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 /* XXX currently fixed, allows max margin ~68.72 secs */
  77 #define prescale_value 0xffff
  78
  79 /* Resource of the WDT registers */
  80 static struct resource *ar7_regs_wdt;
  81 /* Pointer to the remapped WDT IO space */
  82 static struct ar7_wdt *ar7_wdt;
  83
  84 static struct clk *vbus_clk;
  85
  86 static void ar7_wdt_kick(u32 value)
  87 {
  88         WRITE_REG(ar7_wdt->kick_lock, 0x5555);
  89         if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
  90                 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
  91                 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
  92                         WRITE_REG(ar7_wdt->kick, value);
  93                         return;
  94                 }
  95         }
  96         printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
  97 }
  98
  99 static void ar7_wdt_prescale(u32 value)
 100 {
 101         WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
 102         if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
 103                 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
 104                 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
 105                         WRITE_REG(ar7_wdt->prescale, value);
 106                         return;
 107                 }
 108         }
 109         printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
 110 }
 111
 112 static void ar7_wdt_change(u32 value)
 113 {
 114         WRITE_REG(ar7_wdt->change_lock, 0x6666);
 115         if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
 116                 WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
 117                 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
 118                         WRITE_REG(ar7_wdt->change, value);
 119                         return;
 120                 }
 121         }
 122         printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
 123 }
 124
 125 static void ar7_wdt_disable(u32 value)
 126 {
 127         WRITE_REG(ar7_wdt->disable_lock, 0x7777);
 128         if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
 129                 WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
 130                 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
 131                         WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
 132                         if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
 133                                 WRITE_REG(ar7_wdt->disable, value);
 134                                 return;
 135                         }
 136                 }
 137         }
 138         printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
 139 }
 140
 141 static void ar7_wdt_update_margin(int new_margin)
 142 {
 143         u32 change;
 144         u32 vbus_rate;
 145
 146         vbus_rate = clk_get_rate(vbus_clk);
 147         change = new_margin * (vbus_rate / prescale_value);
 148         if (change < 1)
 149                 change = 1;
 150         if (change > 0xffff)
 151                 change = 0xffff;
 152         ar7_wdt_change(change);
 153         margin = change * prescale_value / vbus_rate;
 154         printk(KERN_INFO DRVNAME
 155                ": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
 156                margin, prescale_value, change, vbus_rate);
 157 }
 158
 159 static void ar7_wdt_enable_wdt(void)
 160 {
 161         printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
 162         ar7_wdt_disable(1);
 163         ar7_wdt_kick(1);
 164 }
 165
 166 static void ar7_wdt_disable_wdt(void)
 167 {
 168         printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
 169         ar7_wdt_disable(0);
 170 }
 171
 172 static int ar7_wdt_open(struct inode *inode, struct file *file)
 173 {
 174         /* only allow one at a time */
 175         if (test_and_set_bit(0, &wdt_is_open))
 176                 return -EBUSY;
 177         ar7_wdt_enable_wdt();
 178         expect_close = 0;
 179
 180         return nonseekable_open(inode, file);
 181 }
 182
 183 static int ar7_wdt_release(struct inode *inode, struct file *file)
 184 {
 185         if (!expect_close)
 186                 printk(KERN_WARNING DRVNAME
 187                 ": watchdog device closed unexpectedly,"
 188                 "will not disable the watchdog timer\n");
 189         else if (!nowayout)
 190                 ar7_wdt_disable_wdt();
 191         clear_bit(0, &wdt_is_open);
 192         return 0;
 193 }
 194
 195 static ssize_t ar7_wdt_write(struct file *file, const char *data,
 196                              size_t len, loff_t *ppos)
 197 {
 198         /* check for a magic close character */
 199         if (len) {
 200                 size_t i;
 201
 202                 spin_lock(&wdt_lock);
 203                 ar7_wdt_kick(1);
 204                 spin_unlock(&wdt_lock);
 205
 206                 expect_close = 0;
 207                 for (i = 0; i < len; ++i) {
 208                         char c;
 209                         if (get_user(c, data + i))
 210                                 return -EFAULT;
 211                         if (c == 'V')
 212                                 expect_close = 1;
