drivers/char/watchdog/m5272_wdt.c

   1 /*
   2  *      Watchdog driver for the MCF5272
   3  *
   4  *      (c) Copyright 2005 Javier Herrero <jherrero@hvsistemas.es>
   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 2005           Javier Herrero <jherrero@hvsistemas.es>
  17  *
  18  *      03/05/2005 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 #include <asm/bitops.h>
  30 #include <asm/uaccess.h>
  31
  32 #include <asm/coldfire.h>
  33 #include <asm/m5272sim.h>
  34
  35 #define M5272_CLOSE_MAGIC       (0x5afc4453)
  36
  37 static unsigned long m5272wdt_users;
  38 static int expect_close;
  39 static unsigned short wdt_reset_ref;
  40 static int boot_status;
  41 #ifdef CONFIG_WATCHDOG_NOWAYOUT
  42 static int nowayout = 1;
  43 #else
  44 static int nowayout = 0;
  45 #endif
  46
  47 /*
  48  *      Allow only one person to hold it open
  49  */
  50 static int m5272dog_open(struct inode *inode, struct file *file)
  51 {
  52         unsigned short* w;
  53
  54         nonseekable_open(inode, file);
  55         if (test_and_set_bit(1,&m5272wdt_users))
  56                 return -EBUSY;
  57
  58         /* Activate M5272 Watchdog timer */
  59
  60         w = (unsigned short*)(MCF_MBAR + MCFSIM_WRRR);
  61         *w = wdt_reset_ref | 0x0001;
  62         w = (unsigned short*)(MCF_MBAR + MCFSIM_WCR);
  63         *w = 0;
  64         return 0;
  65 }
  66
  67 /*
  68  *      Shut off the timer.
  69  *      Lock it in if it's a module and we defined ...NOWAYOUT
  70  *      Oddly, the watchdog can only be enabled, but we can turn off
  71  *      the interrupt, which appears to prevent the watchdog timing out.
  72  */
  73 static int m5272dog_release(struct inode *inode, struct file *file)
  74 {
  75         unsigned short* w;
  76
  77         w = (unsigned short*)(MCF_MBAR + MCFSIM_WRRR);
  78
  79         if (expect_close == M5272_CLOSE_MAGIC) {
  80                 *w = 0;
  81         } else {
  82                 printk(KERN_CRIT "WATCHDOG: WDT device closed unexpectedly.  WDT will not stop!\n");
  83         }
  84         clear_bit(1, &m5272wdt_users);
  85         expect_close = 0;
  86         return 0;
  87 }
  88
  89 static ssize_t m5272dog_write(struct file *file, const char *data, size_t len, loff_t *ppos)
  90 {
  91         unsigned short* w;
  92
  93         if (len) {
  94                 if (!nowayout) {
  95                         size_t i;
  96
  97                         expect_close = 0;
  98
  99                         for (i = 0; i != len; i++) {
 100                                 char c;
 101
 102                                 if (get_user(c, data + i))
 103                                         return -EFAULT;
 104                                 if (c == 'V')
 105                                         expect_close = M5272_CLOSE_MAGIC;
 106                         }
 107                 }
 108                 /* Refresh watchdog timer. */
 109                 w = (unsigned short*)(MCF_MBAR + MCFSIM_WCR);
 110                 *w = 0;
 111         }
 112
 113         return len;
 114 }
 115
 116 static struct watchdog_info ident = {
 117         .options        = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
 118                           WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 119         .identity       = "MCF5272 Watchdog",
 120 };
 121
 122 static int m5272dog_ioctl(struct inode *inode, struct file *file,
 123         unsigned int cmd, unsigned long arg)
 124 {
 125         int ret = -ENOIOCTLCMD;
 126         int time;
 127         unsigned short* w;
 128
 129         switch (cmd) {
 130         case WDIOC_GETSUPPORT:
 131                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 132                                    sizeof(ident)) ? -EFAULT : 0;
 133                 break;
 134
 135         case WDIOC_GETSTATUS:
 136                 ret = put_user(0, (int *)arg);
 137                 break;
 138
 139         case WDIOC_GETBOOTSTATUS:
 140                 ret = put_user(boot_status, (int *)arg);
 141                 break;
 142
 143         case WDIOC_SETTIMEOUT:
 144                 ret = get_user(time, (int *)arg);
 145                 if (ret)
 146                         break;
 147
 148                 if (time <= 0 || time > (32768*16384/MCF_CLK)) {
 149                         ret = -EINVAL;
 150                         break;
 151                 }
 152
 153                 wdt_reset_ref = (MCF_CLK / 16384) * time;
 154                 w = (unsigned short*)(MCF_MBAR + MCFSIM_WRRR);
 155                 *w = wdt_reset_ref | 0x0001;
 156                 /*fall through*/
 157
 158         case WDIOC_GETTIMEOUT:
 159                 ret = put_user(wdt_reset_ref * 16384 / MCF_CLK, (int *)arg);
 160                 break;
 161
 162         case WDIOC_KEEPALIVE:
 163                 w = (unsigned short*)(MCF_MBAR + MCFSIM_WCR);
 164                 *w = 0;
 165                 ret = 0;
 166                 break;
 167         }
 168         return ret;
 169 }
 170
 171 static struct file_operations m5272dog_fops =
 172 {
 173         .owner          = THIS_MODULE,
 174         .llseek         = no_llseek,
 175         .write          = m5272dog_write,
 176         .ioctl          = m5272dog_ioctl,
 177         .open           = m5272dog_open,
 178         .release        = m5272dog_release,
 179 };
 180
 181 static struct miscdevice m5272dog_miscdev =
 182 {
 183         .minor          = WATCHDOG_MINOR,
 184         .name           = "MCF5272 watchdog",
 185         .fops           = &m5272dog_fops,
 186 };
 187
 188 static int margin __initdata = 16;              /* (secs) Default is 1 minute */
 189
 190 static int __init m5272dog_init(void)
 191 {
 192         int ret;
 193
 194         /*
 195          * Read the reset status, and save it for later.  If
 196          * we suspend, RCSR will be cleared, and the watchdog
 197          * reset reason will be lost.
 198          */
 199 //      boot_status = (RCSR & RCSR_WDR) ? WDIOF_CARDRESET : 0;
 200         wdt_reset_ref = (MCF_CLK / 16384) * margin;
 201
 202         ret = misc_register(&m5272dog_miscdev);
 203         if (ret == 0)
 204                 printk("MCF5272 Watchdog Timer: timer margin %d sec\n",
 205                        margin);
 206
 207         return ret;
 208 }
 209
 210 static void __exit m5272dog_exit(void)
 211 {
 212         misc_deregister(&m5272dog_miscdev);
 213 }
 214
 215 module_init(m5272dog_init);
 216 module_exit(m5272dog_exit);
 217
 218 MODULE_AUTHOR("Javier Herrero <jherrero@hvsistemas.es>");
 219 MODULE_DESCRIPTION("MCF5272 Watchdog");
 220
 221 module_param(margin, int, 0);
 222 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 16s)");
 223
 224 module_param(nowayout, int, 0);
 225 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 226
 227 MODULE_LICENSE("GPL");
 228 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);