1 /*
2 * drivers/watchdog/ar7_wdt.c
3 *
4 * Copyright (C) 2007 Nicolas Thill <nico@openwrt.org>
5 * Copyright (c) 2005 Enrik Berkhan <Enrik.Berkhan@akk.org>
6 *
7 * Some code taken from:
8 * National Semiconductor SCx200 Watchdog support
9 * Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
24 */
25
26 #include <linux/module.h>
27 #include <linux/moduleparam.h>
28 #include <linux/errno.h>
29 #include <linux/init.h>
30 #include <linux/miscdevice.h>
31 #include <linux/watchdog.h>
32 #include <linux/notifier.h>
33 #include <linux/reboot.h>
34 #include <linux/fs.h>
35 #include <linux/ioport.h>
36 #include <linux/io.h>
37 #include <linux/uaccess.h>
38
39 #include <asm/addrspace.h>
40 #include <asm/ar7/ar7.h>
41
42 #define DRVNAME "ar7_wdt"
43 #define LONGNAME "TI AR7 Watchdog Timer"
44
45 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
46 MODULE_DESCRIPTION(LONGNAME);
47 MODULE_LICENSE("GPL");
48 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
49
50 static int margin = 60;
51 module_param(margin, int, 0);
52 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
53
54 static int nowayout = WATCHDOG_NOWAYOUT;
55 module_param(nowayout, int, 0);
56 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
57
58 #define READ_REG(x) readl((void __iomem *)&(x))
59 #define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))
60
61 struct ar7_wdt {
62 u32 kick_lock;
63 u32 kick;
64 u32 change_lock;
65 u32 change;
66 u32 disable_lock;
67 u32 disable;
68 u32 prescale_lock;
69 u32 prescale;
70 };
71
72 static unsigned long wdt_is_open;
73 static spinlock_t wdt_lock;
74 static unsigned expect_close;
75
76 /* XXX currently fixed, allows max margin ~68.72 secs */
77 #define prescale_value 0xffff
78
79 /* Offset of the WDT registers */
80 static unsigned long ar7_regs_wdt;
81 /* Pointer to the remapped WDT IO space */
82 static struct ar7_wdt *ar7_wdt;
ar7_wdt_get_regs(void)83 static void ar7_wdt_get_regs(void)
84 {
85 u16 chip_id = ar7_chip_id();
86 switch (chip_id) {
87 case AR7_CHIP_7100:
88 case AR7_CHIP_7200:
89 ar7_regs_wdt = AR7_REGS_WDT;
90 break;
91 default:
92 ar7_regs_wdt = UR8_REGS_WDT;
93 break;
94 }
95 }
96
97
ar7_wdt_kick(u32 value)98 static void ar7_wdt_kick(u32 value)
99 {
100 WRITE_REG(ar7_wdt->kick_lock, 0x5555);
101 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
102 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
103 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
104 WRITE_REG(ar7_wdt->kick, value);
105 return;
106 }
107 }
108 printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
109 }
110
ar7_wdt_prescale(u32 value)111 static void ar7_wdt_prescale(u32 value)
112 {
113 WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
114 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
115 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
116 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
117 WRITE_REG(ar7_wdt->prescale, value);
118 return;
119 }
120 }
121 printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
122 }
123
ar7_wdt_change(u32 value)124 static void ar7_wdt_change(u32 value)
125 {
126 WRITE_REG(ar7_wdt->change_lock, 0x6666);
127 if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
128 WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
129 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
130 WRITE_REG(ar7_wdt->change, value);
131 return;
132 }
133 }
134 printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
135 }
136
ar7_wdt_disable(u32 value)137 static void ar7_wdt_disable(u32 value)
138 {
139 WRITE_REG(ar7_wdt->disable_lock, 0x7777);
140 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
141 WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
142 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
143 WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
144 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
145 WRITE_REG(ar7_wdt->disable, value);
146 return;
147 }
148 }
149 }
150 printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
151 }
152
ar7_wdt_update_margin(int new_margin)153 static void ar7_wdt_update_margin(int new_margin)
154 {
155 u32 change;
156
157 change = new_margin * (ar7_vbus_freq() / prescale_value);
158 if (change < 1)
159 change = 1;
160 if (change > 0xffff)
161 change = 0xffff;
162 ar7_wdt_change(change);
163 margin = change * prescale_value / ar7_vbus_freq();
164 printk(KERN_INFO DRVNAME
165 ": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
166 margin, prescale_value, change, ar7_vbus_freq());
167 }
168
ar7_wdt_enable_wdt(void)169 static void ar7_wdt_enable_wdt(void)
170 {
171 printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
172 ar7_wdt_disable(1);
173 ar7_wdt_kick(1);
174 }
175
