drivers/watchdog/riowd.c

   1 /* riowd.c - driver for hw watchdog inside Super I/O of RIO
   2  *
   3  * Copyright (C) 2001, 2008 David S. Miller (davem@davemloft.net)
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/module.h>
   8 #include <linux/types.h>
   9 #include <linux/fs.h>
  10 #include <linux/errno.h>
  11 #include <linux/init.h>
  12 #include <linux/miscdevice.h>
  13 #include <linux/watchdog.h>
  14 #include <linux/of.h>
  15 #include <linux/of_device.h>
  16 #include <linux/io.h>
  17 #include <linux/uaccess.h>
  18
  19
  20 /* RIO uses the NatSemi Super I/O power management logical device
  21  * as its' watchdog.
  22  *
  23  * When the watchdog triggers, it asserts a line to the BBC (Boot Bus
  24  * Controller) of the machine.  The BBC can only be configured to
  25  * trigger a power-on reset when the signal is asserted.  The BBC
  26  * can be configured to ignore the signal entirely as well.
  27  *
  28  * The only Super I/O device register we care about is at index
  29  * 0x05 (WDTO_INDEX) which is the watchdog time-out in minutes (1-255).
  30  * If set to zero, this disables the watchdog.  When set, the system
  31  * must periodically (before watchdog expires) clear (set to zero) and
  32  * re-set the watchdog else it will trigger.
  33  *
  34  * There are two other indexed watchdog registers inside this Super I/O
  35  * logical device, but they are unused.  The first, at index 0x06 is
  36  * the watchdog control and can be used to make the watchdog timer re-set
  37  * when the PS/2 mouse or serial lines show activity.  The second, at
  38  * index 0x07 is merely a sampling of the line from the watchdog to the
  39  * BBC.
  40  *
  41  * The watchdog device generates no interrupts.
  42  */
  43
  44 MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
  45 MODULE_DESCRIPTION("Hardware watchdog driver for Sun RIO");
  46 MODULE_SUPPORTED_DEVICE("watchdog");
  47 MODULE_LICENSE("GPL");
  48
  49 #define DRIVER_NAME     "riowd"
  50 #define PFX             DRIVER_NAME ": "
  51
  52 struct riowd {
  53         void __iomem            *regs;
  54         spinlock_t              lock;
  55 };
  56
  57 static struct riowd *riowd_device;
  58
  59 #define WDTO_INDEX      0x05
  60
  61 static int riowd_timeout = 1;           /* in minutes */
  62 module_param(riowd_timeout, int, 0);
  63 MODULE_PARM_DESC(riowd_timeout, "Watchdog timeout in minutes");
  64
  65 static void riowd_writereg(struct riowd *p, u8 val, int index)
  66 {
  67         unsigned long flags;
  68
  69         spin_lock_irqsave(&p->lock, flags);
  70         writeb(index, p->regs + 0);
  71         writeb(val, p->regs + 1);
  72         spin_unlock_irqrestore(&p->lock, flags);
  73 }
  74
  75 static int riowd_open(struct inode *inode, struct file *filp)
  76 {
  77         nonseekable_open(inode, filp);
  78         return 0;
  79 }
  80
  81 static int riowd_release(struct inode *inode, struct file *filp)
  82 {
  83         return 0;
  84 }
  85
  86 static long riowd_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
  87 {
  88         static const struct watchdog_info info = {
  89                 .options                = WDIOF_SETTIMEOUT,
  90                 .firmware_version       = 1,
  91                 .identity               = DRIVER_NAME,
  92         };
  93         void __user *argp = (void __user *)arg;
  94         struct riowd *p = riowd_device;
  95         unsigned int options;
  96         int new_margin;
  97
  98         switch (cmd) {
  99         case WDIOC_GETSUPPORT:
 100                 if (copy_to_user(argp, &info, sizeof(info)))
 101                         return -EFAULT;
 102                 break;
 103
 104         case WDIOC_GETSTATUS:
 105         case WDIOC_GETBOOTSTATUS:
 106                 if (put_user(0, (int __user *)argp))
 107                         return -EFAULT;
 108                 break;
 109
 110         case WDIOC_KEEPALIVE:
 111                 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
 112                 break;
 113
 114         case WDIOC_SETOPTIONS:
 115                 if (copy_from_user(&options, argp, sizeof(options)))
 116                         return -EFAULT;
 117
 118                 if (options & WDIOS_DISABLECARD)
 119                         riowd_writereg(p, 0, WDTO_INDEX);
