1// SPDX-License-Identifier: GPL-2.0-only
2/* riowd.c - driver for hw watchdog inside Super I/O of RIO
3 *
4 * Copyright (C) 2001, 2008 David S. Miller (davem@davemloft.net)
5 */
6
7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <linux/kernel.h>
10#include <linux/module.h>
11#include <linux/types.h>
12#include <linux/fs.h>
13#include <linux/errno.h>
14#include <linux/miscdevice.h>
15#include <linux/watchdog.h>
16#include <linux/of.h>
17#include <linux/of_device.h>
18#include <linux/io.h>
19#include <linux/uaccess.h>
20#include <linux/slab.h>
21
22
23/* RIO uses the NatSemi Super I/O power management logical device
24 * as its' watchdog.
25 *
26 * When the watchdog triggers, it asserts a line to the BBC (Boot Bus
27 * Controller) of the machine.  The BBC can only be configured to
28 * trigger a power-on reset when the signal is asserted.  The BBC
29 * can be configured to ignore the signal entirely as well.
30 *
31 * The only Super I/O device register we care about is at index
32 * 0x05 (WDTO_INDEX) which is the watchdog time-out in minutes (1-255).
33 * If set to zero, this disables the watchdog.  When set, the system
34 * must periodically (before watchdog expires) clear (set to zero) and
35 * re-set the watchdog else it will trigger.
36 *
37 * There are two other indexed watchdog registers inside this Super I/O
38 * logical device, but they are unused.  The first, at index 0x06 is
39 * the watchdog control and can be used to make the watchdog timer re-set
40 * when the PS/2 mouse or serial lines show activity.  The second, at
41 * index 0x07 is merely a sampling of the line from the watchdog to the
42 * BBC.
43 *
44 * The watchdog device generates no interrupts.
45 */
46
47MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
48MODULE_DESCRIPTION("Hardware watchdog driver for Sun RIO");
49MODULE_SUPPORTED_DEVICE("watchdog");
50MODULE_LICENSE("GPL");
51
52#define DRIVER_NAME	"riowd"
53#define PFX		DRIVER_NAME ": "
54
55struct riowd {
56	void __iomem		*regs;
57	spinlock_t		lock;
58};
59
60static struct riowd *riowd_device;
61
62#define WDTO_INDEX	0x05
63
64static int riowd_timeout = 1;		/* in minutes */
65module_param(riowd_timeout, int, 0);
66MODULE_PARM_DESC(riowd_timeout, "Watchdog timeout in minutes");
67
68static void riowd_writereg(struct riowd *p, u8 val, int index)
69{
70	unsigned long flags;
71
72	spin_lock_irqsave(&p->lock, flags);
73	writeb(index, p->regs + 0);
74	writeb(val, p->regs + 1);
75	spin_unlock_irqrestore(&p->lock, flags);
76}
77
78static int riowd_open(struct inode *inode, struct file *filp)
79{
80	stream_open(inode, filp);
81	return 0;
82}
83
84static int riowd_release(struct inode *inode, struct file *filp)
85{
86	return 0;
87}
88
89static long riowd_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
90{
91	static const struct watchdog_info info = {
92		.options		= WDIOF_SETTIMEOUT,
93		.firmware_version	= 1,
94		.identity		= DRIVER_NAME,
95	};
96	void __user *argp = (void __user *)arg;
97	struct riowd *p = riowd_device;
98	unsigned int options;
99	int new_margin;
100
101	switch (cmd) {
102	case WDIOC_GETSUPPORT:
103		if (copy_to_user(argp, &info, sizeof(info)))
104			return -EFAULT;
105		break;
106
107	case WDIOC_GETSTATUS:
