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 #include <linux/slab.h>
  19
  20
  21 /* RIO uses the NatSemi Super I/O power management logical device
  22  * as its' watchdog.
  23  *
  24  * When the watchdog triggers, it asserts a line to the BBC (Boot Bus
  25  * Controller) of the machine.  The BBC can only be configured to
  26  * trigger a power-on reset when the signal is asserted.  The BBC
  27  * can be configured to ignore the signal entirely as well.
  28  *
  29  * The only Super I/O device register we care about is at index
  30  * 0x05 (WDTO_INDEX) which is the watchdog time-out in minutes (1-255).
  31  * If set to zero, this disables the watchdog.  When set, the system
  32  * must periodically (before watchdog expires) clear (set to zero) and
  33  * re-set the watchdog else it will trigger.
  34  *
  35  * There are two other indexed watchdog registers inside this Super I/O
  36  * logical device, but they are unused.  The first, at index 0x06 is
  37  * the watchdog control and can be used to make the watchdog timer re-set
  38  * when the PS/2 mouse or serial lines show activity.  The second, at
  39  * index 0x07 is merely a sampling of the line from the watchdog to the
  40  * BBC.
  41  *
  42  * The watchdog device generates no interrupts.
  43  */
  44
  45 MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
  46 MODULE_DESCRIPTION("Hardware watchdog driver for Sun RIO");
  47 MODULE_SUPPORTED_DEVICE("watchdog");
  48 MODULE_LICENSE("GPL");
  49
  50 #define DRIVER_NAME     "riowd"
  51 #define PFX             DRIVER_NAME ": "
  52
  53 struct riowd {
  54         void __iomem            *regs;
  55         spinlock_t              lock;
  56 };
  57
  58 static struct riowd *riowd_device;
  59
  60 #define WDTO_INDEX      0x05
  61
  62 static int riowd_timeout = 1;           /* in minutes */
  63 module_param(riowd_timeout, int, 0);
  64 MODULE_PARM_DESC(riowd_timeout, "Watchdog timeout in minutes");
  65
  66 static void riowd_writereg(struct riowd *p, u8 val, int index)
  67 {
  68         unsigned long flags;
  69
  70         spin_lock_irqsave(&p->lock, flags);
  71         writeb(index, p->regs + 0);
  72         writeb(val, p->regs + 1);
  73         spin_unlock_irqrestore(&p->lock, flags);
  74 }
  75
  76 static int riowd_open(struct inode *inode, struct file *filp)
  77 {
  78         nonseekable_open(inode, filp);
  79         return 0;
  80 }
  81
  82 static int riowd_release(struct inode *inode, struct file *filp)
  83 {
  84         return 0;
  85 }
  86
  87 static long riowd_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
  88 {
  89         static const struct watchdog_info info = {
  90                 .options                = WDIOF_SETTIMEOUT,
  91                 .firmware_version       = 1,
  92                 .identity               = DRIVER_NAME,
  93         };
  94         void __user *argp = (void __user *)arg;
  95         struct riowd *p = riowd_device;
  96         unsigned int options;
  97         int new_margin;
  98
  99         switch (cmd) {
 100         case WDIOC_GETSUPPORT:
 101                 if (copy_to_user(argp, &info, sizeof(info)))
 102                         return -EFAULT;
 103                 break;
 104
 105         case WDIOC_GETSTATUS:
 106         case WDIOC_GETBOOTSTATUS:
 107                 if (put_user(0, (int __user *)argp))
 108                         return -EFAULT;
 109                 break;
 110
 111         case WDIOC_KEEPALIVE:
 112                 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
 113                 break;
 114
 115         case WDIOC_SETOPTIONS:
 116                 if (copy_from_user(&options, argp, sizeof(options)))
 117                         return -EFAULT;
 118
 119                 if (options & WDIOS_DISABLECARD)
 120                         riowd_writereg(p, 0, WDTO_INDEX);
 121                 else if (options & WDIOS_ENABLECARD)
 122                         riowd_writereg(p, riowd_timeout, WDTO_INDEX);
 123                 else
 124                         return -EINVAL;
 125
 126                 break;
 127
