Root/drivers/watchdog/sbc7240_wdt.c

1/*
2 * NANO7240 SBC Watchdog device driver
3 *
4 * Based on w83877f.c by Scott Jennings,
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation;
9 *
10 * Software distributed under the License is distributed on an "AS IS"
11 * basis, WITHOUT WARRANTY OF ANY KIND, either express or
12 * implied. See the License for the specific language governing
13 * rights and limitations under the License.
14 *
15 * (c) Copyright 2007 Gilles GIGAN <gilles.gigan@jcu.edu.au>
16 *
17 */
18
19#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21#include <linux/fs.h>
22#include <linux/init.h>
23#include <linux/ioport.h>
24#include <linux/jiffies.h>
25#include <linux/module.h>
26#include <linux/moduleparam.h>
27#include <linux/miscdevice.h>
28#include <linux/notifier.h>
29#include <linux/reboot.h>
30#include <linux/types.h>
31#include <linux/watchdog.h>
32#include <linux/io.h>
33#include <linux/uaccess.h>
34#include <linux/atomic.h>
35
36#define SBC7240_ENABLE_PORT 0x443
37#define SBC7240_DISABLE_PORT 0x043
38#define SBC7240_SET_TIMEOUT_PORT SBC7240_ENABLE_PORT
39#define SBC7240_MAGIC_CHAR 'V'
40
41#define SBC7240_TIMEOUT 30
42#define SBC7240_MAX_TIMEOUT 255
43static int timeout = SBC7240_TIMEOUT; /* in seconds */
44module_param(timeout, int, 0);
45MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<="
46         __MODULE_STRING(SBC7240_MAX_TIMEOUT) ", default="
47         __MODULE_STRING(SBC7240_TIMEOUT) ")");
48
49static bool nowayout = WATCHDOG_NOWAYOUT;
50module_param(nowayout, bool, 0);
51MODULE_PARM_DESC(nowayout, "Disable watchdog when closing device file");
52
53#define SBC7240_OPEN_STATUS_BIT 0
54#define SBC7240_ENABLED_STATUS_BIT 1
55#define SBC7240_EXPECT_CLOSE_STATUS_BIT 2
56static unsigned long wdt_status;
57
58/*
59 * Utility routines
60 */
61
62static void wdt_disable(void)
63{
64    /* disable the watchdog */
65    if (test_and_clear_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
66        inb_p(SBC7240_DISABLE_PORT);
67        pr_info("Watchdog timer is now disabled\n");
68    }
69}
70
71static void wdt_enable(void)
72{
73    /* enable the watchdog */
74    if (!test_and_set_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status)) {
75        inb_p(SBC7240_ENABLE_PORT);
76        pr_info("Watchdog timer is now enabled\n");
77    }
78}
79
80static int wdt_set_timeout(int t)
81{
82    if (t < 1 || t > SBC7240_MAX_TIMEOUT) {
83        pr_err("timeout value must be 1<=x<=%d\n", SBC7240_MAX_TIMEOUT);
84        return -1;
85    }
86    /* set the timeout */
87    outb_p((unsigned)t, SBC7240_SET_TIMEOUT_PORT);
88    timeout = t;
89    pr_info("timeout set to %d seconds\n", t);
90    return 0;
91}
92
93/* Whack the dog */
94static inline void wdt_keepalive(void)
95{
96    if (test_bit(SBC7240_ENABLED_STATUS_BIT, &wdt_status))
97        inb_p(SBC7240_ENABLE_PORT);
98}
99
100/*
101 * /dev/watchdog handling
102 */
103static ssize_t fop_write(struct file *file, const char __user *buf,
104             size_t count, loff_t *ppos)
105{
106    size_t i;
107    char c;
108
109    if (count) {
110        if (!nowayout) {
111            clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
112                &wdt_status);
113
114            /* is there a magic char ? */
115            for (i = 0; i != count; i++) {
116                if (get_user(c, buf + i))
117                    return -EFAULT;
118                if (c == SBC7240_MAGIC_CHAR) {
119                    set_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT,
120                        &wdt_status);
121                    break;
122                }
123            }
124        }
125
126        wdt_keepalive();
127    }
128
129    return count;
130}
131
132static int fop_open(struct inode *inode, struct file *file)
133{
134    if (test_and_set_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status))
135        return -EBUSY;
136
137    wdt_enable();
138
139    return nonseekable_open(inode, file);
140}
141
142static int fop_close(struct inode *inode, struct file *file)
143{
144    if (test_and_clear_bit(SBC7240_EXPECT_CLOSE_STATUS_BIT, &wdt_status)
145        || !nowayout) {
146        wdt_disable();
147    } else {
148        pr_crit("Unexpected close, not stopping watchdog!\n");
149        wdt_keepalive();
150    }
151
152    clear_bit(SBC7240_OPEN_STATUS_BIT, &wdt_status);
