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 #include <linux/init.h>
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/miscdevice.h>
  16 #include <linux/fs.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/watchdog.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/io.h>
  21 #include <linux/spinlock.h>
  22
  23 #define TIMEOUT_MIN             1
  24 #define TIMEOUT_MAX             2
  25 #define TIMEOUT_DEFAULT         TIMEOUT_MAX
  26
  27 /* module parameters */
  28 static int timeout =  TIMEOUT_DEFAULT;
  29 module_param(timeout, int, 0);
  30 MODULE_PARM_DESC(timeout,
  31                 "Timeout value. Limited to be 1 or 2 seconds. (default="
  32                 __MODULE_STRING(TIMEOUT_DEFAULT) ")");
  33
  34 static int nowayout = WATCHDOG_NOWAYOUT;
  35 module_param(nowayout, int, 0);
  36 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  37                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  38
  39 /* Watchdog registers and write/read macro */
  40 #define WDT_CTRL                0x00
  41 #define WDT_CTRL_EN                0
  42 #define WDT_CTRL_PSEL              8
  43 #define WDT_CTRL_KEY              24
  44
  45 #define WDT_CLR                 0x04
  46
  47 #define WDT_BIT(name)           (1 << WDT_##name)
  48 #define WDT_BF(name, value)     ((value) << WDT_##name)
  49
  50 #define wdt_readl(dev, reg)                             \
  51         __raw_readl((dev)->regs + WDT_##reg)
  52 #define wdt_writel(dev, reg, value)                     \
  53         __raw_writel((value), (dev)->regs + WDT_##reg)
  54
  55 struct wdt_at32ap700x {
  56         void __iomem            *regs;
  57         spinlock_t              io_lock;
  58         int                     timeout;
  59         unsigned long           users;
  60         struct miscdevice       miscdev;
  61 };
  62
  63 static struct wdt_at32ap700x *wdt;
  64 static char expect_release;
  65
  66 /*
  67  * Disable the watchdog.
  68  */
  69 static inline void at32_wdt_stop(void)
  70 {
  71         unsigned long psel;
  72
  73         spin_lock(&wdt->io_lock);
  74         psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f);
  75         wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0x55));
  76         wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0xaa));
  77         spin_unlock(&wdt->io_lock);
  78 }
  79
  80 /*
  81  * Enable and reset the watchdog.
  82  */
  83 static inline void at32_wdt_start(void)
  84 {
  85         /* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */
  86         unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe;
  87
  88         spin_lock(&wdt->io_lock);
  89         wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
  90                         | WDT_BF(CTRL_PSEL, psel)
  91                         | WDT_BF(CTRL_KEY, 0x55));
  92         wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
  93                         | WDT_BF(CTRL_PSEL, psel)
  94                         | WDT_BF(CTRL_KEY, 0xaa));
  95         spin_unlock(&wdt->io_lock);
  96 }
  97
  98 /*
  99  * Pat the watchdog timer.
 100  */
 101 static inline void at32_wdt_pat(void)
 102 {
 103         spin_lock(&wdt->io_lock);
 104         wdt_writel(wdt, CLR, 0x42);
 105         spin_unlock(&wdt->io_lock);
 106 }
 107
 108 /*
 109  * Watchdog device is opened, and watchdog starts running.
 110  */
 111 static int at32_wdt_open(struct inode *inode, struct file *file)
 112 {
 113         if (test_and_set_bit(1, &wdt->users))
 114                 return -EBUSY;
 115
 116         at32_wdt_start();
 117         return nonseekable_open(inode, file);
 118 }
 119
 120 /*
 121  * Close the watchdog device.
 122  */
 123 static int at32_wdt_close(struct inode *inode, struct file *file)
 124 {
 125         if (expect_release == 42) {
 126                 at32_wdt_stop();
 127         } else {
 128                 dev_dbg(wdt->miscdev.parent,
 129                         "Unexpected close, not stopping watchdog!\n");
 130                 at32_wdt_pat();
 131         }
 132         clear_bit(1, &wdt->users);
 133         expect_release = 0;
 134         return 0;
 135 }
 136
 137 /*
 138  * Change the watchdog time interval.
