drivers/char/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@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/config.h>
  21 #include <linux/module.h>
  22 #include <linux/moduleparam.h>
  23 #include <linux/types.h>
  24 #include <linux/kernel.h>
  25 #include <linux/fs.h>
  26 #include <linux/miscdevice.h>
  27 #include <linux/watchdog.h>
  28 #include <linux/init.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/bitops.h>
  36 #include <asm/uaccess.h>
  37
  38 #define OSCR_FREQ               CLOCK_TICK_RATE
  39 #define SA1100_CLOSE_MAGIC      (0x5afc4453)
  40
  41 static unsigned long sa1100wdt_users;
  42 static int expect_close;
  43 static int pre_margin;
  44 static int boot_status;
  45 #ifdef CONFIG_WATCHDOG_NOWAYOUT
  46 static int nowayout = 1;
  47 #else
  48 static int nowayout = 0;
  49 #endif
  50
  51 /*
  52  *      Allow only one person to hold it open
  53  */
  54 static int sa1100dog_open(struct inode *inode, struct file *file)
  55 {
  56         nonseekable_open(inode, file);
  57         if (test_and_set_bit(1,&sa1100wdt_users))
  58                 return -EBUSY;
  59
  60         /* Activate SA1100 Watchdog timer */
  61         OSMR3 = OSCR + pre_margin;
  62         OSSR = OSSR_M3;
  63         OWER = OWER_WME;
  64         OIER |= OIER_E3;
  65         return 0;
  66 }
  67
  68 /*
  69  *      Shut off the timer.
  70  *      Lock it in if it's a module and we defined ...NOWAYOUT
  71  *      Oddly, the watchdog can only be enabled, but we can turn off
  72  *      the interrupt, which appears to prevent the watchdog timing out.
  73  */
  74 static int sa1100dog_release(struct inode *inode, struct file *file)
  75 {
  76         OSMR3 = OSCR + pre_margin;
  77
  78         if (expect_close == SA1100_CLOSE_MAGIC) {
  79                 OIER &= ~OIER_E3;
  80         } else {
  81                 printk(KERN_CRIT "WATCHDOG: WDT device closed unexpectedly.  WDT will not stop!\n");
  82         }
  83
  84         clear_bit(1, &sa1100wdt_users);
  85         expect_close = 0;
  86
  87         return 0;
  88 }
  89
  90 static ssize_t sa1100dog_write(struct file *file, const char *data, size_t len, loff_t *ppos)
  91 {
  92         if (len) {
  93                 if (!nowayout) {
  94                         size_t i;
  95
  96                         expect_close = 0;
  97
  98                         for (i = 0; i != len; i++) {
  99                                 char c;
 100
 101                                 if (get_user(c, data + i))
 102                                         return -EFAULT;
 103                                 if (c == 'V')
 104                                         expect_close = SA1100_CLOSE_MAGIC;
 105                         }
 106                 }
 107                 /* Refresh OSMR3 timer. */
 108                 OSMR3 = OSCR + pre_margin;
 109         }
 110
 111         return len;
 112 }
 113
 114 static struct watchdog_info ident = {
 115         .options        = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
 116                           WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 117         .identity       = "SA1100 Watchdog",
 118 };
 119
 120 static int sa1100dog_ioctl(struct inode *inode, struct file *file,
 121         unsigned int cmd, unsigned long arg)
 122 {
 123         int ret = -ENOIOCTLCMD;
 124         int time;
 125
 126         switch (cmd) {
 127         case WDIOC_GETSUPPORT:
 128                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 129                                    sizeof(ident)) ? -EFAULT : 0;
 130                 break;
 131
 132         case WDIOC_GETSTATUS:
 133                 ret = put_user(0, (int *)arg);
 134                 break;
 135
 136         case WDIOC_GETBOOTSTATUS:
 137                 ret = put_user(boot_status, (int *)arg);
 138                 break;
 139
 140         case WDIOC_SETTIMEOUT:
 141                 ret = get_user(time, (int *)arg);
 142                 if (ret)
 143                         break;
 144
 145                 if (time <= 0 || time > 255) {
 146                         ret = -EINVAL;
 147                         break;
 148                 }
 149
 150                 pre_margin = OSCR_FREQ * time;
 151                 OSMR3 = OSCR + pre_margin;
 152                 /*fall through*/
 153
 154         case WDIOC_GETTIMEOUT:
 155                 ret = put_user(pre_margin / OSCR_FREQ, (int *)arg);
 156                 break;
 157
 158         case WDIOC_KEEPALIVE:
 159                 OSMR3 = OSCR + pre_margin;
 160                 ret = 0;
 161                 break;
 162         }
 163         return ret;
 164 }
 165
 166 static struct file_operations sa1100dog_fops =
 167 {
 168         .owner          = THIS_MODULE,
 169         .llseek         = no_llseek,
 170         .write          = sa1100dog_write,
 171         .ioctl          = sa1100dog_ioctl,
 172         .open           = sa1100dog_open,
 173         .release        = sa1100dog_release,
 174 };
 175
 176 static struct miscdevice sa1100dog_miscdev =
 177 {
 178         .minor          = WATCHDOG_MINOR,
 179         .name           = "SA1100/PXA2xx watchdog",
 180         .fops           = &sa1100dog_fops,
 181 };
 182
 183 static int margin __initdata = 60;              /* (secs) Default is 1 minute */
 184
 185 static int __init sa1100dog_init(void)
 186 {
 187         int ret;
 188
 189         /*
 190          * Read the reset status, and save it for later.  If
 191          * we suspend, RCSR will be cleared, and the watchdog
 192          * reset reason will be lost.
 193          */
 194         boot_status = (RCSR & RCSR_WDR) ? WDIOF_CARDRESET : 0;
 195         pre_margin = OSCR_FREQ * margin;
 196
 197         ret = misc_register(&sa1100dog_miscdev);
 198         if (ret == 0)
 199                 printk("SA1100/PXA2xx Watchdog Timer: timer margin %d sec\n",
 200                        margin);
 201
 202         return ret;
 203 }
 204
 205 static void __exit sa1100dog_exit(void)
 206 {
 207         misc_deregister(&sa1100dog_miscdev);
 208 }
 209
 210 module_init(sa1100dog_init);
 211 module_exit(sa1100dog_exit);
 212
 213 MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
 214 MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
 215
 216 module_param(margin, int, 0);
 217 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
 218
 219 module_param(nowayout, int, 0);
 220 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 221
 222 MODULE_LICENSE("GPL");
 223 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);