       <gdavis@mvista.com> or <source@mvista.com>
 *
 * 2003 (c) MontaVista Software, Inc. This file is licensed under the
 * terms of the GNU General Public License version 2. This program is
 * licensed "as is" without any warranty of any kind, whether express
 * or implied.
 *
 * History:
 *
 * 20030527: George G. Davis <gdavis@mvista.com>
 *      Initially based on linux-2.4.19-rmk7-pxa1/drivers/char/sa1100_wdt.c
 *      (c) Copyright 2000 Oleg Drokin <green@crimea.edu>
 *      Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>
 *
 * Copyright (c) 2004 Texas Instruments.
 *      1. Modified to support OMAP1610 32-KHz watchdog timer
 *      2. Ported to 2.6 kernel
 *
 * Copyright (c) 2005 David Brownell
 *      Use the driver model and standard identifiers; handle bigger timeouts.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/moduleparam.h>
#include <linux/bitops.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>
#include <mach/hardware.h>
#include <plat/prcm.h>

#include "omap_wdt.h"

static struct platform_device *omap_wdt_dev;

static unsigned timer_margin;
module_param(timer_margin, uint, 0);
MODULE_PARM_DESC(timer_margin, "initial watchdog timeout (in seconds)");

static unsigned int wdt_trgr_pattern = 0x1234;
static DEFINE_SPINLOCK(wdt_lock);

struct omap_wdt_dev {
        void __iomem    *base;          /* physical */
        struct device   *dev;
        int             omap_wdt_users;
        struct resource *mem;
        struct miscdevice omap_wdt_miscdev;
};

static void omap_wdt_ping(struct omap_wdt_dev *wdev)
{
        void __iomem    *base = wdev->base;

        /* wait for posted write to complete */
        while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x08)
                cpu_relax();

        wdt_trgr_pattern = ~wdt_trgr_pattern;
        __raw_writel(wdt_trgr_pattern, (base + OMAP_WATCHDOG_TGR));

        /* wait for posted write to complete */
        while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x08)
                cpu_relax();
        /* reloaded WCRR from WLDR */
}

static void omap_wdt_enable(struct omap_wdt_dev *wdev)
{
        void __iomem *base = wdev->base;

        /* Sequence to enable the watchdog */
        __raw_writel(0xBBBB, base + OMAP_WATCHDOG_SPR);
        while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x10)
                cpu_relax();

        __raw_writel(0x4444, base + OMAP_WATCHDOG_SPR);
        while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x10)
                cpu_relax();
}

static void omap_wdt_disable(struct omap_wdt_dev *wdev)
{
        void __iomem *base = wdev->base;

        /* sequence required to disable watchdog */
        __raw_writel(0xAAAA, base + OMAP_WATCHDOG_SPR); /* TIMER_MODE */
        while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x10)
                cpu_relax();

        __raw_writel(0x5555, base + OMAP_WATCHDOG_SPR); /* TIMER_MODE */
        while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x10)
                cpu_relax();
}

static void omap_wdt_adjust_timeout(unsigned new_timeout)
{
        if (new_timeout < TIMER_MARGIN_MIN)
                new_timeout = TIMER_MARGIN_DEFAULT;
        if (new_timeout > TIMER_MARGIN_MAX)
                new_timeout = TIMER_MARGIN_MAX;
        timer_margin = new_timeout;
}

static void omap_wdt_set_timeout(struct omap_wdt_dev *wdev)
{
        u32 pre_margin = GET_WLDR_VAL(timer_margin);
        void __iomem *base = wdev->base;

        /* just count up at 32 KHz */
        while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)
                cpu_relax();

        __raw_writel(pre_margin, base + OMAP_WATCHDOG_LDR);
        while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)
                cpu_relax();
}

/*
 *      Allow only one task to hold it open
 */
static int omap_wdt_open(struct inode *inode, struct file *file)
{
        struct omap_wdt_dev *wdev = platform_get_drvdata(omap_wdt_dev);
        void __iomem *base = wdev->base;

        if (test_and_set_bit(1, (unsigned long *)&(wdev->omap_wdt_users)))
                return -EBUSY;

        pm_runtime_get_sync(wdev->dev);

