drivers/watchdog/at32ap700x_wdt.c

   1 /*
   2  * Watchdog driver for Atmel AT32AP700X devices
   3  *
   4  * Copyright (C) 2005-2006 Atmel Corporation
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  *
  11  * Errata: WDT Clear is blocked after WDT Reset
  12  *
  13  * A watchdog timer event will, after reset, block writes to the WDT_CLEAR
  14  * register, preventing the program to clear the next Watchdog Timer Reset.
  15  *
  16  * If you still want to use the WDT after a WDT reset a small code can be
  17  * insterted at the startup checking the AVR32_PM.rcause register for WDT reset
  18  * and use a GPIO pin to reset the system. This method requires that one of the
  19  * GPIO pins are available and connected externally to the RESET_N pin. After
  20  * the GPIO pin has pulled down the reset line the GPIO will be reset and leave
  21  * the pin tristated with pullup.
  22  */
  23
  24 #include <linux/init.h>
  25 #include <linux/kernel.h>
  26 #include <linux/module.h>
  27 #include <linux/moduleparam.h>
  28 #include <linux/miscdevice.h>
  29 #include <linux/fs.h>
  30 #include <linux/platform_device.h>
  31 #include <linux/watchdog.h>
  32 #include <linux/uaccess.h>
  33 #include <linux/io.h>
  34 #include <linux/spinlock.h>
  35
  36 #define TIMEOUT_MIN             1
  37 #define TIMEOUT_MAX             2
  38 #define TIMEOUT_DEFAULT         TIMEOUT_MAX
  39
  40 /* module parameters */
  41 static int timeout =  TIMEOUT_DEFAULT;
  42 module_param(timeout, int, 0);
  43 MODULE_PARM_DESC(timeout,
  44                 "Timeout value. Limited to be 1 or 2 seconds. (default="
  45                 __MODULE_STRING(TIMEOUT_DEFAULT) ")");
  46
  47 static int nowayout = WATCHDOG_NOWAYOUT;
  48 module_param(nowayout, int, 0);
  49 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  50                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  51
  52 /* Watchdog registers and write/read macro */
  53 #define WDT_CTRL                0x00
  54 #define WDT_CTRL_EN                0
  55 #define WDT_CTRL_PSEL              8
  56 #define WDT_CTRL_KEY              24
  57
  58 #define WDT_CLR                 0x04
  59
  60 #define WDT_RCAUSE              0x10
  61 #define WDT_RCAUSE_POR             0
  62 #define WDT_RCAUSE_EXT             2
  63 #define WDT_RCAUSE_WDT             3
  64 #define WDT_RCAUSE_JTAG            4
  65 #define WDT_RCAUSE_SERP            5
  66
  67 #define WDT_BIT(name)           (1 << WDT_##name)
  68 #define WDT_BF(name, value)     ((value) << WDT_##name)
  69
  70 #define wdt_readl(dev, reg)                             \
  71         __raw_readl((dev)->regs + WDT_##reg)
  72 #define wdt_writel(dev, reg, value)                     \
  73         __raw_writel((value), (dev)->regs + WDT_##reg)
  74
  75 struct wdt_at32ap700x {
  76         void __iomem            *regs;
  77         spinlock_t              io_lock;
  78         int                     timeout;
  79         int                     boot_status;
  80         unsigned long           users;
  81         struct miscdevice       miscdev;
  82 };
  83
  84 static struct wdt_at32ap700x *wdt;
  85 static char expect_release;
  86
  87 /*
  88  * Disable the watchdog.
  89  */
  90 static inline void at32_wdt_stop(void)
  91 {
  92         unsigned long psel;
  93
  94         spin_lock(&wdt->io_lock);
  95         psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f);
  96         wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0x55));
  97         wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0xaa));
  98         spin_unlock(&wdt->io_lock);
  99 }
 100
 101 /*
 102  * Enable and reset the watchdog.
