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/platform_device.h>
  32 #include <linux/watchdog.h>
  33 #include <linux/fs.h>
  34 #include <linux/ioport.h>
  35 #include <linux/io.h>
  36 #include <linux/uaccess.h>
  37
  38 #include <asm/addrspace.h>
  39 #include <asm/mach-ar7/ar7.h>
  40
  41 #define DRVNAME "ar7_wdt"
  42 #define LONGNAME "TI AR7 Watchdog Timer"
  43
  44 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
  45 MODULE_DESCRIPTION(LONGNAME);
  46 MODULE_LICENSE("GPL");
  47 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  48
  49 static int margin = 60;
  50 module_param(margin, int, 0);
  51 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
  52
  53 static int nowayout = WATCHDOG_NOWAYOUT;
  54 module_param(nowayout, int, 0);
  55 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
  56
  57 #define READ_REG(x) readl((void __iomem *)&(x))
  58 #define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))
  59
  60 struct ar7_wdt {
  61         u32 kick_lock;
  62         u32 kick;
  63         u32 change_lock;
  64         u32 change;
  65         u32 disable_lock;
  66         u32 disable;
  67         u32 prescale_lock;
  68         u32 prescale;
  69 };
  70
  71 static unsigned long wdt_is_open;
  72 static spinlock_t wdt_lock;
  73 static unsigned expect_close;
  74
  75 /* XXX currently fixed, allows max margin ~68.72 secs */
  76 #define prescale_value 0xffff
  77
  78 /* Resource of the WDT registers */
  79 static struct resource *ar7_regs_wdt;
  80 /* Pointer to the remapped WDT IO space */
  81 static struct ar7_wdt *ar7_wdt;
  82
  83 static void ar7_wdt_kick(u32 value)
  84 {
  85         WRITE_REG(ar7_wdt->kick_lock, 0x5555);
  86         if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
  87                 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
  88                 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
  89                         WRITE_REG(ar7_wdt->kick, value);
  90                         return;
  91                 }
  92         }
  93         printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
  94 }
  95
  96 static void ar7_wdt_prescale(u32 value)
  97 {
  98         WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
  99         if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
 100                 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
 101                 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
 102                         WRITE_REG(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         WRITE_REG(ar7_wdt->change_lock, 0x6666);
 112         if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
 113                 WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
 114                 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
 115                         WRITE_REG(ar7_wdt->change, value);
 116                         return;
 117                 }
 118         }
 119         printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
 120 }
 121
 122 static void ar7_wdt_disable(u32 value)
 123 {
 124         WRITE_REG(ar7_wdt->disable_lock, 0x7777);
 125         if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
 126                 WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
 127                 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
 128                         WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
 129                         if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
 130                                 WRITE_REG(ar7_wdt->disable, value);
 131                                 return;
 132                         }
 133                 }
 134         }
 135         printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
 136 }
 137
 138 static void ar7_wdt_update_margin(int new_margin)
 139 {
 140         u32 change;
 141
 142         change = new_margin * (ar7_vbus_freq() / prescale_value);
 143         if (change < 1)
 144                 change = 1;
 145         if (change > 0xffff)
 146                 change = 0xffff;
 147         ar7_wdt_change(change);
 148         margin = change * prescale_value / ar7_vbus_freq();
 149         printk(KERN_INFO DRVNAME
 150                ": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
 151                margin, prescale_value, change, ar7_vbus_freq());
 152 }
 153
 154 static void ar7_wdt_enable_wdt(void)
 155 {
 156         printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
 157         ar7_wdt_disable(1);
 158         ar7_wdt_kick(1);
 159 }
 160
 161 static void ar7_wdt_disable_wdt(void)
 162 {
 163         printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
 164         ar7_wdt_disable(0);
 165 }
 166
 167 static int ar7_wdt_open(struct inode *inode, struct file *file)
 168 {
 169         /* only allow one at a time */
 170         if (test_and_set_bit(0, &wdt_is_open))
 171                 return -EBUSY;
 172         ar7_wdt_enable_wdt();
 173         expect_close = 0;
 174
 175         return nonseekable_open(inode, file);
 176 }
 177
 178 static int ar7_wdt_release(struct inode *inode, struct file *file)
 179 {
 180         if (!expect_close)
 181                 printk(KERN_WARNING DRVNAME
 182                 ": watchdog device closed unexpectedly,"
 183                 "will not disable the watchdog timer\n");
 184         else if (!nowayout)
 185                 ar7_wdt_disable_wdt();
 186         clear_bit(0, &wdt_is_open);
 187         return 0;
 188 }
 189
 190 static ssize_t ar7_wdt_write(struct file *file, const char *data,
