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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   7
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/types.h>
  11 #include <linux/fs.h>
  12 #include <linux/errno.h>
  13 #include <linux/miscdevice.h>
  14 #include <linux/watchdog.h>
  15 #include <linux/of.h>
  16 #include <linux/of_device.h>
  17 #include <linux/io.h>
  18 #include <linux/uaccess.h>
  19 #include <linux/slab.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         nonseekable_open(inode, filp);
  80         return 0;
  81 }
  82
  83 static int riowd_release(struct inode *inode, struct file *filp)
  84 {
  85         return 0;
  86 }
  87
  88 static long riowd_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
  89 {
  90         static const struct watchdog_info info = {
  91                 .options                = WDIOF_SETTIMEOUT,
  92                 .firmware_version       = 1,
  93                 .identity               = DRIVER_NAME,
  94         };
  95         void __user *argp = (void __user *)arg;
  96         struct riowd *p = riowd_device;
  97         unsigned int options;
  98         int new_margin;
  99
 100         switch (cmd) {
 101         case WDIOC_GETSUPPORT:
 102                 if (copy_to_user(argp, &info, sizeof(info)))
 103                         return -EFAULT;
 104                 break;
 105
 106         case WDIOC_GETSTATUS:
 107         case WDIOC_GETBOOTSTATUS:
 108                 if (put_user(0, (int __user *)argp))
 109                         return -EFAULT;
 110                 break;
 111
 112         case WDIOC_KEEPALIVE:
 113                 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
 114                 break;
 115
 116         case WDIOC_SETOPTIONS:
 117                 if (copy_from_user(&options, argp, sizeof(options)))
 118                         return -EFAULT;
 119
 120                 if (options & WDIOS_DISABLECARD)
 121                         riowd_writereg(p, 0, WDTO_INDEX);
 122                 else if (options & WDIOS_ENABLECARD)
 123                         riowd_writereg(p, riowd_timeout, WDTO_INDEX);
 124                 else
 125                         return -EINVAL;
 126
 127                 break;
 128
 129         case WDIOC_SETTIMEOUT:
 130                 if (get_user(new_margin, (int __user *)argp))
 131                         return -EFAULT;
 132                 if ((new_margin < 60) || (new_margin > (255 * 60)))
 133                         return -EINVAL;
 134                 riowd_timeout = (new_margin + 59) / 60;
 135                 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
 136                 /* Fall */
 137
 138         case WDIOC_GETTIMEOUT:
 139                 return put_user(riowd_timeout * 60, (int __user *)argp);
 140
 141         default:
 142                 return -EINVAL;
 143         };
 144
 145         return 0;
 146 }
 147
 148 static ssize_t riowd_write(struct file *file, const char __user *buf,
 149                                                 size_t count, loff_t *ppos)
 150 {
 151         struct riowd *p = riowd_device;
 152
 153         if (count) {
 154                 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
 155                 return 1;
 156         }
 157
 158         return 0;
 159 }
 160
 161 static const struct file_operations riowd_fops = {
 162         .owner =                THIS_MODULE,
 163         .llseek =               no_llseek,
 164         .unlocked_ioctl =       riowd_ioctl,
 165         .open =                 riowd_open,
 166         .write =                riowd_write,
 167         .release =              riowd_release,
 168 };
 169
 170 static struct miscdevice riowd_miscdev = {
 171         .minor  = WATCHDOG_MINOR,
 172         .name   = "watchdog",
 173         .fops   = &riowd_fops
 174 };
 175
 176 static int riowd_probe(struct platform_device *op)
 177 {
 178         struct riowd *p;
 179         int err = -EINVAL;
 180
 181         if (riowd_device)
 182                 goto out;
 183
 184         err = -ENOMEM;
 185         p = devm_kzalloc(&op->dev, 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                 pr_err("Cannot map registers\n");
 194                 goto out;
 195         }
 196         /* Make miscdev useable right away */
 197         riowd_device = p;
 198
 199         err = misc_register(&riowd_miscdev);
 200         if (err) {
 201                 pr_err("Cannot register watchdog misc device\n");
 202                 goto out_iounmap;
 203         }
 204
 205         pr_info("Hardware watchdog [%i minutes], regs at %p\n",
 206                 riowd_timeout, p->regs);
 207
 208         platform_set_drvdata(op, p);
 209         return 0;
 210
 211 out_iounmap:
 212         riowd_device = NULL;
 213         of_iounmap(&op->resource[0], p->regs, 2);
 214
 215 out:
 216         return err;
 217 }
 218
 219 static int riowd_remove(struct platform_device *op)
 220 {
 221         struct riowd *p = platform_get_drvdata(op);
 222
 223         misc_deregister(&riowd_miscdev);
 224         of_iounmap(&op->resource[0], p->regs, 2);
 225
 226         return 0;
 227 }
 228
 229 static const struct of_device_id riowd_match[] = {
 230         {
 231                 .name = "pmc",
 232         },
 233         {},
 234 };
 235 MODULE_DEVICE_TABLE(of, riowd_match);
 236
 237 static struct platform_driver riowd_driver = {
 238         .driver = {
 239                 .name = DRIVER_NAME,
 240                 .owner = THIS_MODULE,
 241                 .of_match_table = riowd_match,
 242         },
 243         .probe          = riowd_probe,
 244         .remove         = riowd_remove,
 245 };
 246
 247 module_platform_driver(riowd_driver);