linux/drivers/watchdog/riowd.c
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   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
  45MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
  46MODULE_DESCRIPTION("Hardware watchdog driver for Sun RIO");
  47MODULE_SUPPORTED_DEVICE("watchdog");
  48MODULE_LICENSE("GPL");
  49
  50#define DRIVER_NAME     "riowd"
  51#define PFX             DRIVER_NAME ": "
  52
  53struct riowd {
  54        void __iomem            *regs;
  55        spinlock_t              lock;
  56};
  57
  58static struct riowd *riowd_device;
  59
  60#define WDTO_INDEX      0x05
  61
  62static int riowd_timeout = 1;           /* in minutes */
  63module_param(riowd_timeout, int, 0);
  64MODULE_PARM_DESC(riowd_timeout, "Watchdog timeout in minutes");
  65
  66static 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
  76static int riowd_open(struct inode *inode, struct file *filp)
  77{
  78        nonseekable_open(inode, filp);
  79        return 0;
  80}
  81
  82static int riowd_release(struct inode *inode, struct file *filp)
  83{
  84        return 0;
  85}
  86
  87static 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
 147static 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
 160static 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
 169static struct miscdevice riowd_miscdev = {
 170        .minor  = WATCHDOG_MINOR,
 171        .name   = "watchdog",
 172        .fops   = &riowd_fops
 173};
 174
 175static 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
 211out_iounmap:
 212        riowd_device = NULL;
 213        of_iounmap(&op->resource[0], p->regs, 2);
 214
 215out_free:
 216        kfree(p);
 217
 218out:
 219        return err;
 220}
 221
 222static 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
 233static const struct of_device_id riowd_match[] = {
 234        {
 235                .name = "pmc",
 236        },
 237        {},
 238};
 239MODULE_DEVICE_TABLE(of, riowd_match);
 240
 241static 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
 251static int __init riowd_init(void)
 252{
 253        return of_register_platform_driver(&riowd_driver);
 254}
 255
 256static void __exit riowd_exit(void)
 257{
 258        of_unregister_platform_driver(&riowd_driver);
 259}
 260
 261module_init(riowd_init);
 262module_exit(riowd_exit);
 263