sp5100_tco.c

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/*
 *  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 <[email protected]>, 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);