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/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
  29 #ifdef CONFIG_ARCH_PXA
  30 #include <asm/arch/pxa-regs.h>
  31 #endif
  32
  33 #include <asm/hardware.h>
  34 #include <asm/bitops.h>
  35 #include <asm/uaccess.h>
  36
  37 #define OSCR_FREQ               CLOCK_TICK_RATE
  38
  39 static unsigned long sa1100wdt_users;
  40 static int pre_margin;
  41 static int boot_status;
  42
  43 /*
  44  *      Allow only one person to hold it open
  45  */
  46 static int sa1100dog_open(struct inode *inode, struct file *file)
  47 {
  48         nonseekable_open(inode, file);
  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 0;
  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
  71         clear_bit(1, &sa1100wdt_users);
  72
  73         return 0;
  74 }
  75
  76 static ssize_t sa1100dog_write(struct file *file, const char __user *data, size_t len, loff_t *ppos)
  77 {
  78         if (len)
  79                 /* Refresh OSMR3 timer. */
  80                 OSMR3 = OSCR + pre_margin;
  81
  82         return len;
  83 }
  84
  85 static struct watchdog_info ident = {
  86         .options        = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  87         .identity       = "SA1100/PXA255 Watchdog",
  88 };
  89
  90 static int sa1100dog_ioctl(struct inode *inode, struct file *file,
  91         unsigned int cmd, unsigned long arg)
  92 {
  93         int ret = -ENOTTY;
  94         int time;
  95         void __user *argp = (void __user *)arg;
  96         int __user *p = argp;
  97
  98         switch (cmd) {
  99         case WDIOC_GETSUPPORT:
 100                 ret = copy_to_user(argp, &ident,
 101                                    sizeof(ident)) ? -EFAULT : 0;
 102                 break;
 103
 104         case WDIOC_GETSTATUS:
 105                 ret = put_user(0, p);
 106                 break;
 107
 108         case WDIOC_GETBOOTSTATUS:
 109                 ret = put_user(boot_status, p);
 110                 break;
 111
 112         case WDIOC_SETTIMEOUT:
 113                 ret = get_user(time, p);
 114                 if (ret)
 115                         break;
 116
 117                 if (time <= 0 || time > 255) {
 118                         ret = -EINVAL;
 119                         break;
 120                 }
 121
 122                 pre_margin = OSCR_FREQ * time;
 123                 OSMR3 = OSCR + pre_margin;
 124                 /*fall through*/
 125
 126         case WDIOC_GETTIMEOUT:
 127                 ret = put_user(pre_margin / OSCR_FREQ, p);
 128                 break;
 129
 130         case WDIOC_KEEPALIVE:
 131                 OSMR3 = OSCR + pre_margin;
 132                 ret = 0;
 133                 break;
 134         }
 135         return ret;
 136 }
 137
 138 static const struct file_operations sa1100dog_fops =
 139 {
 140         .owner          = THIS_MODULE,
 141         .llseek         = no_llseek,
 142         .write          = sa1100dog_write,
 143         .ioctl          = sa1100dog_ioctl,
 144         .open           = sa1100dog_open,
 145         .release        = sa1100dog_release,
 146 };
 147
 148 static struct miscdevice sa1100dog_miscdev =
 149 {
 150         .minor          = WATCHDOG_MINOR,
 151         .name           = "watchdog",
 152         .fops           = &sa1100dog_fops,
 153 };
 154
 155 static int margin __initdata = 60;              /* (secs) Default is 1 minute */
 156
 157 static int __init sa1100dog_init(void)
 158 {
 159         int ret;
 160
 161         /*
 162          * Read the reset status, and save it for later.  If
 163          * we suspend, RCSR will be cleared, and the watchdog
 164          * reset reason will be lost.
 165          */
 166         boot_status = (RCSR & RCSR_WDR) ? WDIOF_CARDRESET : 0;
 167         pre_margin = OSCR_FREQ * margin;
 168
 169         ret = misc_register(&sa1100dog_miscdev);
 170         if (ret == 0)
 171                 printk("SA1100/PXA2xx Watchdog Timer: timer margin %d sec\n",
 172                        margin);
 173         return ret;
 174 }
 175
 176 static void __exit sa1100dog_exit(void)
 177 {
 178         misc_deregister(&sa1100dog_miscdev);
 179 }
 180
 181 module_init(sa1100dog_init);
 182 module_exit(sa1100dog_exit);
 183
 184 MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
 185 MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
 186
 187 module_param(margin, int, 0);
 188 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
 189
 190 MODULE_LICENSE("GPL");
 191 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);