 103  */
 104 static inline void at32_wdt_start(void)
 105 {
 106         /* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */
 107         unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe;
 108
 109         spin_lock(&wdt->io_lock);
 110         wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
 111                         | WDT_BF(CTRL_PSEL, psel)
 112                         | WDT_BF(CTRL_KEY, 0x55));
 113         wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
 114                         | WDT_BF(CTRL_PSEL, psel)
 115                         | WDT_BF(CTRL_KEY, 0xaa));
 116         spin_unlock(&wdt->io_lock);
 117 }
 118
 119 /*
 120  * Pat the watchdog timer.
 121  */
 122 static inline void at32_wdt_pat(void)
 123 {
 124         spin_lock(&wdt->io_lock);
 125         wdt_writel(wdt, CLR, 0x42);
 126         spin_unlock(&wdt->io_lock);
 127 }
 128
 129 /*
 130  * Watchdog device is opened, and watchdog starts running.
 131  */
 132 static int at32_wdt_open(struct inode *inode, struct file *file)
 133 {
 134         if (test_and_set_bit(1, &wdt->users))
 135                 return -EBUSY;
 136
 137         at32_wdt_start();
 138         return nonseekable_open(inode, file);
 139 }
 140
 141 /*
 142  * Close the watchdog device.
 143  */
 144 static int at32_wdt_close(struct inode *inode, struct file *file)
 145 {
 146         if (expect_release == 42) {
 147                 at32_wdt_stop();
 148         } else {
 149                 dev_dbg(wdt->miscdev.parent,
 150                         "unexpected close, not stopping watchdog!\n");
 151                 at32_wdt_pat();
 152         }
 153         clear_bit(1, &wdt->users);
 154         expect_release = 0;
 155         return 0;
 156 }
 157
 158 /*
 159  * Change the watchdog time interval.
 160  */
 161 static int at32_wdt_settimeout(int time)
 162 {
 163         /*
 164          * All counting occurs at 1 / SLOW_CLOCK (32 kHz) and max prescaler is
 165          * 2 ^ 16 allowing up to 2 seconds timeout.
 166          */
 167         if ((time < TIMEOUT_MIN) || (time > TIMEOUT_MAX))
 168                 return -EINVAL;
 169
 170         /*
 171          * Set new watchdog time. It will be used when at32_wdt_start() is
 172          * called.
 173          */
 174         wdt->timeout = time;
 175         return 0;
 176 }
 177
 178 /*
 179  * Get the watchdog status.
 180  */
 181 static int at32_wdt_get_status(void)
 182 {
 183         int rcause;
 184         int status = 0;
 185
 186         rcause = wdt_readl(wdt, RCAUSE);
 187
 188         switch (rcause) {
 189         case WDT_BIT(RCAUSE_EXT):
 190                 status = WDIOF_EXTERN1;
 191                 break;
 192         case WDT_BIT(RCAUSE_WDT):
 193                 status = WDIOF_CARDRESET;
 194                 break;
 195         case WDT_BIT(RCAUSE_POR):  /* fall through */
 196         case WDT_BIT(RCAUSE_JTAG): /* fall through */
 197         case WDT_BIT(RCAUSE_SERP): /* fall through */
 198         default:
 199                 break;
 200         }
 201
 202         return status;
 203 }
 204
 205 static struct watchdog_info at32_wdt_info = {
 206         .identity       = "at32ap700x watchdog",
 207         .options        = WDIOF_SETTIMEOUT |
 208                           WDIOF_KEEPALIVEPING |
 209                           WDIOF_MAGICCLOSE,
 210 };
 211
 212 /*
 213  * Handle commands from user-space.
