target/linux/ar7-2.6/files/drivers/char/watchdog/ar7_wdt.c

   1 /*
   2  * linux/drivers/char/ar7_wdt.c
   3  *
   4  * Copyright (C) 2007 OpenWrt.org
   5  * Copyright (c) 2005 Enrik Berkhan <Enrik.Berkhan@akk.org>
   6  *
   7  * Some code taken from:
   8  * National Semiconductor SCx200 Watchdog support
   9  * Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  24  */
  25
  26 #include <linux/module.h>
  27 #include <linux/moduleparam.h>
  28 #include <linux/errno.h>
  29 #include <linux/init.h>
  30 #include <linux/miscdevice.h>
  31 #include <linux/watchdog.h>
  32 #include <linux/notifier.h>
  33 #include <linux/reboot.h>
  34 #include <linux/fs.h>
  35 #include <linux/ioport.h>
  36
  37 #include <asm/addrspace.h>
  38 #include <asm/io.h>
  39 #include <asm/uaccess.h>
  40
  41 #include <asm/ar7/ar7.h>
  42
  43 #define DRVNAME "ar7_wdt"
  44 #define LONGNAME "TI AR7 Watchdog Timer"
  45
  46 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
  47 MODULE_DESCRIPTION(LONGNAME);
  48 MODULE_LICENSE("GPL");
  49 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  50
  51 static int margin = 60;
  52 module_param(margin, int, 0);
  53 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
  54
  55 static int nowayout = WATCHDOG_NOWAYOUT;
  56 module_param(nowayout, int, 0);
  57 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
  58
  59 typedef struct {
  60         u32 kick_lock;
  61         u32 kick;
  62         u32 change_lock;
  63         u32 change ;
  64         u32 disable_lock;
  65         u32 disable;
  66         u32 prescale_lock;
  67         u32 prescale;
  68 } ar7_wdt_t;
  69
  70 static struct semaphore open_semaphore;
  71 static unsigned expect_close;
  72
  73 /* XXX currently fixed, allows max margin ~68.72 secs */
  74 #define prescale_value 0xFFFF
  75
  76 static void ar7_wdt_kick(u32 value)
  77 {
  78         volatile ar7_wdt_t *ar7_wdt = (ar7_wdt_t *)ioremap(AR7_REGS_WDT, sizeof(ar7_wdt_t));
  79
  80         ar7_wdt->kick_lock = 0x5555;
  81         if ((ar7_wdt->kick_lock & 3) == 1) {
  82                 ar7_wdt->kick_lock = 0xAAAA;
  83                 if ((ar7_wdt->kick_lock & 3) == 3) {
  84                         ar7_wdt->kick = value;
  85                         return;
  86                 }
  87         }
  88         printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
  89 }
  90
  91 static void ar7_wdt_prescale(u32 value)
  92 {
  93         volatile ar7_wdt_t *ar7_wdt = (ar7_wdt_t *)ioremap(AR7_REGS_WDT, sizeof(ar7_wdt_t));
  94
  95         ar7_wdt->prescale_lock = 0x5A5A;
  96         if ((ar7_wdt->prescale_lock & 3) == 1) {
  97                 ar7_wdt->prescale_lock = 0xA5A5;
  98                 if ((ar7_wdt->prescale_lock & 3) == 3) {
  99                         ar7_wdt->prescale = value;
 100                         return;
 101                 }
 102         }
 103         printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
 104 }
 105
 106 static void ar7_wdt_change(u32 value)
 107 {
 108         volatile ar7_wdt_t *ar7_wdt = (ar7_wdt_t *)ioremap(AR7_REGS_WDT, sizeof(ar7_wdt_t));
 109
 110         ar7_wdt->change_lock = 0x6666;
 111         if ((ar7_wdt->change_lock & 3) == 1) {
 112                 ar7_wdt->change_lock = 0xBBBB;
 113                 if ((ar7_wdt->change_lock & 3) == 3) {
 114                         ar7_wdt->change = value;
 115                         return;
 116                 }
 117         }
 118         printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
 119 }
 120
 121 static void ar7_wdt_disable(u32 value)
 122 {
 123         volatile ar7_wdt_t *ar7_wdt = (ar7_wdt_t *)ioremap(AR7_REGS_WDT, sizeof(ar7_wdt_t));
 124
 125         ar7_wdt->disable_lock = 0x7777;
 126         if ((ar7_wdt->disable_lock & 3) == 1) {
 127                 ar7_wdt->disable_lock = 0xCCCC;
 128                 if ((ar7_wdt->disable_lock & 3) == 2) {
 129                         ar7_wdt->disable_lock = 0xDDDD;
 130                         if ((ar7_wdt->disable_lock & 3) == 3) {
 131                                 ar7_wdt->disable = value;
 132                                 return;
 133                         }
 134                 }
 135         }
 136         printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
 137 }
 138
 139 static void ar7_wdt_update_margin(int new_margin)
 140 {
 141         u32 change;
 142
 143         change = new_margin * (ar7_vbus_freq() / prescale_value);
 144         if (change < 1) change = 1;
 145         if (change > 0xFFFF) change = 0xFFFF;
 146         ar7_wdt_change(change);
 147         margin = change * prescale_value / ar7_vbus_freq();
 148         printk(KERN_INFO DRVNAME
 149                ": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
 150                margin, prescale_value, change, ar7_vbus_freq());
 151 }
 152
 153 static void ar7_wdt_enable_wdt(void)
 154 {
 155         printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
 156         ar7_wdt_disable(1);
 157         ar7_wdt_kick(1);
 158 }
 159
 160 static void ar7_wdt_disable_wdt(void)
 161 {
 162         printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
 163         ar7_wdt_disable(0);
 164 }
 165
 166 static int ar7_wdt_open(struct inode *inode, struct file *file)
 167 {
