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
46MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
47MODULE_DESCRIPTION("Hardware watchdog driver for Sun RIO");
48MODULE_SUPPORTED_DEVICE("watchdog");
49MODULE_LICENSE("GPL");
50
51#define DRIVER_NAME	"riowd"
52#define PFX		DRIVER_NAME ": "
53
54struct riowd {
55	void __iomem		*regs;
56	spinlock_t		lock;
57};
58
59static struct riowd *riowd_device;
60
61#define WDTO_INDEX	0x05
62
63static int riowd_timeout = 1;		/* in minutes */
64module_param(riowd_timeout, int, 0);
65MODULE_PARM_DESC(riowd_timeout, "Watchdog timeout in minutes");
66
67static 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
77static int riowd_open(struct inode *inode, struct file *filp)
78{
79	nonseekable_open(inode, filp);
80	return 0;
81}
82
83static int riowd_release(struct inode *inode, struct file *filp)
84{
85	return 0;
86}
87
88static 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
148static 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
161static 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
170static struct miscdevice riowd_miscdev = {
171	.minor	= WATCHDOG_MINOR,
172	.name	= "watchdog",
173	.fops	= &riowd_fops
174};
175
176static 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
211out_iounmap:
212	riowd_device = NULL;
213	of_iounmap(&op->resource[0], p->regs, 2);
214
215out:
216	return err;
217}
218
219static 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
229static const struct of_device_id riowd_match[] = {
230	{
231		.name = "pmc",
232	},
233	{},
234};
235MODULE_DEVICE_TABLE(of, riowd_match);
236
237static struct platform_driver riowd_driver = {
238	.driver = {
239		.name = DRIVER_NAME,
240		.of_match_table = riowd_match,
241	},
242	.probe		= riowd_probe,
243	.remove		= riowd_remove,
244};
245
246module_platform_driver(riowd_driver);
247