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
  37 #define DRIVER_NAME "imx2-wdt"
  38
  39 #define IMX2_WDT_WCR            0x00            /* Control Register */
  40 #define IMX2_WDT_WCR_WT         (0xFF << 8)     /* -> Watchdog Timeout Field */
  41 #define IMX2_WDT_WCR_WRE        (1 << 3)        /* -> WDOG Reset Enable */
  42 #define IMX2_WDT_WCR_WDE        (1 << 2)        /* -> Watchdog Enable */
  43
  44 #define IMX2_WDT_WSR            0x02            /* Service Register */
  45 #define IMX2_WDT_SEQ1           0x5555          /* -> service sequence 1 */
  46 #define IMX2_WDT_SEQ2           0xAAAA          /* -> service sequence 2 */
  47
  48 #define IMX2_WDT_WRSR           0x04            /* Reset Status Register */
  49 #define IMX2_WDT_WRSR_TOUT      (1 << 1)        /* -> Reset due to Timeout */
  50
  51 #define IMX2_WDT_MAX_TIME       128
  52 #define IMX2_WDT_DEFAULT_TIME   60              /* in seconds */
  53
  54 #define WDOG_SEC_TO_COUNT(s)    ((s * 2 - 1) << 8)
  55
  56 #define IMX2_WDT_STATUS_OPEN    0
  57 #define IMX2_WDT_STATUS_STARTED 1
  58 #define IMX2_WDT_EXPECT_CLOSE   2
  59
  60 static struct {
  61         struct clk *clk;
  62         void __iomem *base;
  63         unsigned timeout;
  64         unsigned long status;
  65         struct timer_list timer;        /* Pings the watchdog when closed */
  66 } imx2_wdt;
  67
  68 static struct miscdevice imx2_wdt_miscdev;
  69
  70 static bool nowayout = WATCHDOG_NOWAYOUT;
  71 module_param(nowayout, bool, 0);
  72 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  73                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  74
  75
  76 static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
  77 module_param(timeout, uint, 0);
  78 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  79                                 __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
  80
  81 static const struct watchdog_info imx2_wdt_info = {
  82         .identity = "imx2+ watchdog",
  83         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
  84 };
  85
  86 static inline void imx2_wdt_setup(void)
  87 {
  88         u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
  89
  90         /* Strip the old watchdog Time-Out value */
  91         val &= ~IMX2_WDT_WCR_WT;
  92         /* Generate reset if WDOG times out */
  93         val &= ~IMX2_WDT_WCR_WRE;
  94         /* Keep Watchdog Disabled */
  95         val &= ~IMX2_WDT_WCR_WDE;
  96         /* Set the watchdog's Time-Out value */
  97         val |= WDOG_SEC_TO_COUNT(imx2_wdt.timeout);
  98
  99         __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
 100
 101         /* enable the watchdog */
 102         val |= IMX2_WDT_WCR_WDE;
 103         __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
 104 }
 105
 106 static inline void imx2_wdt_ping(void)
 107 {
 108         __raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
 109         __raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
 110 }
 111
 112 static void imx2_wdt_timer_ping(unsigned long arg)
 113 {
 114         /* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */
 115         imx2_wdt_ping();
 116         mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2);
 117 }
 118
 119 static void imx2_wdt_start(void)
 120 {
 121         if (!test_and_set_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
 122                 /* at our first start we enable clock and do initialisations */
 123                 clk_prepare_enable(imx2_wdt.clk);
 124
 125                 imx2_wdt_setup();
 126         } else  /* delete the timer that pings the watchdog after close */
 127                 del_timer_sync(&imx2_wdt.timer);
 128
 129         /* Watchdog is enabled - time to reload the timeout value */
 130         imx2_wdt_ping();
 131 }
 132
 133 static void imx2_wdt_stop(void)
 134 {
 135         /* we don't need a clk_disable, it cannot be disabled once started.
