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
  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 // Offset of the WDT registers
  77 static unsigned long ar7_regs_wdt;
  78 // Pointer to the remapped WDT IO space
  79 static ar7_wdt_t *ar7_wdt;
  80 static void ar7_wdt_get_regs(void)
  81 {
  82         u16 chip_id = ar7_chip_id();
  83         switch (chip_id)
  84         {
  85         case AR7_CHIP_7100:
  86         case AR7_CHIP_7200:
  87                 ar7_regs_wdt = AR7_REGS_WDT;
  88                 break;
  89         default:
  90                 ar7_regs_wdt = UR8_REGS_WDT;
  91                 break;
  92         }
  93 }
  94
  95 static void ar7_wdt_kick(u32 value)
  96 {
  97         ar7_wdt->kick_lock = 0x5555;
  98         if ((ar7_wdt->kick_lock & 3) == 1) {
  99                 ar7_wdt->kick_lock = 0xaaaa;
 100                 if ((ar7_wdt->kick_lock & 3) == 3) {
 101                         ar7_wdt->kick = value;
 102                         return;
 103                 }
 104         }
 105         printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
 106 }
 107
 108 static void ar7_wdt_prescale(u32 value)
 109 {
 110         ar7_wdt->prescale_lock = 0x5a5a;
 111         if ((ar7_wdt->prescale_lock & 3) == 1) {
 112                 ar7_wdt->prescale_lock = 0xa5a5;
 113                 if ((ar7_wdt->prescale_lock & 3) == 3) {
 114                         ar7_wdt->prescale = value;
 115                         return;
 116                 }
 117         }
 118         printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
 119 }
 120
 121 static void ar7_wdt_change(u32 value)
 122 {
 123         ar7_wdt->change_lock = 0x6666;
 124         if ((ar7_wdt->change_lock & 3) == 1) {
 125                 ar7_wdt->change_lock = 0xbbbb;
 126                 if ((ar7_wdt->change_lock & 3) == 3) {
 127                         ar7_wdt->change = value;
 128                         return;
 129                 }
 130         }
 131         printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
 132 }
 133
 134 static void ar7_wdt_disable(u32 value)
 135 {
 136         ar7_wdt->disable_lock = 0x7777;
 137         if ((ar7_wdt->disable_lock & 3) == 1) {
 138                 ar7_wdt->disable_lock = 0xcccc;
 139                 if ((ar7_wdt->disable_lock & 3) == 2) {
 140                         ar7_wdt->disable_lock = 0xdddd;
 141                         if ((ar7_wdt->disable_lock & 3) == 3) {
 142                                 ar7_wdt->disable = value;
 143                                 return;
 144                         }
 145                 }
 146         }
 147         printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
 148 }
 149
 150 static void ar7_wdt_update_margin(int new_margin)
 151 {
 152         u32 change;
 153
 154         change = new_margin * (ar7_vbus_freq() / prescale_value);
 155         if (change < 1) change = 1;
 156         if (change > 0xffff) change = 0xffff;
 157         ar7_wdt_change(change);
 158         margin = change * prescale_value / ar7_vbus_freq();
 159         printk(KERN_INFO DRVNAME
 160                ": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
 161                margin, prescale_value, change, ar7_vbus_freq());
 162 }
 163
 164 static void ar7_wdt_enable_wdt(void)
 165 {
 166         printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
 167         ar7_wdt_disable(1);
 168         ar7_wdt_kick(1);
 169 }
 170
 171 static void ar7_wdt_disable_wdt(void)
 172 {
 173         printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
 174         ar7_wdt_disable(0);
 175 }
 176
 177 static int ar7_wdt_open(struct inode *inode, struct file *file)
 178 {
 179         /* only allow one at a time */
 180         if (down_trylock(&open_semaphore))
 181                 return -EBUSY;
 182         ar7_wdt_enable_wdt();
 183         expect_close = 0;
 184
 185         return 0;
 186 }
 187
 188 static int ar7_wdt_release(struct inode *inode, struct file *file)
 189 {
 190         if (!expect_close) {
 191                 printk(KERN_WARNING DRVNAME ": watchdog device closed unexpectedly, will not disable the watchdog timer\n");
 192         } else if (!nowayout) {
 193                 ar7_wdt_disable_wdt();
 194         }
 195         up(&open_semaphore);
 196
 197         return 0;
 198 }
 199
 200 static int ar7_wdt_notify_sys(struct notifier_block *this,
 201         unsigned long code, void *unused)
 202 {
 203         if (code == SYS_HALT || code == SYS_POWER_OFF)
 204                 if (!nowayout)
 205                         ar7_wdt_disable_wdt();
 206
 207         return NOTIFY_DONE;
 208 }
 209
 210 static struct notifier_block ar7_wdt_notifier =
 211 {
 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         case WDIOC_GETSUPPORT:
 252                 if(copy_to_user((struct watchdog_info *)arg, &ident,
 253                                 sizeof(ident)))
 254                         return -EFAULT;
 255                 return 0;
 256         case WDIOC_GETSTATUS:
 257         case WDIOC_GETBOOTSTATUS:
 258                 if (put_user(0, (int *)arg))
 259                         return -EFAULT;
 260                 return 0;
 261         case WDIOC_KEEPALIVE:
 262                 ar7_wdt_kick(1);
 263                 return 0;
 264         case WDIOC_SETTIMEOUT:
 265                 if (get_user(new_margin, (int *)arg))
 266                         return -EFAULT;
 267                 if (new_margin < 1)
 268                         return -EINVAL;
 269
 270                 ar7_wdt_update_margin(new_margin);
 271                 ar7_wdt_kick(1);
 272
 273         case WDIOC_GETTIMEOUT:
 274                 if (put_user(margin, (int *)arg))
 275                         return -EFAULT;
 276                 return 0;
 277         default:
 278                 return -ENOTTY;
 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(ar7_wdt_t), LONGNAME)) {
 303                 printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
 304                 return -EBUSY;
 305         }
 306
 307         ar7_wdt = (ar7_wdt_t *)ioremap(ar7_regs_wdt, sizeof(ar7_wdt_t));
 308
 309         ar7_wdt_disable_wdt();
 310         ar7_wdt_prescale(prescale_value);
 311         ar7_wdt_update_margin(margin);
 312
 313         sema_init(&open_semaphore, 1);
 314
 315         rc = misc_register(&ar7_wdt_miscdev);
 316         if (rc) {
 317                 printk(KERN_ERR DRVNAME ": unable to register misc device\n");
 318                 goto out_alloc;
 319         }
 320
 321         rc = register_reboot_notifier(&ar7_wdt_notifier);
 322         if (rc) {
 323                 printk(KERN_ERR DRVNAME ": unable to register reboot notifier\n");
 324                 goto out_register;
 325         }
 326         goto out;
 327
 328 out_register:
 329         misc_deregister(&ar7_wdt_miscdev);
 330 out_alloc:
 331         release_mem_region(ar7_regs_wdt, sizeof(ar7_wdt_t));
 332 out:
 333         return rc;
 334 }
 335
 336 static void __exit ar7_wdt_cleanup(void)
 337 {
 338         unregister_reboot_notifier(&ar7_wdt_notifier);
 339         misc_deregister(&ar7_wdt_miscdev);
 340         iounmap(ar7_wdt);
 341         release_mem_region(ar7_regs_wdt, sizeof(ar7_wdt_t));
 342 }
 343
 344 module_init(ar7_wdt_init);
 345 module_exit(ar7_wdt_cleanup);