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         struct resource *res;
 251
 252         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 253         if (!res) {
 254                 dev_err(&pdev->dev, "can't get device resources\n");
 255                 return -ENODEV;
 256         }
 257
 258         imx2_wdt.base = devm_request_and_ioremap(&pdev->dev, res);
 259         if (!imx2_wdt.base) {
 260                 dev_err(&pdev->dev, "ioremap failed\n");
 261                 return -ENOMEM;
 262         }
 263
 264         imx2_wdt.clk = clk_get(&pdev->dev, NULL);
 265         if (IS_ERR(imx2_wdt.clk)) {
 266                 dev_err(&pdev->dev, "can't get Watchdog clock\n");
 267                 return PTR_ERR(imx2_wdt.clk);
 268         }
 269
 270         imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
 271         if (imx2_wdt.timeout != timeout)
 272                 dev_warn(&pdev->dev, "Initial timeout out of range! "
 273                         "Clamped from %u to %u\n", timeout, imx2_wdt.timeout);
 274
 275         setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
 276
 277         imx2_wdt_miscdev.parent = &pdev->dev;
 278         ret = misc_register(&imx2_wdt_miscdev);
 279         if (ret)
 280                 goto fail;
 281
 282         dev_info(&pdev->dev,
 283                 "IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
 284                                                 imx2_wdt.timeout, nowayout);
 285         return 0;
 286
 287 fail:
 288         imx2_wdt_miscdev.parent = NULL;
 289         clk_put(imx2_wdt.clk);
 290         return ret;
 291 }
 292
 293 static int __exit imx2_wdt_remove(struct platform_device *pdev)
 294 {
 295         misc_deregister(&imx2_wdt_miscdev);
 296
 297         if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
 298                 del_timer_sync(&imx2_wdt.timer);
 299
 300                 dev_crit(imx2_wdt_miscdev.parent,
 301                         "Device removed: Expect reboot!\n");
 302         } else
 303                 clk_put(imx2_wdt.clk);
 304
 305         imx2_wdt_miscdev.parent = NULL;
 306         return 0;
 307 }
 308
 309 static void imx2_wdt_shutdown(struct platform_device *pdev)
 310 {
 311         if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
 312                 /* we are running, we need to delete the timer but will give
 313                  * max timeout before reboot will take place */
 314                 del_timer_sync(&imx2_wdt.timer);
 315                 imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
 316                 imx2_wdt_ping();
 317
 318                 dev_crit(imx2_wdt_miscdev.parent,
 319                         "Device shutdown: Expect reboot!\n");
 320         }
 321 }
 322
 323 static const struct of_device_id imx2_wdt_dt_ids[] = {
 324         { .compatible = "fsl,imx21-wdt", },
 325         { /* sentinel */ }
 326 };
 327
 328 static struct platform_driver imx2_wdt_driver = {
 329         .remove         = __exit_p(imx2_wdt_remove),
 330         .shutdown       = imx2_wdt_shutdown,
 331         .driver         = {
 332                 .name   = DRIVER_NAME,
 333                 .owner  = THIS_MODULE,
 334                 .of_match_table = imx2_wdt_dt_ids,
 335         },
 336 };
 337
 338 static int __init imx2_wdt_init(void)
 339 {
 340         return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
 341 }
 342 module_init(imx2_wdt_init);
 343
 344 static void __exit imx2_wdt_exit(void)
 345 {
 346         platform_driver_unregister(&imx2_wdt_driver);
 347 }
 348 module_exit(imx2_wdt_exit);
 349
 350 MODULE_AUTHOR("Wolfram Sang");
 351 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
 352 MODULE_LICENSE("GPL v2");
 353 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 354 MODULE_ALIAS("platform:" DRIVER_NAME);