1 /*
2  * Watchdog driver for SBC-FITPC2 board
3  *
4  * Author: Denis Turischev <denis@compulab.co.il>
5  *
6  * Adapted from the IXP2000 watchdog driver by Deepak Saxena.
7  *
8  * This file is licensed under  the terms of the GNU General Public
9  * License version 2. This program is licensed "as is" without any
10  * warranty of any kind, whether express or implied.
11  */
12 
13 #define pr_fmt(fmt) KBUILD_MODNAME " WATCHDOG: " fmt
14 
15 #include <linux/module.h>
16 #include <linux/types.h>
17 #include <linux/miscdevice.h>
18 #include <linux/watchdog.h>
19 #include <linux/ioport.h>
20 #include <linux/delay.h>
21 #include <linux/fs.h>
22 #include <linux/init.h>
23 #include <linux/moduleparam.h>
24 #include <linux/dmi.h>
25 #include <linux/io.h>
26 #include <linux/uaccess.h>
27 
28 
29 static bool nowayout = WATCHDOG_NOWAYOUT;
30 static unsigned int margin = 60;	/* (secs) Default is 1 minute */
31 static unsigned long wdt_status;
32 static DEFINE_MUTEX(wdt_lock);
33 
34 #define WDT_IN_USE		0
35 #define WDT_OK_TO_CLOSE		1
36 
37 #define COMMAND_PORT		0x4c
38 #define DATA_PORT		0x48
39 
40 #define IFACE_ON_COMMAND	1
41 #define REBOOT_COMMAND		2
42 
43 #define WATCHDOG_NAME		"SBC-FITPC2 Watchdog"
44 
45 static void wdt_send_data(unsigned char command, unsigned char data)
46 {
47 	outb(data, DATA_PORT);
48 	msleep(200);
49 	outb(command, COMMAND_PORT);
50 	msleep(100);
51 }
52 
53 static void wdt_enable(void)
54 {
55 	mutex_lock(&wdt_lock);
56 	wdt_send_data(IFACE_ON_COMMAND, 1);
57 	wdt_send_data(REBOOT_COMMAND, margin);
58 	mutex_unlock(&wdt_lock);
59 }
60 
61 static void wdt_disable(void)
62 {
63 	mutex_lock(&wdt_lock);
64 	wdt_send_data(IFACE_ON_COMMAND, 0);
65 	wdt_send_data(REBOOT_COMMAND, 0);
66 	mutex_unlock(&wdt_lock);
67 }
68 
69 static int fitpc2_wdt_open(struct inode *inode, struct file *file)
70 {
71 	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
72 		return -EBUSY;
73 
74 	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
75 
76 	wdt_enable();
77 
78 	return stream_open(inode, file);
79 }
80 
81 static ssize_t fitpc2_wdt_write(struct file *file, const char __user *data,
82 						size_t len, loff_t *ppos)
83 {
84 	size_t i;
85 
86 	if (!len)
87 		return 0;
88 
89 	if (nowayout) {
90 		len = 0;
91 		goto out;
92 	}
93 
94 	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
95 
96 	for (i = 0; i != len; i++) {
97 		char c;
98 
99 		if (get_user(c, data + i))
100 			return -EFAULT;
101 
102 		if (c == 'V')
103 			set_bit(WDT_OK_TO_CLOSE, &wdt_status);
104 	}
105 
106 out:
107 	wdt_enable();
108 
109 	return len;
110 }
111 
112 
113 static const struct watchdog_info ident = {
114 	.options	= WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
115 				WDIOF_KEEPALIVEPING,
116 	.identity	= WATCHDOG_NAME,
117 };
118 
119 
120 static long fitpc2_wdt_ioctl(struct file *file, unsigned int cmd,
121 							unsigned long arg)
122 {
123 	int ret = -ENOTTY;
124 	int time;
125 
126 	switch (cmd) {
127 	case WDIOC_GETSUPPORT:
128 		ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
129 				   sizeof(ident)) ? -EFAULT : 0;
130 		break;
131 
132 	case WDIOC_GETSTATUS:
133 		ret = put_user(0, (int __user *)arg);
134 		break;
135 
