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