        /* initialize prescaler */
        while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x01)
                cpu_relax();

        __raw_writel((1 << 5) | (PTV << 2), base + OMAP_WATCHDOG_CNTRL);
        while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x01)
                cpu_relax();

        file->private_data = (void *) wdev;

        omap_wdt_set_timeout(wdev);
        omap_wdt_ping(wdev); /* trigger loading of new timeout value */
        omap_wdt_enable(wdev);

        return nonseekable_open(inode, file);
}

static int omap_wdt_release(struct inode *inode, struct file *file)
{
        struct omap_wdt_dev *wdev = file->private_data;

        /*
         *      Shut off the timer unless NOWAYOUT is defined.
         */
#ifndef CONFIG_WATCHDOG_NOWAYOUT
        omap_wdt_disable(wdev);

        pm_runtime_put_sync(wdev->dev);
#else
        pr_crit("Unexpected close, not stopping!\n");
#endif
        wdev->omap_wdt_users = 0;

        return 0;
}

static ssize_t omap_wdt_write(struct file *file, const char __user *data,
                size_t len, loff_t *ppos)
{
        struct omap_wdt_dev *wdev = file->private_data;

        /* Refresh LOAD_TIME. */
        if (len) {
                spin_lock(&wdt_lock);
                omap_wdt_ping(wdev);
                spin_unlock(&wdt_lock);
        }
        return len;
}

static long omap_wdt_ioctl(struct file *file, unsigned int cmd,
                                                unsigned long arg)
{
        struct omap_wdt_dev *wdev;
        int new_margin;
        static const struct watchdog_info ident = {
                .identity = "OMAP Watchdog",
                .options = WDIOF_SETTIMEOUT,
                .firmware_version = 0,
        };

        wdev = file->private_data;

        switch (cmd) {
        case WDIOC_GETSUPPORT:
                return copy_to_user((struct watchdog_info __user *)arg, &ident,
                                sizeof(ident));
        case WDIOC_GETSTATUS:
                return put_user(0, (int __user *)arg);
        case WDIOC_GETBOOTSTATUS:
                if (cpu_is_omap16xx())
                        return put_user(__raw_readw(ARM_SYSST),
                                        (int __user *)arg);
                if (cpu_is_omap24xx())
                        return put_user(omap_prcm_get_reset_sources(),
                                        (int __user *)arg);
                return put_user(0, (int __user *)arg);
        case WDIOC_KEEPALIVE:
                spin_lock(&wdt_lock);
                omap_wdt_ping(wdev);
                spin_unlock(&wdt_lock);
                return 0;
        case WDIOC_SETTIMEOUT:
                if (get_user(new_margin, (int __user *)arg))
                        return -EFAULT;
                omap_wdt_adjust_timeout(new_margin);

                spin_lock(&wdt_lock);
                omap_wdt_disable(wdev);
                omap_wdt_set_timeout(wdev);
                omap_wdt_enable(wdev);

                omap_wdt_ping(wdev);
                spin_unlock(&wdt_lock);
                /* Fall */
        case WDIOC_GETTIMEOUT:
                return put_user(timer_margin, (int __user *)arg);
        default:
                return -ENOTTY;
        }
}

static const struct file_operations omap_wdt_fops = {
        .owner = THIS_MODULE,
        .write = omap_wdt_write,
        .unlocked_ioctl = omap_wdt_ioctl,
        .open = omap_wdt_open,
        .release = omap_wdt_release,
        .llseek = no_llseek,
};

static int __devinit omap_wdt_probe(struct platform_device *pdev)
{
        struct resource *res, *mem;
        struct omap_wdt_dev *wdev;
        int ret;

