LXR linux/drivers/watchdog/sa1100

   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@redhat.com>
   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
  30#ifdef CONFIG_ARCH_PXA
  31#include <asm/arch/pxa-regs.h>
  32#endif
  33
  34#include <asm/hardware.h>
  35#include <asm/uaccess.h>
  36
  37#define OSCR_FREQ               CLOCK_TICK_RATE
  38
  39static unsigned long sa1100wdt_users;
  40static int pre_margin;
  41static int boot_status;
  42
  43/*
  44 *      Allow only one person to hold it open
  45 */
  46static int sa1100dog_open(struct inode *inode, struct file *file)
  47{
  48        if (test_and_set_bit(1,&sa1100wdt_users))
  49                return -EBUSY;
  50
  51        /* Activate SA1100 Watchdog timer */
  52        OSMR3 = OSCR + pre_margin;
  53        OSSR = OSSR_M3;
  54        OWER = OWER_WME;
  55        OIER |= OIER_E3;
  56        return nonseekable_open(inode, file);
  57}
  58
  59/*
  60 * The watchdog cannot be disabled.
  61 *
  62 * Previous comments suggested that turning off the interrupt by
  63 * clearing OIER[E3] would prevent the watchdog timing out but this
  64 * does not appear to be true (at least on the PXA255).
  65 */
  66static int sa1100dog_release(struct inode *inode, struct file *file)
  67{
  68        printk(KERN_CRIT "WATCHDOG: Device closed - timer will not stop\n");
  69
  70        clear_bit(1, &sa1100wdt_users);
  71
  72        return 0;
  73}
  74
  75static ssize_t sa1100dog_write(struct file *file, const char __user *data, size_t len, loff_t *ppos)
  76{
  77        if (len)
  78                /* Refresh OSMR3 timer. */
  79                OSMR3 = OSCR + pre_margin;
  80
  81        return len;
  82}
  83
  84static struct watchdog_info ident = {
  85        .options        = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  86        .identity       = "SA1100/PXA255 Watchdog",
  87};
  88
  89static int sa1100dog_ioctl(struct inode *inode, struct file *file,
  90        unsigned int cmd, 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_SETTIMEOUT:
 112                ret = get_user(time, p);
 113                if (ret)
 114                        break;
 115
 116                if (time <= 0 || time > 255) {
 117                        ret = -EINVAL;
 118                        break;
 119                }
 120
 121                pre_margin = OSCR_FREQ * time;
 122                OSMR3 = OSCR + pre_margin;
 123                /*fall through*/
 124
 125        case WDIOC_GETTIMEOUT:
 126                ret = put_user(pre_margin / OSCR_FREQ, p);
 127                break;
 128
 129        case WDIOC_KEEPALIVE:
 130                OSMR3 = OSCR + pre_margin;
 131                ret = 0;
 132                break;
 133        }
 134        return ret;
 135}
 136
 137static const struct file_operations sa1100dog_fops =
 138{
 139        .owner          = THIS_MODULE,
 140        .llseek         = no_llseek,
 141        .write          = sa1100dog_write,
 142        .ioctl          = sa1100dog_ioctl,
 143        .open           = sa1100dog_open,
 144        .release        = sa1100dog_release,
 145};
 146
 147static struct miscdevice sa1100dog_miscdev =
 148{
 149        .minor          = WATCHDOG_MINOR,
 150        .name           = "watchdog",
 151        .fops           = &sa1100dog_fops,
 152};
 153
 154static int margin __initdata = 60;              /* (secs) Default is 1 minute */
 155
 156static int __init sa1100dog_init(void)
 157{
 158        int ret;
 159
 160        /*
 161         * Read the reset status, and save it for later.  If
 162         * we suspend, RCSR will be cleared, and the watchdog
 163         * reset reason will be lost.
 164         */
 165        boot_status = (RCSR & RCSR_WDR) ? WDIOF_CARDRESET : 0;
 166        pre_margin = OSCR_FREQ * margin;
 167
 168        ret = misc_register(&sa1100dog_miscdev);
 169        if (ret == 0)
 170                printk("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