linux/drivers/watchdog/nuc900_wdt.c
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   1/*
   2 * Copyright (c) 2009 Nuvoton technology corporation.
   3 *
   4 * Wan ZongShun <mcuos.com@gmail.com>
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation;version 2 of the License.
   9 *
  10 */
  11
  12#include <linux/bitops.h>
  13#include <linux/errno.h>
  14#include <linux/fs.h>
  15#include <linux/init.h>
  16#include <linux/io.h>
  17#include <linux/clk.h>
  18#include <linux/kernel.h>
  19#include <linux/miscdevice.h>
  20#include <linux/module.h>
  21#include <linux/moduleparam.h>
  22#include <linux/platform_device.h>
  23#include <linux/slab.h>
  24#include <linux/interrupt.h>
  25#include <linux/types.h>
  26#include <linux/watchdog.h>
  27#include <linux/uaccess.h>
  28
  29#define REG_WTCR                0x1c
  30#define WTCLK                   (0x01 << 10)
  31#define WTE                     (0x01 << 7)     /*wdt enable*/
  32#define WTIS                    (0x03 << 4)
  33#define WTIF                    (0x01 << 3)
  34#define WTRF                    (0x01 << 2)
  35#define WTRE                    (0x01 << 1)
  36#define WTR                     (0x01 << 0)
  37/*
  38 * The watchdog time interval can be calculated via following formula:
  39 * WTIS         real time interval (formula)
  40 * 0x00         ((2^ 14 ) * ((external crystal freq) / 256))seconds
  41 * 0x01         ((2^ 16 ) * ((external crystal freq) / 256))seconds
  42 * 0x02         ((2^ 18 ) * ((external crystal freq) / 256))seconds
  43 * 0x03         ((2^ 20 ) * ((external crystal freq) / 256))seconds
  44 *
  45 * The external crystal freq is 15Mhz in the nuc900 evaluation board.
  46 * So 0x00 = +-0.28 seconds, 0x01 = +-1.12 seconds, 0x02 = +-4.48 seconds,
  47 * 0x03 = +- 16.92 seconds..
  48 */
  49#define WDT_HW_TIMEOUT          0x02
  50#define WDT_TIMEOUT             (HZ/2)
  51#define WDT_HEARTBEAT           15
  52
  53static int heartbeat = WDT_HEARTBEAT;
  54module_param(heartbeat, int, 0);
  55MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
  56        "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
  57
  58static bool nowayout = WATCHDOG_NOWAYOUT;
  59module_param(nowayout, bool, 0);
  60MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  61        "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  62
  63struct nuc900_wdt {
  64        struct resource  *res;
  65        struct clk       *wdt_clock;
  66        struct platform_device *pdev;
  67        void __iomem     *wdt_base;
  68        char             expect_close;
  69        struct timer_list timer;
  70        spinlock_t       wdt_lock;
  71        unsigned long next_heartbeat;
  72};
  73
  74static unsigned long nuc900wdt_busy;
  75static struct nuc900_wdt *nuc900_wdt;
  76
  77static inline void nuc900_wdt_keepalive(void)
  78{
  79        unsigned int val;
  80
  81        spin_lock(&nuc900_wdt->wdt_lock);
  82
  83        val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
  84        val |= (WTR | WTIF);
  85        __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
  86
  87        spin_unlock(&nuc900_wdt->wdt_lock);
  88}
  89
  90static inline void nuc900_wdt_start(void)
  91{
  92        unsigned int val;
  93
  94        spin_lock(&nuc900_wdt->wdt_lock);
  95
  96        val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
  97        val |= (WTRE | WTE | WTR | WTCLK | WTIF);
  98        val &= ~WTIS;
  99        val |= (WDT_HW_TIMEOUT << 0x04);
 100        __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
 101
 102        spin_unlock(&nuc900_wdt->wdt_lock);
 103
 104        nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
 105        mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
 106}
 107
 108static inline void nuc900_wdt_stop(void)
 109{
 110        unsigned int val;
 111
 112        del_timer(&nuc900_wdt->timer);
 113