ar7_wdt_disable_wdt(void)176 static void ar7_wdt_disable_wdt(void)
177 {
178 printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
179 ar7_wdt_disable(0);
180 }
181
ar7_wdt_open(struct inode * inode,struct file * file)182 static int ar7_wdt_open(struct inode *inode, struct file *file)
183 {
184 /* only allow one at a time */
185 if (test_and_set_bit(0, &wdt_is_open))
186 return -EBUSY;
187 ar7_wdt_enable_wdt();
188 expect_close = 0;
189
190 return nonseekable_open(inode, file);
191 }
192
ar7_wdt_release(struct inode * inode,struct file * file)193 static int ar7_wdt_release(struct inode *inode, struct file *file)
194 {
195 if (!expect_close)
196 printk(KERN_WARNING DRVNAME
197 ": watchdog device closed unexpectedly,"
198 "will not disable the watchdog timer\n");
199 else if (!nowayout)
200 ar7_wdt_disable_wdt();
201 clear_bit(0, &wdt_is_open);
202 return 0;
203 }
204
ar7_wdt_notify_sys(struct notifier_block * this,unsigned long code,void * unused)205 static int ar7_wdt_notify_sys(struct notifier_block *this,
206 unsigned long code, void *unused)
207 {
208 if (code == SYS_HALT || code == SYS_POWER_OFF)
209 if (!nowayout)
210 ar7_wdt_disable_wdt();
211
212 return NOTIFY_DONE;
213 }
214
215 static struct notifier_block ar7_wdt_notifier = {
216 .notifier_call = ar7_wdt_notify_sys,
217 };
218
ar7_wdt_write(struct file * file,const char * data,size_t len,loff_t * ppos)219 static ssize_t ar7_wdt_write(struct file *file, const char *data,
220 size_t len, loff_t *ppos)
221 {
222 /* check for a magic close character */
223 if (len) {
224 size_t i;
225
226 spin_lock(&wdt_lock);
227 ar7_wdt_kick(1);
228 spin_unlock(&wdt_lock);
229
230 expect_close = 0;
231 for (i = 0; i < len; ++i) {
232 char c;
233 if (get_user(c, data + i))
234 return -EFAULT;
235 if (c == 'V')
236 expect_close = 1;
237 }
238
239 }
240 return len;
241 }
242
ar7_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)243 static long ar7_wdt_ioctl(struct file *file,
244 unsigned int cmd, unsigned long arg)
245 {
246 static struct watchdog_info ident = {
247 .identity = LONGNAME,
248 .firmware_version = 1,
249 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING),
250 };
251 int new_margin;
252
253 switch (cmd) {
254 case WDIOC_GETSUPPORT:
255 if (copy_to_user((struct watchdog_info *)arg, &ident,
256 sizeof(ident)))
257 return -EFAULT;
258 return 0;
259 case WDIOC_GETSTATUS:
260 case WDIOC_GETBOOTSTATUS:
261 if (put_user(0, (int *)arg))
262 return -EFAULT;
263 return 0;
264 case WDIOC_KEEPALIVE:
265 ar7_wdt_kick(1);
266 return 0;
267 case WDIOC_SETTIMEOUT:
268 if (get_user(new_margin, (int *)arg))
269 return -EFAULT;
270 if (new_margin < 1)
271 return -EINVAL;
272
273 spin_lock(&wdt_lock);
274 ar7_wdt_update_margin(new_margin);
275 ar7_wdt_kick(1);
276 spin_unlock(&wdt_lock);
277
278 case WDIOC_GETTIMEOUT:
279 if (put_user(margin, (int *)arg))
280 return -EFAULT;
281 return 0;
282 default:
283 return -ENOTTY;
284 }
285 }
286
287 static const struct file_operations ar7_wdt_fops = {
288 .owner = THIS_MODULE,
289 .write = ar7_wdt_write,
290 .unlocked_ioctl = ar7_wdt_ioctl,
291 .open = ar7_wdt_open,
292 .release = ar7_wdt_release,
293 };
294
295 static struct miscdevice ar7_wdt_miscdev = {
296 .minor = WATCHDOG_MINOR,
297 .name = "watchdog",
298 .fops = &ar7_wdt_fops,
299 };
300
ar7_wdt_init(void)301 static int __init ar7_wdt_init(void)
302 {
303 int rc;
304
305 spin_lock_init(&wdt_lock);
306
307 ar7_wdt_get_regs();
308
309 if (!request_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt),
310 LONGNAME)) {
311 printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
312 return -EBUSY;
313 }
314
315 ar7_wdt = (struct ar7_wdt *)
316 ioremap(ar7_regs_wdt, sizeof(struct ar7_wdt));
317
318 ar7_wdt_disable_wdt();
319 ar7_wdt_prescale(prescale_value);
320 ar7_wdt_update_margin(margin);
321
322 rc = register_reboot_notifier(&ar7_wdt_notifier);
323 if (rc) {
324 printk(KERN_ERR DRVNAME
325 ": unable to register reboot notifier\n");
326 goto out_alloc;
327 }
328
329 rc = misc_register(&ar7_wdt_miscdev);
330 if (rc) {
331 printk(KERN_ERR DRVNAME ": unable to register misc device\n");
332 goto out_register;
333 }
334 goto out;
335
336 out_register:
337 unregister_reboot_notifier(&ar7_wdt_notifier);
338 out_alloc:
339 iounmap(ar7_wdt);
340 release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt));
341 out:
342 return rc;
343 }
344
ar7_wdt_cleanup(void)345 static void __exit ar7_wdt_cleanup(void)
346 {
347 misc_deregister(&ar7_wdt_miscdev);
348 unregister_reboot_notifier(&ar7_wdt_notifier);
349 iounmap(ar7_wdt);
350 release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt));
351 }
352
353 module_init(ar7_wdt_init);
354 module_exit(ar7_wdt_cleanup);
355