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(value: data, DATA_PORT);
46 msleep(msecs: 200);
47 outb(value: command, COMMAND_PORT);
48 msleep(msecs: 100);
49}
50
51static void wdt_enable(void)
52{
53 mutex_lock(&wdt_lock);
54 wdt_send_data(IFACE_ON_COMMAND, data: 1);
55 wdt_send_data(REBOOT_COMMAND, data: margin);
56 mutex_unlock(lock: &wdt_lock);
57}
58
59static void wdt_disable(void)
60{
61 mutex_lock(&wdt_lock);
62 wdt_send_data(IFACE_ON_COMMAND, data: 0);
63 wdt_send_data(REBOOT_COMMAND, data: 0);
64 mutex_unlock(lock: &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, addr: &wdt_status))
70 return -EBUSY;
71
72 clear_bit(WDT_OK_TO_CLOSE, addr: &wdt_status);
73
74 wdt_enable();
75
76 return stream_open(inode, filp: 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, addr: &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, addr: &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(to: (struct watchdog_info __user *)arg, from: &ident,
127 n: 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, addr: &wdt_status);
176 clear_bit(WDT_OK_TO_CLOSE, addr: &wdt_status);
177
178 return 0;
179}
180
181
182static const struct file_operations fitpc2_wdt_fops = {
183 .owner = THIS_MODULE,
184 .write = fitpc2_wdt_write,
185 .unlocked_ioctl = fitpc2_wdt_ioctl,
186 .compat_ioctl = compat_ptr_ioctl,
187 .open = fitpc2_wdt_open,
188 .release = fitpc2_wdt_release,
189};
190
191static struct miscdevice fitpc2_wdt_miscdev = {
192 .minor = WATCHDOG_MINOR,
193 .name = "watchdog",
194 .fops = &fitpc2_wdt_fops,
195};
196
197static int __init fitpc2_wdt_init(void)
198{
199 int err;
200 const char *brd_name;
201
202 brd_name = dmi_get_system_info(field: DMI_BOARD_NAME);
203
204 if (!brd_name || !strstr(brd_name, "SBC-FITPC2"))
205 return -ENODEV;
206
207 pr_info("%s found\n", brd_name);
208
209 if (!request_region(COMMAND_PORT, 1, WATCHDOG_NAME)) {
210 pr_err("I/O address 0x%04x already in use\n", COMMAND_PORT);
211 return -EIO;
212 }
213
214 if (!request_region(DATA_PORT, 1, WATCHDOG_NAME)) {
215 pr_err("I/O address 0x%04x already in use\n", DATA_PORT);
216 err = -EIO;
217 goto err_data_port;
218 }
219
220 if (margin < 31 || margin > 255) {
221 pr_err("margin must be in range 31 - 255 seconds, you tried to set %d\n",
222 margin);
223 err = -EINVAL;
224 goto err_margin;
225 }
226
227 err = misc_register(misc: &fitpc2_wdt_miscdev);
228 if (err) {
229 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
230 WATCHDOG_MINOR, err);
231 goto err_margin;
232 }
233
234 return 0;
235
236err_margin:
237 release_region(DATA_PORT, 1);
238err_data_port:
239 release_region(COMMAND_PORT, 1);
240
241 return err;
242}
243
244static void __exit fitpc2_wdt_exit(void)
245{
246 misc_deregister(misc: &fitpc2_wdt_miscdev);
247 release_region(DATA_PORT, 1);
248 release_region(COMMAND_PORT, 1);
249}
250
251module_init(fitpc2_wdt_init);
252module_exit(fitpc2_wdt_exit);
253
254MODULE_AUTHOR("Denis Turischev <denis@compulab.co.il>");
255MODULE_DESCRIPTION("SBC-FITPC2 Watchdog");
256
257module_param(margin, int, 0);
258MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
259
260module_param(nowayout, bool, 0);
261MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
262
263MODULE_LICENSE("GPL");
264

source code of linux/drivers/watchdog/sbc_fitpc2_wdt.c