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 unsigned long wdt_is_open;
  73 static spinlock_t wdt_lock;
  74 static unsigned expect_close;
  75
  76 /* XXX currently fixed, allows max margin ~68.72 secs */
  77 #define prescale_value 0xffff
  78
  79 /* Offset of the WDT registers */
  80 static unsigned long ar7_regs_wdt;
  81 /* Pointer to the remapped WDT IO space */
  82 static struct ar7_wdt *ar7_wdt;
  83 static void ar7_wdt_get_regs(void)
  84 {
  85         u16 chip_id = ar7_chip_id();
  86         switch (chip_id) {
  87         case AR7_CHIP_7100:
  88         case AR7_CHIP_7200:
  89                 ar7_regs_wdt = AR7_REGS_WDT;
  90                 break;
  91         default:
  92                 ar7_regs_wdt = UR8_REGS_WDT;
  93                 break;
  94         }
  95 }
  96
  97
  98 static void ar7_wdt_kick(u32 value)
  99 {
 100         WRITE_REG(ar7_wdt->kick_lock, 0x5555);
 101         if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
 102                 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
 103                 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
 104                         WRITE_REG(ar7_wdt->kick, value);
 105                         return;
 106                 }
 107         }
 108         printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
 109 }
 110
 111 static void ar7_wdt_prescale(u32 value)
 112 {
 113         WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
 114         if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
 115                 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
 116                 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
 117                         WRITE_REG(ar7_wdt->prescale, value);
 118                         return;
 119                 }
 120         }
 121         printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
 122 }
 123
 124 static void ar7_wdt_change(u32 value)
 125 {
 126         WRITE_REG(ar7_wdt->change_lock, 0x6666);
 127         if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
 128                 WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
 129                 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
 130                         WRITE_REG(ar7_wdt->change, value);
 131                         return;
 132                 }
 133         }
 134         printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
 135 }
 136
 137 static void ar7_wdt_disable(u32 value)
 138 {
 139         WRITE_REG(ar7_wdt->disable_lock, 0x7777);
 140         if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
 141                 WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
 142                 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
 143                         WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
 144                         if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
 145                                 WRITE_REG(ar7_wdt->disable, value);
 146                                 return;
 147                         }
 148                 }
 149         }
 150         printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
 151 }
 152
 153 static void ar7_wdt_update_margin(int new_margin)
 154 {
 155         u32 change;
 156
 157         change = new_margin * (ar7_vbus_freq() / prescale_value);
 158         if (change < 1)
 159                 change = 1;
 160         if (change > 0xffff)
 161                 change = 0xffff;
 162         ar7_wdt_change(change);
 163         margin = change * prescale_value / ar7_vbus_freq();
 164         printk(KERN_INFO DRVNAME
 165                ": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
 166                margin, prescale_value, change, ar7_vbus_freq());
 167 }
 168
 169 static void ar7_wdt_enable_wdt(void)
 170 {
 171         printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
 172         ar7_wdt_disable(1);
 173         ar7_wdt_kick(1);
 174 }
 175
 176 static void ar7_wdt_disable_wdt(void)
 177 {
 178         printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
 179         ar7_wdt_disable(0);
 180 }
 181
 182 static int ar7_wdt_open(struct inode *inode, struct file *file)
 183 {
 184         /* only allow one at a time */
 185         if (test_and_set_bit(0, &wdt_is_open))
 186                 return -EBUSY;
 187         ar7_wdt_enable_wdt();
 188         expect_close = 0;
 189
 190         return nonseekable_open(inode, file);
 191 }
 192
 193 static int ar7_wdt_release(struct inode *inode, struct file *file)
 194 {
 195         if (!expect_close)
 196                 printk(KERN_WARNING DRVNAME
 197                 ": watchdog device closed unexpectedly,"
 198                 "will not disable the watchdog timer\n");
 199         else if (!nowayout)
 200                 ar7_wdt_disable_wdt();
 201         clear_bit(0, &wdt_is_open);
 202         return 0;
 203 }
 204
 205 static int ar7_wdt_notify_sys(struct notifier_block *this,
 206                               unsigned long code, void *unused)
