linux/drivers/watchdog/imx2_wdt.c
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   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
  58static 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
  66static struct miscdevice imx2_wdt_miscdev;
  67
  68static int nowayout = WATCHDOG_NOWAYOUT;
  69module_param(nowayout, int, 0);
  70MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  71                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  72
  73
  74static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
  75module_param(timeout, uint, 0);
  76MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  77                                __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
  78
  79static const struct watchdog_info imx2_wdt_info = {
  80        .identity = "imx2+ watchdog",
  81        .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
  82};
  83
  84static 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
 104static 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
 110static 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
 117static 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
 131static 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
 138static 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
 148static 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
 157static 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
 172static 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
 210static 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
 232static 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
 241static struct miscdevice imx2_wdt_miscdev = {
 242        .minor = WATCHDOG_MINOR,
 243        .name = "watchdog",
 244        .fops = &imx2_wdt_fops,
 245};
 246
 247static 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_sys("imx-wdt.0", 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
 296fail:
 297        imx2_wdt_miscdev.parent = NULL;
 298        clk_put(imx2_wdt.clk);
 299        return ret;
 300}
 301
 302static 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
 318static 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
 332static 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
 341static int __init imx2_wdt_init(void)
 342{
 343        return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
 344}
 345module_init(imx2_wdt_init);
 346
 347static void __exit imx2_wdt_exit(void)
 348{
 349        platform_driver_unregister(&imx2_wdt_driver);
 350}
 351module_exit(imx2_wdt_exit);
 352
 353MODULE_AUTHOR("Wolfram Sang");
 354MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
 355MODULE_LICENSE("GPL v2");
 356MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 357MODULE_ALIAS("platform:" DRIVER_NAME);
 358