 120                 else if (options & WDIOS_ENABLECARD)
 121                         riowd_writereg(p, riowd_timeout, WDTO_INDEX);
 122                 else
 123                         return -EINVAL;
 124
 125                 break;
 126
 127         case WDIOC_SETTIMEOUT:
 128                 if (get_user(new_margin, (int __user *)argp))
 129                         return -EFAULT;
 130                 if ((new_margin < 60) || (new_margin > (255 * 60)))
 131                         return -EINVAL;
 132                 riowd_timeout = (new_margin + 59) / 60;
 133                 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
 134                 /* Fall */
 135
 136         case WDIOC_GETTIMEOUT:
 137                 return put_user(riowd_timeout * 60, (int __user *)argp);
 138
 139         default:
 140                 return -EINVAL;
 141         };
 142
 143         return 0;
 144 }
 145
 146 static ssize_t riowd_write(struct file *file, const char __user *buf,
 147                                                 size_t count, loff_t *ppos)
 148 {
 149         struct riowd *p = riowd_device;
 150
 151         if (count) {
 152                 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
 153                 return 1;
 154         }
 155
 156         return 0;
 157 }
 158
 159 static const struct file_operations riowd_fops = {
 160         .owner =                THIS_MODULE,
 161         .llseek =               no_llseek,
 162         .unlocked_ioctl =       riowd_ioctl,
 163         .open =                 riowd_open,
 164         .write =                riowd_write,
 165         .release =              riowd_release,
 166 };
 167
 168 static struct miscdevice riowd_miscdev = {
 169         .minor  = WATCHDOG_MINOR,
 170         .name   = "watchdog",
 171         .fops   = &riowd_fops
 172 };
 173
 174 static int __devinit riowd_probe(struct of_device *op,
 175                                  const struct of_device_id *match)
 176 {
 177         struct riowd *p;
 178         int err = -EINVAL;
 179
 180         if (riowd_device)
 181                 goto out;
 182
 183         err = -ENOMEM;
 184         p = kzalloc(sizeof(*p), GFP_KERNEL);
 185         if (!p)
 186                 goto out;
 187
 188         spin_lock_init(&p->lock);
 189
 190         p->regs = of_ioremap(&op->resource[0], 0, 2, DRIVER_NAME);
 191         if (!p->regs) {
 192                 printk(KERN_ERR PFX "Cannot map registers.\n");
 193                 goto out_free;
 194         }
 195         /* Make miscdev useable right away */
 196         riowd_device = p;
 197
 198         err = misc_register(&riowd_miscdev);
 199         if (err) {
 200                 printk(KERN_ERR PFX "Cannot register watchdog misc device.\n");
 201                 goto out_iounmap;
 202         }
 203
 204         printk(KERN_INFO PFX "Hardware watchdog [%i minutes], "
 205                "regs at %p\n", riowd_timeout, p->regs);
 206
 207         dev_set_drvdata(&op->dev, p);
 208         return 0;
 209
 210 out_iounmap:
 211         riowd_device = NULL;
 212         of_iounmap(&op->resource[0], p->regs, 2);
 213
 214 out_free:
 215         kfree(p);
 216
 217 out:
 218         return err;
 219 }
 220
 221 static int __devexit riowd_remove(struct of_device *op)
 222 {
 223         struct riowd *p = dev_get_drvdata(&op->dev);
 224
 225         misc_deregister(&riowd_miscdev);
 226         of_iounmap(&op->resource[0], p->regs, 2);
 227         kfree(p);
 228
 229         return 0;
 230 }
 231
 232 static const struct of_device_id riowd_match[] = {
 233         {
 234                 .name = "pmc",
 235         },
 236         {},
 237 };
 238 MODULE_DEVICE_TABLE(of, riowd_match);
 239
 240 static struct of_platform_driver riowd_driver = {
 241         .name           = DRIVER_NAME,
 242         .match_table    = riowd_match,
 243         .probe          = riowd_probe,
 244         .remove         = __devexit_p(riowd_remove),
 245 };
 246
 247 static int __init riowd_init(void)
 248 {
 249         return of_register_driver(&riowd_driver, &of_bus_type);
 250 }
 251
 252 static void __exit riowd_exit(void)
 253 {
 254         of_unregister_driver(&riowd_driver);
 255 }
 256
 257 module_init(riowd_init);
 258 module_exit(riowd_exit);