drivers/watchdog/imx2_wdt.c

   1 /*
   2  * Watchdog driver for IMX2 and later processors
   3  *
   4  *  Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <w.sang@pengutronix.de>
   5  *
   6  * some parts adapted by similar drivers from Darius Augulis and Vladimir
   7  * Zapolskiy, additional improvements by Wim Van Sebroeck.
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU General Public License version 2 as published by
  11  * the Free Software Foundation.
  12  *
  13  * NOTE: MX1 has a slightly different Watchdog than MX2 and later:
  14  *
  15  *                      MX1:            MX2+:
  16  *                      ----            -----
  17  * Registers:           32-bit          16-bit
  18  * Stopable timer:      Yes             No
  19  * Need to enable clk:  No              Yes
  20  * Halt on suspend:     Manual          Can be automatic
  21  */
  22
  23 #include <linux/init.h>
  24 #include <linux/kernel.h>
  25 #include <linux/miscdevice.h>
  26 #include <linux/module.h>
  27 #include <linux/moduleparam.h>
  28 #include <linux/platform_device.h>
  29 #include <linux/watchdog.h>
  30 #include <linux/clk.h>
  31 #include <linux/fs.h>
  32 #include <linux/io.h>
  33 #include <linux/uaccess.h>
  34 #include <linux/timer.h>
  35 #include <linux/jiffies.h>
  36 #include <mach/hardware.h>
  37
  38 #define DRIVER_NAME "imx2-wdt"
  39
  40 #define IMX2_WDT_WCR            0x00            /* Control Register */
  41 #define IMX2_WDT_WCR_WT         (0xFF << 8)     /* -> Watchdog Timeout Field */
  42 #define IMX2_WDT_WCR_WRE        (1 << 3)        /* -> WDOG Reset Enable */
  43 #define IMX2_WDT_WCR_WDE        (1 << 2)        /* -> Watchdog Enable */
  44
  45 #define IMX2_WDT_WSR            0x02            /* Service Register */
  46 #define IMX2_WDT_SEQ1           0x5555          /* -> service sequence 1 */
  47 #define IMX2_WDT_SEQ2           0xAAAA          /* -> service sequence 2 */
  48
  49 #define IMX2_WDT_MAX_TIME       128
  50 #define IMX2_WDT_DEFAULT_TIME   60              /* in seconds */
  51
  52 #define WDOG_SEC_TO_COUNT(s)    ((s * 2 - 1) << 8)
  53
  54 #define IMX2_WDT_STATUS_OPEN    0
  55 #define IMX2_WDT_STATUS_STARTED 1
  56 #define IMX2_WDT_EXPECT_CLOSE   2
  57
  58 static struct {
  59         struct clk *clk;
  60         void __iomem *base;
  61         unsigned timeout;
  62         unsigned long status;
  63         struct timer_list timer;        /* Pings the watchdog when closed */
  64 } imx2_wdt;
  65
  66 static struct miscdevice imx2_wdt_miscdev;
  67
  68 static int nowayout = WATCHDOG_NOWAYOUT;
  69 module_param(nowayout, int, 0);
  70 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  71                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  72
  73
  74 static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
  75 module_param(timeout, uint, 0);
  76 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  77                                 __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
  78
  79 static const struct watchdog_info imx2_wdt_info = {
  80         .identity = "imx2+ watchdog",
  81         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
  82 };
  83
  84 static inline void imx2_wdt_setup(void)
  85 {
  86         u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
  87
  88         /* Strip the old watchdog Time-Out value */
  89         val &= ~IMX2_WDT_WCR_WT;
  90         /* Generate reset if WDOG times out */
  91         val &= ~IMX2_WDT_WCR_WRE;
  92         /* Keep Watchdog Disabled */
  93         val &= ~IMX2_WDT_WCR_WDE;
  94         /* Set the watchdog's Time-Out value */
  95         val |= WDOG_SEC_TO_COUNT(imx2_wdt.timeout);
  96
  97         __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
  98
  99         /* enable the watchdog */
 100         val |= IMX2_WDT_WCR_WDE;
 101         __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
 102 }
 103
 104 static inline void imx2_wdt_ping(void)
 105 {
 106         __raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
 107         __raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
 108 }
 109
 110 static void imx2_wdt_timer_ping(unsigned long arg)
 111 {
 112         /* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */
 113         imx2_wdt_ping();
 114         mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2);
 115 }
 116
 117 static void imx2_wdt_start(void)
 118 {
 119         if (!test_and_set_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
 120                 /* at our first start we enable clock and do initialisations */
 121                 clk_enable(imx2_wdt.clk);
 122
 123                 imx2_wdt_setup();
 124         } else  /* delete the timer that pings the watchdog after close */
 125                 del_timer_sync(&imx2_wdt.timer);
 126
 127         /* Watchdog is enabled - time to reload the timeout value */
 128         imx2_wdt_ping();
 129 }
 130
 131 static void imx2_wdt_stop(void)
 132 {
 133         /* we don't need a clk_disable, it cannot be disabled once started.