 128         case WDIOC_SETTIMEOUT:
 129                 if (get_user(new_margin, (int __user *)argp))
 130                         return -EFAULT;
 131                 if ((new_margin < 60) || (new_margin > (255 * 60)))
 132                         return -EINVAL;
 133                 riowd_timeout = (new_margin + 59) / 60;
 134                 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
 135                 /* Fall */
 136
 137         case WDIOC_GETTIMEOUT:
 138                 return put_user(riowd_timeout * 60, (int __user *)argp);
 139
 140         default:
 141                 return -EINVAL;
 142         };
 143
 144         return 0;
 145 }
 146
 147 static ssize_t riowd_write(struct file *file, const char __user *buf,
 148                                                 size_t count, loff_t *ppos)
 149 {
 150         struct riowd *p = riowd_device;
 151
 152         if (count) {
 153                 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
 154                 return 1;
 155         }
 156
 157         return 0;
 158 }
 159
 160 static const struct file_operations riowd_fops = {
 161         .owner =                THIS_MODULE,
 162         .llseek =               no_llseek,
 163         .unlocked_ioctl =       riowd_ioctl,
 164         .open =                 riowd_open,
 165         .write =                riowd_write,
 166         .release =              riowd_release,
 167 };
 168
 169 static struct miscdevice riowd_miscdev = {
 170         .minor  = WATCHDOG_MINOR,
 171         .name   = "watchdog",
 172         .fops   = &riowd_fops
 173 };
 174
 175 static int __devinit riowd_probe(struct platform_device *op,
 176                                  const struct of_device_id *match)
 177 {
 178         struct riowd *p;
 179         int err = -EINVAL;
 180
 181         if (riowd_device)
 182                 goto out;
 183
 184         err = -ENOMEM;
 185         p = kzalloc(sizeof(*p), GFP_KERNEL);
 186         if (!p)
 187                 goto out;
 188
 189         spin_lock_init(&p->lock);
 190
 191         p->regs = of_ioremap(&op->resource[0], 0, 2, DRIVER_NAME);
 192         if (!p->regs) {
 193                 printk(KERN_ERR PFX "Cannot map registers.\n");
 194                 goto out_free;
 195         }
 196         /* Make miscdev useable right away */
 197         riowd_device = p;
 198
 199         err = misc_register(&riowd_miscdev);
 200         if (err) {
 201                 printk(KERN_ERR PFX "Cannot register watchdog misc device.\n");
 202                 goto out_iounmap;
 203         }
 204
 205         printk(KERN_INFO PFX "Hardware watchdog [%i minutes], "
 206                "regs at %p\n", riowd_timeout, p->regs);
 207
 208         dev_set_drvdata(&op->dev, p);
 209         return 0;
 210
 211 out_iounmap:
 212         riowd_device = NULL;
 213         of_iounmap(&op->resource[0], p->regs, 2);
 214
 215 out_free:
 216         kfree(p);
 217
 218 out:
 219         return err;
 220 }
 221
 222 static int __devexit riowd_remove(struct platform_device *op)
 223 {
 224         struct riowd *p = dev_get_drvdata(&op->dev);
 225
 226         misc_deregister(&riowd_miscdev);
 227         of_iounmap(&op->resource[0], p->regs, 2);
 228         kfree(p);
 229
 230         return 0;
 231 }
 232
 233 static const struct of_device_id riowd_match[] = {
 234         {
 235                 .name = "pmc",
 236         },
 237         {},
 238 };
 239 MODULE_DEVICE_TABLE(of, riowd_match);
 240
 241 static struct of_platform_driver riowd_driver = {
 242         .driver = {
 243                 .name = DRIVER_NAME,
 244                 .owner = THIS_MODULE,
 245                 .of_match_table = riowd_match,
 246         },
 247         .probe          = riowd_probe,
 248         .remove         = __devexit_p(riowd_remove),
 249 };
 250
 251 static int __init riowd_init(void)
 252 {
 253         return of_register_platform_driver(&riowd_driver);
 254 }
 255
 256 static void __exit riowd_exit(void)
 257 {
 258         of_unregister_platform_driver(&riowd_driver);
 259 }
 260
 261 module_init(riowd_init);
 262 module_exit(riowd_exit);