 136          * We use a timer to ping the watchdog while /dev/watchdog is closed */
 137         imx2_wdt_timer_ping(0);
 138 }
 139
 140 static void imx2_wdt_set_timeout(int new_timeout)
 141 {
 142         u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
 143
 144         /* set the new timeout value in the WSR */
 145         val &= ~IMX2_WDT_WCR_WT;
 146         val |= WDOG_SEC_TO_COUNT(new_timeout);
 147         __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
 148 }
 149
 150 static int imx2_wdt_open(struct inode *inode, struct file *file)
 151 {
 152         if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
 153                 return -EBUSY;
 154
 155         imx2_wdt_start();
 156         return nonseekable_open(inode, file);
 157 }
 158
 159 static int imx2_wdt_close(struct inode *inode, struct file *file)
 160 {
 161         if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout)
 162                 imx2_wdt_stop();
 163         else {
 164                 dev_crit(imx2_wdt_miscdev.parent,
 165                         "Unexpected close: Expect reboot!\n");
 166                 imx2_wdt_ping();
 167         }
 168
 169         clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
 170         clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status);
 171         return 0;
 172 }
 173
 174 static long imx2_wdt_ioctl(struct file *file, unsigned int cmd,
 175                                                         unsigned long arg)
 176 {
 177         void __user *argp = (void __user *)arg;
 178         int __user *p = argp;
 179         int new_value;
 180         u16 val;
 181
 182         switch (cmd) {
 183         case WDIOC_GETSUPPORT:
 184                 return copy_to_user(argp, &imx2_wdt_info,
 185                         sizeof(struct watchdog_info)) ? -EFAULT : 0;
 186
 187         case WDIOC_GETSTATUS:
 188                 return put_user(0, p);
 189
 190         case WDIOC_GETBOOTSTATUS:
 191                 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WRSR);
 192                 new_value = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
 193                 return put_user(new_value, p);
 194
 195         case WDIOC_KEEPALIVE:
 196                 imx2_wdt_ping();
 197                 return 0;
 198
 199         case WDIOC_SETTIMEOUT:
 200                 if (get_user(new_value, p))
 201                         return -EFAULT;
 202                 if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME))
 203                         return -EINVAL;
 204                 imx2_wdt_set_timeout(new_value);
 205                 imx2_wdt.timeout = new_value;
 206                 imx2_wdt_ping();
 207
 208                 /* Fallthrough to return current value */
 209         case WDIOC_GETTIMEOUT:
 210                 return put_user(imx2_wdt.timeout, p);
 211
 212         default:
 213                 return -ENOTTY;
 214         }
 215 }
 216
 217 static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
 218                                                 size_t len, loff_t *ppos)
 219 {
 220         size_t i;
 221         char c;
 222
 223         if (len == 0)   /* Can we see this even ? */
 224                 return 0;
 225
 226         clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
 227         /* scan to see whether or not we got the magic character */
 228         for (i = 0; i != len; i++) {
 229                 if (get_user(c, data + i))
 230                         return -EFAULT;
 231                 if (c == 'V')
 232                         set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
 233         }
 234
 235         imx2_wdt_ping();
 236         return len;
 237 }
 238
 239 static const struct file_operations imx2_wdt_fops = {
 240         .owner = THIS_MODULE,
 241         .llseek = no_llseek,
 242         .unlocked_ioctl = imx2_wdt_ioctl,
 243         .open = imx2_wdt_open,
 244         .release = imx2_wdt_close,
 245         .write = imx2_wdt_write,
 246 };
 247
 248 static struct miscdevice imx2_wdt_miscdev = {
 249         .minor = WATCHDOG_MINOR,
 250         .name = "watchdog",
 251         .fops = &imx2_wdt_fops,
 252 };
 253
 254 static int __init imx2_wdt_probe(struct platform_device *pdev)
 255 {
 256         int ret;
 257         struct resource *res;
 258
 259         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 260         imx2_wdt.base = devm_ioremap_resource(&pdev->dev, res);
 261         if (IS_ERR(imx2_wdt.base))
 262                 return PTR_ERR(imx2_wdt.base);
 263
 264         imx2_wdt.clk = devm_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         return ret;
 290 }
 291
 292 static int __exit imx2_wdt_remove(struct platform_device *pdev)
 293 {
 294         misc_deregister(&imx2_wdt_miscdev);
 295
 296         if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
 297                 del_timer_sync(&imx2_wdt.timer);
 298
 299                 dev_crit(imx2_wdt_miscdev.parent,
 300                         "Device removed: Expect reboot!\n");
 301         }
 302
 303         imx2_wdt_miscdev.parent = NULL;
 304         return 0;
 305 }
 306
 307 static void imx2_wdt_shutdown(struct platform_device *pdev)
 308 {
 309         if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
 310                 /* we are running, we need to delete the timer but will give
 311                  * max timeout before reboot will take place */
 312                 del_timer_sync(&imx2_wdt.timer);
 313                 imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
 314                 imx2_wdt_ping();
 315
 316                 dev_crit(imx2_wdt_miscdev.parent,
 317                         "Device shutdown: Expect reboot!\n");
 318         }
 319 }
 320
 321 static const struct of_device_id imx2_wdt_dt_ids[] = {
 322         { .compatible = "fsl,imx21-wdt", },
 323         { /* sentinel */ }
 324 };
 325
 326 static struct platform_driver imx2_wdt_driver = {
 327         .remove         = __exit_p(imx2_wdt_remove),
 328         .shutdown       = imx2_wdt_shutdown,
 329         .driver         = {
 330                 .name   = DRIVER_NAME,
 331                 .owner  = THIS_MODULE,
 332                 .of_match_table = imx2_wdt_dt_ids,
 333         },
 334 };
 335
 336 module_platform_driver_probe(imx2_wdt_driver, imx2_wdt_probe);
 337
 338 MODULE_AUTHOR("Wolfram Sang");
 339 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
 340 MODULE_LICENSE("GPL v2");
 341 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 342 MODULE_ALIAS("platform:" DRIVER_NAME);