/*
 * RDC321x watchdog driver
 *
 * Copyright (C) 2007-2010 Florian Fainelli <florian@openwrt.org>
 *
 * This driver is highly inspired from the cpu5_wdt driver
 *
 * 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; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/timer.h>
#include <linux/completion.h>
#include <linux/jiffies.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/mfd/rdc321x.h>

#define RDC_WDT_MASK    0x80000000 /* Mask */
#define RDC_WDT_EN      0x00800000 /* Enable bit */
#define RDC_WDT_WTI     0x00200000 /* Generate CPU reset/NMI/WDT on timeout */
#define RDC_WDT_RST     0x00100000 /* Reset bit */
#define RDC_WDT_WIF     0x00040000 /* WDT IRQ Flag */
#define RDC_WDT_IRT     0x00000100 /* IRQ Routing table */
#define RDC_WDT_CNT     0x00000001 /* WDT count */

#define RDC_CLS_TMR     0x80003844 /* Clear timer */

#define RDC_WDT_INTERVAL        (HZ/10+1)

static int ticks = 1000;

/* some device data */

static struct {
        struct completion stop;
        int running;
        struct timer_list timer;
        int queue;
        int default_ticks;
        unsigned long inuse;
        spinlock_t lock;
        struct pci_dev *sb_pdev;
        int base_reg;
} rdc321x_wdt_device;

/* generic helper functions */

static void rdc321x_wdt_trigger(unsigned long unused)
{
        unsigned long flags;
        u32 val;

        if (rdc321x_wdt_device.running)
                ticks--;

        /* keep watchdog alive */
        spin_lock_irqsave(&rdc321x_wdt_device.lock, flags);
        pci_read_config_dword(rdc321x_wdt_device.sb_pdev,
                                        rdc321x_wdt_device.base_reg, &val);
        val |= RDC_WDT_EN;
        pci_write_config_dword(rdc321x_wdt_device.sb_pdev,
                                        rdc321x_wdt_device.base_reg, val);
        spin_unlock_irqrestore(&rdc321x_wdt_device.lock, flags);

        /* requeue?? */
        if (rdc321x_wdt_device.queue && ticks)
                mod_timer(&rdc321x_wdt_device.timer,
                                jiffies + RDC_WDT_INTERVAL);
        else {
                /* ticks doesn't matter anyway */
                complete(&rdc321x_wdt_device.stop);
        }

}

static void rdc321x_wdt_reset(void)
{
        ticks = rdc321x_wdt_device.default_ticks;
}

static void rdc321x_wdt_start(void)
{
        unsigned long flags;

        if (!rdc321x_wdt_device.queue) {
                rdc321x_wdt_device.queue = 1;

                /* Clear the timer */
                spin_lock_irqsave(&rdc321x_wdt_device.lock, flags);
                pci_write_config_dword(rdc321x_wdt_device.sb_pdev,
                                rdc321x_wdt_device.base_reg, RDC_CLS_TMR);

                /* Enable watchdog and set the timeout to 81.92 us */
                pci_write_config_dword(rdc321x_wdt_device.sb_pdev,
                                        rdc321x_wdt_device.base_reg,
                                        RDC_WDT_EN | RDC_WDT_CNT);
                spin_unlock_irqrestore(&rdc321x_wdt_device.lock, flags);

                mod_timer(&rdc321x_wdt_device.timer,
                                jiffies + RDC_WDT_INTERVAL);
        }

        /* if process dies, counter is not decremented */
        rdc321x_wdt_device.running++;
}

static int rdc321x_wdt_stop(void)
{
        if (rdc321x_wdt_device.running)
                rdc321x_wdt_device.running = 0;

        ticks = rdc321x_wdt_device.default_ticks;

        return -EIO;
}

/* filesystem operations */
static int rdc321x_wdt_open(struct inode *inode, struct file *file)
{
        if (test_and_set_bit(0, &rdc321x_wdt_device.inuse))
                return -EBUSY;

        return nonseekable_open(inode, file);
}

static int rdc321x_wdt_release(struct inode *inode, struct file *file)
{
        clear_bit(0, &rdc321x_wdt_device.inuse);
        return 0;
}

static long rdc321x_wdt_ioctl(struct file *file, unsigned int cmd,
                                unsigned long arg)
{
        void __user *argp = (void __user *)arg;
        u32 value;
        static const struct watchdog_info ident = {
                .options = WDIOF_CARDRESET,
                .identity = "RDC321x WDT",
        };
        unsigned long flags;