 114        spin_lock(&nuc900_wdt->wdt_lock);
 115
 116        val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
 117        val &= ~WTE;
 118        __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
 119
 120        spin_unlock(&nuc900_wdt->wdt_lock);
 121}
 122
 123static inline void nuc900_wdt_ping(void)
 124{
 125        nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
 126}
 127
 128static int nuc900_wdt_open(struct inode *inode, struct file *file)
 129{
 130
 131        if (test_and_set_bit(0, &nuc900wdt_busy))
 132                return -EBUSY;
 133
 134        nuc900_wdt_start();
 135
 136        return nonseekable_open(inode, file);
 137}
 138
 139static int nuc900_wdt_close(struct inode *inode, struct file *file)
 140{
 141        if (nuc900_wdt->expect_close == 42)
 142                nuc900_wdt_stop();
 143        else {
 144                dev_crit(&nuc900_wdt->pdev->dev,
 145                        "Unexpected close, not stopping watchdog!\n");
 146                nuc900_wdt_ping();
 147        }
 148
 149        nuc900_wdt->expect_close = 0;
 150        clear_bit(0, &nuc900wdt_busy);
 151        return 0;
 152}
 153
 154static const struct watchdog_info nuc900_wdt_info = {
 155        .identity       = "nuc900 watchdog",
 156        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 157                                                WDIOF_MAGICCLOSE,
 158};
 159
 160static long nuc900_wdt_ioctl(struct file *file,
 161                                        unsigned int cmd, unsigned long arg)
 162{
 163        void __user *argp = (void __user *)arg;
 164        int __user *p = argp;
 165        int new_value;
 166
 167        switch (cmd) {
 168        case WDIOC_GETSUPPORT:
 169                return copy_to_user(argp, &nuc900_wdt_info,
 170                                sizeof(nuc900_wdt_info)) ? -EFAULT : 0;
 171        case WDIOC_GETSTATUS:
 172        case WDIOC_GETBOOTSTATUS:
 173                return put_user(0, p);
 174
 175        case WDIOC_KEEPALIVE:
 176                nuc900_wdt_ping();
 177                return 0;
 178
 179        case WDIOC_SETTIMEOUT:
 180                if (get_user(new_value, p))
 181                        return -EFAULT;
 182
 183                heartbeat = new_value;
 184                nuc900_wdt_ping();
 185
 186                return put_user(new_value, p);
 187        case WDIOC_GETTIMEOUT:
 188                return put_user(heartbeat, p);
 189        default:
 190                return -ENOTTY;
 191        }
 192}
 193
 194static ssize_t nuc900_wdt_write(struct file *file, const char __user *data,
 195                                                size_t len, loff_t *ppos)
 196{
 197        if (!len)
 198                return 0;
 199
 200        /* Scan for magic character */
 201        if (!nowayout) {
 202                size_t i;
 203
 204                nuc900_wdt->expect_close = 0;
 205
 206                for (i = 0; i < len; i++) {
 207                        char c;
 208                        if (get_user(c, data + i))
 209                                return -EFAULT;
 210                        if (c == 'V') {
 211                                nuc900_wdt->expect_close = 42;
 212                                break;
 213                        }
 214                }
 215        }
 216
 217        nuc900_wdt_ping();
 218        return len;
 219}
 220
 221static void nuc900_wdt_timer_ping(unsigned long data)
 222{
 223        if (time_before(jiffies, nuc900_wdt->next_heartbeat)) {
 224                nuc900_wdt_keepalive();
 225                mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
 226        } else
 227                dev_warn(&nuc900_wdt->pdev->dev, "Will reset the machine !\n");
 228}
 229
 230static const struct file_operations nuc900wdt_fops = {
 231        .owner          = THIS_MODULE,
 232        .llseek         = no_llseek,
