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_WRSR           0x04            /* Reset Status Register */
  50#define IMX2_WDT_WRSR_TOUT      (1 << 1)        /* -> Reset due to Timeout */
  51
  52#define IMX2_WDT_MAX_TIME       128
  53#define IMX2_WDT_DEFAULT_TIME   60              /* in seconds */
  54
  55#define WDOG_SEC_TO_COUNT(s)    ((s * 2 - 1) << 8)
  56
  57#define IMX2_WDT_STATUS_OPEN    0
  58#define IMX2_WDT_STATUS_STARTED 1
  59#define IMX2_WDT_EXPECT_CLOSE   2
  60
  61static struct {
  62        struct clk *clk;
  63        void __iomem *base;
  64        unsigned timeout;
  65        unsigned long status;
  66        struct timer_list timer;        /* Pings the watchdog when closed */
  67} imx2_wdt;
  68
  69static struct miscdevice imx2_wdt_miscdev;
  70
  71static bool nowayout = WATCHDOG_NOWAYOUT;
  72module_param(nowayout, bool, 0);
  73MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  74                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  75
  76
  77static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
  78module_param(timeout, uint, 0);
  79MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  80                                __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
  81
  82static const struct watchdog_info imx2_wdt_info = {
  83        .identity = "imx2+ watchdog",
  84        .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
  85};
  86
  87static inline void imx2_wdt_setup(void)
  88{
  89        u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
  90
  91        /* Strip the old watchdog Time-Out value */
  92        val &= ~IMX2_WDT_WCR_WT;
  93        /* Generate reset if WDOG times out */
  94        val &= ~IMX2_WDT_WCR_WRE;
  95        /* Keep Watchdog Disabled */
  96        val &= ~IMX2_WDT_WCR_WDE;
  97        /* Set the watchdog's Time-Out value */
  98        val |= WDOG_SEC_TO_COUNT(imx2_wdt.timeout);
  99
 100        __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
 101
 102        /* enable the watchdog */
 103        val |= IMX2_WDT_WCR_WDE;
 104        __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
 105}
 106
 107static inline void imx2_wdt_ping(void)
 108{
 109        __raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
 110        __raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
 111}
 112
 113static void imx2_wdt_timer_ping(unsigned long arg)
 114{
 115        /* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */
 116        imx2_wdt_ping();
 117        mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2);
 118}
 119
 120static void imx2_wdt_start(void)
 121{
 122        if (!test_and_set_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
 123                /* at our first start we enable clock and do initialisations */
 124                clk_prepare_enable(imx2_wdt.clk);
 125
 126                imx2_wdt_setup();
 127        } else  /* delete the timer that pings the watchdog after close */
 128                del_timer_sync(&imx2_wdt.timer);
 129
 130        /* Watchdog is enabled - time to reload the timeout value */
 131        imx2_wdt_ping();
 132}
 133
 134static void imx2_wdt_stop(void)
 135{
 136        /* we don't need a clk_disable, it cannot be disabled once started.
 137         * We use a timer to ping the watchdog while /dev/watchdog is closed */
 138        imx2_wdt_timer_ping(0);
 139}
 140
 141static void imx2_wdt_set_timeout(int new_timeout)
 142{
 143        u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
 144
 145        /* set the new timeout value in the WSR */
 146        val &= ~IMX2_WDT_WCR_WT;
 147        val |= WDOG_SEC_TO_COUNT(new_timeout);
 148        __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
 149}
 150
 151static int imx2_wdt_open(struct inode *inode, struct file *file)
 152{
 153        if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
 154                return -EBUSY;
 155
 156        imx2_wdt_start();
 157        return nonseekable_open(inode, file);
 158}
 159
 160static int imx2_wdt_close(struct inode *inode, struct file *file)
 161{
 162        if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout)
 163                imx2_wdt_stop();
 164        else {
 165                dev_crit(imx2_wdt_miscdev.parent,
 166                        "Unexpected close: Expect reboot!\n");
 167                imx2_wdt_ping();
 168        }
 169
 170        clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
 171        clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status);
 172        return 0;
 173}
 174
 175static long imx2_wdt_ioctl(struct file *file, unsigned int cmd,
 176                                                        unsigned long arg)
 177{
 178        void __user *argp = (void __user *)arg;
 179        int __user *p = argp;
 180        int new_value;
 181        u16 val;
 182
 183        switch (cmd) {
 184        case WDIOC_GETSUPPORT:
 185                return copy_to_user(argp, &imx2_wdt_info,
 186                        sizeof(struct watchdog_info)) ? -EFAULT : 0;
 187
 188        case WDIOC_GETSTATUS:
 189                return put_user(0, p);
 190
 191        case WDIOC_GETBOOTSTATUS:
 192                val = __raw_readw(imx2_wdt.base + IMX2_WDT_WRSR);
 193                new_value = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
 194                return put_user(new_value, p);
 195
 196        case WDIOC_KEEPALIVE:
 197                imx2_wdt_ping();
 198                return 0;
 199
 200        case WDIOC_SETTIMEOUT:
 201                if (get_user(new_value, p))
