linux/drivers/watchdog/adx_wdt.c
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   1/*
   2 * Copyright (C) 2008-2009 Avionic Design GmbH
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 */
   8
   9#include <linux/fs.h>
  10#include <linux/gfp.h>
  11#include <linux/io.h>
  12#include <linux/miscdevice.h>
  13#include <linux/module.h>
  14#include <linux/platform_device.h>
  15#include <linux/types.h>
  16#include <linux/uaccess.h>
  17#include <linux/watchdog.h>
  18
  19#define WATCHDOG_NAME "adx-wdt"
  20
  21/* register offsets */
  22#define ADX_WDT_CONTROL         0x00
  23#define ADX_WDT_CONTROL_ENABLE  (1 << 0)
  24#define ADX_WDT_CONTROL_nRESET  (1 << 1)
  25#define ADX_WDT_TIMEOUT         0x08
  26
  27static struct platform_device *adx_wdt_dev;
  28static unsigned long driver_open;
  29
  30#define WDT_STATE_STOP  0
  31#define WDT_STATE_START 1
  32
  33struct adx_wdt {
  34        void __iomem *base;
  35        unsigned long timeout;
  36        unsigned int state;
  37        unsigned int wake;
  38        spinlock_t lock;
  39};
  40
  41static const struct watchdog_info adx_wdt_info = {
  42        .identity = "Avionic Design Xanthos Watchdog",
  43        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  44};
  45
  46static void adx_wdt_start_locked(struct adx_wdt *wdt)
  47{
  48        u32 ctrl;
  49
  50        ctrl = readl(wdt->base + ADX_WDT_CONTROL);
  51        ctrl |= ADX_WDT_CONTROL_ENABLE;
  52        writel(ctrl, wdt->base + ADX_WDT_CONTROL);
  53        wdt->state = WDT_STATE_START;
  54}
  55
  56static void adx_wdt_start(struct adx_wdt *wdt)
  57{
  58        unsigned long flags;
  59
  60        spin_lock_irqsave(&wdt->lock, flags);
  61        adx_wdt_start_locked(wdt);
  62        spin_unlock_irqrestore(&wdt->lock, flags);
  63}
  64
  65static void adx_wdt_stop_locked(struct adx_wdt *wdt)
  66{
  67        u32 ctrl;
  68
  69        ctrl = readl(wdt->base + ADX_WDT_CONTROL);
  70        ctrl &= ~ADX_WDT_CONTROL_ENABLE;
  71        writel(ctrl, wdt->base + ADX_WDT_CONTROL);
  72        wdt->state = WDT_STATE_STOP;
  73}
  74
  75static void adx_wdt_stop(struct adx_wdt *wdt)
  76{
  77        unsigned long flags;
  78
  79        spin_lock_irqsave(&wdt->lock, flags);
  80        adx_wdt_stop_locked(wdt);
  81        spin_unlock_irqrestore(&wdt->lock, flags);
  82}
  83
  84static void adx_wdt_set_timeout(struct adx_wdt *wdt, unsigned long seconds)
  85{
  86        unsigned long timeout = seconds * 1000;
  87        unsigned long flags;
  88        unsigned int state;
  89
  90        spin_lock_irqsave(&wdt->lock, flags);
  91        state = wdt->state;
  92        adx_wdt_stop_locked(wdt);
  93        writel(timeout, wdt->base + ADX_WDT_TIMEOUT);
  94
  95        if (state == WDT_STATE_START)
  96                adx_wdt_start_locked(wdt);
  97
  98        wdt->timeout = timeout;
  99        spin_unlock_irqrestore(&wdt->lock, flags);
 100}
 101
 102static void adx_wdt_get_timeout(struct adx_wdt *wdt, unsigned long *seconds)
 103{
 104        *seconds = wdt->timeout / 1000;
 105}
 106
 107static void adx_wdt_keepalive(struct adx_wdt *wdt)
 108{
 109        unsigned long flags;
 110
 111        spin_lock_irqsave(&wdt->lock, flags);
 112        writel(wdt->timeout, wdt->base + ADX_WDT_TIMEOUT);
 113        spin_unlock_irqrestore(&wdt->lock, flags);
 114}
 115
 116static int adx_wdt_open(struct inode *inode, struct file *file)
 117{
 118        struct adx_wdt *wdt = platform_get_drvdata(adx_wdt_dev);
 119
 120        if (test_and_set_bit(0, &driver_open))
 121                return -EBUSY;
