linux-imx

/*

 * VIA Chipset Watchdog Driver

 *

 * Copyright (C) 2011 Sigfox

 * License terms: GNU General Public License (GPL) version 2

 * Author: Marc Vertes <marc.vertes@sigfox.com>

 * Based on a preliminary version from Harald Welte <HaraldWelte@viatech.com>

 * Timer code by Wim Van Sebroeck <wim@iguana.be>

 *

 * 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 watchdog 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(struct timer_list *unused);

static DEFINE_TIMER(timer, wdt_timer_tick);

                    /* 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 watchdog 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(struct timer_list *unused)

{