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
  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         nonseekable_open(inode, file);
  50         if (test_and_set_bit(1,&sa1100wdt_users))
  51                 return -EBUSY;
  52
  53         /* Activate SA1100 Watchdog timer */
  54         OSMR3 = OSCR + pre_margin;
  55         OSSR = OSSR_M3;
  56         OWER = OWER_WME;
  57         OIER |= OIER_E3;
  58         return 0;
  59 }
  60
  61 /*
  62  * The watchdog cannot be disabled.
  63  *
  64  * Previous comments suggested that turning off the interrupt by
  65  * clearing OIER[E3] would prevent the watchdog timing out but this
  66  * does not appear to be true (at least on the PXA255).
  67  */
  68 static int sa1100dog_release(struct inode *inode, struct file *file)
  69 {
  70         printk(KERN_CRIT "WATCHDOG: Device closed - timer will not stop\n");
  71
  72         clear_bit(1, &sa1100wdt_users);
  73
  74         return 0;
  75 }
  76
  77 static ssize_t sa1100dog_write(struct file *file, const char __user *data, size_t len, loff_t *ppos)
  78 {
  79         if (len)
  80                 /* Refresh OSMR3 timer. */
  81                 OSMR3 = OSCR + pre_margin;
  82
  83         return len;
  84 }
  85
  86 static struct watchdog_info ident = {
  87         .options        = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  88         .identity       = "SA1100/PXA255 Watchdog",
  89 };
  90
  91 static int sa1100dog_ioctl(struct inode *inode, struct file *file,
  92         unsigned int cmd, unsigned long arg)
  93 {
  94         int ret = -ENOIOCTLCMD;
  95         int time;
  96
  97         switch (cmd) {
  98         case WDIOC_GETSUPPORT:
  99                 ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
 100                                    sizeof(ident)) ? -EFAULT : 0;
 101                 break;
 102
 103         case WDIOC_GETSTATUS:
 104                 ret = put_user(0, (int __user *)arg);
 105                 break;
 106
 107         case WDIOC_GETBOOTSTATUS:
 108                 ret = put_user(boot_status, (int __user *)arg);
 109                 break;
 110
 111         case WDIOC_SETTIMEOUT:
 112                 ret = get_user(time, (int __user *)arg);
 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, (int __user *)arg);
 127                 break;
 128
 129         case WDIOC_KEEPALIVE:
 130                 OSMR3 = OSCR + pre_margin;
 131                 ret = 0;
 132                 break;
 133         }
 134         return ret;
 135 }
 136
 137 static 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
 147 static struct miscdevice sa1100dog_miscdev =
 148 {
 149         .minor          = WATCHDOG_MINOR,
 150         .name           = "watchdog",
 151         .fops           = &sa1100dog_fops,
 152 };
 153
 154 static int margin __initdata = 60;              /* (secs) Default is 1 minute */
 155
 156 static 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
 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);