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 correct? assumed to be sysfreq/2. get this dynamically ... */
  74 #define vbus_freq (ar7_bus_freq() / 2)
  75
  76 /* XXX currently fixed, allows max margin ~68.72 secs */
  77 #define prescale_value 0xFFFF
  78
  79 static void ar7_wdt_kick(u32 value)
  80 {
  81         volatile ar7_wdt_t *ar7_wdt = (ar7_wdt_t *)ioremap(AR7_REGS_WDT, sizeof(ar7_wdt_t));
  82
  83         ar7_wdt->kick_lock = 0x5555;
  84         if ((ar7_wdt->kick_lock & 3) == 1) {
  85                 ar7_wdt->kick_lock = 0xAAAA;
  86                 if ((ar7_wdt->kick_lock & 3) == 3) {
  87                         ar7_wdt->kick = value;
  88                         return;
  89                 }
  90         }
  91         printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
  92 }
  93
  94 static void ar7_wdt_prescale(u32 value)
  95 {
  96         volatile ar7_wdt_t *ar7_wdt = (ar7_wdt_t *)ioremap(AR7_REGS_WDT, sizeof(ar7_wdt_t));
  97
  98         ar7_wdt->prescale_lock = 0x5A5A;
  99         if ((ar7_wdt->prescale_lock & 3) == 1) {
 100                 ar7_wdt->prescale_lock = 0xA5A5;
 101                 if ((ar7_wdt->prescale_lock & 3) == 3) {
 102                         ar7_wdt->prescale = value;
 103                         return;
 104                 }
 105         }
 106         printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
 107 }
 108
 109 static void ar7_wdt_change(u32 value)
 110 {
 111         volatile ar7_wdt_t *ar7_wdt = (ar7_wdt_t *)ioremap(AR7_REGS_WDT, sizeof(ar7_wdt_t));
 112
 113         ar7_wdt->change_lock = 0x6666;
 114         if ((ar7_wdt->change_lock & 3) == 1) {
 115                 ar7_wdt->change_lock = 0xBBBB;
 116                 if ((ar7_wdt->change_lock & 3) == 3) {
 117                         ar7_wdt->change = value;
 118                         return;
 119                 }
 120         }
 121         printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
 122 }
 123
 124 static void ar7_wdt_disable(u32 value)
 125 {
 126         volatile ar7_wdt_t *ar7_wdt = (ar7_wdt_t *)ioremap(AR7_REGS_WDT, sizeof(ar7_wdt_t));
 127
 128         ar7_wdt->disable_lock = 0x7777;
 129         if ((ar7_wdt->disable_lock & 3) == 1) {
 130                 ar7_wdt->disable_lock = 0xCCCC;
 131                 if ((ar7_wdt->disable_lock & 3) == 2) {
 132                         ar7_wdt->disable_lock = 0xDDDD;
 133                         if ((ar7_wdt->disable_lock & 3) == 3) {
 134                                 ar7_wdt->disable = value;
 135                                 return;
 136                         }
 137                 }
 138         }
 139         printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
 140 }
 141
 142 static void ar7_wdt_update_margin(int new_margin)
 143 {
 144         u32 change;
 145
 146         change = new_margin * (vbus_freq / prescale_value);
 147         if (change < 1) change = 1;
 148         if (change > 0xFFFF) change = 0xFFFF;
 149         ar7_wdt_change(change);
 150         margin = change * prescale_value / vbus_freq;
 151         printk(KERN_INFO DRVNAME
 152                ": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
 153                margin, prescale_value, change, vbus_freq);
 154 }
 155
 156 static void ar7_wdt_enable_wdt(void)
 157 {
 158         printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
 159         ar7_wdt_disable(1);
 160         ar7_wdt_kick(1);
 161 }
 162
 163 static void ar7_wdt_disable_wdt(void)
 164 {
 165         printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
 166         ar7_wdt_disable(0);
 167 }
 168
 169 static int ar7_wdt_open(struct inode *inode, struct file *file)
 170 {
 171         /* only allow one at a time */
 172         if (down_trylock(&open_semaphore))
 173                 return -EBUSY;
 174         ar7_wdt_enable_wdt();
 175         expect_close = 0;
 176
 177         return 0;
 178 }
 179
 180 static int ar7_wdt_release(struct inode *inode, struct file *file)
 181 {
 182         if (!expect_close) {
 183                 printk(KERN_WARNING DRVNAME ": watchdog device closed unexpectedly, will not disable the watchdog timer\n");
 184         } else if (!nowayout) {
 185                 ar7_wdt_disable_wdt();
 186         }
 187         up(&open_semaphore);
 188
 189         return 0;
 190 }
 191
 192 static int ar7_wdt_notify_sys(struct notifier_block *this,
 193                               unsigned long code, void *unused)
 194 {