 191                              size_t len, loff_t *ppos)
 192 {
 193         /* check for a magic close character */
 194         if (len) {
 195                 size_t i;
 196
 197                 spin_lock(&wdt_lock);
 198                 ar7_wdt_kick(1);
 199                 spin_unlock(&wdt_lock);
 200
 201                 expect_close = 0;
 202                 for (i = 0; i < len; ++i) {
 203                         char c;
 204                         if (get_user(c, data + i))
 205                                 return -EFAULT;
 206                         if (c == 'V')
 207                                 expect_close = 1;
 208                 }
 209
 210         }
 211         return len;
 212 }
 213
 214 static long ar7_wdt_ioctl(struct file *file,
 215                                         unsigned int cmd, unsigned long arg)
 216 {
 217         static struct watchdog_info ident = {
 218                 .identity = LONGNAME,
 219                 .firmware_version = 1,
 220                 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 221                                                 WDIOF_MAGICCLOSE),
 222         };
 223         int new_margin;
 224
 225         switch (cmd) {
 226         case WDIOC_GETSUPPORT:
 227                 if (copy_to_user((struct watchdog_info *)arg, &ident,
 228                                 sizeof(ident)))
 229                         return -EFAULT;
 230                 return 0;
 231         case WDIOC_GETSTATUS:
 232         case WDIOC_GETBOOTSTATUS:
 233                 if (put_user(0, (int *)arg))
 234                         return -EFAULT;
 235                 return 0;
 236         case WDIOC_KEEPALIVE:
 237                 ar7_wdt_kick(1);
 238                 return 0;
 239         case WDIOC_SETTIMEOUT:
 240                 if (get_user(new_margin, (int *)arg))
 241                         return -EFAULT;
 242                 if (new_margin < 1)
 243                         return -EINVAL;
 244
 245                 spin_lock(&wdt_lock);
 246                 ar7_wdt_update_margin(new_margin);
 247                 ar7_wdt_kick(1);
 248                 spin_unlock(&wdt_lock);
 249
 250         case WDIOC_GETTIMEOUT:
 251                 if (put_user(margin, (int *)arg))
 252                         return -EFAULT;
 253                 return 0;
 254         default:
 255                 return -ENOTTY;
 256         }
 257 }
 258
 259 static const struct file_operations ar7_wdt_fops = {
 260         .owner          = THIS_MODULE,
 261         .write          = ar7_wdt_write,
 262         .unlocked_ioctl = ar7_wdt_ioctl,
 263         .open           = ar7_wdt_open,
 264         .release        = ar7_wdt_release,
 265 };
 266
 267 static struct miscdevice ar7_wdt_miscdev = {
 268         .minor          = WATCHDOG_MINOR,
 269         .name           = "watchdog",
 270         .fops           = &ar7_wdt_fops,
 271 };
 272
 273 static int __devinit ar7_wdt_probe(struct platform_device *pdev)
 274 {
 275         int rc;
 276
 277         spin_lock_init(&wdt_lock);
 278
 279         ar7_regs_wdt =
 280                 platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs");
 281         if (!ar7_regs_wdt) {
 282                 printk(KERN_ERR DRVNAME ": could not get registers resource\n");
 283                 rc = -ENODEV;
 284                 goto out;
 285         }
 286
 287         if (!request_mem_region(ar7_regs_wdt->start,
 288                                 resource_size(ar7_regs_wdt), LONGNAME)) {
 289                 printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
 290                 rc = -EBUSY;
 291                 goto out;
 292         }
 293
 294         ar7_wdt = ioremap(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
 295         if (!ar7_wdt) {
 296                 printk(KERN_ERR DRVNAME ": could not ioremap registers\n");
 297                 rc = -ENXIO;
 298                 goto out_mem_region;
 299         }
 300
 301         ar7_wdt_disable_wdt();
 302         ar7_wdt_prescale(prescale_value);
 303         ar7_wdt_update_margin(margin);
 304
 305         rc = misc_register(&ar7_wdt_miscdev);
 306         if (rc) {
 307                 printk(KERN_ERR DRVNAME ": unable to register misc device\n");
 308                 goto out_alloc;
 309         }
 310         goto out;
 311
 312 out_alloc:
 313         iounmap(ar7_wdt);
 314 out_mem_region:
 315         release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
 316 out:
 317         return rc;
 318 }
 319
 320 static int __devexit ar7_wdt_remove(struct platform_device *pdev)
 321 {
 322         misc_deregister(&ar7_wdt_miscdev);
 323         iounmap(ar7_wdt);
 324         release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
 325
 326         return 0;
 327 }
 328
 329 static void ar7_wdt_shutdown(struct platform_device *pdev)
 330 {
 331         if (!nowayout)
 332                 ar7_wdt_disable_wdt();
 333 }
 334
 335 static struct platform_driver ar7_wdt_driver = {
 336         .probe = ar7_wdt_probe,
 337         .remove = __devexit_p(ar7_wdt_remove),
 338         .shutdown = ar7_wdt_shutdown,
 339         .driver = {
 340                 .owner = THIS_MODULE,
 341                 .name = "ar7_wdt",
 342         },
 343 };
 344
 345 static int __init ar7_wdt_init(void)
 346 {
 347         return platform_driver_register(&ar7_wdt_driver);
 348 }
 349
 350 static void __exit ar7_wdt_cleanup(void)
 351 {
 352         platform_driver_unregister(&ar7_wdt_driver);
 353 }
 354
 355 module_init(ar7_wdt_init);
 356 module_exit(ar7_wdt_cleanup);