drivers/watchdog/adx_wdt.c

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