drivers/char/watchdog/mpc5200_wdt.c

   1 #include <linux/init.h>
   2 #include <linux/module.h>
   3 #include <linux/miscdevice.h>
   4 #include <linux/watchdog.h>
   5 #include <linux/io.h>
   6 #include <linux/spinlock.h>
   7 #include <asm/of_platform.h>
   8 #include <asm/uaccess.h>
   9 #include <asm/mpc52xx.h>
  10
  11
  12 #define GPT_MODE_WDT            (1<<15)
  13 #define GPT_MODE_CE             (1<<12)
  14 #define GPT_MODE_MS_TIMER       (0x4)
  15
  16
  17 struct mpc5200_wdt {
  18         unsigned count; /* timer ticks before watchdog kicks in */
  19         long ipb_freq;
  20         struct miscdevice miscdev;
  21         struct resource mem;
  22         struct mpc52xx_gpt __iomem *regs;
  23         spinlock_t io_lock;
  24 };
  25
  26 /* is_active stores wether or not the /dev/watchdog device is opened */
  27 static unsigned long is_active;
  28
  29 /* misc devices don't provide a way, to get back to 'dev' or 'miscdev' from
  30  * file operations, which sucks. But there can be max 1 watchdog anyway, so...
  31  */
  32 static struct mpc5200_wdt *wdt_global;
  33
  34
  35 /* helper to calculate timeout in timer counts */
  36 static void mpc5200_wdt_set_timeout(struct mpc5200_wdt *wdt, int timeout)
  37 {
  38         /* use biggest prescaler of 64k */
  39         wdt->count = (wdt->ipb_freq + 0xffff) / 0x10000 * timeout;
  40
  41         if (wdt->count > 0xffff)
  42                 wdt->count = 0xffff;
  43 }
  44 /* return timeout in seconds (calculated from timer count) */
  45 static int mpc5200_wdt_get_timeout(struct mpc5200_wdt *wdt)
  46 {
  47         return wdt->count * 0x10000 / wdt->ipb_freq;
  48 }
  49
  50
  51 /* watchdog operations */
  52 static int mpc5200_wdt_start(struct mpc5200_wdt *wdt)
  53 {
  54         spin_lock(&wdt->io_lock);
  55         /* disable */
  56         out_be32(&wdt->regs->mode, 0);
  57         /* set timeout, with maximum prescaler */
  58         out_be32(&wdt->regs->count, 0x0 | wdt->count);
  59         /* enable watchdog */
  60         out_be32(&wdt->regs->mode, GPT_MODE_CE | GPT_MODE_WDT | GPT_MODE_MS_TIMER);
  61         spin_unlock(&wdt->io_lock);
  62
  63         return 0;
  64 }
  65 static int mpc5200_wdt_ping(struct mpc5200_wdt *wdt)
  66 {
  67         spin_lock(&wdt->io_lock);
  68         /* writing A5 to OCPW resets the watchdog */
  69         out_be32(&wdt->regs->mode, 0xA5000000 | (0xffffff & in_be32(&wdt->regs->mode)));
  70         spin_unlock(&wdt->io_lock);
  71         return 0;
  72 }
  73 static int mpc5200_wdt_stop(struct mpc5200_wdt *wdt)
  74 {
  75         spin_lock(&wdt->io_lock);
  76         /* disable */
  77         out_be32(&wdt->regs->mode, 0);
  78         spin_unlock(&wdt->io_lock);
  79         return 0;
  80 }
  81
  82
  83 /* file operations */
  84 static ssize_t mpc5200_wdt_write(struct file *file, const char *data,
  85                 size_t len, loff_t *ppos)
  86 {
  87         struct mpc5200_wdt *wdt = file->private_data;
  88         mpc5200_wdt_ping(wdt);
  89         return 0;
  90 }
  91 static struct watchdog_info mpc5200_wdt_info = {
  92         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  93         .identity       = "mpc5200 watchdog on GPT0",
  94 };
  95 static int mpc5200_wdt_ioctl(struct inode *inode, struct file *file,
  96                 unsigned int cmd, unsigned long arg)
  97 {
  98         struct mpc5200_wdt *wdt = file->private_data;
  99         int __user *data = (int __user *)arg;
 100         int timeout;
 101         int ret = 0;
 102
 103         switch (cmd) {
 104         case WDIOC_GETSUPPORT:
 105                 ret = copy_to_user(data, &mpc5200_wdt_info,
 106                         sizeof(mpc5200_wdt_info));
 107                 if (ret)
 108                         ret = -EFAULT;
 109                 break;
 110
 111         case WDIOC_GETSTATUS:
 112         case WDIOC_GETBOOTSTATUS:
 113                 ret = put_user(0, data);
 114                 break;
 115
 116         case WDIOC_KEEPALIVE:
 117                 mpc5200_wdt_ping(wdt);
 118                 break;
 119
 120         case WDIOC_SETTIMEOUT:
 121                 ret = get_user(timeout, data);
 122                 if (ret)
 123                         break;
 124                 mpc5200_wdt_set_timeout(wdt, timeout);
 125                 mpc5200_wdt_start(wdt);
 126                 /* fall through and return the timeout */
 127
 128         case WDIOC_GETTIMEOUT:
 129                 timeout = mpc5200_wdt_get_timeout(wdt);
 130                 ret = put_user(timeout, data);
 131                 break;
 132
 133         default:
 134                 ret = -ENOTTY;
 135         }
 136         return ret;
 137 }
 138 static int mpc5200_wdt_open(struct inode *inode, struct file *file)
 139 {
 140         /* /dev/watchdog can only be opened once */