        /* reserve static register mappings */
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res) {
                ret = -ENOENT;
                goto err_get_resource;
        }

        if (omap_wdt_dev) {
                ret = -EBUSY;
                goto err_busy;
        }

        mem = request_mem_region(res->start, resource_size(res), pdev->name);
        if (!mem) {
                ret = -EBUSY;
                goto err_busy;
        }

        wdev = kzalloc(sizeof(struct omap_wdt_dev), GFP_KERNEL);
        if (!wdev) {
                ret = -ENOMEM;
                goto err_kzalloc;
        }

        wdev->omap_wdt_users = 0;
        wdev->mem = mem;
        wdev->dev = &pdev->dev;

        wdev->base = ioremap(res->start, resource_size(res));
        if (!wdev->base) {
                ret = -ENOMEM;
                goto err_ioremap;
        }

        platform_set_drvdata(pdev, wdev);

        pm_runtime_enable(wdev->dev);
        pm_runtime_get_sync(wdev->dev);

        omap_wdt_disable(wdev);
        omap_wdt_adjust_timeout(timer_margin);

        wdev->omap_wdt_miscdev.parent = &pdev->dev;
        wdev->omap_wdt_miscdev.minor = WATCHDOG_MINOR;
        wdev->omap_wdt_miscdev.name = "watchdog";
        wdev->omap_wdt_miscdev.fops = &omap_wdt_fops;

        ret = misc_register(&(wdev->omap_wdt_miscdev));
        if (ret)
                goto err_misc;

        pr_info("OMAP Watchdog Timer Rev 0x%02x: initial timeout %d sec\n",
                __raw_readl(wdev->base + OMAP_WATCHDOG_REV) & 0xFF,
                timer_margin);

        pm_runtime_put_sync(wdev->dev);

        omap_wdt_dev = pdev;

        return 0;

err_misc:
        pm_runtime_disable(wdev->dev);
        platform_set_drvdata(pdev, NULL);
        iounmap(wdev->base);

err_ioremap:
        wdev->base = NULL;
        kfree(wdev);

err_kzalloc:
        release_mem_region(res->start, resource_size(res));

err_busy:
err_get_resource:

        return ret;
}

static void omap_wdt_shutdown(struct platform_device *pdev)
{
        struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

        if (wdev->omap_wdt_users) {
                omap_wdt_disable(wdev);
                pm_runtime_put_sync(wdev->dev);
        }
}

static int __devexit omap_wdt_remove(struct platform_device *pdev)
{
        struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
        struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

        pm_runtime_disable(wdev->dev);
        if (!res)
                return -ENOENT;

        misc_deregister(&(wdev->omap_wdt_miscdev));
        release_mem_region(res->start, resource_size(res));
        platform_set_drvdata(pdev, NULL);

        iounmap(wdev->base);

        kfree(wdev);
        omap_wdt_dev = NULL;

        return 0;
}

#ifdef  CONFIG_PM

/* REVISIT ... not clear this is the best way to handle system suspend; and
 * it's very inappropriate for selective device suspend (e.g. suspending this
 * through sysfs rather than by stopping the watchdog daemon).  Also, this
 * may not play well enough with NOWAYOUT...
 */

static int omap_wdt_suspend(struct platform_device *pdev, pm_message_t state)
{
        struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

        if (wdev->omap_wdt_users) {
                omap_wdt_disable(wdev);
                pm_runtime_put_sync(wdev->dev);
        }

        return 0;
}

static int omap_wdt_resume(struct platform_device *pdev)
{
        struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

        if (wdev->omap_wdt_users) {
                pm_runtime_get_sync(wdev->dev);
                omap_wdt_enable(wdev);
                omap_wdt_ping(wdev);
        }

        return 0;
}

#else
#define omap_wdt_suspend        NULL
#define omap_wdt_resume         NULL
#endif

static const struct of_device_id omap_wdt_of_match[] = {
        { .compatible = "ti,omap3-wdt", },
        {},
};
MODULE_DEVICE_TABLE(of, omap_wdt_of_match);

static struct platform_driver omap_wdt_driver = {
        .probe          = omap_wdt_probe,
        .remove         = __devexit_p(omap_wdt_remove),
        .shutdown       = omap_wdt_shutdown,
        .suspend        = omap_wdt_suspend,
        .resume         = omap_wdt_resume,
        .driver         = {
                .owner  = THIS_MODULE,
                .name   = "omap_wdt",
                .of_match_table = omap_wdt_of_match,
        },
};

module_platform_driver(omap_wdt_driver);

MODULE_AUTHOR("George G. Davis");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("platform:omap_wdt");