linux/drivers/watchdog/geodewdt.c
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   1/* Watchdog timer for the Geode GX/LX with the CS5535/CS5536 companion chip
   2 *
   3 * Copyright (C) 2006-2007, Advanced Micro Devices, Inc.
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License
   7 * as published by the Free Software Foundation; either version
   8 * 2 of the License, or (at your option) any later version.
   9 */
  10
  11
  12#include <linux/module.h>
  13#include <linux/moduleparam.h>
  14#include <linux/types.h>
  15#include <linux/miscdevice.h>
  16#include <linux/watchdog.h>
  17#include <linux/fs.h>
  18#include <linux/platform_device.h>
  19#include <linux/reboot.h>
  20#include <linux/uaccess.h>
  21
  22#include <asm/geode.h>
  23
  24#define GEODEWDT_HZ 500
  25#define GEODEWDT_SCALE 6
  26#define GEODEWDT_MAX_SECONDS 131
  27
  28#define WDT_FLAGS_OPEN 1
  29#define WDT_FLAGS_ORPHAN 2
  30
  31#define DRV_NAME "geodewdt"
  32#define WATCHDOG_NAME "Geode GX/LX WDT"
  33#define WATCHDOG_TIMEOUT 60
  34
  35static int timeout = WATCHDOG_TIMEOUT;
  36module_param(timeout, int, 0);
  37MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. 1<= timeout <=131, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ".");
  38
  39static int nowayout = WATCHDOG_NOWAYOUT;
  40module_param(nowayout, int, 0);
  41MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  42
  43static struct platform_device *geodewdt_platform_device;
  44static unsigned long wdt_flags;
  45static int wdt_timer;
  46static int safe_close;
  47
  48static void geodewdt_ping(void)
  49{
  50        /* Stop the counter */
  51        geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
  52
  53        /* Reset the counter */
  54        geode_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
  55
  56        /* Enable the counter */
  57        geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
  58}
  59
  60static void geodewdt_disable(void)
  61{
  62        geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
  63        geode_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
  64}
  65
  66static int geodewdt_set_heartbeat(int val)
  67{
  68        if (val < 1 || val > GEODEWDT_MAX_SECONDS)
  69                return -EINVAL;
  70
  71        geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
  72        geode_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, val * GEODEWDT_HZ);
  73        geode_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
  74        geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
  75
  76        timeout = val;
  77        return 0;
  78}
  79
  80static int geodewdt_open(struct inode *inode, struct file *file)
  81{
  82        if (test_and_set_bit(WDT_FLAGS_OPEN, &wdt_flags))
  83                return -EBUSY;
  84
  85        if (!test_and_clear_bit(WDT_FLAGS_ORPHAN, &wdt_flags))
  86                __module_get(THIS_MODULE);
  87
  88        geodewdt_ping();
  89        return nonseekable_open(inode, file);
  90}
  91
  92static int geodewdt_release(struct inode *inode, struct file *file)
  93{
  94        if (safe_close) {
  95                geodewdt_disable();
  96                module_put(THIS_MODULE);
  97        } else {
  98                printk(KERN_CRIT "Unexpected close - watchdog is not stopping.\n");
  99                geodewdt_ping();
 100
 101                set_bit(WDT_FLAGS_ORPHAN, &wdt_flags);
 102        }
 103
 104        clear_bit(WDT_FLAGS_OPEN, &wdt_flags);
 105        safe_close = 0;
 106        return 0;
 107}
 108
 109static ssize_t geodewdt_write(struct file *file, const char __user *data,
 110                                size_t len, loff_t *ppos)
 111{
 112        if (len) {
 113                if (!nowayout) {
 114                        size_t i;
 115                        safe_close = 0;
 116
 117                        for (i = 0; i != len; i++) {
 118                                char c;
 119
 120                                if (get_user(c, data + i))
 121                                        return -EFAULT;
 122
 123                                if (c == 'V')
 124                                        safe_close = 1;
 125                        }
 126                }
 127
 128                geodewdt_ping();
 129        }
 130        return len;
 131}
 132
 133static long geodewdt_ioctl(struct file *file, unsigned int cmd,
 134                                unsigned long arg)
 135{
 136        void __user *argp = (void __user *)arg;
 137        int __user *p = argp;
 138        int interval;
 139
 140        static struct watchdog_info ident = {
 141                .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING
 142                | WDIOF_MAGICCLOSE,