153    return 0;
154}
155
156static const struct watchdog_info ident = {
157    .options = WDIOF_KEEPALIVEPING|
158           WDIOF_SETTIMEOUT|
159           WDIOF_MAGICCLOSE,
160    .firmware_version = 1,
161    .identity = "SBC7240",
162};
163
164
165static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
166{
167    switch (cmd) {
168    case WDIOC_GETSUPPORT:
169        return copy_to_user((void __user *)arg, &ident, sizeof(ident))
170                         ? -EFAULT : 0;
171    case WDIOC_GETSTATUS:
172    case WDIOC_GETBOOTSTATUS:
173        return put_user(0, (int __user *)arg);
174    case WDIOC_SETOPTIONS:
175    {
176        int options;
177        int retval = -EINVAL;
178
179        if (get_user(options, (int __user *)arg))
180            return -EFAULT;
181
182        if (options & WDIOS_DISABLECARD) {
183            wdt_disable();
184            retval = 0;
185        }
186
187        if (options & WDIOS_ENABLECARD) {
188            wdt_enable();
189            retval = 0;
190        }
191
192        return retval;
193    }
194    case WDIOC_KEEPALIVE:
195        wdt_keepalive();
196        return 0;
197    case WDIOC_SETTIMEOUT:
198    {
199        int new_timeout;
200
201        if (get_user(new_timeout, (int __user *)arg))
202            return -EFAULT;
203
204        if (wdt_set_timeout(new_timeout))
205            return -EINVAL;
206
207        /* Fall through */
208    }
209    case WDIOC_GETTIMEOUT:
210        return put_user(timeout, (int __user *)arg);
211    default:
212        return -ENOTTY;
213    }
214}
215
216static const struct file_operations wdt_fops = {
217    .owner = THIS_MODULE,
218    .llseek = no_llseek,
219    .write = fop_write,
220    .open = fop_open,
221    .release = fop_close,
222    .unlocked_ioctl = fop_ioctl,
223};
224
225static struct miscdevice wdt_miscdev = {
226    .minor = WATCHDOG_MINOR,
227    .name = "watchdog",
228    .fops = &wdt_fops,
229};
230
231/*
232 * Notifier for system down
233 */
234
235static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
236              void *unused)
237{
238    if (code == SYS_DOWN || code == SYS_HALT)
239        wdt_disable();
240    return NOTIFY_DONE;
241}
242
243static struct notifier_block wdt_notifier = {
244    .notifier_call = wdt_notify_sys,
245};
246
247static void __exit sbc7240_wdt_unload(void)
248{
249    pr_info("Removing watchdog\n");
250    misc_deregister(&wdt_miscdev);
251
252    unregister_reboot_notifier(&wdt_notifier);
253    release_region(SBC7240_ENABLE_PORT, 1);
254}
255
256static int __init sbc7240_wdt_init(void)
257{
258    int rc = -EBUSY;
259
260    if (!request_region(SBC7240_ENABLE_PORT, 1, "SBC7240 WDT")) {
261        pr_err("I/O address 0x%04x already in use\n",
262               SBC7240_ENABLE_PORT);
263        rc = -EIO;
264        goto err_out;
265    }
266
267    /* The IO port 0x043 used to disable the watchdog
268     * is already claimed by the system timer, so we
269     * can't request_region() it ...*/
270
271    if (timeout < 1 || timeout > SBC7240_MAX_TIMEOUT) {
272        timeout = SBC7240_TIMEOUT;
273        pr_info("timeout value must be 1<=x<=%d, using %d\n",
274            SBC7240_MAX_TIMEOUT, timeout);
275    }
276    wdt_set_timeout(timeout);
277    wdt_disable();
278
279    rc = register_reboot_notifier(&wdt_notifier);
280    if (rc) {
281        pr_err("cannot register reboot notifier (err=%d)\n", rc);
282        goto err_out_region;
283    }
284
285    rc = misc_register(&wdt_miscdev);
286    if (rc) {
287        pr_err("cannot register miscdev on minor=%d (err=%d)\n",
288               wdt_miscdev.minor, rc);
289        goto err_out_reboot_notifier;
290    }
291
292    pr_info("Watchdog driver for SBC7240 initialised (nowayout=%d)\n",
293        nowayout);
294
295    return 0;
296
297err_out_reboot_notifier:
298    unregister_reboot_notifier(&wdt_notifier);
299err_out_region:
300    release_region(SBC7240_ENABLE_PORT, 1);
301err_out:
302    return rc;
303}
304
305module_init(sbc7240_wdt_init);
306module_exit(sbc7240_wdt_unload);
307
308MODULE_AUTHOR("Gilles Gigan");
309MODULE_DESCRIPTION("Watchdog device driver for single board"
310           " computers EPIC Nano 7240 from iEi");
311MODULE_LICENSE("GPL");
312MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
313
314

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