136 	case WDIOC_GETBOOTSTATUS:
137 		ret = put_user(0, (int __user *)arg);
138 		break;
139 
140 	case WDIOC_KEEPALIVE:
141 		wdt_enable();
142 		ret = 0;
143 		break;
144 
145 	case WDIOC_SETTIMEOUT:
146 		ret = get_user(time, (int __user *)arg);
147 		if (ret)
148 			break;
149 
150 		if (time < 31 || time > 255) {
151 			ret = -EINVAL;
152 			break;
153 		}
154 
155 		margin = time;
156 		wdt_enable();
157 		fallthrough;
158 
159 	case WDIOC_GETTIMEOUT:
160 		ret = put_user(margin, (int __user *)arg);
161 		break;
162 	}
163 
164 	return ret;
165 }
166 
167 static int fitpc2_wdt_release(struct inode *inode, struct file *file)
168 {
169 	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
170 		wdt_disable();
171 		pr_info("Device disabled\n");
172 	} else {
173 		pr_warn("Device closed unexpectedly - timer will not stop\n");
174 		wdt_enable();
175 	}
176 
177 	clear_bit(WDT_IN_USE, &wdt_status);
178 	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
179 
180 	return 0;
181 }
182 
183 
184 static const struct file_operations fitpc2_wdt_fops = {
185 	.owner		= THIS_MODULE,
186 	.llseek		= no_llseek,
187 	.write		= fitpc2_wdt_write,
188 	.unlocked_ioctl	= fitpc2_wdt_ioctl,
189 	.compat_ioctl	= compat_ptr_ioctl,
190 	.open		= fitpc2_wdt_open,
191 	.release	= fitpc2_wdt_release,
192 };
193 
194 static struct miscdevice fitpc2_wdt_miscdev = {
195 	.minor		= WATCHDOG_MINOR,
196 	.name		= "watchdog",
197 	.fops		= &fitpc2_wdt_fops,
198 };
199 
200 static int __init fitpc2_wdt_init(void)
201 {
202 	int err;
203 	const char *brd_name;
204 
205 	brd_name = dmi_get_system_info(DMI_BOARD_NAME);
206 
207 	if (!brd_name || !strstr(brd_name, "SBC-FITPC2"))
208 		return -ENODEV;
209 
210 	pr_info("%s found\n", brd_name);
211 
212 	if (!request_region(COMMAND_PORT, 1, WATCHDOG_NAME)) {
213 		pr_err("I/O address 0x%04x already in use\n", COMMAND_PORT);
214 		return -EIO;
215 	}
216 
217 	if (!request_region(DATA_PORT, 1, WATCHDOG_NAME)) {
218 		pr_err("I/O address 0x%04x already in use\n", DATA_PORT);
219 		err = -EIO;
220 		goto err_data_port;
221 	}
222 
223 	if (margin < 31 || margin > 255) {
224 		pr_err("margin must be in range 31 - 255 seconds, you tried to set %d\n",
225 		       margin);
226 		err = -EINVAL;
227 		goto err_margin;
228 	}
229 
230 	err = misc_register(&fitpc2_wdt_miscdev);
231 	if (err) {
232 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
233 		       WATCHDOG_MINOR, err);
234 		goto err_margin;
235 	}
236 
237 	return 0;
238 
239 err_margin:
240 	release_region(DATA_PORT, 1);
241 err_data_port:
242 	release_region(COMMAND_PORT, 1);
243 
244 	return err;
245 }
246 
247 static void __exit fitpc2_wdt_exit(void)
248 {
249 	misc_deregister(&fitpc2_wdt_miscdev);
250 	release_region(DATA_PORT, 1);
251 	release_region(COMMAND_PORT, 1);
252 }
253 
254 module_init(fitpc2_wdt_init);
255 module_exit(fitpc2_wdt_exit);
256 
257 MODULE_AUTHOR("Denis Turischev <denis@compulab.co.il>");
258 MODULE_DESCRIPTION("SBC-FITPC2 Watchdog");
259 
260 module_param(margin, int, 0);
261 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
262 
263 module_param(nowayout, bool, 0);
264 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
265 
266 MODULE_LICENSE("GPL");
267