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
  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
  60static 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
  68static struct miscdevice imx2_wdt_miscdev;
  69
  70static bool nowayout = WATCHDOG_NOWAYOUT;
  71module_param(nowayout, bool, 0);
  72MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  73                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  74
  75
  76static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
  77module_param(timeout, uint, 0);
  78MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  79                                __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
  80
  81static const struct watchdog_info imx2_wdt_info = {
  82        .identity = "imx2+ watchdog",
  83        .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
  84};
  85
  86static 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
 106static 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
 112static 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
 119static 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
 133static 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
 140static 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
 150static 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
 159static 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
 174static 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
 217static 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
 239static 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
 248static struct miscdevice imx2_wdt_miscdev = {
 249        .minor = WATCHDOG_MINOR,
 250        .name = "watchdog",
 251        .fops = &imx2_wdt_fops,
 252};
 253
 254static 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        if (!res) {
 261                dev_err(&pdev->dev, "can't get device resources\n");
 262                return -ENODEV;
 263        }
 264
 265        imx2_wdt.base = devm_request_and_ioremap(&pdev->dev, res);
 266        if (!imx2_wdt.base) {
 267                dev_err(&pdev->dev, "ioremap failed\n");
 268                return -ENOMEM;
 269        }
 270
 271        imx2_wdt.clk = clk_get(&pdev->dev, NULL);
 272        if (IS_ERR(imx2_wdt.clk)) {
 273                dev_err(&pdev->dev, "can't get Watchdog clock\n");
 274                return PTR_ERR(imx2_wdt.clk);
 275        }
 276
 277        imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
 278        if (imx2_wdt.timeout != timeout)
 279                dev_warn(&pdev->dev, "Initial timeout out of range! "
 280                        "Clamped from %u to %u\n", timeout, imx2_wdt.timeout);
 281
 282        setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
 283
 284        imx2_wdt_miscdev.parent = &pdev->dev;
 285        ret = misc_register(&imx2_wdt_miscdev);
 286        if (ret)
 287                goto fail;
 288
 289        dev_info(&pdev->dev,
 290                "IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
 291                                                imx2_wdt.timeout, nowayout);
 292        return 0;
 293
 294fail:
 295        imx2_wdt_miscdev.parent = NULL;
 296        clk_put(imx2_wdt.clk);
 297        return ret;
 298}
 299
 300static int __exit imx2_wdt_remove(struct platform_device *pdev)
 301{
 302        misc_deregister(&imx2_wdt_miscdev);
 303
 304        if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
 305                del_timer_sync(&imx2_wdt.timer);
 306
 307                dev_crit(imx2_wdt_miscdev.parent,
 308                        "Device removed: Expect reboot!\n");
 309        } else
 310                clk_put(imx2_wdt.clk);
 311
 312        imx2_wdt_miscdev.parent = NULL;
 313        return 0;
 314}
 315
 316static void imx2_wdt_shutdown(struct platform_device *pdev)
 317{
 318        if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
 319                /* we are running, we need to delete the timer but will give
 320                 * max timeout before reboot will take place */
 321                del_timer_sync(&imx2_wdt.timer);
 322                imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
 323                imx2_wdt_ping();
 324
 325                dev_crit(imx2_wdt_miscdev.parent,
 326                        "Device shutdown: Expect reboot!\n");
 327        }
 328}
 329
 330static const struct of_device_id imx2_wdt_dt_ids[] = {
 331        { .compatible = "fsl,imx21-wdt", },
 332        { /* sentinel */ }
 333};
 334
 335static struct platform_driver imx2_wdt_driver = {
 336        .remove         = __exit_p(imx2_wdt_remove),
 337        .shutdown       = imx2_wdt_shutdown,
 338        .driver         = {
 339                .name   = DRIVER_NAME,
 340                .owner  = THIS_MODULE,
 341                .of_match_table = imx2_wdt_dt_ids,
 342        },
 343};
 344
 345static int __init imx2_wdt_init(void)
 346{
 347        return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
 348}
 349module_init(imx2_wdt_init);
 350
 351static void __exit imx2_wdt_exit(void)
 352{
 353        platform_driver_unregister(&imx2_wdt_driver);
 354}
 355module_exit(imx2_wdt_exit);
 356
 357MODULE_AUTHOR("Wolfram Sang");
 358MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
 359MODULE_LICENSE("GPL v2");
 360MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 361MODULE_ALIAS("platform:" DRIVER_NAME);
 362
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