 139  */
 140 static int at32_wdt_settimeout(int time)
 141 {
 142         /*
 143          * All counting occurs at 1 / SLOW_CLOCK (32 kHz) and max prescaler is
 144          * 2 ^ 16 allowing up to 2 seconds timeout.
 145          */
 146         if ((time < TIMEOUT_MIN) || (time > TIMEOUT_MAX))
 147                 return -EINVAL;
 148
 149         /*
 150          * Set new watchdog time. It will be used when at32_wdt_start() is
 151          * called.
 152          */
 153         wdt->timeout = time;
 154         return 0;
 155 }
 156
 157 static struct watchdog_info at32_wdt_info = {
 158         .identity       = "at32ap700x watchdog",
 159         .options        = WDIOF_SETTIMEOUT |
 160                           WDIOF_KEEPALIVEPING |
 161                           WDIOF_MAGICCLOSE,
 162 };
 163
 164 /*
 165  * Handle commands from user-space.
 166  */
 167 static int at32_wdt_ioctl(struct inode *inode, struct file *file,
 168                 unsigned int cmd, unsigned long arg)
 169 {
 170         int ret = -ENOTTY;
 171         int time;
 172         void __user *argp = (void __user *)arg;
 173         int __user *p = argp;
 174
 175         switch (cmd) {
 176         case WDIOC_KEEPALIVE:
 177                 at32_wdt_pat();
 178                 ret = 0;
 179                 break;
 180         case WDIOC_GETSUPPORT:
 181                 ret = copy_to_user(argp, &at32_wdt_info,
 182                                 sizeof(at32_wdt_info)) ? -EFAULT : 0;
 183                 break;
 184         case WDIOC_SETTIMEOUT:
 185                 ret = get_user(time, p);
 186                 if (ret)
 187                         break;
 188                 ret = at32_wdt_settimeout(time);
 189                 if (ret)
 190                         break;
 191                 /* Enable new time value */
 192                 at32_wdt_start();
 193                 /* fall through */
 194         case WDIOC_GETTIMEOUT:
 195                 ret = put_user(wdt->timeout, p);
 196                 break;
 197         case WDIOC_GETSTATUS: /* fall through */
 198         case WDIOC_GETBOOTSTATUS:
 199                 ret = put_user(0, p);
 200                 break;
 201         case WDIOC_SETOPTIONS:
 202                 ret = get_user(time, p);
 203                 if (ret)
 204                         break;
 205                 if (time & WDIOS_DISABLECARD)
 206                         at32_wdt_stop();
 207                 if (time & WDIOS_ENABLECARD)
 208                         at32_wdt_start();
 209                 ret = 0;
 210                 break;
 211         }
 212
 213         return ret;
 214 }
 215
 216 static ssize_t at32_wdt_write(struct file *file, const char __user *data,
 217                                 size_t len, loff_t *ppos)
 218 {
 219         /* See if we got the magic character 'V' and reload the timer */
 220         if (len) {
 221                 if (!nowayout) {
 222                         size_t i;
 223
 224                         /*
 225                          * note: just in case someone wrote the magic
 226                          * character five months ago...