 122
 123        file->private_data = wdt;
 124        adx_wdt_set_timeout(wdt, 30);
 125        adx_wdt_start(wdt);
 126
 127        return nonseekable_open(inode, file);
 128}
 129
 130static int adx_wdt_release(struct inode *inode, struct file *file)
 131{
 132        struct adx_wdt *wdt = file->private_data;
 133
 134        adx_wdt_stop(wdt);
 135        clear_bit(0, &driver_open);
 136
 137        return 0;
 138}
 139
 140static long adx_wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 141{
 142        struct adx_wdt *wdt = file->private_data;
 143        void __user *argp = (void __user *)arg;
 144        unsigned long __user *p = argp;
 145        unsigned long seconds = 0;
 146        unsigned int options;
 147        long ret = -EINVAL;
 148
 149        switch (cmd) {
 150        case WDIOC_GETSUPPORT:
 151                if (copy_to_user(argp, &adx_wdt_info, sizeof(adx_wdt_info)))
 152                        return -EFAULT;
 153                else
 154                        return 0;
 155
 156        case WDIOC_GETSTATUS:
 157        case WDIOC_GETBOOTSTATUS:
 158                return put_user(0, p);
 159
 160        case WDIOC_KEEPALIVE:
 161                adx_wdt_keepalive(wdt);
 162                return 0;
 163
 164        case WDIOC_SETTIMEOUT:
 165                if (get_user(seconds, p))
 166                        return -EFAULT;
 167
 168                adx_wdt_set_timeout(wdt, seconds);
 169
 170                /* fallthrough */
 171        case WDIOC_GETTIMEOUT:
 172                adx_wdt_get_timeout(wdt, &seconds);
 173                return put_user(seconds, p);
 174
 175        case WDIOC_SETOPTIONS:
 176                if (copy_from_user(&options, argp, sizeof(options)))
 177                        return -EFAULT;
 178
 179                if (options & WDIOS_DISABLECARD) {
 180                        adx_wdt_stop(wdt);
 181                        ret = 0;
 182                }
 183
 184                if (options & WDIOS_ENABLECARD) {
 185                        adx_wdt_start(wdt);
 186                        ret = 0;
 187                }
 188
 189                return ret;
 190
 191        default:
 192                break;
 193        }
 194
 195        return -ENOTTY;
 196}
 197
 198static ssize_t adx_wdt_write(struct file *file, const char __user *data,
 199                size_t len, loff_t *ppos)
 200{
 201        struct adx_wdt *wdt = file->private_data;
 202
 203        if (len)
 204                adx_wdt_keepalive(wdt);
 205
 206        return len;
 207}
 208
 209static const struct file_operations adx_wdt_fops = {
 210        .owner = THIS_MODULE,
 211        .llseek = no_llseek,
 212        .open = adx_wdt_open,
 213        .release = adx_wdt_release,
 214        .unlocked_ioctl = adx_wdt_ioctl,
 215        .write = adx_wdt_write,
 216};
 217
 218static struct miscdevice adx_wdt_miscdev = {
 219        .minor = WATCHDOG_MINOR,
 220        .name = "watchdog",
 221        .fops = &adx_wdt_fops,
 222};
 223
 224static int __devinit adx_wdt_probe(struct platform_device *pdev)
 225{
 226        struct resource *res;
 227        struct adx_wdt *wdt;
 228        int ret = 0;
 229        u32 ctrl;
 230
 231        wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
 232        if (!wdt) {
 233                dev_err(&pdev->dev, "cannot allocate WDT structure\n");
 234                return -ENOMEM;
 235        }
 236
 237        spin_lock_init(&wdt->lock);
 238
 239        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 240        if (!res) {
