linux-imx

/*

 * GE watchdog userspace interface

 *

 * Author:  Martyn Welch <martyn.welch@ge.com>

 *

 * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.

 *

 * 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.

 *

 * Based on: mv64x60_wdt.c (MV64X60 watchdog userspace interface)

 *   Author: James Chapman <jchapman@katalix.com>

 */

​

/* TODO:

 * This driver does not provide support for the hardwares capability of sending

 * an interrupt at a programmable threshold.

 *

 * This driver currently can only support 1 watchdog - there are 2 in the

 * hardware that this driver supports. Thus one could be configured as a

 * process-based watchdog (via /dev/watchdog), the second (using the interrupt

 * capabilities) a kernel-based watchdog.

 */

​

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

​

#include <linux/kernel.h>

#include <linux/compiler.h>

#include <linux/init.h>

#include <linux/module.h>

#include <linux/miscdevice.h>

#include <linux/watchdog.h>

#include <linux/fs.h>

#include <linux/of.h>

#include <linux/of_address.h>

#include <linux/of_platform.h>

#include <linux/io.h>

#include <linux/uaccess.h>

​

#include <sysdev/fsl_soc.h>

​

/*

 * The watchdog configuration register contains a pair of 2-bit fields,

 *   1.  a reload field, bits 27-26, which triggers a reload of

 *       the countdown register, and

 *   2.  an enable field, bits 25-24, which toggles between

 *       enabling and disabling the watchdog timer.

 * Bit 31 is a read-only field which indicates whether the

 * watchdog timer is currently enabled.

 *

 * The low 24 bits contain the timer reload value.

 */

#define GEF_WDC_ENABLE_SHIFT    24

#define GEF_WDC_SERVICE_SHIFT   26

#define GEF_WDC_ENABLED_SHIFT   31

​

#define GEF_WDC_ENABLED_TRUE    1

#define GEF_WDC_ENABLED_FALSE   0

​

/* Flags bits */

#define GEF_WDOG_FLAG_OPENED    0

​

static unsigned long wdt_flags;

static int wdt_status;

static void __iomem *gef_wdt_regs;

static int gef_wdt_timeout;

static int gef_wdt_count;

static unsigned int bus_clk;

static char expect_close;

static DEFINE_SPINLOCK(gef_wdt_spinlock);

​

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 int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift)

{

    u32 data;

    u32 enabled;

    int ret = 0;

​

    spin_lock(&gef_wdt_spinlock);

    data = ioread32be(gef_wdt_regs);

    enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1;

​

    /* only toggle the requested field if enabled state matches predicate */

    if ((enabled ^ enabled_predicate) == 0) {

        /* We write a 1, then a 2 -- to the appropriate field */