 214  */
 215 static long at32_wdt_ioctl(struct file *file,
 216                                 unsigned int cmd, unsigned long arg)
 217 {
 218         int ret = -ENOTTY;
 219         int time;
 220         void __user *argp = (void __user *)arg;
 221         int __user *p = argp;
 222
 223         switch (cmd) {
 224         case WDIOC_GETSUPPORT:
 225                 ret = copy_to_user(argp, &at32_wdt_info,
 226                                 sizeof(at32_wdt_info)) ? -EFAULT : 0;
 227                 break;
 228         case WDIOC_GETSTATUS:
 229                 ret = put_user(0, p);
 230                 break;
 231         case WDIOC_GETBOOTSTATUS:
 232                 ret = put_user(wdt->boot_status, p);
 233                 break;
 234         case WDIOC_SETOPTIONS:
 235                 ret = get_user(time, p);
 236                 if (ret)
 237                         break;
 238                 if (time & WDIOS_DISABLECARD)
 239                         at32_wdt_stop();
 240                 if (time & WDIOS_ENABLECARD)
 241                         at32_wdt_start();
 242                 ret = 0;
 243                 break;
 244         case WDIOC_KEEPALIVE:
 245                 at32_wdt_pat();
 246                 ret = 0;
 247                 break;
 248         case WDIOC_SETTIMEOUT:
 249                 ret = get_user(time, p);
 250                 if (ret)
 251                         break;
 252                 ret = at32_wdt_settimeout(time);
 253                 if (ret)
 254                         break;
 255                 /* Enable new time value */
 256                 at32_wdt_start();
 257                 /* fall through */
 258         case WDIOC_GETTIMEOUT:
 259                 ret = put_user(wdt->timeout, p);
 260                 break;
 261         }
 262
 263         return ret;
 264 }
 265
 266 static ssize_t at32_wdt_write(struct file *file, const char __user *data,
 267                                 size_t len, loff_t *ppos)
 268 {
 269         /* See if we got the magic character 'V' and reload the timer */
 270         if (len) {
 271                 if (!nowayout) {
 272                         size_t i;
 273
 274                         /*
 275                          * note: just in case someone wrote the magic
 276                          * character five months ago...
 277                          */
 278                         expect_release = 0;
 279
 280                         /*
 281                          * scan to see whether or not we got the magic
 282                          * character
 283                          */
 284                         for (i = 0; i != len; i++) {
 285                                 char c;
 286                                 if (get_user(c, data + i))
 287                                         return -EFAULT;
 288                                 if (c == 'V')
 289                                         expect_release = 42;
 290                         }
 291                 }
 292                 /* someone wrote to us, we should pat the watchdog */
 293                 at32_wdt_pat();
 294         }
 295         return len;
 296 }
 297
 298 static const struct file_operations at32_wdt_fops = {
 299         .owner          = THIS_MODULE,
 300         .llseek         = no_llseek,
 301         .unlocked_ioctl = at32_wdt_ioctl,
 302         .open           = at32_wdt_open,
 303         .release        = at32_wdt_close,
 304         .write          = at32_wdt_write,
 305 };
 306
 307 static int __init at32_wdt_probe(struct platform_device *pdev)
 308 {
 309         struct resource *regs;
 310         int ret;
 311
 312         if (wdt) {
 313                 dev_dbg(&pdev->dev, "only 1 wdt instance supported.\n");
 314                 return -EBUSY;
 315         }
 316
 317         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 318         if (!regs) {
 319                 dev_dbg(&pdev->dev, "missing mmio resource\n");
 320                 return -ENXIO;
 321         }
 322
 323         wdt = kzalloc(sizeof(struct wdt_at32ap700x), GFP_KERNEL);
 324         if (!wdt) {
