release/src-rt-6.x.4708/linux/linux-2.6.36/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 #include <linux/clk.h>
  38
  39 #include <asm/addrspace.h>
  40 #include <asm/mach-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 #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 struct clk *vbus_clk;
  84
  85 static void ar7_wdt_kick(u32 value)
  86 {
  87         WRITE_REG(ar7_wdt->kick_lock, 0x5555);
  88         if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
  89                 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
  90                 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
  91                         WRITE_REG(ar7_wdt->kick, value);
  92                         return;
  93                 }
  94         }
  95         printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
  96 }
  97
  98 static void ar7_wdt_prescale(u32 value)
  99 {
 100         WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
 101         if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
 102                 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
 103                 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
 104                         WRITE_REG(ar7_wdt->prescale, value);
 105                         return;
 106                 }
 107         }
 108         printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
 109 }
 110
 111 static void ar7_wdt_change(u32 value)
 112 {
 113         WRITE_REG(ar7_wdt->change_lock, 0x6666);
 114         if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
 115                 WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
 116                 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
 117                         WRITE_REG(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         WRITE_REG(ar7_wdt->disable_lock, 0x7777);
 127         if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
 128                 WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
 129                 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
 130                         WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
 131                         if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
 132                                 WRITE_REG(ar7_wdt->disable, value);
 133                                 return;
 134                         }
 135                 }
 136         }
 137         printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
 138 }
 139
 140 static void ar7_wdt_update_margin(int new_margin)
 141 {
 142         u32 change;
 143         u32 vbus_rate;
 144
 145         vbus_rate = clk_get_rate(vbus_clk);
 146         change = new_margin * (vbus_rate / prescale_value);
 147         if (change < 1)
 148                 change = 1;
 149         if (change > 0xffff)
 150                 change = 0xffff;
 151         ar7_wdt_change(change);
 152         margin = change * prescale_value / vbus_rate;
 153         printk(KERN_INFO DRVNAME
 154                ": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
 155                margin, prescale_value, change, vbus_rate);
 156 }
 157
 158 static void ar7_wdt_enable_wdt(void)
 159 {
 160         printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
 161         ar7_wdt_disable(1);
 162         ar7_wdt_kick(1);
 163 }
 164
 165 static void ar7_wdt_disable_wdt(void)
 166 {
 167         printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
 168         ar7_wdt_disable(0);
 169 }
 170
 171 static int ar7_wdt_open(struct inode *inode, struct file *file)
 172 {
 173         /* only allow one at a time */
 174         if (test_and_set_bit(0, &wdt_is_open))
 175                 return -EBUSY;
 176         ar7_wdt_enable_wdt();
 177         expect_close = 0;
 178
 179         return nonseekable_open(inode, file);
 180 }
 181
 182 static int ar7_wdt_release(struct inode *inode, struct file *file)
 183 {
 184         if (!expect_close)
 185                 printk(KERN_WARNING DRVNAME
 186                 ": watchdog device closed unexpectedly,"
 187                 "will not disable the watchdog timer\n");
 188         else if (!nowayout)
 189                 ar7_wdt_disable_wdt();
 190         clear_bit(0, &wdt_is_open);
 191         return 0;
 192 }
 193
 194 static ssize_t ar7_wdt_write(struct file *file, const char *data,
 195                              size_t len, loff_t *ppos)
 196 {
 197         /* check for a magic close character */
 198         if (len) {
 199                 size_t i;
 200
 201                 spin_lock(&wdt_lock);
 202                 ar7_wdt_kick(1);
 203                 spin_unlock(&wdt_lock);
 204
 205                 expect_close = 0;
 206                 for (i = 0; i < len; ++i) {
 207                         char c;
 208                         if (get_user(c, data + i))
 209                                 return -EFAULT;
 210                         if (c == 'V')
 211                                 expect_close = 1;
 212                 }
 213
 214         }
 215         return len;
 216 }
 217