 213                 }
 214
 215         }
 216         return len;
 217 }
 218
 219 static long ar7_wdt_ioctl(struct file *file,
 220                                         unsigned int cmd, unsigned long arg)
 221 {
 222         static const struct watchdog_info ident = {
 223                 .identity = LONGNAME,
 224                 .firmware_version = 1,
 225                 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 226                                                 WDIOF_MAGICCLOSE),
 227         };
 228         int new_margin;
 229
 230         switch (cmd) {
 231         case WDIOC_GETSUPPORT:
 232                 if (copy_to_user((struct watchdog_info *)arg, &ident,
 233                                 sizeof(ident)))
 234                         return -EFAULT;
 235                 return 0;
 236         case WDIOC_GETSTATUS:
 237         case WDIOC_GETBOOTSTATUS:
 238                 if (put_user(0, (int *)arg))
 239                         return -EFAULT;
 240                 return 0;
 241         case WDIOC_KEEPALIVE:
 242                 ar7_wdt_kick(1);
 243                 return 0;
 244         case WDIOC_SETTIMEOUT:
 245                 if (get_user(new_margin, (int *)arg))
 246                         return -EFAULT;
 247                 if (new_margin < 1)
 248                         return -EINVAL;
 249
 250                 spin_lock(&wdt_lock);
 251                 ar7_wdt_update_margin(new_margin);
 252                 ar7_wdt_kick(1);
 253                 spin_unlock(&wdt_lock);
 254
 255         case WDIOC_GETTIMEOUT:
 256                 if (put_user(margin, (int *)arg))
 257                         return -EFAULT;
 258                 return 0;
 259         default:
 260                 return -ENOTTY;
 261         }
 262 }
 263
 264 static const struct file_operations ar7_wdt_fops = {
 265         .owner          = THIS_MODULE,
 266         .write          = ar7_wdt_write,
 267         .unlocked_ioctl = ar7_wdt_ioctl,
 268         .open           = ar7_wdt_open,
 269         .release        = ar7_wdt_release,
 270         .llseek         = no_llseek,
 271 };
 272
 273 static struct miscdevice ar7_wdt_miscdev = {
 274         .minor          = WATCHDOG_MINOR,
 275         .name           = "watchdog",
 276         .fops           = &ar7_wdt_fops,
 277 };
 278
 279 static int __devinit ar7_wdt_probe(struct platform_device *pdev)
 280 {
 281         int rc;
 282
 283         spin_lock_init(&wdt_lock);
 284
 285         ar7_regs_wdt =
 286                 platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs");
 287         if (!ar7_regs_wdt) {
 288                 printk(KERN_ERR DRVNAME ": could not get registers resource\n");
 289                 rc = -ENODEV;
 290                 goto out;
 291         }
 292
 293         if (!request_mem_region(ar7_regs_wdt->start,
 294                                 resource_size(ar7_regs_wdt), LONGNAME)) {
 295                 printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
 296                 rc = -EBUSY;
 297                 goto out;
 298         }
 299
 300         ar7_wdt = ioremap(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
 301         if (!ar7_wdt) {
 302                 printk(KERN_ERR DRVNAME ": could not ioremap registers\n");
 303                 rc = -ENXIO;
 304                 goto out_mem_region;
 305         }
 306
 307         vbus_clk = clk_get(NULL, "vbus");
 308         if (IS_ERR(vbus_clk)) {
 309                 printk(KERN_ERR DRVNAME ": could not get vbus clock\n");
 310                 rc = PTR_ERR(vbus_clk);
 311                 goto out_mem_region;
 312         }
 313
 314         ar7_wdt_disable_wdt();
 315         ar7_wdt_prescale(prescale_value);
 316         ar7_wdt_update_margin(margin);
 317
 318         rc = misc_register(&ar7_wdt_miscdev);
 319         if (rc) {
 320                 printk(KERN_ERR DRVNAME ": unable to register misc device\n");
 321                 goto out_alloc;
 322         }
 323         goto out;
 324
 325 out_alloc:
 326         iounmap(ar7_wdt);
 327 out_mem_region:
 328         release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
 329 out:
 330         return rc;
 331 }
 332
 333 static int __devexit ar7_wdt_remove(struct platform_device *pdev)
 334 {
 335         misc_deregister(&ar7_wdt_miscdev);
 336         iounmap(ar7_wdt);
 337         release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt));
 338
 339         return 0;
 340 }
 341
 342 static void ar7_wdt_shutdown(struct platform_device *pdev)
 343 {
 344         if (!nowayout)
 345                 ar7_wdt_disable_wdt();
 346 }
 347
 348 static struct platform_driver ar7_wdt_driver = {
 349         .probe = ar7_wdt_probe,
 350         .remove = __devexit_p(ar7_wdt_remove),
 351         .shutdown = ar7_wdt_shutdown,
 352         .driver = {
 353                 .owner = THIS_MODULE,
 354                 .name = "ar7_wdt",
 355         },
 356 };
 357
 358 static int __init ar7_wdt_init(void)
 359 {
 360         return platform_driver_register(&ar7_wdt_driver);
 361 }
 362
 363 static void __exit ar7_wdt_cleanup(void)
 364 {
 365         platform_driver_unregister(&ar7_wdt_driver);
 366 }
 367
 368 module_init(ar7_wdt_init);
 369 module_exit(ar7_wdt_cleanup);