 168         /* only allow one at a time */
 169         if (down_trylock(&open_semaphore))
 170                 return -EBUSY;
 171         ar7_wdt_enable_wdt();
 172         expect_close = 0;
 173
 174         return 0;
 175 }
 176
 177 static int ar7_wdt_release(struct inode *inode, struct file *file)
 178 {
 179         if (!expect_close) {
 180                 printk(KERN_WARNING DRVNAME ": watchdog device closed unexpectedly, will not disable the watchdog timer\n");
 181         } else if (!nowayout) {
 182                 ar7_wdt_disable_wdt();
 183         }
 184         up(&open_semaphore);
 185
 186         return 0;
 187 }
 188
 189 static int ar7_wdt_notify_sys(struct notifier_block *this,
 190                               unsigned long code, void *unused)
 191 {
 192         if (code == SYS_HALT || code == SYS_POWER_OFF)
 193                 if (!nowayout)
 194                         ar7_wdt_disable_wdt();
 195
 196         return NOTIFY_DONE;
 197 }
 198
 199 static struct notifier_block ar7_wdt_notifier =
 200 {
 201         .notifier_call = ar7_wdt_notify_sys
 202 };
 203
 204 static ssize_t ar7_wdt_write(struct file *file, const char *data,
 205                              size_t len, loff_t *ppos)
 206 {
 207         if (ppos != &file->f_pos)
 208                 return -ESPIPE;
 209
 210         /* check for a magic close character */
 211         if (len) {
 212                 size_t i;
 213
 214                 ar7_wdt_kick(1);
 215
 216                 expect_close = 0;
 217                 for (i = 0; i < len; ++i) {
 218                         char c;
 219                         if (get_user(c, data+i))
 220                                 return -EFAULT;
 221                         if (c == 'V')
 222                                 expect_close = 1;
 223                 }
 224
 225         }
 226         return len;
 227 }
 228
 229 static int ar7_wdt_ioctl(struct inode *inode, struct file *file,
 230                          unsigned int cmd, unsigned long arg)
 231 {
 232         static struct watchdog_info ident = {
 233                 .identity = LONGNAME,
 234                 .firmware_version = 1,
 235                 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING),
 236         };
 237         int new_margin;
 238
 239         switch (cmd) {
 240         default:
 241                 return -ENOTTY;
 242         case WDIOC_GETSUPPORT:
 243                 if(copy_to_user((struct watchdog_info *)arg, &ident,
 244                                 sizeof(ident)))
 245                         return -EFAULT;
 246                 return 0;
 247         case WDIOC_GETSTATUS:
 248         case WDIOC_GETBOOTSTATUS:
 249                 if (put_user(0, (int *)arg))
 250                         return -EFAULT;
 251                 return 0;
 252         case WDIOC_KEEPALIVE:
 253                 ar7_wdt_kick(1);
 254                 return 0;
 255         case WDIOC_SETTIMEOUT:
 256                 if (get_user(new_margin, (int *)arg))
 257                         return -EFAULT;
 258                 if (new_margin < 1)
 259                         return -EINVAL;
 260
 261                 ar7_wdt_update_margin(new_margin);
 262                 ar7_wdt_kick(1);
 263
 264         case WDIOC_GETTIMEOUT:
 265                 if (put_user(margin, (int *)arg))
 266                         return -EFAULT;
 267                 return 0;
 268         }
 269 }
 270
 271 static struct file_operations ar7_wdt_fops = {
 272         .owner   = THIS_MODULE,
 273         .write   = ar7_wdt_write,
 274         .ioctl   = ar7_wdt_ioctl,
 275         .open    = ar7_wdt_open,
 276         .release = ar7_wdt_release,
 277 };
 278
 279 static struct miscdevice ar7_wdt_miscdev = {
 280         .minor = WATCHDOG_MINOR,
 281         .name  = "watchdog",
 282         .fops  = &ar7_wdt_fops,
 283 };
 284
 285 static int __init ar7_wdt_init(void)
 286 {
 287         int rc;
 288
 289         if (!request_mem_region(AR7_REGS_WDT, sizeof(ar7_wdt_t), LONGNAME)) {
 290                 printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
 291                 return -EBUSY;
 292         }
 293
 294         ar7_wdt_disable_wdt();
 295         ar7_wdt_prescale(prescale_value);
 296         ar7_wdt_update_margin(margin);
 297
 298         sema_init(&open_semaphore, 1);
 299
 300         rc = misc_register(&ar7_wdt_miscdev);
 301         if (rc) {
 302                 printk(KERN_ERR DRVNAME ": unable to register misc device\n");
 303                 goto out_alloc;
 304         }
 305
 306         rc = register_reboot_notifier(&ar7_wdt_notifier);
 307         if (rc) {
 308                 printk(KERN_ERR DRVNAME ": unable to register reboot notifier\n");
 309                 goto out_register;
 310         }
 311         goto out;
 312
 313 out_register:
 314         misc_deregister(&ar7_wdt_miscdev);
 315 out_alloc:
 316         release_mem_region(AR7_REGS_WDT, sizeof(ar7_wdt_t));
 317 out:
 318         return rc;
 319 }
 320
 321 static void __exit ar7_wdt_cleanup(void)
 322 {
 323         unregister_reboot_notifier(&ar7_wdt_notifier);
 324         misc_deregister(&ar7_wdt_miscdev);
 325         release_mem_region(AR7_REGS_WDT, sizeof(ar7_wdt_t));
 326 }
 327
 328 module_init(ar7_wdt_init);
 329 module_exit(ar7_wdt_cleanup);