via_wdt.c

Go to the documentation of this file.

/*
 * VIA Chipset Watchdog Driver
 *
 * Copyright (C) 2011 Sigfox
 * License terms: GNU General Public License (GPL) version 2
 * Author: Marc Vertes <[email protected]>
 * Based on a preliminary version from Harald Welte <[email protected]>
 * Timer code by Wim Van Sebroeck <[email protected]>
 *
 * Caveat: PnP must be enabled in BIOS to allow full access to watchdog
 * control registers. If not, the watchdog must be configured in BIOS manually.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/device.h>
#include <linux/io.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/timer.h>
#include <linux/watchdog.h>

/* Configuration registers relative to the pci device */
#define VIA_WDT_MMIO_BASE   0xe8    /* MMIO region base address */
#define VIA_WDT_CONF        0xec    /* watchdog enable state */

/* Relevant bits for the VIA_WDT_CONF register */
#define VIA_WDT_CONF_ENABLE 0x01    /* 1: enable watchdog */
#define VIA_WDT_CONF_MMIO   0x02    /* 1: enable watchdog MMIO */

/*
 * The MMIO region contains the watchog control register and the
 * hardware timer counter.
 */
#define VIA_WDT_MMIO_LEN    8   /* MMIO region length in bytes */
#define VIA_WDT_CTL     0   /* MMIO addr+0: state/control reg. */
#define VIA_WDT_COUNT       4   /* MMIO addr+4: timer counter reg. */

/* Bits for the VIA_WDT_CTL register */
#define VIA_WDT_RUNNING     0x01    /* 0: stop, 1: running */
#define VIA_WDT_FIRED       0x02    /* 1: restarted by expired watchdog */
#define VIA_WDT_PWROFF      0x04    /* 0: reset, 1: poweroff */
#define VIA_WDT_DISABLED    0x08    /* 1: timer is disabled */
#define VIA_WDT_TRIGGER     0x80    /* 1: start a new countdown */

/* Hardware heartbeat in seconds */
#define WDT_HW_HEARTBEAT 1

/* Timer heartbeat (500ms) */
#define WDT_HEARTBEAT   (HZ/2)  /* should be <= ((WDT_HW_HEARTBEAT*HZ)/2) */

/* User space timeout in seconds */
#define WDT_TIMEOUT_MAX 1023    /* approx. 17 min. */
#define WDT_TIMEOUT 60
static int timeout = WDT_TIMEOUT;
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds, between 1 and 1023 "
    "(default = " __MODULE_STRING(WDT_TIMEOUT) ")");

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) ")");

static struct watchdog_device wdt_dev;
static struct resource wdt_res;
static void __iomem *wdt_mem;
static unsigned int mmio;
static void wdt_timer_tick(unsigned long data);
static DEFINE_TIMER(timer, wdt_timer_tick, 0, 0);
                    /* The timer that pings the watchdog */
static unsigned long next_heartbeat;    /* the next_heartbeat for the timer */

static inline void wdt_reset(void)
{
    unsigned int ctl = readl(wdt_mem);

    writel(ctl | VIA_WDT_TRIGGER, wdt_mem);
}

/*
 * Timer tick: the timer will make sure that the watchdog timer hardware
 * is being reset in time. The conditions to do this are:
 *  1) the watchog timer has been started and /dev/watchdog is open
 *     and there is still time left before userspace should send the
 *     next heartbeat/ping. (note: the internal heartbeat is much smaller
 *     then the external/userspace heartbeat).
 *  2) the watchdog timer has been stopped by userspace.
 */
static void wdt_timer_tick(unsigned long data)
{
    if (time_before(jiffies, next_heartbeat) ||
       (!watchdog_active(&wdt_dev))) {
        wdt_reset();
        mod_timer(&timer, jiffies + WDT_HEARTBEAT);
    } else
        pr_crit("I will reboot your machine !\n");
}

static int wdt_ping(struct watchdog_device *wdd)
{
    /* calculate when the next userspace timeout will be */
    next_heartbeat = jiffies + wdd->timeout * HZ;
    return 0;
}

static int wdt_start(struct watchdog_device *wdd)
{
    unsigned int ctl = readl(wdt_mem);

    writel(wdd->timeout, wdt_mem + VIA_WDT_COUNT);
    writel(ctl | VIA_WDT_RUNNING | VIA_WDT_TRIGGER, wdt_mem);
    wdt_ping(wdd);
    mod_timer(&timer, jiffies + WDT_HEARTBEAT);
    return 0;
}

static int wdt_stop(struct watchdog_device *wdd)
{
    unsigned int ctl = readl(wdt_mem);

    writel(ctl & ~VIA_WDT_RUNNING, wdt_mem);
    return 0;
}

static int wdt_set_timeout(struct watchdog_device *wdd,
               unsigned int new_timeout)
{
    writel(new_timeout, wdt_mem + VIA_WDT_COUNT);
    wdd->timeout = new_timeout;
    return 0;
}