 143                .firmware_version =     1,
 144                .identity =             WATCHDOG_NAME,
 145        };
 146
 147        switch (cmd) {
 148        case WDIOC_GETSUPPORT:
 149                return copy_to_user(argp, &ident,
 150                                    sizeof(ident)) ? -EFAULT : 0;
 151                break;
 152
 153        case WDIOC_GETSTATUS:
 154        case WDIOC_GETBOOTSTATUS:
 155                return put_user(0, p);
 156
 157        case WDIOC_SETOPTIONS:
 158        {
 159                int options, ret = -EINVAL;
 160
 161                if (get_user(options, p))
 162                        return -EFAULT;
 163
 164                if (options & WDIOS_DISABLECARD) {
 165                        geodewdt_disable();
 166                        ret = 0;
 167                }
 168
 169                if (options & WDIOS_ENABLECARD) {
 170                        geodewdt_ping();
 171                        ret = 0;
 172                }
 173
 174                return ret;
 175        }
 176        case WDIOC_KEEPALIVE:
 177                geodewdt_ping();
 178                return 0;
 179
 180        case WDIOC_SETTIMEOUT:
 181                if (get_user(interval, p))
 182                        return -EFAULT;
 183
 184                if (geodewdt_set_heartbeat(interval))
 185                        return -EINVAL;
 186        /* Fall through */
 187        case WDIOC_GETTIMEOUT:
 188                return put_user(timeout, p);
 189
 190        default:
 191                return -ENOTTY;
 192        }
 193
 194        return 0;
 195}
 196
 197static const struct file_operations geodewdt_fops = {
 198        .owner          = THIS_MODULE,
 199        .llseek         = no_llseek,
 200        .write          = geodewdt_write,
 201        .unlocked_ioctl = geodewdt_ioctl,
 202        .open           = geodewdt_open,
 203        .release        = geodewdt_release,
 204};
 205
 206static struct miscdevice geodewdt_miscdev = {
 207        .minor = WATCHDOG_MINOR,
 208        .name = "watchdog",
 209        .fops = &geodewdt_fops,
 210};
 211
 212static int __devinit geodewdt_probe(struct platform_device *dev)
 213{
 214        int ret, timer;
 215
 216        timer = geode_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING);
 217
 218        if (timer == -1) {
 219                printk(KERN_ERR "geodewdt:  No timers were available\n");
 220                return -ENODEV;
 221        }
 222
 223        wdt_timer = timer;
 224
 225        /* Set up the timer */
 226
 227        geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP,
 228                          GEODEWDT_SCALE | (3 << 8));
 229
 230        /* Set up comparator 2 to reset when the event fires */
 231        geode_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1);
 232
 233        /* Set up the initial timeout */
 234
 235        geode_mfgpt_write(wdt_timer, MFGPT_REG_CMP2,
 236                timeout * GEODEWDT_HZ);
 237
 238        ret = misc_register(&geodewdt_miscdev);
 239
 240        return ret;
 241}
 242
 243static int __devexit geodewdt_remove(struct platform_device *dev)
 244{
 245        misc_deregister(&geodewdt_miscdev);
 246        return 0;
 247}
 248
 249static void geodewdt_shutdown(struct platform_device *dev)
 250{
 251        geodewdt_disable();
 252}
 253
 254static struct platform_driver geodewdt_driver = {
 255        .probe          = geodewdt_probe,
 256        .remove         = __devexit_p(geodewdt_remove),
 257        .shutdown       = geodewdt_shutdown,
 258        .driver         = {
 259                .owner  = THIS_MODULE,
 260                .name   = DRV_NAME,
 261        },
 262};
 263
 264static int __init geodewdt_init(void)
 265{
 266        int ret;
 267
 268        ret = platform_driver_register(&geodewdt_driver);
 269        if (ret)
 270                return ret;
 271
 272        geodewdt_platform_device = platform_device_register_simple(DRV_NAME, -1, NULL, 0);
 273        if (IS_ERR(geodewdt_platform_device)) {
 274                ret = PTR_ERR(geodewdt_platform_device);
 275                goto err;
 276        }
 277
 278        return 0;
 279err:
 280        platform_driver_unregister(&geodewdt_driver);
 281        return ret;
 282}
 283
 284static void __exit geodewdt_exit(void)
 285{
 286        platform_device_unregister(geodewdt_platform_device);
 287        platform_driver_unregister(&geodewdt_driver);
 288}
 289
 290module_init(geodewdt_init);
 291module_exit(geodewdt_exit);
 292
 293MODULE_AUTHOR("Advanced Micro Devices, Inc");
 294MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver");
 295MODULE_LICENSE("GPL");
 296MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 297