 241                dev_err(&pdev->dev, "cannot obtain I/O memory region\n");
 242                return -ENXIO;
 243        }
 244
 245        res = devm_request_mem_region(&pdev->dev, res->start,
 246                        resource_size(res), res->name);
 247        if (!res) {
 248                dev_err(&pdev->dev, "cannot request I/O memory region\n");
 249                return -ENXIO;
 250        }
 251
 252        wdt->base = devm_ioremap_nocache(&pdev->dev, res->start,
 253                        resource_size(res));
 254        if (!wdt->base) {
 255                dev_err(&pdev->dev, "cannot remap I/O memory region\n");
 256                return -ENXIO;
 257        }
 258
 259        /* disable watchdog and reboot on timeout */
 260        ctrl = readl(wdt->base + ADX_WDT_CONTROL);
 261        ctrl &= ~ADX_WDT_CONTROL_ENABLE;
 262        ctrl &= ~ADX_WDT_CONTROL_nRESET;
 263        writel(ctrl, wdt->base + ADX_WDT_CONTROL);
 264
 265        platform_set_drvdata(pdev, wdt);
 266        adx_wdt_dev = pdev;
 267
 268        ret = misc_register(&adx_wdt_miscdev);
 269        if (ret) {
 270                dev_err(&pdev->dev, "cannot register miscdev on minor %d "
 271                                "(err=%d)\n", WATCHDOG_MINOR, ret);
 272                return ret;
 273        }
 274
 275        return 0;
 276}
 277
 278static int __devexit adx_wdt_remove(struct platform_device *pdev)
 279{
 280        struct adx_wdt *wdt = platform_get_drvdata(pdev);
 281
 282        misc_deregister(&adx_wdt_miscdev);
 283        adx_wdt_stop(wdt);
 284        platform_set_drvdata(pdev, NULL);
 285
 286        return 0;
 287}
 288
 289static void adx_wdt_shutdown(struct platform_device *pdev)
 290{
 291        struct adx_wdt *wdt = platform_get_drvdata(pdev);
 292        adx_wdt_stop(wdt);
 293}
 294
 295#ifdef CONFIG_PM
 296static int adx_wdt_suspend(struct device *dev)
 297{
 298        struct platform_device *pdev = to_platform_device(dev);
 299        struct adx_wdt *wdt = platform_get_drvdata(pdev);
 300
 301        wdt->wake = (wdt->state == WDT_STATE_START) ? 1 : 0;
 302        adx_wdt_stop(wdt);
 303
 304        return 0;
 305}
 306
 307static int adx_wdt_resume(struct device *dev)
 308{
 309        struct platform_device *pdev = to_platform_device(dev);
 310        struct adx_wdt *wdt = platform_get_drvdata(pdev);
 311
 312        if (wdt->wake)
 313                adx_wdt_start(wdt);
 314
 315        return 0;
 316}
 317
 318static const struct dev_pm_ops adx_wdt_pm_ops = {
 319        .suspend = adx_wdt_suspend,
 320        .resume = adx_wdt_resume,
 321};
 322
 323#  define ADX_WDT_PM_OPS        (&adx_wdt_pm_ops)
 324#else
 325#  define ADX_WDT_PM_OPS        NULL
 326#endif
 327
 328static struct platform_driver adx_wdt_driver = {
 329        .probe = adx_wdt_probe,
 330        .remove = __devexit_p(adx_wdt_remove),
 331        .shutdown = adx_wdt_shutdown,
 332        .driver = {
 333                .name = WATCHDOG_NAME,
 334                .owner = THIS_MODULE,
 335                .pm = ADX_WDT_PM_OPS,
 336        },
 337};
 338
 339static int __init adx_wdt_init(void)
 340{
 341        return platform_driver_register(&adx_wdt_driver);
 342}
 343
 344static void __exit adx_wdt_exit(void)
 345{
 346        platform_driver_unregister(&adx_wdt_driver);
 347}
 348
 349module_init(adx_wdt_init);
 350module_exit(adx_wdt_exit);
 351
 352MODULE_DESCRIPTION("Avionic Design Xanthos Watchdog Driver");
 353MODULE_LICENSE("GPL v2");
 354MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
 355MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 356