static const struct watchdog_info wdt_info = {
    .identity = "VIA watchdog",
    .options =  WDIOF_CARDRESET |
            WDIOF_SETTIMEOUT |
            WDIOF_MAGICCLOSE |
            WDIOF_KEEPALIVEPING,
};

static const struct watchdog_ops wdt_ops = {
    .owner =    THIS_MODULE,
    .start =    wdt_start,
    .stop =     wdt_stop,
    .ping =     wdt_ping,
    .set_timeout =  wdt_set_timeout,
};

static struct watchdog_device wdt_dev = {
    .info =     &wdt_info,
    .ops =      &wdt_ops,
    .min_timeout =  1,
    .max_timeout =  WDT_TIMEOUT_MAX,
};

static int __devinit wdt_probe(struct pci_dev *pdev,
                   const struct pci_device_id *ent)
{
    unsigned char conf;
    int ret = -ENODEV;

    if (pci_enable_device(pdev)) {
        dev_err(&pdev->dev, "cannot enable PCI device\n");
        return -ENODEV;
    }

    /*
     * Allocate a MMIO region which contains watchdog control register
     * and counter, then configure the watchdog to use this region.
     * This is possible only if PnP is properly enabled in BIOS.
     * If not, the watchdog must be configured in BIOS manually.
     */
    if (allocate_resource(&iomem_resource, &wdt_res, VIA_WDT_MMIO_LEN,
                  0xf0000000, 0xffffff00, 0xff, NULL, NULL)) {
        dev_err(&pdev->dev, "MMIO allocation failed\n");
        goto err_out_disable_device;
    }

    pci_write_config_dword(pdev, VIA_WDT_MMIO_BASE, wdt_res.start);
    pci_read_config_byte(pdev, VIA_WDT_CONF, &conf);
    conf |= VIA_WDT_CONF_ENABLE | VIA_WDT_CONF_MMIO;
    pci_write_config_byte(pdev, VIA_WDT_CONF, conf);

    pci_read_config_dword(pdev, VIA_WDT_MMIO_BASE, &mmio);
    if (mmio) {
        dev_info(&pdev->dev, "VIA Chipset watchdog MMIO: %x\n", mmio);
    } else {
        dev_err(&pdev->dev, "MMIO setting failed. Check BIOS.\n");
        goto err_out_resource;
    }

    if (!request_mem_region(mmio, VIA_WDT_MMIO_LEN, "via_wdt")) {
        dev_err(&pdev->dev, "MMIO region busy\n");
        goto err_out_resource;
    }

    wdt_mem = ioremap(mmio, VIA_WDT_MMIO_LEN);
    if (wdt_mem == NULL) {
        dev_err(&pdev->dev, "cannot remap VIA wdt MMIO registers\n");
        goto err_out_release;
    }

    if (timeout < 1 || timeout > WDT_TIMEOUT_MAX)
        timeout = WDT_TIMEOUT;

    wdt_dev.timeout = timeout;
    watchdog_set_nowayout(&wdt_dev, nowayout);
    if (readl(wdt_mem) & VIA_WDT_FIRED)
        wdt_dev.bootstatus |= WDIOF_CARDRESET;

    ret = watchdog_register_device(&wdt_dev);
    if (ret)
        goto err_out_iounmap;

    /* start triggering, in case of watchdog already enabled by BIOS */
    mod_timer(&timer, jiffies + WDT_HEARTBEAT);
    return 0;

err_out_iounmap:
    iounmap(wdt_mem);
err_out_release:
    release_mem_region(mmio, VIA_WDT_MMIO_LEN);
err_out_resource:
    release_resource(&wdt_res);
err_out_disable_device:
    pci_disable_device(pdev);
    return ret;
}

static void __devexit wdt_remove(struct pci_dev *pdev)
{
    watchdog_unregister_device(&wdt_dev);
    del_timer(&timer);
    iounmap(wdt_mem);
    release_mem_region(mmio, VIA_WDT_MMIO_LEN);
    release_resource(&wdt_res);
    pci_disable_device(pdev);
}

static DEFINE_PCI_DEVICE_TABLE(wdt_pci_table) = {
    { PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_CX700) },
    { PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_VX800) },
    { PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_VX855) },
    { 0 }
};

static struct pci_driver wdt_driver = {
    .name       = "via_wdt",
    .id_table   = wdt_pci_table,
    .probe      = wdt_probe,
    .remove     = __devexit_p(wdt_remove),
};

module_pci_driver(wdt_driver);

MODULE_AUTHOR("Marc Vertes");
MODULE_DESCRIPTION("Driver for watchdog timer on VIA chipset");
MODULE_LICENSE("GPL");