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 clk       *wdt_clock;
  65        struct platform_device *pdev;
  66        void __iomem     *wdt_base;
  67        char             expect_close;
  68        struct timer_list timer;
  69        spinlock_t       wdt_lock;
  70        unsigned long next_heartbeat;
  71};
  72
  73static unsigned long nuc900wdt_busy;
  74static struct nuc900_wdt *nuc900_wdt;
  75
  76static inline void nuc900_wdt_keepalive(void)
  77{
  78        unsigned int val;
  79
  80        spin_lock(&nuc900_wdt->wdt_lock);
  81
  82        val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
  83        val |= (WTR | WTIF);
  84        __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
  85
  86        spin_unlock(&nuc900_wdt->wdt_lock);
  87}
  88
  89static inline void nuc900_wdt_start(void)
  90{
  91        unsigned int val;
  92
  93        spin_lock(&nuc900_wdt->wdt_lock);
  94
  95        val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
  96        val |= (WTRE | WTE | WTR | WTCLK | WTIF);
  97        val &= ~WTIS;
  98        val |= (WDT_HW_TIMEOUT << 0x04);
  99        __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
 100
 101        spin_unlock(&nuc900_wdt->wdt_lock);
 102
 103        nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
 104        mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
 105}
 106
 107static inline void nuc900_wdt_stop(void)
 108{
 109        unsigned int val;
 110
 111        del_timer(&nuc900_wdt->timer);
 112
 113        spin_lock(&nuc900_wdt->wdt_lock);
 114
 115        val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
 116        val &= ~WTE;
 117        __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
 118
 119        spin_unlock(&nuc900_wdt->wdt_lock);
 120}
 121
 122static inline void nuc900_wdt_ping(void)
 123{
 124        nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
 125}
 126
 127static int nuc900_wdt_open(struct inode *inode, struct file *file)
 128{
 129
 130        if (test_and_set_bit(0, &nuc900wdt_busy))
 131                return -EBUSY;
 132
 133        nuc900_wdt_start();
 134
 135        return nonseekable_open(inode, file);
 136}
 137
 138static int nuc900_wdt_close(struct inode *inode, struct file *file)
 139{
 140        if (nuc900_wdt->expect_close == 42)
 141                nuc900_wdt_stop();
 142        else {
 143                dev_crit(&nuc900_wdt->pdev->dev,
 144                        "Unexpected close, not stopping watchdog!\n");
 145                nuc900_wdt_ping();
 146        }
 147
 148        nuc900_wdt->expect_close = 0;
 149        clear_bit(0, &nuc900wdt_busy);
 150        return 0;
 151}
 152
 153static const struct watchdog_info nuc900_wdt_info = {
 154        .identity       = "nuc900 watchdog",
 155        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 156                                                WDIOF_MAGICCLOSE,
 157};
 158
 159static long nuc900_wdt_ioctl(struct file *file,
 160                                        unsigned int cmd, unsigned long arg)
 161{
 162        void __user *argp = (void __user *)arg;
 163        int __user *p = argp;
 164        int new_value;
 165
 166        switch (cmd) {
 167        case WDIOC_GETSUPPORT:
 168                return copy_to_user(argp, &nuc900_wdt_info,
 169                                sizeof(nuc900_wdt_info)) ? -EFAULT : 0;
 170        case WDIOC_GETSTATUS:
 171        case WDIOC_GETBOOTSTATUS:
 172                return put_user(0, p);
 173
 174        case WDIOC_KEEPALIVE:
 175                nuc900_wdt_ping();
 176                return 0;
 177
 178        case WDIOC_SETTIMEOUT:
 179                if (get_user(new_value, p))
 180                        return -EFAULT;
 181
 182                heartbeat = new_value;
 183                nuc900_wdt_ping();
 184
 185                return put_user(new_value, p);
 186        case WDIOC_GETTIMEOUT:
 187                return put_user(heartbeat, p);
 188        default:
 189                return -ENOTTY;
 190        }
 191}
 192
 193static ssize_t nuc900_wdt_write(struct file *file, const char __user *data,