108	case WDIOC_GETBOOTSTATUS:
109		if (put_user(0, (int __user *)argp))
110			return -EFAULT;
111		break;
112
113	case WDIOC_KEEPALIVE:
114		riowd_writereg(p, riowd_timeout, WDTO_INDEX);
115		break;
116
117	case WDIOC_SETOPTIONS:
118		if (copy_from_user(&options, argp, sizeof(options)))
119			return -EFAULT;
120
121		if (options & WDIOS_DISABLECARD)
122			riowd_writereg(p, 0, WDTO_INDEX);
123		else if (options & WDIOS_ENABLECARD)
124			riowd_writereg(p, riowd_timeout, WDTO_INDEX);
125		else
126			return -EINVAL;
127
128		break;
129
130	case WDIOC_SETTIMEOUT:
131		if (get_user(new_margin, (int __user *)argp))
132			return -EFAULT;
133		if ((new_margin < 60) || (new_margin > (255 * 60)))
134			return -EINVAL;
135		riowd_timeout = (new_margin + 59) / 60;
136		riowd_writereg(p, riowd_timeout, WDTO_INDEX);
137		fallthrough;
138
139	case WDIOC_GETTIMEOUT:
140		return put_user(riowd_timeout * 60, (int __user *)argp);
141
142	default:
143		return -EINVAL;
144	}
145
146	return 0;
147}
148
149static ssize_t riowd_write(struct file *file, const char __user *buf,
150						size_t count, loff_t *ppos)
151{
152	struct riowd *p = riowd_device;
153
154	if (count) {
155		riowd_writereg(p, riowd_timeout, WDTO_INDEX);
156		return 1;
157	}
158
159	return 0;
160}
161
162static const struct file_operations riowd_fops = {
163	.owner =		THIS_MODULE,
164	.llseek =		no_llseek,
165	.unlocked_ioctl =	riowd_ioctl,
166	.compat_ioctl	=	compat_ptr_ioctl,
167	.open =			riowd_open,
168	.write =		riowd_write,
169	.release =		riowd_release,
170};
171
172static struct miscdevice riowd_miscdev = {
173	.minor	= WATCHDOG_MINOR,
174	.name	= "watchdog",
175	.fops	= &riowd_fops
176};
177
178static int riowd_probe(struct platform_device *op)
179{
180	struct riowd *p;
181	int err = -EINVAL;
182
183	if (riowd_device)
184		goto out;
185
186	err = -ENOMEM;
187	p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
188	if (!p)
189		goto out;
190
191	spin_lock_init(&p->lock);
192
193	p->regs = of_ioremap(&op->resource[0], 0, 2, DRIVER_NAME);
194	if (!p->regs) {
195		pr_err("Cannot map registers\n");
196		goto out;
197	}
198	/* Make miscdev useable right away */
199	riowd_device = p;
200
201	err = misc_register(&riowd_miscdev);
202	if (err) {
203		pr_err("Cannot register watchdog misc device\n");
204		goto out_iounmap;
205	}
206
207	pr_info("Hardware watchdog [%i minutes], regs at %p\n",
208		riowd_timeout, p->regs);
209
210	platform_set_drvdata(op, p);
211	return 0;
212
213out_iounmap:
214	riowd_device = NULL;
215	of_iounmap(&op->resource[0], p->regs, 2);
216
217out:
218	return err;
219}
220
221static int riowd_remove(struct platform_device *op)
222{
223	struct riowd *p = platform_get_drvdata(op);
224
225	misc_deregister(&riowd_miscdev);
226	of_iounmap(&op->resource[0], p->regs, 2);
227
228	return 0;
229}
230
231static const struct of_device_id riowd_match[] = {
232	{
233		.name = "pmc",
234	},
235	{},
236};
237MODULE_DEVICE_TABLE(of, riowd_match);
238
239static struct platform_driver riowd_driver = {
240	.driver = {
241		.name = DRIVER_NAME,
242		.of_match_table = riowd_match,
243	},
244	.probe		= riowd_probe,
245	.remove		= riowd_remove,
246};
247
248module_platform_driver(riowd_driver);
249