        switch (cmd) {
        case WDIOC_KEEPALIVE:
                rdc321x_wdt_reset();
                break;
        case WDIOC_GETSTATUS:
                /* Read the value from the DATA register */
                spin_lock_irqsave(&rdc321x_wdt_device.lock, flags);
                pci_read_config_dword(rdc321x_wdt_device.sb_pdev,
                                        rdc321x_wdt_device.base_reg, &value);
                spin_unlock_irqrestore(&rdc321x_wdt_device.lock, flags);
                if (copy_to_user(argp, &value, sizeof(u32)))
                        return -EFAULT;
                break;
        case WDIOC_GETSUPPORT:
                if (copy_to_user(argp, &ident, sizeof(ident)))
                        return -EFAULT;
                break;
        case WDIOC_SETOPTIONS:
                if (copy_from_user(&value, argp, sizeof(int)))
                        return -EFAULT;
                switch (value) {
                case WDIOS_ENABLECARD:
                        rdc321x_wdt_start();
                        break;
                case WDIOS_DISABLECARD:
                        return rdc321x_wdt_stop();
                default:
                        return -EINVAL;
                }
                break;
        default:
                return -ENOTTY;
        }
        return 0;
}

static ssize_t rdc321x_wdt_write(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        if (!count)
                return -EIO;

        rdc321x_wdt_reset();

        return count;
}

static const struct file_operations rdc321x_wdt_fops = {
        .owner          = THIS_MODULE,
        .llseek         = no_llseek,
        .unlocked_ioctl = rdc321x_wdt_ioctl,
        .open           = rdc321x_wdt_open,
        .write          = rdc321x_wdt_write,
        .release        = rdc321x_wdt_release,
};

static struct miscdevice rdc321x_wdt_misc = {
        .minor  = WATCHDOG_MINOR,
        .name   = "watchdog",
        .fops   = &rdc321x_wdt_fops,
};

static int rdc321x_wdt_probe(struct platform_device *pdev)
{
        int err;
        struct resource *r;
        struct rdc321x_wdt_pdata *pdata;

        pdata = dev_get_platdata(&pdev->dev);
        if (!pdata) {
                dev_err(&pdev->dev, "no platform data supplied\n");
                return -ENODEV;
        }

        r = platform_get_resource_byname(pdev, IORESOURCE_IO, "wdt-reg");
        if (!r) {
                dev_err(&pdev->dev, "failed to get wdt-reg resource\n");
                return -ENODEV;
        }

        rdc321x_wdt_device.sb_pdev = pdata->sb_pdev;
        rdc321x_wdt_device.base_reg = r->start;

        err = misc_register(&rdc321x_wdt_misc);
        if (err < 0) {
                dev_err(&pdev->dev, "misc_register failed\n");
                return err;
        }

        spin_lock_init(&rdc321x_wdt_device.lock);

        /* Reset the watchdog */
        pci_write_config_dword(rdc321x_wdt_device.sb_pdev,
                                rdc321x_wdt_device.base_reg, RDC_WDT_RST);

        init_completion(&rdc321x_wdt_device.stop);
        rdc321x_wdt_device.queue = 0;

        clear_bit(0, &rdc321x_wdt_device.inuse);

        setup_timer(&rdc321x_wdt_device.timer, rdc321x_wdt_trigger, 0);

        rdc321x_wdt_device.default_ticks = ticks;

        dev_info(&pdev->dev, "watchdog init success\n");

        return 0;
}

static int rdc321x_wdt_remove(struct platform_device *pdev)
{
        if (rdc321x_wdt_device.queue) {
                rdc321x_wdt_device.queue = 0;
                wait_for_completion(&rdc321x_wdt_device.stop);
        }

        misc_deregister(&rdc321x_wdt_misc);

        return 0;
}

static struct platform_driver rdc321x_wdt_driver = {
        .probe = rdc321x_wdt_probe,
        .remove = rdc321x_wdt_remove,
        .driver = {
                .name = "rdc321x-wdt",
        },
};

module_platform_driver(rdc321x_wdt_driver);

MODULE_AUTHOR("Florian Fainelli <florian@openwrt.org>");
MODULE_DESCRIPTION("RDC321x watchdog driver");
MODULE_LICENSE("GPL");