 134          * We use a timer to ping the watchdog while /dev/watchdog is closed */
 135         imx2_wdt_timer_ping(0);
 136 }
 137
 138 static void imx2_wdt_set_timeout(int new_timeout)
 139 {
 140         u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
 141
 142         /* set the new timeout value in the WSR */
 143         val &= ~IMX2_WDT_WCR_WT;
 144         val |= WDOG_SEC_TO_COUNT(new_timeout);
 145         __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
 146 }
 147
 148 static int imx2_wdt_open(struct inode *inode, struct file *file)
 149 {
 150         if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
 151                 return -EBUSY;
 152
 153         imx2_wdt_start();
 154         return nonseekable_open(inode, file);
 155 }
 156
 157 static int imx2_wdt_close(struct inode *inode, struct file *file)
 158 {
 159         if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout)
 160                 imx2_wdt_stop();
 161         else {
 162                 dev_crit(imx2_wdt_miscdev.parent,
 163                         "Unexpected close: Expect reboot!\n");
 164                 imx2_wdt_ping();
 165         }
 166
 167         clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
 168         clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status);
 169         return 0;
 170 }
 171
 172 static long imx2_wdt_ioctl(struct file *file, unsigned int cmd,
 173                                                         unsigned long arg)
 174 {
 175         void __user *argp = (void __user *)arg;
 176         int __user *p = argp;
 177         int new_value;
 178
 179         switch (cmd) {
 180         case WDIOC_GETSUPPORT:
 181                 return copy_to_user(argp, &imx2_wdt_info,
 182                         sizeof(struct watchdog_info)) ? -EFAULT : 0;
 183
 184         case WDIOC_GETSTATUS:
 185         case WDIOC_GETBOOTSTATUS:
 186                 return put_user(0, p);
 187
 188         case WDIOC_KEEPALIVE:
 189                 imx2_wdt_ping();
 190                 return 0;
 191
 192         case WDIOC_SETTIMEOUT:
 193                 if (get_user(new_value, p))
 194                         return -EFAULT;
 195                 if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME))
 196                         return -EINVAL;
 197                 imx2_wdt_set_timeout(new_value);
 198                 imx2_wdt.timeout = new_value;
 199                 imx2_wdt_ping();
 200
 201                 /* Fallthrough to return current value */
 202         case WDIOC_GETTIMEOUT:
 203                 return put_user(imx2_wdt.timeout, p);
 204
 205         default:
 206                 return -ENOTTY;
 207         }
 208 }
 209
 210 static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
 211                                                 size_t len, loff_t *ppos)
 212 {
 213         size_t i;
 214         char c;
 215
 216         if (len == 0)   /* Can we see this even ? */
 217                 return 0;
 218
 219         clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
 220         /* scan to see whether or not we got the magic character */
 221         for (i = 0; i != len; i++) {
 222                 if (get_user(c, data + i))
 223                         return -EFAULT;
 224                 if (c == 'V')
 225                         set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
 226         }
 227
 228         imx2_wdt_ping();
 229         return len;
 230 }
 231
 232 static const struct file_operations imx2_wdt_fops = {
 233         .owner = THIS_MODULE,
 234         .llseek = no_llseek,
 235         .unlocked_ioctl = imx2_wdt_ioctl,
 236         .open = imx2_wdt_open,
 237         .release = imx2_wdt_close,
 238         .write = imx2_wdt_write,
 239 };
 240
 241 static struct miscdevice imx2_wdt_miscdev = {
 242         .minor = WATCHDOG_MINOR,
 243         .name = "watchdog",
 244         .fops = &imx2_wdt_fops,
 245 };
 246
 247 static int __init imx2_wdt_probe(struct platform_device *pdev)
