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