 227                          */
 228                         expect_release = 0;
 229
 230                         /*
 231                          * scan to see whether or not we got the magic
 232                          * character
 233                          */
 234                         for (i = 0; i != len; i++) {
 235                                 char c;
 236                                 if (get_user(c, data+i))
 237                                         return -EFAULT;
 238                                 if (c == 'V')
 239                                         expect_release = 42;
 240                         }
 241                 }
 242                 /* someone wrote to us, we should pat the watchdog */
 243                 at32_wdt_pat();
 244         }
 245         return len;
 246 }
 247
 248 static const struct file_operations at32_wdt_fops = {
 249         .owner          = THIS_MODULE,
 250         .llseek         = no_llseek,
 251         .ioctl          = at32_wdt_ioctl,
 252         .open           = at32_wdt_open,
 253         .release        = at32_wdt_close,
 254         .write          = at32_wdt_write,
 255 };
 256
 257 static int __init at32_wdt_probe(struct platform_device *pdev)
 258 {
 259         struct resource *regs;
 260         int ret;
 261
 262         if (wdt) {
 263                 dev_dbg(&pdev->dev, "only 1 wdt instance supported.\n");
 264                 return -EBUSY;
 265         }
 266
 267         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 268         if (!regs) {
 269                 dev_dbg(&pdev->dev, "missing mmio resource\n");
 270                 return -ENXIO;
 271         }
 272
 273         wdt = kzalloc(sizeof(struct wdt_at32ap700x), GFP_KERNEL);
 274         if (!wdt) {
 275                 dev_dbg(&pdev->dev, "no memory for wdt structure\n");
 276                 return -ENOMEM;
 277         }
 278
 279         wdt->regs = ioremap(regs->start, regs->end - regs->start + 1);
 280         if (!wdt->regs) {
 281                 ret = -ENOMEM;
 282                 dev_dbg(&pdev->dev, "could not map I/O memory\n");
 283                 goto err_free;
 284         }
 285         spin_lock_init(&wdt->io_lock);
 286         wdt->users = 0;
 287         wdt->miscdev.minor = WATCHDOG_MINOR;
 288         wdt->miscdev.name = "watchdog";
 289         wdt->miscdev.fops = &at32_wdt_fops;
 290
 291         if (at32_wdt_settimeout(timeout)) {
 292                 at32_wdt_settimeout(TIMEOUT_DEFAULT);
 293                 dev_dbg(&pdev->dev,
 294                         "default timeout invalid, set to %d sec.\n",
 295                         TIMEOUT_DEFAULT);
 296         }
 297
 298         ret = misc_register(&wdt->miscdev);
 299         if (ret) {
 300                 dev_dbg(&pdev->dev, "failed to register wdt miscdev\n");
 301                 goto err_iounmap;
 302         }
 303
 304         platform_set_drvdata(pdev, wdt);
 305         wdt->miscdev.parent = &pdev->dev;
 306         dev_info(&pdev->dev,
 307                 "AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d)\n",
 308                 wdt->regs, wdt->timeout, nowayout);
 309
 310         return 0;
 311
 312 err_iounmap:
 313         iounmap(wdt->regs);
 314 err_free:
 315         kfree(wdt);
 316         wdt = NULL;
 317         return ret;
 318 }
 319
 320 static int __exit at32_wdt_remove(struct platform_device *pdev)
 321 {
 322         if (wdt && platform_get_drvdata(pdev) == wdt) {
 323                 /* Stop the timer before we leave */
 324                 if (!nowayout)
 325                         at32_wdt_stop();
 326
 327                 misc_deregister(&wdt->miscdev);
 328                 iounmap(wdt->regs);
 329                 kfree(wdt);
 330                 wdt = NULL;
 331                 platform_set_drvdata(pdev, NULL);
 332         }
 333
 334         return 0;
 335 }
 336
 337 static void at32_wdt_shutdown(struct platform_device *pdev)
 338 {
 339         at32_wdt_stop();
 340 }
 341
 342 #ifdef CONFIG_PM
 343 static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message)
 344 {
 345         at32_wdt_stop();
 346         return 0;
 347 }
 348
 349 static int at32_wdt_resume(struct platform_device *pdev)
 350 {
 351         if (wdt->users)
 352                 at32_wdt_start();
 353         return 0;
 354 }
 355 #else
 356 #define at32_wdt_suspend NULL
 357 #define at32_wdt_resume NULL
 358 #endif
 359
 360 static struct platform_driver at32_wdt_driver = {
 361         .remove         = __exit_p(at32_wdt_remove),
 362         .suspend        = at32_wdt_suspend,
 363         .resume         = at32_wdt_resume,
 364         .driver         = {
 365                 .name   = "at32_wdt",
 366                 .owner  = THIS_MODULE,
 367         },
 368         .shutdown       = at32_wdt_shutdown,
 369 };
 370
 371 static int __init at32_wdt_init(void)
 372 {
 373         return platform_driver_probe(&at32_wdt_driver, at32_wdt_probe);
 374 }
 375 module_init(at32_wdt_init);
 376
 377 static void __exit at32_wdt_exit(void)
 378 {
 379         platform_driver_unregister(&at32_wdt_driver);
 380 }
 381 module_exit(at32_wdt_exit);
 382
 383 MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
 384 MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X");
 385 MODULE_LICENSE("GPL");
 386 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);