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 #include <linux/io.h>
18 #include <linux/uaccess.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 cycle_kernel_lock();
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 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 __devinit riowd_probe(struct of_device *op,
177 const struct of_device_id *match)
178 {
179 struct riowd *p;
180 int err = -EINVAL;
181
182 if (riowd_device)
183 goto out;
184
185 err = -ENOMEM;
186 p = kzalloc(sizeof(*p), GFP_KERNEL);
187 if (!p)
188 goto out;
189
190 spin_lock_init(&p->lock);
191
192 p->regs = of_ioremap(&op->resource[0], 0, 2, DRIVER_NAME);
193 if (!p->regs) {
194 printk(KERN_ERR PFX "Cannot map registers.\n");
195 goto out_free;
196 }
197
198 err = misc_register(&riowd_miscdev);
199 if (err) {
200 printk(KERN_ERR PFX "Cannot register watchdog misc device.\n");
201 goto out_iounmap;
202 }
203
204 printk(KERN_INFO PFX "Hardware watchdog [%i minutes], "
205 "regs at %p\n", riowd_timeout, p->regs);
206
207 dev_set_drvdata(&op->dev, p);
208 riowd_device = p;
209 return 0;
210
211 out_iounmap:
212 of_iounmap(&op->resource[0], p->regs, 2);
213
214 out_free:
215 kfree(p);
216
217 out:
218 return err;
219 }
220
221 static int __devexit riowd_remove(struct of_device *op)
222 {
223 struct riowd *p = dev_get_drvdata(&op->dev);
224
225 misc_deregister(&riowd_miscdev);
226 of_iounmap(&op->resource[0], p->regs, 2);
227 kfree(p);
228
229 return 0;
230 }
231
232 static const struct of_device_id riowd_match[] = {
233 {
234 .name = "pmc",
235 },
236 {},
237 };
238 MODULE_DEVICE_TABLE(of, riowd_match);
239
240 static struct of_platform_driver riowd_driver = {
241 .name = DRIVER_NAME,
242 .match_table = riowd_match,
243 .probe = riowd_probe,
244 .remove = __devexit_p(riowd_remove),
245 };
246
247 static int __init riowd_init(void)
248 {
249 return of_register_driver(&riowd_driver, &of_bus_type);
250 }
251
252 static void __exit riowd_exit(void)
253 {
254 of_unregister_driver(&riowd_driver);
255 }
256
257 module_init(riowd_init);
258 module_exit(riowd_exit);
259
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