 248 {
 249         int ret;
 250         int res_size;
 251         struct resource *res;
 252
 253         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 254         if (!res) {
 255                 dev_err(&pdev->dev, "can't get device resources\n");
 256                 return -ENODEV;
 257         }
 258
 259         res_size = resource_size(res);
 260         if (!devm_request_mem_region(&pdev->dev, res->start, res_size,
 261                 res->name)) {
 262                 dev_err(&pdev->dev, "can't allocate %d bytes at %d address\n",
 263                         res_size, res->start);
 264                 return -ENOMEM;
 265         }
 266
 267         imx2_wdt.base = devm_ioremap_nocache(&pdev->dev, res->start, res_size);
 268         if (!imx2_wdt.base) {
 269                 dev_err(&pdev->dev, "ioremap failed\n");
 270                 return -ENOMEM;
 271         }
 272
 273         imx2_wdt.clk = clk_get(&pdev->dev, NULL);
 274         if (IS_ERR(imx2_wdt.clk)) {
 275                 dev_err(&pdev->dev, "can't get Watchdog clock\n");
 276                 return PTR_ERR(imx2_wdt.clk);
 277         }
 278
 279         imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
 280         if (imx2_wdt.timeout != timeout)
 281                 dev_warn(&pdev->dev, "Initial timeout out of range! "
 282                         "Clamped from %u to %u\n", timeout, imx2_wdt.timeout);
 283
 284         setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
 285
 286         imx2_wdt_miscdev.parent = &pdev->dev;
 287         ret = misc_register(&imx2_wdt_miscdev);
 288         if (ret)
 289                 goto fail;
 290
 291         dev_info(&pdev->dev,
 292                 "IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
 293                                                 imx2_wdt.timeout, nowayout);
 294         return 0;
 295
 296 fail:
 297         imx2_wdt_miscdev.parent = NULL;
 298         clk_put(imx2_wdt.clk);
 299         return ret;
 300 }
 301
 302 static int __exit imx2_wdt_remove(struct platform_device *pdev)
 303 {
 304         misc_deregister(&imx2_wdt_miscdev);
 305
 306         if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
 307                 del_timer_sync(&imx2_wdt.timer);
 308
 309                 dev_crit(imx2_wdt_miscdev.parent,
 310                         "Device removed: Expect reboot!\n");
 311         } else
 312                 clk_put(imx2_wdt.clk);
 313
 314         imx2_wdt_miscdev.parent = NULL;
 315         return 0;
 316 }
 317
 318 static void imx2_wdt_shutdown(struct platform_device *pdev)
 319 {
 320         if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
 321                 /* we are running, we need to delete the timer but will give
 322                  * max timeout before reboot will take place */
 323                 del_timer_sync(&imx2_wdt.timer);
 324                 imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
 325                 imx2_wdt_ping();
 326
 327                 dev_crit(imx2_wdt_miscdev.parent,
 328                         "Device shutdown: Expect reboot!\n");
 329         }
 330 }
 331
 332 static struct platform_driver imx2_wdt_driver = {
 333         .remove         = __exit_p(imx2_wdt_remove),
 334         .shutdown       = imx2_wdt_shutdown,
 335         .driver         = {
 336                 .name   = DRIVER_NAME,
 337                 .owner  = THIS_MODULE,
 338         },
 339 };
 340
 341 static int __init imx2_wdt_init(void)
 342 {
 343         return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
 344 }
 345 module_init(imx2_wdt_init);
 346
 347 static void __exit imx2_wdt_exit(void)
 348 {
 349         platform_driver_unregister(&imx2_wdt_driver);
 350 }
 351 module_exit(imx2_wdt_exit);
 352
 353 MODULE_AUTHOR("Wolfram Sang");
 354 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
 355 MODULE_LICENSE("GPL v2");
 356 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 357 MODULE_ALIAS("platform:" DRIVER_NAME);