1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Watchdog driver for SBC-FITPC2 board
4 *
5 * Author: Denis Turischev <denis@compulab.co.il>
6 *
7 * Adapted from the IXP2000 watchdog driver by Deepak Saxena.
8 *
9 */
10
11#define pr_fmt(fmt) KBUILD_MODNAME " WATCHDOG: " fmt
12
13#include <linux/module.h>
14#include <linux/types.h>
15#include <linux/miscdevice.h>
16#include <linux/watchdog.h>
17#include <linux/ioport.h>
18#include <linux/delay.h>
19#include <linux/fs.h>
20#include <linux/init.h>
21#include <linux/moduleparam.h>
22#include <linux/dmi.h>
23#include <linux/io.h>
24#include <linux/uaccess.h>
25
26
27static bool nowayout = WATCHDOG_NOWAYOUT;
28static unsigned int margin = 60;	/* (secs) Default is 1 minute */
29static unsigned long wdt_status;
30static DEFINE_MUTEX(wdt_lock);
31
32#define WDT_IN_USE		0
33#define WDT_OK_TO_CLOSE		1
34
35#define COMMAND_PORT		0x4c
36#define DATA_PORT		0x48
37
38#define IFACE_ON_COMMAND	1
39#define REBOOT_COMMAND		2
40
41#define WATCHDOG_NAME		"SBC-FITPC2 Watchdog"
42
43static void wdt_send_data(unsigned char command, unsigned char data)
44{
45	outb(data, DATA_PORT);
46	msleep(200);
47	outb(command, COMMAND_PORT);
48	msleep(100);
49}
50
51static void wdt_enable(void)
52{
53	mutex_lock(&wdt_lock);
54	wdt_send_data(IFACE_ON_COMMAND, 1);
55	wdt_send_data(REBOOT_COMMAND, margin);
56	mutex_unlock(&wdt_lock);
57}
58
59static void wdt_disable(void)
60{
61	mutex_lock(&wdt_lock);
62	wdt_send_data(IFACE_ON_COMMAND, 0);
63	wdt_send_data(REBOOT_COMMAND, 0);
64	mutex_unlock(&wdt_lock);
65}
66
67static int fitpc2_wdt_open(struct inode *inode, struct file *file)
68{
69	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
70		return -EBUSY;
71
72	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
73
74	wdt_enable();
75
76	return stream_open(inode, file);
77}
78
79static ssize_t fitpc2_wdt_write(struct file *file, const char __user *data,
80						size_t len, loff_t *ppos)
81{
82	size_t i;
83
84	if (!len)
85		return 0;
86
87	if (nowayout) {
88		len = 0;
89		goto out;
90	}
91
92	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
93
94	for (i = 0; i != len; i++) {
95		char c;
96
97		if (get_user(c, data + i))
98			return -EFAULT;
99
100		if (c == 'V')
101			set_bit(WDT_OK_TO_CLOSE, &wdt_status);
102	}
103
104out:
105	wdt_enable();
106
107	return len;
108}
109
110
111static const struct watchdog_info ident = {
112	.options	= WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
113				WDIOF_KEEPALIVEPING,
114	.identity	= WATCHDOG_NAME,
115};
116
117
118static long fitpc2_wdt_ioctl(struct file *file, unsigned int cmd,
119							unsigned long arg)
120{
121	int ret = -ENOTTY;
122	int time;
123
124	switch (cmd) {
125	case WDIOC_GETSUPPORT:
126		ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
127				   sizeof(ident)) ? -EFAULT : 0;
128		break;
129
130	case WDIOC_GETSTATUS:
131		ret = put_user(0, (int __user *)arg);
132		break;
133
134	case WDIOC_GETBOOTSTATUS:
135		ret = put_user(0, (int __user *)arg);
136		break;
137
138	case WDIOC_KEEPALIVE:
139		wdt_enable();
140		ret = 0;
141		break;
142
143	case WDIOC_SETTIMEOUT:
144		ret = get_user(time, (int __user *)arg);
145		if (ret)
146			break;
147
148		if (time < 31 || time > 255) {
149			ret = -EINVAL;
150			break;
151		}
152
153		margin = time;
154		wdt_enable();
155		fallthrough;
156
157	case WDIOC_GETTIMEOUT:
158		ret = put_user(margin, (int __user *)arg);
159		break;
160	}
161
162	return ret;
163}
164
165static int fitpc2_wdt_release(struct inode *inode, struct file *file)
166{
167	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
168		wdt_disable();
169		pr_info("Device disabled\n");
170	} else {
171		pr_warn("Device closed unexpectedly - timer will not stop\n");
172		wdt_enable();
173	}
174
175	clear_bit(WDT_IN_USE, &wdt_status);
176	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
177
178	return 0;
179}
180
181
182static const struct file_operations fitpc2_wdt_fops = {
183	.owner		= THIS_MODULE,
184	.llseek		= no_llseek,
185	.write		= fitpc2_wdt_write,
186	.unlocked_ioctl	= fitpc2_wdt_ioctl,
187	.compat_ioctl	= compat_ptr_ioctl,
188	.open		= fitpc2_wdt_open,
189	.release	= fitpc2_wdt_release,
190};
191
192static struct miscdevice fitpc2_wdt_miscdev = {
193	.minor		= WATCHDOG_MINOR,
194	.name		= "watchdog",
195	.fops		= &fitpc2_wdt_fops,
196};
197
198static int __init fitpc2_wdt_init(void)
199{
200	int err;
201	const char *brd_name;
202
203	brd_name = dmi_get_system_info(DMI_BOARD_NAME);
204
205	if (!brd_name || !strstr(brd_name, "SBC-FITPC2"))
206		return -ENODEV;
207
208	pr_info("%s found\n", brd_name);
209
210	if (!request_region(COMMAND_PORT, 1, WATCHDOG_NAME)) {
211		pr_err("I/O address 0x%04x already in use\n", COMMAND_PORT);
212		return -EIO;
213	}
214
215	if (!request_region(DATA_PORT, 1, WATCHDOG_NAME)) {
216		pr_err("I/O address 0x%04x already in use\n", DATA_PORT);
217		err = -EIO;
218		goto err_data_port;
219	}
220
221	if (margin < 31 || margin > 255) {
222		pr_err("margin must be in range 31 - 255 seconds, you tried to set %d\n",
223		       margin);
224		err = -EINVAL;
225		goto err_margin;
226	}
227
228	err = misc_register(&fitpc2_wdt_miscdev);
229	if (err) {
230		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
231		       WATCHDOG_MINOR, err);
232		goto err_margin;
233	}
234
235	return 0;
236
237err_margin:
238	release_region(DATA_PORT, 1);
239err_data_port:
240	release_region(COMMAND_PORT, 1);
241
242	return err;
243}
244
245static void __exit fitpc2_wdt_exit(void)
246{
247	misc_deregister(&fitpc2_wdt_miscdev);
248	release_region(DATA_PORT, 1);
249	release_region(COMMAND_PORT, 1);
250}
251
252module_init(fitpc2_wdt_init);
253module_exit(fitpc2_wdt_exit);
254
255MODULE_AUTHOR("Denis Turischev <denis@compulab.co.il>");
256MODULE_DESCRIPTION("SBC-FITPC2 Watchdog");
257
258module_param(margin, int, 0);
259MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
260
261module_param(nowayout, bool, 0);
262MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
263
264MODULE_LICENSE("GPL");
265