 325                 dev_dbg(&pdev->dev, "no memory for wdt structure\n");
 326                 return -ENOMEM;
 327         }
 328
 329         wdt->regs = ioremap(regs->start, regs->end - regs->start + 1);
 330         if (!wdt->regs) {
 331                 ret = -ENOMEM;
 332                 dev_dbg(&pdev->dev, "could not map I/O memory\n");
 333                 goto err_free;
 334         }
 335
 336         spin_lock_init(&wdt->io_lock);
 337         wdt->boot_status = at32_wdt_get_status();
 338
 339         /* Work-around for watchdog silicon errata. */
 340         if (wdt->boot_status & WDIOF_CARDRESET) {
 341                 dev_info(&pdev->dev, "CPU must be reset with external "
 342                                 "reset or POR due to silicon errata.\n");
 343                 ret = -EIO;
 344                 goto err_iounmap;
 345         } else {
 346                 wdt->users = 0;
 347         }
 348         wdt->miscdev.minor = WATCHDOG_MINOR;
 349         wdt->miscdev.name = "watchdog";
 350         wdt->miscdev.fops = &at32_wdt_fops;
 351
 352         if (at32_wdt_settimeout(timeout)) {
 353                 at32_wdt_settimeout(TIMEOUT_DEFAULT);
 354                 dev_dbg(&pdev->dev,
 355                         "default timeout invalid, set to %d sec.\n",
 356                         TIMEOUT_DEFAULT);
 357         }
 358
 359         ret = misc_register(&wdt->miscdev);
 360         if (ret) {
 361                 dev_dbg(&pdev->dev, "failed to register wdt miscdev\n");
 362                 goto err_iounmap;
 363         }
 364
 365         platform_set_drvdata(pdev, wdt);
 366         wdt->miscdev.parent = &pdev->dev;
 367         dev_info(&pdev->dev,
 368                 "AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d)\n",
 369                 wdt->regs, wdt->timeout, nowayout);
 370
 371         return 0;
 372
 373 err_iounmap:
 374         iounmap(wdt->regs);
 375 err_free:
 376         kfree(wdt);
 377         wdt = NULL;
 378         return ret;
 379 }
 380
 381 static int __exit at32_wdt_remove(struct platform_device *pdev)
 382 {
 383         if (wdt && platform_get_drvdata(pdev) == wdt) {
 384                 /* Stop the timer before we leave */
 385                 if (!nowayout)
 386                         at32_wdt_stop();
 387
 388                 misc_deregister(&wdt->miscdev);
 389                 iounmap(wdt->regs);
 390                 kfree(wdt);
 391                 wdt = NULL;
 392                 platform_set_drvdata(pdev, NULL);
 393         }
 394         return 0;
 395 }
 396
 397 static void at32_wdt_shutdown(struct platform_device *pdev)
 398 {
 399         at32_wdt_stop();
 400 }
 401
 402 #ifdef CONFIG_PM
 403 static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message)
 404 {
 405         at32_wdt_stop();
 406         return 0;
 407 }
 408
 409 static int at32_wdt_resume(struct platform_device *pdev)
 410 {
 411         if (wdt->users)
 412                 at32_wdt_start();
 413         return 0;
 414 }
 415 #else
 416 #define at32_wdt_suspend NULL
 417 #define at32_wdt_resume NULL
 418 #endif
 419
 420 /* work with hotplug and coldplug */
 421 MODULE_ALIAS("platform:at32_wdt");
 422
 423 static struct platform_driver at32_wdt_driver = {
 424         .remove         = __exit_p(at32_wdt_remove),
 425         .suspend        = at32_wdt_suspend,
 426         .resume         = at32_wdt_resume,
 427         .driver         = {
 428                 .name   = "at32_wdt",
 429                 .owner  = THIS_MODULE,
 430         },
 431         .shutdown       = at32_wdt_shutdown,
 432 };
 433
 434 static int __init at32_wdt_init(void)
 435 {
 436         return platform_driver_probe(&at32_wdt_driver, at32_wdt_probe);
 437 }
 438 module_init(at32_wdt_init);
 439
 440 static void __exit at32_wdt_exit(void)
 441 {
 442         platform_driver_unregister(&at32_wdt_driver);
 443 }
 444 module_exit(at32_wdt_exit);
 445
 446 MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
 447 MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X");
 448 MODULE_LICENSE("GPL");
 449 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);