 233        .unlocked_ioctl = nuc900_wdt_ioctl,
 234        .open           = nuc900_wdt_open,
 235        .release        = nuc900_wdt_close,
 236        .write          = nuc900_wdt_write,
 237};
 238
 239static struct miscdevice nuc900wdt_miscdev = {
 240        .minor          = WATCHDOG_MINOR,
 241        .name           = "watchdog",
 242        .fops           = &nuc900wdt_fops,
 243};
 244
 245static int __devinit nuc900wdt_probe(struct platform_device *pdev)
 246{
 247        int ret = 0;
 248
 249        nuc900_wdt = kzalloc(sizeof(struct nuc900_wdt), GFP_KERNEL);
 250        if (!nuc900_wdt)
 251                return -ENOMEM;
 252
 253        nuc900_wdt->pdev = pdev;
 254
 255        spin_lock_init(&nuc900_wdt->wdt_lock);
 256
 257        nuc900_wdt->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 258        if (nuc900_wdt->res == NULL) {
 259                dev_err(&pdev->dev, "no memory resource specified\n");
 260                ret = -ENOENT;
 261                goto err_get;
 262        }
 263
 264        if (!request_mem_region(nuc900_wdt->res->start,
 265                                resource_size(nuc900_wdt->res), pdev->name)) {
 266                dev_err(&pdev->dev, "failed to get memory region\n");
 267                ret = -ENOENT;
 268                goto err_get;
 269        }
 270
 271        nuc900_wdt->wdt_base = ioremap(nuc900_wdt->res->start,
 272                                        resource_size(nuc900_wdt->res));
 273        if (nuc900_wdt->wdt_base == NULL) {
 274                dev_err(&pdev->dev, "failed to ioremap() region\n");
 275                ret = -EINVAL;
 276                goto err_req;
 277        }
 278
 279        nuc900_wdt->wdt_clock = clk_get(&pdev->dev, NULL);
 280        if (IS_ERR(nuc900_wdt->wdt_clock)) {
 281                dev_err(&pdev->dev, "failed to find watchdog clock source\n");
 282                ret = PTR_ERR(nuc900_wdt->wdt_clock);
 283                goto err_map;
 284        }
 285
 286        clk_enable(nuc900_wdt->wdt_clock);
 287
 288        setup_timer(&nuc900_wdt->timer, nuc900_wdt_timer_ping, 0);
 289
 290        ret = misc_register(&nuc900wdt_miscdev);
 291        if (ret) {
 292                dev_err(&pdev->dev, "err register miscdev on minor=%d (%d)\n",
 293                        WATCHDOG_MINOR, ret);
 294                goto err_clk;
 295        }
 296
 297        return 0;
 298
 299err_clk:
 300        clk_disable(nuc900_wdt->wdt_clock);
 301        clk_put(nuc900_wdt->wdt_clock);
 302err_map:
 303        iounmap(nuc900_wdt->wdt_base);
 304err_req:
 305        release_mem_region(nuc900_wdt->res->start,
 306                                        resource_size(nuc900_wdt->res));
 307err_get:
 308        kfree(nuc900_wdt);
 309        return ret;
 310}
 311
 312static int __devexit nuc900wdt_remove(struct platform_device *pdev)
 313{
 314        misc_deregister(&nuc900wdt_miscdev);
 315
 316        clk_disable(nuc900_wdt->wdt_clock);
 317        clk_put(nuc900_wdt->wdt_clock);
 318
 319        iounmap(nuc900_wdt->wdt_base);
 320
 321        release_mem_region(nuc900_wdt->res->start,
 322                                        resource_size(nuc900_wdt->res));
 323
 324        kfree(nuc900_wdt);
 325
 326        return 0;
 327}
 328
 329static struct platform_driver nuc900wdt_driver = {
 330        .probe          = nuc900wdt_probe,
 331        .remove         = __devexit_p(nuc900wdt_remove),
 332        .driver         = {
 333                .name   = "nuc900-wdt",
 334                .owner  = THIS_MODULE,
 335        },
 336};
 337
 338module_platform_driver(nuc900wdt_driver);
 339
 340MODULE_AUTHOR("Wan ZongShun <mcuos.com@gmail.com>");
 341MODULE_DESCRIPTION("Watchdog driver for NUC900");
 342MODULE_LICENSE("GPL");
 343MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 344MODULE_ALIAS("platform:nuc900-wdt");
 345
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