 207 {
 208         if (code == SYS_HALT || code == SYS_POWER_OFF)
 209                 if (!nowayout)
 210                         ar7_wdt_disable_wdt();
 211
 212         return NOTIFY_DONE;
 213 }
 214
 215 static struct notifier_block ar7_wdt_notifier = {
 216         .notifier_call = ar7_wdt_notify_sys,
 217 };
 218
 219 static ssize_t ar7_wdt_write(struct file *file, const char *data,
 220                              size_t len, loff_t *ppos)
 221 {
 222         /* check for a magic close character */
 223         if (len) {
 224                 size_t i;
 225
 226                 spin_lock(&wdt_lock);
 227                 ar7_wdt_kick(1);
 228                 spin_unlock(&wdt_lock);
 229
 230                 expect_close = 0;
 231                 for (i = 0; i < len; ++i) {
 232                         char c;
 233                         if (get_user(c, data + i))
 234                                 return -EFAULT;
 235                         if (c == 'V')
 236                                 expect_close = 1;
 237                 }
 238
 239         }
 240         return len;
 241 }
 242
 243 static long ar7_wdt_ioctl(struct file *file,
 244                                         unsigned int cmd, unsigned long arg)
 245 {
 246         static struct watchdog_info ident = {
 247                 .identity = LONGNAME,
 248                 .firmware_version = 1,
 249                 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING),
 250         };
 251         int new_margin;
 252
 253         switch (cmd) {
 254         case WDIOC_GETSUPPORT:
 255                 if (copy_to_user((struct watchdog_info *)arg, &ident,
 256                                 sizeof(ident)))
 257                         return -EFAULT;
 258                 return 0;
 259         case WDIOC_GETSTATUS:
 260         case WDIOC_GETBOOTSTATUS:
 261                 if (put_user(0, (int *)arg))
 262                         return -EFAULT;
 263                 return 0;
 264         case WDIOC_KEEPALIVE:
 265                 ar7_wdt_kick(1);
 266                 return 0;
 267         case WDIOC_SETTIMEOUT:
 268                 if (get_user(new_margin, (int *)arg))
 269                         return -EFAULT;
 270                 if (new_margin < 1)
 271                         return -EINVAL;
 272
 273                 spin_lock(&wdt_lock);
 274                 ar7_wdt_update_margin(new_margin);
 275                 ar7_wdt_kick(1);
 276                 spin_unlock(&wdt_lock);
 277
 278         case WDIOC_GETTIMEOUT:
 279                 if (put_user(margin, (int *)arg))
 280                         return -EFAULT;
 281                 return 0;
 282         default:
 283                 return -ENOTTY;
 284         }
 285 }
 286
 287 static const struct file_operations ar7_wdt_fops = {
 288         .owner          = THIS_MODULE,
 289         .write          = ar7_wdt_write,
 290         .unlocked_ioctl = ar7_wdt_ioctl,
 291         .open           = ar7_wdt_open,
 292         .release        = ar7_wdt_release,
 293 };
 294
 295 static struct miscdevice ar7_wdt_miscdev = {
 296         .minor          = WATCHDOG_MINOR,
 297         .name           = "watchdog",
 298         .fops           = &ar7_wdt_fops,
 299 };
 300
 301 static int __init ar7_wdt_init(void)
 302 {
 303         int rc;
 304
 305         spin_lock_init(&wdt_lock);
 306
 307         ar7_wdt_get_regs();
 308
 309         if (!request_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt),
 310                                                         LONGNAME)) {
 311                 printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
 312                 return -EBUSY;
 313         }
 314
 315         ar7_wdt = (struct ar7_wdt *)
 316                         ioremap(ar7_regs_wdt, sizeof(struct ar7_wdt));
 317
 318         ar7_wdt_disable_wdt();
 319         ar7_wdt_prescale(prescale_value);
 320         ar7_wdt_update_margin(margin);
 321
 322         rc = register_reboot_notifier(&ar7_wdt_notifier);
 323         if (rc) {
 324                 printk(KERN_ERR DRVNAME
 325                         ": unable to register reboot notifier\n");
 326                 goto out_alloc;
 327         }
 328
 329         rc = misc_register(&ar7_wdt_miscdev);
 330         if (rc) {
 331                 printk(KERN_ERR DRVNAME ": unable to register misc device\n");
 332                 goto out_register;
 333         }
 334         goto out;
 335
 336 out_register:
 337         unregister_reboot_notifier(&ar7_wdt_notifier);
 338 out_alloc:
 339         iounmap(ar7_wdt);
 340         release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt));
 341 out:
 342         return rc;
 343 }
 344
 345 static void __exit ar7_wdt_cleanup(void)
 346 {
 347         misc_deregister(&ar7_wdt_miscdev);
 348         unregister_reboot_notifier(&ar7_wdt_notifier);
 349         iounmap(ar7_wdt);
 350         release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt));
 351 }
 352
 353 module_init(ar7_wdt_init);
 354 module_exit(ar7_wdt_cleanup);