 194                                                size_t len, loff_t *ppos)
 195{
 196        if (!len)
 197                return 0;
 198
 199        /* Scan for magic character */
 200        if (!nowayout) {
 201                size_t i;
 202
 203                nuc900_wdt->expect_close = 0;
 204
 205                for (i = 0; i < len; i++) {
 206                        char c;
 207                        if (get_user(c, data + i))
 208                                return -EFAULT;
 209                        if (c == 'V') {
 210                                nuc900_wdt->expect_close = 42;
 211                                break;
 212                        }
 213                }
 214        }
 215
 216        nuc900_wdt_ping();
 217        return len;
 218}
 219
 220static void nuc900_wdt_timer_ping(unsigned long data)
 221{
 222        if (time_before(jiffies, nuc900_wdt->next_heartbeat)) {
 223                nuc900_wdt_keepalive();
 224                mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
 225        } else
 226                dev_warn(&nuc900_wdt->pdev->dev, "Will reset the machine !\n");
 227}
 228
 229static const struct file_operations nuc900wdt_fops = {
 230        .owner          = THIS_MODULE,
 231        .llseek         = no_llseek,
 232        .unlocked_ioctl = nuc900_wdt_ioctl,
 233        .open           = nuc900_wdt_open,
 234        .release        = nuc900_wdt_close,
 235        .write          = nuc900_wdt_write,
 236};
 237
 238static struct miscdevice nuc900wdt_miscdev = {
 239        .minor          = WATCHDOG_MINOR,
 240        .name           = "watchdog",
 241        .fops           = &nuc900wdt_fops,
 242};
 243
 244static int nuc900wdt_probe(struct platform_device *pdev)
 245{
 246        struct resource *res;
 247        int ret = 0;
 248
 249        nuc900_wdt = devm_kzalloc(&pdev->dev, sizeof(*nuc900_wdt),
 250                                GFP_KERNEL);
 251        if (!nuc900_wdt)
 252                return -ENOMEM;
 253
 254        nuc900_wdt->pdev = pdev;
 255
 256        spin_lock_init(&nuc900_wdt->wdt_lock);
 257
 258        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 259        if (res == NULL) {
 260                dev_err(&pdev->dev, "no memory resource specified\n");
 261                return -ENOENT;
 262        }
 263
 264        nuc900_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
 265        if (IS_ERR(nuc900_wdt->wdt_base))
 266                return PTR_ERR(nuc900_wdt->wdt_base);
 267
 268        nuc900_wdt->wdt_clock = devm_clk_get(&pdev->dev, NULL);
 269        if (IS_ERR(nuc900_wdt->wdt_clock)) {
 270                dev_err(&pdev->dev, "failed to find watchdog clock source\n");
 271                return PTR_ERR(nuc900_wdt->wdt_clock);
 272        }
 273
 274        clk_enable(nuc900_wdt->wdt_clock);
 275
 276        setup_timer(&nuc900_wdt->timer, nuc900_wdt_timer_ping, 0);
 277
 278        ret = misc_register(&nuc900wdt_miscdev);
 279        if (ret) {
 280                dev_err(&pdev->dev, "err register miscdev on minor=%d (%d)\n",
 281                        WATCHDOG_MINOR, ret);
 282                goto err_clk;
 283        }
 284
 285        return 0;
 286
 287err_clk:
 288        clk_disable(nuc900_wdt->wdt_clock);
 289        return ret;
 290}
 291
 292static int nuc900wdt_remove(struct platform_device *pdev)
 293{
 294        misc_deregister(&nuc900wdt_miscdev);
 295
 296        clk_disable(nuc900_wdt->wdt_clock);
 297
 298        return 0;
 299}
 300
 301static struct platform_driver nuc900wdt_driver = {
 302        .probe          = nuc900wdt_probe,
 303        .remove         = nuc900wdt_remove,
 304        .driver         = {
 305                .name   = "nuc900-wdt",
 306                .owner  = THIS_MODULE,
 307        },
 308};
 309
 310module_platform_driver(nuc900wdt_driver);
 311
 312MODULE_AUTHOR("Wan ZongShun <mcuos.com@gmail.com>");
 313MODULE_DESCRIPTION("Watchdog driver for NUC900");
 314MODULE_LICENSE("GPL");
 315MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 316MODULE_ALIAS("platform:nuc900-wdt");
 317
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