drivers/watchdog/sa1100_wdt.c

   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
  40 static unsigned long sa1100wdt_users;
  41 static int pre_margin;
  42 static int boot_status;
  43
  44 /*
  45  *      Allow only one person to hold it open
  46  */
  47 static 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  */
  67 static 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
  74 static 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
  83 static const struct watchdog_info ident = {
  84         .options        = WDIOF_CARDRESET | WDIOF_SETTIMEOUT
  85                                 | WDIOF_KEEPALIVEPING,
  86         .identity       = "SA1100/PXA255 Watchdog",
  87 };
  88
  89 static 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
 137 static 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
 146 static struct miscdevice sa1100dog_miscdev = {
 147         .minor          = WATCHDOG_MINOR,
 148         .name           = "watchdog",
 149         .fops           = &sa1100dog_fops,
 150 };
 151
 152 static int margin __initdata = 60;              /* (secs) Default is 1 minute */
 153
 154 static 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
 175 static void __exit sa1100dog_exit(void)
 176 {
 177         misc_deregister(&sa1100dog_miscdev);
 178 }
 179
 180 module_init(sa1100dog_init);
 181 module_exit(sa1100dog_exit);
 182
 183 MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
 184 MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
 185
 186 module_param(margin, int, 0);
 187 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
 188
 189 MODULE_LICENSE("GPL");
 190 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);