/*
 *      sp5100_tco :    TCO timer driver for sp5100 chipsets
 *
 *      (c) Copyright 2009 Google Inc., All Rights Reserved.
 *
 *      Based on i8xx_tco.c:
 *      (c) Copyright 2000 kernel concepts <nils@kernelconcepts.de>, All Rights
 *      Reserved.
 *                              http://www.kernelconcepts.de
 *
 *      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.
 *
 *      See AMD Publication 43009 "AMD SB700/710/750 Register Reference Guide"
 */

/*
 *      Includes, defines, variables, module parameters, ...
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/pci.h>
#include <linux/ioport.h>
#include <linux/platform_device.h>
#include <linux/uaccess.h>
#include <linux/io.h>

#include "sp5100_tco.h"

/* Module and version information */
#define TCO_VERSION "0.01"
#define TCO_MODULE_NAME "SP5100 TCO timer"
#define TCO_DRIVER_NAME   TCO_MODULE_NAME ", v" TCO_VERSION

/* internal variables */
static u32 tcobase_phys;
static void __iomem *tcobase;
static unsigned int pm_iobase;
static DEFINE_SPINLOCK(tco_lock);       /* Guards the hardware */
static unsigned long timer_alive;
static char tco_expect_close;
static struct pci_dev *sp5100_tco_pci;

/* the watchdog platform device */
static struct platform_device *sp5100_tco_platform_device;

/* module parameters */

#define WATCHDOG_HEARTBEAT 60   /* 60 sec default heartbeat. */
static int heartbeat = WATCHDOG_HEARTBEAT;  /* in seconds */
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (default="
                 __MODULE_STRING(WATCHDOG_HEARTBEAT) ")");

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) ")");

/*
 * Some TCO specific functions
 */
static void tco_timer_start(void)
{
        u32 val;
        unsigned long flags;

        spin_lock_irqsave(&tco_lock, flags);
        val = readl(SP5100_WDT_CONTROL(tcobase));
        val |= SP5100_WDT_START_STOP_BIT;
        writel(val, SP5100_WDT_CONTROL(tcobase));
        spin_unlock_irqrestore(&tco_lock, flags);
}

static void tco_timer_stop(void)
{
        u32 val;
        unsigned long flags;

        spin_lock_irqsave(&tco_lock, flags);
        val = readl(SP5100_WDT_CONTROL(tcobase));
        val &= ~SP5100_WDT_START_STOP_BIT;
        writel(val, SP5100_WDT_CONTROL(tcobase));
        spin_unlock_irqrestore(&tco_lock, flags);
}

static void tco_timer_keepalive(void)
{
        u32 val;
        unsigned long flags;

        spin_lock_irqsave(&tco_lock, flags);
        val = readl(SP5100_WDT_CONTROL(tcobase));
        val |= SP5100_WDT_TRIGGER_BIT;
        writel(val, SP5100_WDT_CONTROL(tcobase));
        spin_unlock_irqrestore(&tco_lock, flags);
}

static int tco_timer_set_heartbeat(int t)
{
        unsigned long flags;

        if (t < 0 || t > 0xffff)
                return -EINVAL;

        /* Write new heartbeat to watchdog */
        spin_lock_irqsave(&tco_lock, flags);
        writel(t, SP5100_WDT_COUNT(tcobase));
        spin_unlock_irqrestore(&tco_lock, flags);

        heartbeat = t;
        return 0;
}

/*
 *      /dev/watchdog handling
 */

static int sp5100_tco_open(struct inode *inode, struct file *file)
{
        /* /dev/watchdog can only be opened once */
        if (test_and_set_bit(0, &timer_alive))
                return -EBUSY;

        /* Reload and activate timer */
        tco_timer_start();
        tco_timer_keepalive();
        return nonseekable_open(inode, file);
}

static int sp5100_tco_release(struct inode *inode, struct file *file)
{
        /* Shut off the timer. */
        if (tco_expect_close == 42) {
                tco_timer_stop();
        } else {
                pr_crit("Unexpected close, not stopping watchdog!\n");
                tco_timer_keepalive();
        }
        clear_bit(0, &timer_alive);
        tco_expect_close = 0;
        return 0;
}

static ssize_t sp5100_tco_write(struct file *file, const char __user *data,
                                size_t len, loff_t *ppos)
{
        /* See if we got the magic character 'V' and reload the timer */
        if (len) {
                if (!nowayout) {
                        size_t i;

                        /* note: just in case someone wrote the magic character
                         * five months ago... */
                        tco_expect_close = 0;

