1 /* riowd.c - driver for hw watchdog inside Super I/O of RIO
3 * Copyright (C) 2001, 2008 David S. Miller (davem@davemloft.net)
6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/types.h>
12 #include <linux/errno.h>
13 #include <linux/miscdevice.h>
14 #include <linux/watchdog.h>
16 #include <linux/of_device.h>
18 #include <linux/uaccess.h>
19 #include <linux/slab.h>
22 /* RIO uses the NatSemi Super I/O power management logical device
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.
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.
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
43 * The watchdog device generates no interrupts.
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");
51 #define DRIVER_NAME "riowd"
52 #define PFX DRIVER_NAME ": "
59 static struct riowd *riowd_device;
61 #define WDTO_INDEX 0x05
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");
67 static void riowd_writereg(struct riowd *p, u8 val, int index)
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);
77 static int riowd_open(struct inode *inode, struct file *filp)
79 stream_open(inode, filp);
83 static int riowd_release(struct inode *inode, struct file *filp)
88 static long riowd_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
90 static const struct watchdog_info info = {
91 .options = WDIOF_SETTIMEOUT,
92 .firmware_version = 1,
93 .identity = DRIVER_NAME,
95 void __user *argp = (void __user *)arg;
96 struct riowd *p = riowd_device;
101 case WDIOC_GETSUPPORT:
102 if (copy_to_user(argp, &info, sizeof(info)))
106 case WDIOC_GETSTATUS:
107 case WDIOC_GETBOOTSTATUS:
108 if (put_user(0, (int __user *)argp))
112 case WDIOC_KEEPALIVE:
113 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
116 case WDIOC_SETOPTIONS:
117 if (copy_from_user(&options, argp, sizeof(options)))
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);
129 case WDIOC_SETTIMEOUT:
130 if (get_user(new_margin, (int __user *)argp))
132 if ((new_margin < 60) || (new_margin > (255 * 60)))
134 riowd_timeout = (new_margin + 59) / 60;
135 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
138 case WDIOC_GETTIMEOUT:
139 return put_user(riowd_timeout * 60, (int __user *)argp);
148 static ssize_t riowd_write(struct file *file, const char __user *buf,
149 size_t count, loff_t *ppos)
151 struct riowd *p = riowd_device;
154 riowd_writereg(p, riowd_timeout, WDTO_INDEX);
161 static const struct file_operations riowd_fops = {
162 .owner = THIS_MODULE,
164 .unlocked_ioctl = riowd_ioctl,
166 .write = riowd_write,
167 .release = riowd_release,
170 static struct miscdevice riowd_miscdev = {
171 .minor = WATCHDOG_MINOR,
176 static int riowd_probe(struct platform_device *op)
185 p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
189 spin_lock_init(&p->lock);
191 p->regs = of_ioremap(&op->resource[0], 0, 2, DRIVER_NAME);
193 pr_err("Cannot map registers\n");
196 /* Make miscdev useable right away */
199 err = misc_register(&riowd_miscdev);
201 pr_err("Cannot register watchdog misc device\n");
205 pr_info("Hardware watchdog [%i minutes], regs at %p\n",
206 riowd_timeout, p->regs);
208 platform_set_drvdata(op, p);
213 of_iounmap(&op->resource[0], p->regs, 2);
219 static int riowd_remove(struct platform_device *op)
221 struct riowd *p = platform_get_drvdata(op);
223 misc_deregister(&riowd_miscdev);
224 of_iounmap(&op->resource[0], p->regs, 2);
229 static const struct of_device_id riowd_match[] = {
235 MODULE_DEVICE_TABLE(of, riowd_match);
237 static struct platform_driver riowd_driver = {
240 .of_match_table = riowd_match,
242 .probe = riowd_probe,
243 .remove = riowd_remove,
246 module_platform_driver(riowd_driver);