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
29static bool nowayout = WATCHDOG_NOWAYOUT;
30static unsigned int margin = 60;	/* (secs) Default is 1 minute */
31static unsigned long wdt_status;
32static 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
45static 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
53static 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
61static 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
69static 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 nonseekable_open(inode, file);
79}
80
81static ssize_t fitpc2_wdt_write(struct file *file, const char *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
106out:
107	wdt_enable();
108
109	return len;
110}
111
112
113static const struct watchdog_info ident = {
114	.options	= WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
115				WDIOF_KEEPALIVEPING,
116	.identity	= WATCHDOG_NAME,
117};
118
119
120static 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 *)arg, &ident,
129				   sizeof(ident)) ? -EFAULT : 0;
130		break;
131
132	case WDIOC_GETSTATUS:
133		ret = put_user(0, (int *)arg);
134		break;
135
136	case WDIOC_GETBOOTSTATUS:
137		ret = put_user(0, (int *)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 *)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		/* Fall through */
158
159	case WDIOC_GETTIMEOUT:
160		ret = put_user(margin, (int *)arg);
161		break;
162	}
163
164	return ret;
165}
166
167static 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
184static 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	.open		= fitpc2_wdt_open,
190	.release	= fitpc2_wdt_release,
191};
192
193static struct miscdevice fitpc2_wdt_miscdev = {
194	.minor		= WATCHDOG_MINOR,
195	.name		= "watchdog",
196	.fops		= &fitpc2_wdt_fops,
197};
198
199static int __init fitpc2_wdt_init(void)
200{
201	int err;
202	const char *brd_name;
203
204	brd_name = dmi_get_system_info(DMI_BOARD_NAME);
205
206	if (!brd_name || !strstr(brd_name, "SBC-FITPC2"))
207		return -ENODEV;
208
209	pr_info("%s found\n", brd_name);
210
211	if (!request_region(COMMAND_PORT, 1, WATCHDOG_NAME)) {
212		pr_err("I/O address 0x%04x already in use\n", COMMAND_PORT);
213		return -EIO;
214	}
215
216	if (!request_region(DATA_PORT, 1, WATCHDOG_NAME)) {
217		pr_err("I/O address 0x%04x already in use\n", DATA_PORT);
218		err = -EIO;
219		goto err_data_port;
220	}
221
222	if (margin < 31 || margin > 255) {
223		pr_err("margin must be in range 31 - 255 seconds, you tried to set %d\n",
224		       margin);
225		err = -EINVAL;
226		goto err_margin;
227	}
228
229	err = misc_register(&fitpc2_wdt_miscdev);
230	if (err) {
231		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
232		       WATCHDOG_MINOR, err);
233		goto err_margin;
234	}
235
236	return 0;
237
238err_margin:
239	release_region(DATA_PORT, 1);
240err_data_port:
241	release_region(COMMAND_PORT, 1);
242
243	return err;
244}
245
246static void __exit fitpc2_wdt_exit(void)
247{
248	misc_deregister(&fitpc2_wdt_miscdev);
249	release_region(DATA_PORT, 1);
250	release_region(COMMAND_PORT, 1);
251}
252
253module_init(fitpc2_wdt_init);
254module_exit(fitpc2_wdt_exit);
255
256MODULE_AUTHOR("Denis Turischev <denis@compulab.co.il>");
257MODULE_DESCRIPTION("SBC-FITPC2 Watchdog");
258
259module_param(margin, int, 0);
260MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
261
262module_param(nowayout, bool, 0);
263MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
264
265MODULE_LICENSE("GPL");
266