linux/drivers/watchdog/sa1100_wdt.c
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   1/*
   2 *      Watchdog driver for the SA11x0/PXA2xx
   3 *
   4 *      (c) Copyright 2000 Oleg Drokin <green@crimea.edu>
   5 *          Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>
   6 *
   7 *      This program is free software; you can redistribute it and/or
   8 *      modify it under the terms of the GNU General Public License
   9 *      as published by the Free Software Foundation; either version
  10 *      2 of the License, or (at your option) any later version.
  11 *
  12 *      Neither Oleg Drokin nor iXcelerator.com admit liability nor provide
  13 *      warranty for any of this software. This material is provided
  14 *      "AS-IS" and at no charge.
  15 *
  16 *      (c) Copyright 2000           Oleg Drokin <green@crimea.edu>
  17 *
  18 *      27/11/2000 Initial release
  19 */
  20#include <linux/module.h>
  21#include <linux/moduleparam.h>
  22#include <linux/types.h>
  23#include <linux/kernel.h>
  24#include <linux/fs.h>
  25#include <linux/miscdevice.h>
  26#include <linux/watchdog.h>
  27#include <linux/init.h>
  28#include <linux/bitops.h>
  29#include <linux/uaccess.h>
  30
  31#ifdef CONFIG_ARCH_PXA
  32#include <mach/pxa-regs.h>
  33#endif
  34
  35#include <mach/reset.h>
  36#include <mach/hardware.h>
  37
  38#define OSCR_FREQ               CLOCK_TICK_RATE
  39
  40static unsigned long sa1100wdt_users;
  41static int pre_margin;
  42static int boot_status;
  43
  44/*
  45 *      Allow only one person to hold it open
  46 */
  47static int sa1100dog_open(struct inode *inode, struct file *file)
  48{
  49        if (test_and_set_bit(1, &sa1100wdt_users))
  50                return -EBUSY;
  51
  52        /* Activate SA1100 Watchdog timer */
  53        OSMR3 = OSCR + pre_margin;
  54        OSSR = OSSR_M3;
  55        OWER = OWER_WME;
  56        OIER |= OIER_E3;
  57        return nonseekable_open(inode, file);
  58}
  59
  60/*
  61 * The watchdog cannot be disabled.
  62 *
  63 * Previous comments suggested that turning off the interrupt by
  64 * clearing OIER[E3] would prevent the watchdog timing out but this
  65 * does not appear to be true (at least on the PXA255).
  66 */
  67static int sa1100dog_release(struct inode *inode, struct file *file)
  68{
  69        printk(KERN_CRIT "WATCHDOG: Device closed - timer will not stop\n");
  70        clear_bit(1, &sa1100wdt_users);
  71        return 0;
  72}
  73
  74static ssize_t sa1100dog_write(struct file *file, const char __user *data,
  75                                                size_t len, loff_t *ppos)
  76{
  77        if (len)
  78                /* Refresh OSMR3 timer. */
  79                OSMR3 = OSCR + pre_margin;
  80        return len;
  81}
  82
  83static const struct watchdog_info ident = {
  84        .options        = WDIOF_CARDRESET | WDIOF_SETTIMEOUT
  85                                | WDIOF_KEEPALIVEPING,
  86        .identity       = "SA1100/PXA255 Watchdog",
  87};
  88
  89static long sa1100dog_ioctl(struct file *file, unsigned int cmd,
  90                                                        unsigned long arg)
  91{
  92        int ret = -ENOTTY;
  93        int time;
  94        void __user *argp = (void __user *)arg;
  95        int __user *p = argp;
  96
  97        switch (cmd) {
  98        case WDIOC_GETSUPPORT:
  99                ret = copy_to_user(argp, &ident,
 100                                   sizeof(ident)) ? -EFAULT : 0;
 101                break;
 102
 103        case WDIOC_GETSTATUS:
 104                ret = put_user(0, p);
 105                break;
 106
 107        case WDIOC_GETBOOTSTATUS:
 108                ret = put_user(boot_status, p);
 109                break;
 110
 111        case WDIOC_KEEPALIVE:
 112                OSMR3 = OSCR + pre_margin;
 113                ret = 0;
 114                break;
 115
 116        case WDIOC_SETTIMEOUT:
 117                ret = get_user(time, p);
 118                if (ret)
 119                        break;
 120
 121                if (time <= 0 || time > 255) {
 122                        ret = -EINVAL;
 123                        break;
 124                }
 125
 126                pre_margin = OSCR_FREQ * time;
 127                OSMR3 = OSCR + pre_margin;
 128                /*fall through*/
 129
 130        case WDIOC_GETTIMEOUT:
 131                ret = put_user(pre_margin / OSCR_FREQ, p);
 132                break;
 133        }
 134        return ret;
 135}
 136
 137static const struct file_operations sa1100dog_fops = {
 138        .owner          = THIS_MODULE,
 139        .llseek         = no_llseek,
 140        .write          = sa1100dog_write,
 141        .unlocked_ioctl = sa1100dog_ioctl,
 142        .open           = sa1100dog_open,
 143        .release        = sa1100dog_release,
 144};
 145
 146static struct miscdevice sa1100dog_miscdev = {
 147        .minor          = WATCHDOG_MINOR,
 148        .name           = "watchdog",
 149        .fops           = &sa1100dog_fops,
 150};
 151
 152static int margin __initdata = 60;              /* (secs) Default is 1 minute */
 153
 154static int __init sa1100dog_init(void)
 155{
 156        int ret;
 157
 158        /*
 159         * Read the reset status, and save it for later.  If
 160         * we suspend, RCSR will be cleared, and the watchdog
 161         * reset reason will be lost.
 162         */
 163        boot_status = (reset_status & RESET_STATUS_WATCHDOG) ?
 164                                WDIOF_CARDRESET : 0;
 165        pre_margin = OSCR_FREQ * margin;
 166
 167        ret = misc_register(&sa1100dog_miscdev);
 168        if (ret == 0)
 169                printk(KERN_INFO
 170                        "SA1100/PXA2xx Watchdog Timer: timer margin %d sec\n",
 171                                                margin);
 172        return ret;
 173}
 174
 175static void __exit sa1100dog_exit(void)
 176{
 177        misc_deregister(&sa1100dog_miscdev);
 178}
 179
 180module_init(sa1100dog_init);
 181module_exit(sa1100dog_exit);
 182
 183MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
 184MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
 185
 186module_param(margin, int, 0);
 187MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
 188
 189MODULE_LICENSE("GPL");
 190MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 191