 195         if (code == SYS_HALT || code == SYS_POWER_OFF)
 196                 if (!nowayout)
 197                         ar7_wdt_disable_wdt();
 198
 199         return NOTIFY_DONE;
 200 }
 201
 202 static struct notifier_block ar7_wdt_notifier =
 203 {
 204         .notifier_call = ar7_wdt_notify_sys
 205 };
 206
 207 static ssize_t ar7_wdt_write(struct file *file, const char *data,
 208                              size_t len, loff_t *ppos)
 209 {
 210         if (ppos != &file->f_pos)
 211                 return -ESPIPE;
 212
 213         /* check for a magic close character */
 214         if (len) {
 215                 size_t i;
 216
 217                 ar7_wdt_kick(1);
 218
 219                 expect_close = 0;
 220                 for (i = 0; i < len; ++i) {
 221                         char c;
 222                         if (get_user(c, data+i))
 223                                 return -EFAULT;
 224                         if (c == 'V')
 225                                 expect_close = 1;
 226                 }
 227
 228         }
 229         return len;
 230 }
 231
 232 static int ar7_wdt_ioctl(struct inode *inode, struct file *file,
 233                          unsigned int cmd, unsigned long arg)
 234 {
 235         static struct watchdog_info ident = {
 236                 .identity = LONGNAME,
 237                 .firmware_version = 1,
 238                 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING),
 239         };
 240         int new_margin;
 241
 242         switch (cmd) {
 243         default:
 244                 return -ENOTTY;
 245         case WDIOC_GETSUPPORT:
 246                 if(copy_to_user((struct watchdog_info *)arg, &ident,
 247                                 sizeof(ident)))
 248                         return -EFAULT;
 249                 return 0;
 250         case WDIOC_GETSTATUS:
 251         case WDIOC_GETBOOTSTATUS:
 252                 if (put_user(0, (int *)arg))
 253                         return -EFAULT;
 254                 return 0;
 255         case WDIOC_KEEPALIVE:
 256                 ar7_wdt_kick(1);
 257                 return 0;
 258         case WDIOC_SETTIMEOUT:
 259                 if (get_user(new_margin, (int *)arg))
 260                         return -EFAULT;
 261                 if (new_margin < 1)
 262                         return -EINVAL;
 263
 264                 ar7_wdt_update_margin(new_margin);
 265                 ar7_wdt_kick(1);
 266
 267         case WDIOC_GETTIMEOUT:
 268                 if (put_user(margin, (int *)arg))
 269                         return -EFAULT;
 270                 return 0;
 271         }
 272 }
 273
 274 static struct file_operations ar7_wdt_fops = {
 275         .owner   = THIS_MODULE,
 276         .write   = ar7_wdt_write,
 277         .ioctl   = ar7_wdt_ioctl,
 278         .open    = ar7_wdt_open,
 279         .release = ar7_wdt_release,
 280 };
 281
 282 static struct miscdevice ar7_wdt_miscdev = {
 283         .minor = WATCHDOG_MINOR,
 284         .name  = "watchdog",
 285         .fops  = &ar7_wdt_fops,
 286 };
 287
 288 static int __init ar7_wdt_init(void)
 289 {
 290         int rc;
 291
 292         if (!request_mem_region(AR7_REGS_WDT, sizeof(ar7_wdt_t), LONGNAME)) {
 293                 printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
 294                 return -EBUSY;
 295         }
 296
 297         ar7_wdt_disable_wdt();
 298         ar7_wdt_prescale(prescale_value);
 299         ar7_wdt_update_margin(margin);
 300
 301         sema_init(&open_semaphore, 1);
 302
 303         rc = misc_register(&ar7_wdt_miscdev);
 304         if (rc) {
 305                 printk(KERN_ERR DRVNAME ": unable to register misc device\n");
 306                 goto out_alloc;
 307         }
 308
 309         rc = register_reboot_notifier(&ar7_wdt_notifier);
 310         if (rc) {
 311                 printk(KERN_ERR DRVNAME ": unable to register reboot notifier\n");
 312                 goto out_register;
 313         }
 314         goto out;
 315
 316 out_register:
 317         misc_deregister(&ar7_wdt_miscdev);
 318 out_alloc:
 319         release_mem_region(AR7_REGS_WDT, sizeof(ar7_wdt_t));
 320 out:
 321         return rc;
 322 }
 323
 324 static void __exit ar7_wdt_cleanup(void)
 325 {
 326         unregister_reboot_notifier(&ar7_wdt_notifier);
 327         misc_deregister(&ar7_wdt_miscdev);
 328         release_mem_region(AR7_REGS_WDT, sizeof(ar7_wdt_t));
 329 }
 330
 331 module_init(ar7_wdt_init);
 332 module_exit(ar7_wdt_cleanup);