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
  21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  22
  23 #include <linux/module.h>
  24 #include <linux/moduleparam.h>
  25 #include <linux/types.h>
  26 #include <linux/kernel.h>
  27 #include <linux/fs.h>
  28 #include <linux/miscdevice.h>
  29 #include <linux/watchdog.h>
  30 #include <linux/init.h>
  31 #include <linux/io.h>
  32 #include <linux/bitops.h>
  33 #include <linux/uaccess.h>
  34 #include <linux/timex.h>
  35
  36 #ifdef CONFIG_ARCH_PXA
  37 #include <mach/regs-ost.h>
  38 #endif
  39
  40 #include <mach/reset.h>
  41 #include <mach/hardware.h>
  42
  43 static unsigned long oscr_freq;
  44 static unsigned long sa1100wdt_users;
  45 static unsigned int pre_margin;
  46 static int boot_status;
  47
  48 /*
  49  *      Allow only one person to hold it open
  50  */
  51 static int sa1100dog_open(struct inode *inode, struct file *file)
  52 {
  53         if (test_and_set_bit(1, &sa1100wdt_users))
  54                 return -EBUSY;
  55
  56         /* Activate SA1100 Watchdog timer */
  57         writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
  58         writel_relaxed(OSSR_M3, OSSR);
  59         writel_relaxed(OWER_WME, OWER);
  60         writel_relaxed(readl_relaxed(OIER) | OIER_E3, OIER);
  61         return nonseekable_open(inode, file);
  62 }
  63
  64 /*
  65  * The watchdog cannot be disabled.
  66  *
  67  * Previous comments suggested that turning off the interrupt by
  68  * clearing OIER[E3] would prevent the watchdog timing out but this
  69  * does not appear to be true (at least on the PXA255).
  70  */
  71 static int sa1100dog_release(struct inode *inode, struct file *file)
  72 {
  73         pr_crit("Device closed - timer will not stop\n");
  74         clear_bit(1, &sa1100wdt_users);
  75         return 0;
  76 }
  77
  78 static ssize_t sa1100dog_write(struct file *file, const char __user *data,
  79                                                 size_t len, loff_t *ppos)
  80 {
  81         if (len)
  82                 /* Refresh OSMR3 timer. */
  83                 writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
  84         return len;
  85 }
  86
  87 static const struct watchdog_info ident = {
  88         .options        = WDIOF_CARDRESET | WDIOF_SETTIMEOUT
  89                                 | WDIOF_KEEPALIVEPING,
  90         .identity       = "SA1100/PXA255 Watchdog",
  91         .firmware_version       = 1,
  92 };
  93
  94 static long sa1100dog_ioctl(struct file *file, unsigned int cmd,
  95                                                         unsigned long arg)
  96 {
  97         int ret = -ENOTTY;
  98         int time;
  99         void __user *argp = (void __user *)arg;
 100         int __user *p = argp;
 101
 102         switch (cmd) {
 103         case WDIOC_GETSUPPORT:
 104                 ret = copy_to_user(argp, &ident,
 105                                    sizeof(ident)) ? -EFAULT : 0;
 106                 break;
 107
 108         case WDIOC_GETSTATUS:
 109                 ret = put_user(0, p);
 110                 break;
 111
 112         case WDIOC_GETBOOTSTATUS:
 113                 ret = put_user(boot_status, p);
 114                 break;
 115
 116         case WDIOC_KEEPALIVE:
 117                 writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
 118                 ret = 0;
 119                 break;
 120
 121         case WDIOC_SETTIMEOUT:
 122                 ret = get_user(time, p);
 123                 if (ret)
 124                         break;
 125
 126                 if (time <= 0 || (oscr_freq * (long long)time >= 0xffffffff)) {
 127                         ret = -EINVAL;
 128                         break;
 129                 }
 130
 131                 pre_margin = oscr_freq * time;
 132                 writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
 133                 /*fall through*/
 134
 135         case WDIOC_GETTIMEOUT:
 136                 ret = put_user(pre_margin / oscr_freq, p);
 137                 break;
 138         }
 139         return ret;
 140 }
 141
 142 static const struct file_operations sa1100dog_fops = {
 143         .owner          = THIS_MODULE,
 144         .llseek         = no_llseek,
 145         .write          = sa1100dog_write,
 146         .unlocked_ioctl = sa1100dog_ioctl,
 147         .open           = sa1100dog_open,
 148         .release        = sa1100dog_release,
 149 };
 150
 151 static struct miscdevice sa1100dog_miscdev = {
 152         .minor          = WATCHDOG_MINOR,
 153         .name           = "watchdog",
 154         .fops           = &sa1100dog_fops,
 155 };
 156
 157 static int margin __initdata = 60;              /* (secs) Default is 1 minute */
 158
 159 static int __init sa1100dog_init(void)
 160 {
 161         int ret;
 162
 163         oscr_freq = get_clock_tick_rate();
 164
 165         /*
 166          * Read the reset status, and save it for later.  If
 167          * we suspend, RCSR will be cleared, and the watchdog
 168          * reset reason will be lost.
 169          */
 170         boot_status = (reset_status & RESET_STATUS_WATCHDOG) ?
 171                                 WDIOF_CARDRESET : 0;
 172         pre_margin = oscr_freq * margin;
 173
 174         ret = misc_register(&sa1100dog_miscdev);
 175         if (ret == 0)
 176                 pr_info("SA1100/PXA2xx Watchdog Timer: timer margin %d sec\n",
 177                         margin);
 178         return ret;
 179 }
 180
 181 static void __exit sa1100dog_exit(void)
 182 {
 183         misc_deregister(&sa1100dog_miscdev);
 184 }
 185
 186 module_init(sa1100dog_init);
 187 module_exit(sa1100dog_exit);
 188
 189 MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
 190 MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
 191
 192 module_param(margin, int, 0);
 193 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
 194
 195 MODULE_LICENSE("GPL");
 196 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);