 202                        return -EFAULT;
 203                if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME))
 204                        return -EINVAL;
 205                imx2_wdt_set_timeout(new_value);
 206                imx2_wdt.timeout = new_value;
 207                imx2_wdt_ping();
 208
 209                /* Fallthrough to return current value */
 210        case WDIOC_GETTIMEOUT:
 211                return put_user(imx2_wdt.timeout, p);
 212
 213        default:
 214                return -ENOTTY;
 215        }
 216}
 217
 218static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
 219                                                size_t len, loff_t *ppos)
 220{
 221        size_t i;
 222        char c;
 223
 224        if (len == 0)   /* Can we see this even ? */
 225                return 0;
 226
 227        clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
 228        /* scan to see whether or not we got the magic character */
 229        for (i = 0; i != len; i++) {
 230                if (get_user(c, data + i))
 231                        return -EFAULT;
 232                if (c == 'V')
 233                        set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
 234        }
 235
 236        imx2_wdt_ping();
 237        return len;
 238}
 239
 240static const struct file_operations imx2_wdt_fops = {
 241        .owner = THIS_MODULE,
 242        .llseek = no_llseek,
 243        .unlocked_ioctl = imx2_wdt_ioctl,
 244        .open = imx2_wdt_open,
 245        .release = imx2_wdt_close,
 246        .write = imx2_wdt_write,
 247};
 248
 249static struct miscdevice imx2_wdt_miscdev = {
 250        .minor = WATCHDOG_MINOR,
 251        .name = "watchdog",
 252        .fops = &imx2_wdt_fops,
 253};
 254
 255static int __init imx2_wdt_probe(struct platform_device *pdev)
 256{
 257        int ret;
 258        struct resource *res;
 259
 260        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 261        if (!res) {
 262                dev_err(&pdev->dev, "can't get device resources\n");
 263                return -ENODEV;
 264        }
 265
 266        imx2_wdt.base = devm_request_and_ioremap(&pdev->dev, res);
 267        if (!imx2_wdt.base) {
 268                dev_err(&pdev->dev, "ioremap failed\n");
 269                return -ENOMEM;
 270        }
 271
 272        imx2_wdt.clk = clk_get(&pdev->dev, NULL);
 273        if (IS_ERR(imx2_wdt.clk)) {
 274                dev_err(&pdev->dev, "can't get Watchdog clock\n");
 275                return PTR_ERR(imx2_wdt.clk);
 276        }
 277
 278        imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
 279        if (imx2_wdt.timeout != timeout)
 280                dev_warn(&pdev->dev, "Initial timeout out of range! "
 281                        "Clamped from %u to %u\n", timeout, imx2_wdt.timeout);
 282
 283        setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
 284
 285        imx2_wdt_miscdev.parent = &pdev->dev;
 286        ret = misc_register(&imx2_wdt_miscdev);
 287        if (ret)
 288                goto fail;
 289
 290        dev_info(&pdev->dev,
 291                "IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
 292                                                imx2_wdt.timeout, nowayout);
 293        return 0;
 294
 295fail:
 296        imx2_wdt_miscdev.parent = NULL;
 297        clk_put(imx2_wdt.clk);
 298        return ret;
 299}
 300
 301static int __exit imx2_wdt_remove(struct platform_device *pdev)
 302{
 303        misc_deregister(&imx2_wdt_miscdev);
 304
 305        if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
 306                del_timer_sync(&imx2_wdt.timer);
 307
 308                dev_crit(imx2_wdt_miscdev.parent,
 309                        "Device removed: Expect reboot!\n");
 310        } else
 311                clk_put(imx2_wdt.clk);
 312
 313        imx2_wdt_miscdev.parent = NULL;
 314        return 0;
 315}
 316
 317static void imx2_wdt_shutdown(struct platform_device *pdev)
 318{
 319        if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
 320                /* we are running, we need to delete the timer but will give
 321                 * max timeout before reboot will take place */
 322                del_timer_sync(&imx2_wdt.timer);
 323                imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
 324                imx2_wdt_ping();
 325
 326                dev_crit(imx2_wdt_miscdev.parent,
 327                        "Device shutdown: Expect reboot!\n");
 328        }
 329}
 330
 331static const struct of_device_id imx2_wdt_dt_ids[] = {
 332        { .compatible = "fsl,imx21-wdt", },
 333        { /* sentinel */ }
 334};
 335
 336static struct platform_driver imx2_wdt_driver = {
 337        .remove         = __exit_p(imx2_wdt_remove),
 338        .shutdown       = imx2_wdt_shutdown,
 339        .driver         = {
 340                .name   = DRIVER_NAME,
 341                .owner  = THIS_MODULE,
 342                .of_match_table = imx2_wdt_dt_ids,
 343        },
 344};
 345
 346static int __init imx2_wdt_init(void)
 347{
 348        return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
 349}
 350module_init(imx2_wdt_init);
 351
 352static void __exit imx2_wdt_exit(void)
 353{
 354        platform_driver_unregister(&imx2_wdt_driver);
 355}
 356module_exit(imx2_wdt_exit);
 357
 358MODULE_AUTHOR("Wolfram Sang");
 359MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
 360MODULE_LICENSE("GPL v2");
 361MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 362MODULE_ALIAS("platform:" DRIVER_NAME);
 363
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