 141         if (test_and_set_bit(0, &is_active))
 142                 return -EBUSY;
 143
 144         /* Set and activate the watchdog */
 145         mpc5200_wdt_set_timeout(wdt_global, 30);
 146         mpc5200_wdt_start(wdt_global);
 147         file->private_data = wdt_global;
 148         return nonseekable_open(inode, file);
 149 }
 150 static int mpc5200_wdt_release(struct inode *inode, struct file *file)
 151 {
 152 #if WATCHDOG_NOWAYOUT == 0
 153         struct mpc5200_wdt *wdt = file->private_data;
 154         mpc5200_wdt_stop(wdt);
 155         wdt->count = 0;         /* == disabled */
 156 #endif
 157         clear_bit(0, &is_active);
 158         return 0;
 159 }
 160
 161 static struct file_operations mpc5200_wdt_fops = {
 162         .owner  = THIS_MODULE,
 163         .write  = mpc5200_wdt_write,
 164         .ioctl  = mpc5200_wdt_ioctl,
 165         .open   = mpc5200_wdt_open,
 166         .release = mpc5200_wdt_release,
 167 };
 168
 169 /* module operations */
 170 static int mpc5200_wdt_probe(struct of_device *op, const struct of_device_id *match)
 171 {
 172         struct mpc5200_wdt *wdt;
 173         int err;
 174         const void *has_wdt;
 175         int size;
 176
 177         has_wdt = of_get_property(op->node, "has-wdt", NULL);
 178         if (!has_wdt)
 179                 return -ENODEV;
 180
 181         wdt = kzalloc(sizeof(*wdt), GFP_KERNEL);
 182         if (!wdt)
 183                 return -ENOMEM;
 184
 185         wdt->ipb_freq = mpc52xx_find_ipb_freq(op->node);
 186
 187         err = of_address_to_resource(op->node, 0, &wdt->mem);
 188         if (err)
 189                 goto out_free;
 190         size = wdt->mem.end - wdt->mem.start + 1;
 191         if (!request_mem_region(wdt->mem.start, size, "mpc5200_wdt")) {
 192                 err = -ENODEV;
 193                 goto out_free;
 194         }
 195         wdt->regs = ioremap(wdt->mem.start, size);
 196         if (!wdt->regs) {
 197                 err = -ENODEV;
 198                 goto out_release;
 199         }
 200
 201         dev_set_drvdata(&op->dev, wdt);
 202         spin_lock_init(&wdt->io_lock);
 203
 204         wdt->miscdev = (struct miscdevice) {
 205                 .minor  = WATCHDOG_MINOR,
 206                 .name   = "watchdog",
 207                 .fops   = &mpc5200_wdt_fops,
 208                 .parent = &op->dev,
 209         };
 210         wdt_global = wdt;
 211         err = misc_register(&wdt->miscdev);
 212         if (!err)
 213                 return 0;
 214
 215         iounmap(wdt->regs);
 216  out_release:
 217         release_mem_region(wdt->mem.start, size);
 218  out_free:
 219         kfree(wdt);
 220         return err;
 221 }
 222
 223 static int mpc5200_wdt_remove(struct of_device *op)
 224 {
 225         struct mpc5200_wdt *wdt = dev_get_drvdata(&op->dev);
 226
 227         mpc5200_wdt_stop(wdt);
 228         misc_deregister(&wdt->miscdev);
 229         iounmap(wdt->regs);
 230         release_mem_region(wdt->mem.start, wdt->mem.end - wdt->mem.start + 1);
 231         kfree(wdt);
 232
 233         return 0;
 234 }
 235 static int mpc5200_wdt_suspend(struct of_device *op, pm_message_t state)
 236 {
 237         struct mpc5200_wdt *wdt = dev_get_drvdata(&op->dev);
 238         mpc5200_wdt_stop(wdt);
 239         return 0;
 240 }
 241 static int mpc5200_wdt_resume(struct of_device *op)
 242 {
 243         struct mpc5200_wdt *wdt = dev_get_drvdata(&op->dev);
 244         if (wdt->count)
 245                 mpc5200_wdt_start(wdt);
 246         return 0;
 247 }
 248 static int mpc5200_wdt_shutdown(struct of_device *op)
 249 {
 250         struct mpc5200_wdt *wdt = dev_get_drvdata(&op->dev);
 251         mpc5200_wdt_stop(wdt);
 252         return 0;
 253 }
 254
 255 static struct of_device_id mpc5200_wdt_match[] = {
 256         { .compatible = "mpc5200-gpt", },
 257         {},
 258 };
 259 static struct of_platform_driver mpc5200_wdt_driver = {
 260         .owner          = THIS_MODULE,
 261         .name           = "mpc5200-gpt-wdt",
 262         .match_table    = mpc5200_wdt_match,
 263         .probe          = mpc5200_wdt_probe,
 264         .remove         = mpc5200_wdt_remove,
 265         .suspend        = mpc5200_wdt_suspend,
 266         .resume         = mpc5200_wdt_resume,
 267         .shutdown       = mpc5200_wdt_shutdown,
 268 };
 269
 270
 271 static int __init mpc5200_wdt_init(void)
 272 {
 273         return of_register_platform_driver(&mpc5200_wdt_driver);
 274 }
 275
 276 static void __exit mpc5200_wdt_exit(void)
 277 {
 278         of_unregister_platform_driver(&mpc5200_wdt_driver);
 279 }
 280
 281 module_init(mpc5200_wdt_init);
 282 module_exit(mpc5200_wdt_exit);
 283
 284 MODULE_AUTHOR("Domen Puncer <domen.puncer@telargo.com>");
 285 MODULE_LICENSE("Dual BSD/GPL");
 286 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);