drivers/watchdog/ar7_wdt.c

   1 /*
   2  * drivers/watchdog/ar7_wdt.c
   3  *
   4  * Copyright (C) 2007 Nicolas Thill <nico@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 #include <linux/io.h>
  37 #include <linux/uaccess.h>
  38
  39 #include <asm/addrspace.h>
  40 #include <asm/ar7/ar7.h>
  41
  42 #define DRVNAME "ar7_wdt"
  43 #define LONGNAME "TI AR7 Watchdog Timer"
  44
  45 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
  46 MODULE_DESCRIPTION(LONGNAME);
  47 MODULE_LICENSE("GPL");
  48 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  49
  50 static int margin = 60;
  51 module_param(margin, int, 0);
  52 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
  53
  54 static int nowayout = WATCHDOG_NOWAYOUT;
  55 module_param(nowayout, int, 0);
  56 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
  57
  58 #define READ_REG(x) readl((void __iomem *)&(x))
  59 #define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))
  60
  61 struct ar7_wdt {
  62         u32 kick_lock;
  63         u32 kick;
  64         u32 change_lock;
  65         u32 change;
  66         u32 disable_lock;
  67         u32 disable;
  68         u32 prescale_lock;
  69         u32 prescale;
  70 };
  71
  72 static struct semaphore open_semaphore;
  73 static unsigned expect_close;
  74
  75 /* XXX currently fixed, allows max margin ~68.72 secs */
  76 #define prescale_value 0xffff
  77
  78 /* Offset of the WDT registers */
  79 static unsigned long ar7_regs_wdt;
  80 /* Pointer to the remapped WDT IO space */
  81 static struct ar7_wdt *ar7_wdt;
  82 static void ar7_wdt_get_regs(void)
  83 {
  84         u16 chip_id = ar7_chip_id();
  85         switch (chip_id) {
  86         case AR7_CHIP_7100:
  87         case AR7_CHIP_7200:
  88                 ar7_regs_wdt = AR7_REGS_WDT;
  89                 break;
  90         default:
  91                 ar7_regs_wdt = UR8_REGS_WDT;
  92                 break;
  93         }
  94 }
  95
  96
  97 static void ar7_wdt_kick(u32 value)
  98 {
  99         WRITE_REG(ar7_wdt->kick_lock, 0x5555);
 100         if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
 101                 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
 102                 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
 103                         WRITE_REG(ar7_wdt->kick, value);
 104                         return;
 105                 }
 106         }
 107         printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
 108 }
 109
 110 static void ar7_wdt_prescale(u32 value)
 111 {
 112         WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
 113         if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
 114                 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
 115                 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
 116                         WRITE_REG(ar7_wdt->prescale, value);
 117                         return;
 118                 }
 119         }
 120         printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
 121 }
 122
 123 static void ar7_wdt_change(u32 value)
 124 {
 125         WRITE_REG(ar7_wdt->change_lock, 0x6666);
 126         if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
 127                 WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
 128                 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
 129                         WRITE_REG(ar7_wdt->change, value);
 130                         return;
 131                 }
 132         }
 133         printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
 134 }
 135
 136 static void ar7_wdt_disable(u32 value)
 137 {
 138         WRITE_REG(ar7_wdt->disable_lock, 0x7777);
 139         if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
 140                 WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
 141                 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
 142                         WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
 143                         if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
 144                                 WRITE_REG(ar7_wdt->disable, value);
 145                                 return;
 146                         }
 147                 }
 148         }
 149         printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
 150 }
 151
 152 static void ar7_wdt_update_margin(int new_margin)
 153 {
 154         u32 change;
 155
 156         change = new_margin * (ar7_vbus_freq() / prescale_value);
 157         if (change < 1) change = 1;
 158         if (change > 0xffff) change = 0xffff;
 159         ar7_wdt_change(change);
 160         margin = change * prescale_value / ar7_vbus_freq();
 161         printk(KERN_INFO DRVNAME
 162                ": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
 163                margin, prescale_value, change, ar7_vbus_freq());
 164 }
 165
 166 static void ar7_wdt_enable_wdt(void)
 167 {
 168         printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
 169         ar7_wdt_disable(1);
 170         ar7_wdt_kick(1);
 171 }
 172
 173 static void ar7_wdt_disable_wdt(void)
 174 {
 175         printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
 176         ar7_wdt_disable(0);
 177 }
 178
 179 static int ar7_wdt_open(struct inode *inode, struct file *file)
 180 {
 181         /* only allow one at a time */
 182         if (down_trylock(&open_semaphore))
 183                 return -EBUSY;
 184         ar7_wdt_enable_wdt();
