linux-imx

/* riowd.c - driver for hw watchdog inside Super I/O of RIO

 *

 * Copyright (C) 2001, 2008 David S. Miller (davem@davemloft.net)

 */

​

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

​

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/types.h>

#include <linux/fs.h>

#include <linux/errno.h>

#include <linux/miscdevice.h>

#include <linux/watchdog.h>

#include <linux/of.h>

#include <linux/of_device.h>

#include <linux/io.h>

#include <linux/uaccess.h>

#include <linux/slab.h>

​

​

/* RIO uses the NatSemi Super I/O power management logical device

 * as its' watchdog.

 *

 * When the watchdog triggers, it asserts a line to the BBC (Boot Bus

 * Controller) of the machine.  The BBC can only be configured to

 * trigger a power-on reset when the signal is asserted.  The BBC

 * can be configured to ignore the signal entirely as well.

 *

 * The only Super I/O device register we care about is at index

 * 0x05 (WDTO_INDEX) which is the watchdog time-out in minutes (1-255).

 * If set to zero, this disables the watchdog.  When set, the system

 * must periodically (before watchdog expires) clear (set to zero) and

 * re-set the watchdog else it will trigger.

 *

 * There are two other indexed watchdog registers inside this Super I/O

 * logical device, but they are unused.  The first, at index 0x06 is

 * the watchdog control and can be used to make the watchdog timer re-set

 * when the PS/2 mouse or serial lines show activity.  The second, at

 * index 0x07 is merely a sampling of the line from the watchdog to the

 * BBC.

 *

 * The watchdog device generates no interrupts.

 */

​

MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");

MODULE_DESCRIPTION("Hardware watchdog driver for Sun RIO");

MODULE_SUPPORTED_DEVICE("watchdog");

MODULE_LICENSE("GPL");

​

#define DRIVER_NAME "riowd"

#define PFX     DRIVER_NAME ": "

​

struct riowd {

    void __iomem        *regs;

    spinlock_t      lock;

};

​

static struct riowd *riowd_device;

​

#define WDTO_INDEX  0x05

​

static int riowd_timeout = 1;       /* in minutes */