summaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/riowd.c
blob: 41a2a11535a6a8939cd48c0d7c3239b2ba889dc0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
// SPDX-License-Identifier: GPL-2.0-only
/* riowd.c - driver for hw watchdog inside Super I/O of RIO
 *
 * Copyright (C) 2001, 2008 David S. Miller (davem@davemloft.net)
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/slab.h>


/* RIO uses the NatSemi Super I/O power management logical device
 * as its' watchdog.
 *
 * When the watchdog triggers, it asserts a line to the BBC (Boot Bus
 * Controller) of the machine.  The BBC can only be configured to
 * trigger a power-on reset when the signal is asserted.  The BBC
 * can be configured to ignore the signal entirely as well.
 *
 * The only Super I/O device register we care about is at index
 * 0x05 (WDTO_INDEX) which is the watchdog time-out in minutes (1-255).
 * If set to zero, this disables the watchdog.  When set, the system
 * must periodically (before watchdog expires) clear (set to zero) and
 * re-set the watchdog else it will trigger.
 *
 * There are two other indexed watchdog registers inside this Super I/O
 * logical device, but they are unused.  The first, at index 0x06 is
 * the watchdog control and can be used to make the watchdog timer re-set
 * when the PS/2 mouse or serial lines show activity.  The second, at
 * index 0x07 is merely a sampling of the line from the watchdog to the
 * BBC.
 *
 * The watchdog device generates no interrupts.
 */

MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
MODULE_DESCRIPTION("Hardware watchdog driver for Sun RIO");
MODULE_SUPPORTED_DEVICE("watchdog");
MODULE_LICENSE("GPL");

#define DRIVER_NAME	"riowd"
#define PFX		DRIVER_NAME ": "

struct riowd {
	void __iomem		*regs;
	spinlock_t		lock;
};

static struct riowd *riowd_device;

#define WDTO_INDEX	0x05

static int riowd_timeout = 1;		/* in minutes */
module_param(riowd_timeout, int, 0);
MODULE_PARM_DESC(riowd_timeout, "Watchdog timeout in minutes");

static void riowd_writereg(struct riowd *p, u8 val, int index)
{
	unsigned long flags;

	spin_lock_irqsave(&p->lock, flags);
	writeb(index, p->regs + 0);
	writeb(val, p->regs + 1);
	spin_unlock_irqrestore(&p->lock, flags);
}

static int riowd_open(struct inode *inode, struct file *filp)
{
	stream_open(inode, filp);
	return 0;
}

static int riowd_release(struct inode *inode, struct file *filp)
{
	return 0;
}

static long riowd_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
	static const struct watchdog_info info = {
		.options		= WDIOF_SETTIMEOUT,
		.firmware_version	= 1,
		.identity		= DRIVER_NAME,
	};
	void __user *argp = (void __user *)arg;
	struct riowd *p = riowd_device;
	unsigned int options;
	int new_margin;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		if (copy_to_user(argp, &info, sizeof(info)))
			return -EFAULT;
		break;

	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		if (put_user(0, (int __user *)argp))
			return -EFAULT;
		break;

	case WDIOC_KEEPALIVE:
		riowd_writereg(p, riowd_timeout, WDTO_INDEX);
		break;

	case WDIOC_SETOPTIONS:
		if (copy_from_user(&options, argp, sizeof(options)))
			return -EFAULT;

		if (options & WDIOS_DISABLECARD)
			riowd_writereg(p, 0, WDTO_INDEX);
		else if (options & WDIOS_ENABLECARD)
			riowd_writereg(p, riowd_timeout, WDTO_INDEX);
		else
			return -EINVAL;

		break;

	case WDIOC_SETTIMEOUT:
		if (get_user(new_margin, (int __user *)argp))
			return -EFAULT;
		if ((new_margin < 60) || (new_margin > (255 * 60)))
			return -EINVAL;
		riowd_timeout = (new_margin + 59) / 60;
		riowd_writereg(p, riowd_timeout, WDTO_INDEX);
		/* Fall */

	case WDIOC_GETTIMEOUT:
		return put_user(riowd_timeout * 60, (int __user *)argp);

	default:
		return -EINVAL;
	};

	return 0;
}

static ssize_t riowd_write(struct file *file, const char __user *buf,
						size_t count, loff_t *ppos)
{
	struct riowd *p = riowd_device;

	if (count) {
		riowd_writereg(p, riowd_timeout, WDTO_INDEX);
		return 1;
	}

	return 0;
}

static const struct file_operations riowd_fops = {
	.owner =		THIS_MODULE,
	.llseek =		no_llseek,
	.unlocked_ioctl =	riowd_ioctl,
	.open =			riowd_open,
	.write =		riowd_write,
	.release =		riowd_release,
};

static struct miscdevice riowd_miscdev = {
	.minor	= WATCHDOG_MINOR,
	.name	= "watchdog",
	.fops	= &riowd_fops
};

static int riowd_probe(struct platform_device *op)
{
	struct riowd *p;
	int err = -EINVAL;

	if (riowd_device)
		goto out;

	err = -ENOMEM;
	p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
	if (!p)
		goto out;

	spin_lock_init(&p->lock);

	p->regs = of_ioremap(&op->resource[0], 0, 2, DRIVER_NAME);
	if (!p->regs) {
		pr_err("Cannot map registers\n");
		goto out;
	}
	/* Make miscdev useable right away */
	riowd_device = p;

	err = misc_register(&riowd_miscdev);
	if (err) {
		pr_err("Cannot register watchdog misc device\n");
		goto out_iounmap;
	}

	pr_info("Hardware watchdog [%i minutes], regs at %p\n",
		riowd_timeout, p->regs);

	platform_set_drvdata(op, p);
	return 0;

out_iounmap:
	riowd_device = NULL;
	of_iounmap(&op->resource[0], p->regs, 2);

out:
	return err;
}

static int riowd_remove(struct platform_device *op)
{
	struct riowd *p = platform_get_drvdata(op);

	misc_deregister(&riowd_miscdev);
	of_iounmap(&op->resource[0], p->regs, 2);

	return 0;
}

static const struct of_device_id riowd_match[] = {
	{
		.name = "pmc",
	},
	{},
};
MODULE_DEVICE_TABLE(of, riowd_match);

static struct platform_driver riowd_driver = {
	.driver = {
		.name = DRIVER_NAME,
		.of_match_table = riowd_match,
	},
	.probe		= riowd_probe,
	.remove		= riowd_remove,
};

module_platform_driver(riowd_driver);