target/linux/ar7/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 #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 struct ar7_wdt {
  59         u32 kick_lock;
  60         u32 kick;
  61         u32 change_lock;
  62         u32 change ;
  63         u32 disable_lock;
  64         u32 disable;
  65         u32 prescale_lock;
  66         u32 prescale;
  67 };
  68
  69 static struct semaphore open_semaphore;
  70 static unsigned expect_close;
  71
  72 /* XXX currently fixed, allows max margin ~68.72 secs */
  73 #define prescale_value 0xffff
  74
  75 /* Offset of the WDT registers */
  76 static unsigned long ar7_regs_wdt;
  77 /* Pointer to the remapped WDT IO space */
  78 static struct ar7_wdt *ar7_wdt;
  79 static void ar7_wdt_get_regs(void)
  80 {
  81         u16 chip_id = ar7_chip_id();
  82         switch (chip_id) {
  83         case AR7_CHIP_7100:
  84         case AR7_CHIP_7200:
  85                 ar7_regs_wdt = AR7_REGS_WDT;
  86                 break;
  87         default:
  88                 ar7_regs_wdt = UR8_REGS_WDT;
  89                 break;
  90         }
  91 }
  92
  93
  94 static void ar7_wdt_kick(u32 value)
  95 {
  96         ar7_wdt->kick_lock = 0x5555;
  97         if ((ar7_wdt->kick_lock & 3) == 1) {
  98                 ar7_wdt->kick_lock = 0xaaaa;
  99                 if ((ar7_wdt->kick_lock & 3) == 3) {
 100                         ar7_wdt->kick = value;
 101                         return;
 102                 }
 103         }
 104         printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
 105 }
 106
 107 static void ar7_wdt_prescale(u32 value)
 108 {
 109         ar7_wdt->prescale_lock = 0x5a5a;
 110         if ((ar7_wdt->prescale_lock & 3) == 1) {
 111                 ar7_wdt->prescale_lock = 0xa5a5;
 112                 if ((ar7_wdt->prescale_lock & 3) == 3) {
 113                         ar7_wdt->prescale = value;
 114                         return;
 115                 }
 116         }
 117         printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
 118 }
 119
 120 static void ar7_wdt_change(u32 value)
 121 {
 122         ar7_wdt->change_lock = 0x6666;
 123         if ((ar7_wdt->change_lock & 3) == 1) {
 124                 ar7_wdt->change_lock = 0xbbbb;
 125                 if ((ar7_wdt->change_lock & 3) == 3) {
 126                         ar7_wdt->change = value;
 127                         return;
 128                 }
 129         }
 130         printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
 131 }
 132
 133 static void ar7_wdt_disable(u32 value)
 134 {
 135         ar7_wdt->disable_lock = 0x7777;
 136         if ((ar7_wdt->disable_lock & 3) == 1) {
 137                 ar7_wdt->disable_lock = 0xcccc;
 138                 if ((ar7_wdt->disable_lock & 3) == 2) {
 139                         ar7_wdt->disable_lock = 0xdddd;
 140                         if ((ar7_wdt->disable_lock & 3) == 3) {
 141                                 ar7_wdt->disable = value;
 142                                 return;
 143                         }
 144                 }
 145         }
 146         printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
 147 }
 148
 149 static void ar7_wdt_update_margin(int new_margin)
 150 {
 151         u32 change;
 152
 153         change = new_margin * (ar7_vbus_freq() / prescale_value);
 154         if (change < 1) change = 1;
 155         if (change > 0xffff) change = 0xffff;
 156         ar7_wdt_change(change);
 157         margin = change * prescale_value / ar7_vbus_freq();
 158         printk(KERN_INFO DRVNAME
 159                ": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
 160                margin, prescale_value, change, ar7_vbus_freq());
 161 }
 162
 163 static void ar7_wdt_enable_wdt(void)
 164 {
 165         printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
 166         ar7_wdt_disable(1);
 167         ar7_wdt_kick(1);
 168 }
 169
 170 static void ar7_wdt_disable_wdt(void)
 171 {
 172         printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
 173         ar7_wdt_disable(0);
 174 }
 175
 176 static int ar7_wdt_open(struct inode *inode, struct file *file)
 177 {
 178         /* only allow one at a time */
 179         if (down_trylock(&open_semaphore))
 180                 return -EBUSY;
 181         ar7_wdt_enable_wdt();
 182         expect_close = 0;
 183
 184         return 0;
 185 }
 186
 187 static int ar7_wdt_release(struct inode *inode, struct file *file)
 188 {
 189         if (!expect_close) {
 190                 printk(KERN_WARNING DRVNAME
 191                 ": watchdog device closed unexpectedly,"
 192                 "will not disable the watchdog timer\n");
 193         } else if (!nowayout) {
 194                 ar7_wdt_disable_wdt();
 195         }
 196         up(&open_semaphore);
 197
 198         return 0;
 199 }
 200
 201 static int ar7_wdt_notify_sys(struct notifier_block *this,
 202                               unsigned long code, void *unused)
 203 {
 204         if (code == SYS_HALT || code == SYS_POWER_OFF)
 205                 if (!nowayout)
 206                         ar7_wdt_disable_wdt();
 207
 208         return NOTIFY_DONE;
 209 }
 210
 211 static struct notifier_block ar7_wdt_notifier = {
 212         .notifier_call = ar7_wdt_notify_sys
 213 };
 214
 215 static ssize_t ar7_wdt_write(struct file *file, const char *data,
 216                              size_t len, loff_t *ppos)
 217 {
 218         if (ppos != &file->f_pos)
 219                 return -ESPIPE;
 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 = misc_register(&ar7_wdt_miscdev);
 318         if (rc) {
 319                 printk(KERN_ERR DRVNAME ": unable to register misc device\n");
 320                 goto out_alloc;
 321         }
 322
 323         rc = register_reboot_notifier(&ar7_wdt_notifier);
 324         if (rc) {
 325                 printk(KERN_ERR DRVNAME
 326                         ": unable to register reboot notifier\n");
 327                 goto out_register;
 328         }
 329         goto out;
 330
 331 out_register:
 332         misc_deregister(&ar7_wdt_miscdev);
 333 out_alloc:
 334         release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt));
 335 out:
 336         return rc;
 337 }
 338
 339 static void __exit ar7_wdt_cleanup(void)
 340 {
 341         unregister_reboot_notifier(&ar7_wdt_notifier);
 342         misc_deregister(&ar7_wdt_miscdev);
 343         iounmap(ar7_wdt);
 344         release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt));
 345 }
 346
 347 module_init(ar7_wdt_init);
 348 module_exit(ar7_wdt_cleanup);