 185         expect_close = 0;
 186
 187         return nonseekable_open(inode, file);
 188 }
 189
 190 static int ar7_wdt_release(struct inode *inode, struct file *file)
 191 {
 192         if (!expect_close)
 193                 printk(KERN_WARNING DRVNAME
 194                 ": watchdog device closed unexpectedly,"
 195                 "will not disable the watchdog timer\n");
 196         else if (!nowayout)
 197                 ar7_wdt_disable_wdt();
 198
 199         up(&open_semaphore);
 200
 201         return 0;
 202 }
 203
 204 static int ar7_wdt_notify_sys(struct notifier_block *this,
 205                               unsigned long code, void *unused)
 206 {
 207         if (code == SYS_HALT || code == SYS_POWER_OFF)
 208                 if (!nowayout)
 209                         ar7_wdt_disable_wdt();
 210
 211         return NOTIFY_DONE;
 212 }
 213
 214 static struct notifier_block ar7_wdt_notifier = {
 215         .notifier_call = ar7_wdt_notify_sys
 216 };
 217
 218 static ssize_t ar7_wdt_write(struct file *file, const char *data,
 219                              size_t len, loff_t *ppos)
 220 {
 221         /* check for a magic close character */
 222         if (len) {
 223                 size_t i;
 224
 225                 ar7_wdt_kick(1);
 226
 227                 expect_close = 0;
 228                 for (i = 0; i < len; ++i) {
 229                         char c;
 230                         if (get_user(c, data+i))
 231                                 return -EFAULT;
 232                         if (c == 'V')
 233                                 expect_close = 1;
 234                 }
 235
 236         }
 237         return len;
 238 }
 239
 240 static int ar7_wdt_ioctl(struct inode *inode, struct file *file,
 241                          unsigned int cmd, unsigned long arg)
 242 {
 243         static struct watchdog_info ident = {
 244                 .identity = LONGNAME,
 245                 .firmware_version = 1,
 246                 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING),
 247         };
 248         int new_margin;
 249
 250         switch (cmd) {
 251         default:
 252                 return -ENOTTY;
 253         case WDIOC_GETSUPPORT:
 254                 if (copy_to_user((struct watchdog_info *)arg, &ident,
 255                                 sizeof(ident)))
 256                         return -EFAULT;
 257                 return 0;
 258         case WDIOC_GETSTATUS:
 259         case WDIOC_GETBOOTSTATUS:
 260                 if (put_user(0, (int *)arg))
 261                         return -EFAULT;
 262                 return 0;
 263         case WDIOC_KEEPALIVE:
 264                 ar7_wdt_kick(1);
 265                 return 0;
 266         case WDIOC_SETTIMEOUT:
 267                 if (get_user(new_margin, (int *)arg))
 268                         return -EFAULT;
 269                 if (new_margin < 1)
 270                         return -EINVAL;
 271
 272                 ar7_wdt_update_margin(new_margin);
 273                 ar7_wdt_kick(1);
 274
 275         case WDIOC_GETTIMEOUT:
 276                 if (put_user(margin, (int *)arg))
 277                         return -EFAULT;
 278                 return 0;
 279         }
 280 }
 281
 282 static struct file_operations ar7_wdt_fops = {
 283         .owner          = THIS_MODULE,
 284         .write          = ar7_wdt_write,
 285         .ioctl          = ar7_wdt_ioctl,
 286         .open           = ar7_wdt_open,
 287         .release        = ar7_wdt_release,
 288 };
 289
 290 static struct miscdevice ar7_wdt_miscdev = {
 291         .minor          = WATCHDOG_MINOR,
 292         .name           = "watchdog",
 293         .fops           = &ar7_wdt_fops,
 294 };
 295
 296 static int __init ar7_wdt_init(void)
 297 {
 298         int rc;
 299
 300         ar7_wdt_get_regs();
 301
 302         if (!request_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt),
 303                                                         LONGNAME)) {
 304                 printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
 305                 return -EBUSY;
 306         }
 307
 308         ar7_wdt = (struct ar7_wdt *)
 309                         ioremap(ar7_regs_wdt, sizeof(struct ar7_wdt));
 310
 311         ar7_wdt_disable_wdt();
 312         ar7_wdt_prescale(prescale_value);
 313         ar7_wdt_update_margin(margin);
 314
 315         sema_init(&open_semaphore, 1);
 316
 317         rc = register_reboot_notifier(&ar7_wdt_notifier);
 318         if (rc) {
 319                 printk(KERN_ERR DRVNAME
 320                         ": unable to register reboot notifier\n");
 321                 goto out_alloc;
 322         }
 323
 324         rc = misc_register(&ar7_wdt_miscdev);
 325         if (rc) {
 326                 printk(KERN_ERR DRVNAME ": unable to register misc device\n");
 327                 goto out_register;
 328         }
 329         goto out;
 330
 331 out_register:
 332         unregister_reboot_notifier(&ar7_wdt_notifier);
 333 out_alloc:
 334         iounmap(ar7_wdt);
 335         release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt));
 336 out:
 337         return rc;
 338 }
 339
 340 static void __exit ar7_wdt_cleanup(void)
 341 {
 342         misc_deregister(&ar7_wdt_miscdev);
 343         unregister_reboot_notifier(&ar7_wdt_notifier);
 344         iounmap(ar7_wdt);
 345         release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt));
 346 }
 347
 348 module_init(ar7_wdt_init);
 349 module_exit(ar7_wdt_cleanup);