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

                /* someone wrote to us, we should reload the timer */
                tco_timer_keepalive();
        }
        return len;
}

static long sp5100_tco_ioctl(struct file *file, unsigned int cmd,
                             unsigned long arg)
{
        int new_options, retval = -EINVAL;
        int new_heartbeat;
        void __user *argp = (void __user *)arg;
        int __user *p = argp;
        static const struct watchdog_info ident = {
                .options =              WDIOF_SETTIMEOUT |
                                        WDIOF_KEEPALIVEPING |
                                        WDIOF_MAGICCLOSE,
                .firmware_version =     0,
                .identity =             TCO_MODULE_NAME,
        };

        switch (cmd) {
        case WDIOC_GETSUPPORT:
                return copy_to_user(argp, &ident,
                        sizeof(ident)) ? -EFAULT : 0;
        case WDIOC_GETSTATUS:
        case WDIOC_GETBOOTSTATUS:
                return put_user(0, p);
        case WDIOC_SETOPTIONS:
                if (get_user(new_options, p))
                        return -EFAULT;
                if (new_options & WDIOS_DISABLECARD) {
                        tco_timer_stop();
                        retval = 0;
                }
                if (new_options & WDIOS_ENABLECARD) {
                        tco_timer_start();
                        tco_timer_keepalive();
                        retval = 0;
                }
                return retval;
        case WDIOC_KEEPALIVE:
                tco_timer_keepalive();
                return 0;
        case WDIOC_SETTIMEOUT:
                if (get_user(new_heartbeat, p))
                        return -EFAULT;
                if (tco_timer_set_heartbeat(new_heartbeat))
                        return -EINVAL;
                tco_timer_keepalive();
                /* Fall through */
        case WDIOC_GETTIMEOUT:
                return put_user(heartbeat, p);
        default:
                return -ENOTTY;
        }
}

/*
 * Kernel Interfaces
 */

static const struct file_operations sp5100_tco_fops = {
        .owner =                THIS_MODULE,
        .llseek =               no_llseek,
        .write =                sp5100_tco_write,
        .unlocked_ioctl =       sp5100_tco_ioctl,
        .open =                 sp5100_tco_open,
        .release =              sp5100_tco_release,
};

static struct miscdevice sp5100_tco_miscdev = {
        .minor =        WATCHDOG_MINOR,
        .name =         "watchdog",
        .fops =         &sp5100_tco_fops,
};

/*
 * Data for PCI driver interface
 *
 * This data only exists for exporting the supported
 * PCI ids via MODULE_DEVICE_TABLE.  We do not actually
 * register a pci_driver, because someone else might
 * want to register another driver on the same PCI id.
 */
static DEFINE_PCI_DEVICE_TABLE(sp5100_tco_pci_tbl) = {
        { PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_SBX00_SMBUS, PCI_ANY_ID,
          PCI_ANY_ID, },
        { 0, },                 /* End of list */
};
MODULE_DEVICE_TABLE(pci, sp5100_tco_pci_tbl);

/*
 * Init & exit routines
 */

static unsigned char __devinit sp5100_tco_setupdevice(void)
{
        struct pci_dev *dev = NULL;
        u32 val;

        /* Match the PCI device */
        for_each_pci_dev(dev) {
                if (pci_match_id(sp5100_tco_pci_tbl, dev) != NULL) {
                        sp5100_tco_pci = dev;
                        break;
                }
        }

        if (!sp5100_tco_pci)
                return 0;

        /* Request the IO ports used by this driver */
        pm_iobase = SP5100_IO_PM_INDEX_REG;
        if (!request_region(pm_iobase, SP5100_PM_IOPORTS_SIZE, "SP5100 TCO")) {
                pr_err("I/O address 0x%04x already in use\n", pm_iobase);
                goto exit;
        }

        /* Find the watchdog base address. */
        outb(SP5100_PM_WATCHDOG_BASE3, SP5100_IO_PM_INDEX_REG);
        val = inb(SP5100_IO_PM_DATA_REG);
        outb(SP5100_PM_WATCHDOG_BASE2, SP5100_IO_PM_INDEX_REG);
        val = val << 8 | inb(SP5100_IO_PM_DATA_REG);
        outb(SP5100_PM_WATCHDOG_BASE1, SP5100_IO_PM_INDEX_REG);
        val = val << 8 | inb(SP5100_IO_PM_DATA_REG);
        outb(SP5100_PM_WATCHDOG_BASE0, SP5100_IO_PM_INDEX_REG);
        /* Low three bits of BASE0 are reserved. */
        val = val << 8 | (inb(SP5100_IO_PM_DATA_REG) & 0xf8);

        if (!request_mem_region_exclusive(val, SP5100_WDT_MEM_MAP_SIZE,
                                                                "SP5100 TCO")) {
                pr_err("mmio address 0x%04x already in use\n", val);
                goto unreg_region;
        }
        tcobase_phys = val;

        tcobase = ioremap(val, SP5100_WDT_MEM_MAP_SIZE);
        if (!tcobase) {
                pr_err("failed to get tcobase address\n");
                goto unreg_mem_region;
        }

        /* Enable watchdog decode bit */
        pci_read_config_dword(sp5100_tco_pci,
                              SP5100_PCI_WATCHDOG_MISC_REG,
                              &val);

        val |= SP5100_PCI_WATCHDOG_DECODE_EN;

        pci_write_config_dword(sp5100_tco_pci,
                               SP5100_PCI_WATCHDOG_MISC_REG,
                               val);