 218 static long ar7_wdt_ioctl(struct file *file,
 219                                         unsigned int cmd, unsigned long arg)
 220 {
 221         static const struct watchdog_info ident = {
 222                 .identity = LONGNAME,
 223                 .firmware_version = 1,
 224                 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 225                                                 WDIOF_MAGICCLOSE),
 226         };
 227         int new_margin;
 228
 229         switch (cmd) {
 230         case WDIOC_GETSUPPORT:
 231                 if (copy_to_user((struct watchdog_info *)arg, &ident,
 232                                 sizeof(ident)))
 233                         return -EFAULT;
 234                 return 0;
 235         case WDIOC_GETSTATUS:
 236         case WDIOC_GETBOOTSTATUS:
 237                 if (put_user(0, (int *)arg))
 238                         return -EFAULT;
 239                 return 0;
 240         case WDIOC_KEEPALIVE:
 241                 ar7_wdt_kick(1);
 242                 return 0;
 243         case WDIOC_SETTIMEOUT:
 244                 if (get_user(new_margin, (int *)arg))
 245                         return -EFAULT;
 246                 if (new_margin < 1)
 247                         return -EINVAL;
 248
 249                 spin_lock(&wdt_lock);
 250                 ar7_wdt_update_margin(new_margin);
 251                 ar7_wdt_kick(1);
 252                 spin_unlock(&wdt_lock);
 253
 254         case WDIOC_GETTIMEOUT:
 255                 if (put_user(margin, (int *)arg))
 256                         return -EFAULT;
 257                 return 0;
 258         default:
 259                 return -ENOTTY;
 260         }
 261 }
 262
 263 static const struct file_operations ar7_wdt_fops = {
 264         .owner          = THIS_MODULE,
 265         .write          = ar7_wdt_write,
 266         .unlocked_ioctl = ar7_wdt_ioctl,
 267         .open           = ar7_wdt_open,
 268         .release        = ar7_wdt_release,
 269 };
 270
 271 static struct miscdevice ar7_wdt_miscdev = {
 272         .minor          = WATCHDOG_MINOR,
 273         .name           = "watchdog",
 274         .fops           = &ar7_wdt_fops,
 275 };
 276
 277 static int __devinit ar7_wdt_probe(struct platform_device *pdev)
 278 {
 279         int rc;
 280
 281         spin_lock_init(&wdt_lock);
 282
 283         ar7_regs_wdt =
 284                 platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs");
 285         if (!ar7_regs_wdt) {
 286                 printk(KERN_ERR DRVNAME ": could not get registers resource\n");
 287                 rc = -ENODEV;
 288                 goto out;
 289         }
 290
 291         if (!request_mem_region(ar7_regs_wdt->start,
 292                                 resource_size(ar7_regs_wdt), LONGNAME)) {
 293                 printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
 294                 rc = -EBUSY;
 295                 goto out;
 296         }
 297
 298         ar7_wdt = ioremap(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
 299         if (!ar7_wdt) {
 300                 printk(KERN_ERR DRVNAME ": could not ioremap registers\n");
 301                 rc = -ENXIO;
 302                 goto out_mem_region;
 303         }
 304
 305         vbus_clk = clk_get(NULL, "vbus");
 306         if (IS_ERR(vbus_clk)) {
 307                 printk(KERN_ERR DRVNAME ": could not get vbus clock\n");
 308                 rc = PTR_ERR(vbus_clk);
 309                 goto out_mem_region;
 310         }
 311
 312         ar7_wdt_disable_wdt();
 313         ar7_wdt_prescale(prescale_value);
 314         ar7_wdt_update_margin(margin);
 315
 316         rc = misc_register(&ar7_wdt_miscdev);
 317         if (rc) {
 318                 printk(KERN_ERR DRVNAME ": unable to register misc device\n");
 319                 goto out_alloc;
 320         }
 321         goto out;
 322
 323 out_alloc:
 324         iounmap(ar7_wdt);
 325 out_mem_region:
 326         release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
 327 out:
 328         return rc;
 329 }
 330
 331 static int __devexit ar7_wdt_remove(struct platform_device *pdev)
 332 {
 333         misc_deregister(&ar7_wdt_miscdev);
 334         iounmap(ar7_wdt);
 335         release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
 336
 337         return 0;
 338 }
 339
 340 static void ar7_wdt_shutdown(struct platform_device *pdev)
 341 {
 342         if (!nowayout)
 343                 ar7_wdt_disable_wdt();
 344 }
 345
 346 static struct platform_driver ar7_wdt_driver = {
 347         .probe = ar7_wdt_probe,
 348         .remove = __devexit_p(ar7_wdt_remove),
 349         .shutdown = ar7_wdt_shutdown,
 350         .driver = {
 351                 .owner = THIS_MODULE,
 352                 .name = "ar7_wdt",
 353         },
 354 };
 355
 356 static int __init ar7_wdt_init(void)
 357 {
 358         return platform_driver_register(&ar7_wdt_driver);
 359 }
 360
 361 static void __exit ar7_wdt_cleanup(void)
 362 {
 363         platform_driver_unregister(&ar7_wdt_driver);
 364 }
 365
 366 module_init(ar7_wdt_init);
 367 module_exit(ar7_wdt_cleanup);