        /* Enable Watchdog timer and set the resolution to 1 sec. */
        outb(SP5100_PM_WATCHDOG_CONTROL, SP5100_IO_PM_INDEX_REG);
        val = inb(SP5100_IO_PM_DATA_REG);
        val |= SP5100_PM_WATCHDOG_SECOND_RES;
        val &= ~SP5100_PM_WATCHDOG_DISABLE;
        outb(val, SP5100_IO_PM_DATA_REG);

        /* Check that the watchdog action is set to reset the system. */
        val = readl(SP5100_WDT_CONTROL(tcobase));
        val &= ~SP5100_PM_WATCHDOG_ACTION_RESET;
        writel(val, SP5100_WDT_CONTROL(tcobase));

        /* Set a reasonable heartbeat before we stop the timer */
        tco_timer_set_heartbeat(heartbeat);

        /*
         * Stop the TCO before we change anything so we don't race with
         * a zeroed timer.
         */
        tco_timer_stop();

        /* Done */
        return 1;

unreg_mem_region:
        release_mem_region(tcobase_phys, SP5100_WDT_MEM_MAP_SIZE);
unreg_region:
        release_region(pm_iobase, SP5100_PM_IOPORTS_SIZE);
exit:
        return 0;
}

static int __devinit sp5100_tco_init(struct platform_device *dev)
{
        int ret;
        u32 val;

        /* Check whether or not the hardware watchdog is there. If found, then
         * set it up.
         */
        if (!sp5100_tco_setupdevice())
                return -ENODEV;

        /* Check to see if last reboot was due to watchdog timeout */
        pr_info("Watchdog reboot %sdetected\n",
                readl(SP5100_WDT_CONTROL(tcobase)) & SP5100_PM_WATCHDOG_FIRED ?
                "" : "not ");

        /* Clear out the old status */
        val = readl(SP5100_WDT_CONTROL(tcobase));
        val &= ~SP5100_PM_WATCHDOG_FIRED;
        writel(val, SP5100_WDT_CONTROL(tcobase));

        /*
         * Check that the heartbeat value is within it's range.
         * If not, reset to the default.
         */
        if (tco_timer_set_heartbeat(heartbeat)) {
                heartbeat = WATCHDOG_HEARTBEAT;
                tco_timer_set_heartbeat(heartbeat);
        }

        ret = misc_register(&sp5100_tco_miscdev);
        if (ret != 0) {
                pr_err("cannot register miscdev on minor=%d (err=%d)\n",
                       WATCHDOG_MINOR, ret);
                goto exit;
        }

        clear_bit(0, &timer_alive);

        pr_info("initialized (0x%p). heartbeat=%d sec (nowayout=%d)\n",
                tcobase, heartbeat, nowayout);

        return 0;

exit:
        iounmap(tcobase);
        release_mem_region(tcobase_phys, SP5100_WDT_MEM_MAP_SIZE);
        release_region(pm_iobase, SP5100_PM_IOPORTS_SIZE);
        return ret;
}

static void __devexit sp5100_tco_cleanup(void)
{
        /* Stop the timer before we leave */
        if (!nowayout)
                tco_timer_stop();

        /* Deregister */
        misc_deregister(&sp5100_tco_miscdev);
        iounmap(tcobase);
        release_mem_region(tcobase_phys, SP5100_WDT_MEM_MAP_SIZE);
        release_region(pm_iobase, SP5100_PM_IOPORTS_SIZE);
}

static int __devexit sp5100_tco_remove(struct platform_device *dev)
{
        if (tcobase)
                sp5100_tco_cleanup();
        return 0;
}

static void sp5100_tco_shutdown(struct platform_device *dev)
{
        tco_timer_stop();
}

static struct platform_driver sp5100_tco_driver = {
        .probe          = sp5100_tco_init,
        .remove         = __devexit_p(sp5100_tco_remove),
        .shutdown       = sp5100_tco_shutdown,
        .driver         = {
                .owner  = THIS_MODULE,
                .name   = TCO_MODULE_NAME,
        },
};

static int __init sp5100_tco_init_module(void)
{
        int err;

        pr_info("SP5100 TCO WatchDog Timer Driver v%s\n", TCO_VERSION);

        err = platform_driver_register(&sp5100_tco_driver);
        if (err)
                return err;

        sp5100_tco_platform_device = platform_device_register_simple(
                                        TCO_MODULE_NAME, -1, NULL, 0);
        if (IS_ERR(sp5100_tco_platform_device)) {
                err = PTR_ERR(sp5100_tco_platform_device);
                goto unreg_platform_driver;
        }

        return 0;

unreg_platform_driver:
        platform_driver_unregister(&sp5100_tco_driver);
        return err;
}

static void __exit sp5100_tco_cleanup_module(void)
{
        platform_device_unregister(sp5100_tco_platform_device);
        platform_driver_unregister(&sp5100_tco_driver);
        pr_info("SP5100 TCO Watchdog Module Unloaded\n");
}

module_init(sp5100_tco_init_module);
module_exit(sp5100_tco_cleanup_module);

MODULE_AUTHOR("Priyanka Gupta");
MODULE_DESCRIPTION("TCO timer driver for SP5100 chipset");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);