2 * linux/drivers/char/ar7_wdt.c
4 * Copyright (C) 2007 OpenWrt.org
5 * Copyright (c) 2005 Enrik Berkhan <Enrik.Berkhan@akk.org>
7 * Some code taken from:
8 * National Semiconductor SCx200 Watchdog support
9 * Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
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.
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.
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
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>
35 #include <linux/ioport.h>
37 #include <asm/addrspace.h>
39 #include <asm/uaccess.h>
41 #include <asm/ar7/ar7.h>
43 #define DRVNAME "ar7_wdt"
44 #define LONGNAME "TI AR7 Watchdog Timer"
46 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
47 MODULE_DESCRIPTION(LONGNAME);
48 MODULE_LICENSE("GPL");
49 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
51 static int margin = 60;
52 module_param(margin, int, 0);
53 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
55 static int nowayout = WATCHDOG_NOWAYOUT;
56 module_param(nowayout, int, 0);
57 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
70 static struct semaphore open_semaphore;
71 static unsigned expect_close;
73 /* XXX currently fixed, allows max margin ~68.72 secs */
74 #define prescale_value 0xFFFF
76 static void ar7_wdt_kick(u32 value)
78 volatile ar7_wdt_t *ar7_wdt = (ar7_wdt_t *)ioremap(AR7_REGS_WDT, sizeof(ar7_wdt_t));
80 ar7_wdt->kick_lock = 0x5555;
81 if ((ar7_wdt->kick_lock & 3) == 1) {
82 ar7_wdt->kick_lock = 0xAAAA;
83 if ((ar7_wdt->kick_lock & 3) == 3) {
84 ar7_wdt->kick = value;
88 printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
91 static void ar7_wdt_prescale(u32 value)
93 volatile ar7_wdt_t *ar7_wdt = (ar7_wdt_t *)ioremap(AR7_REGS_WDT, sizeof(ar7_wdt_t));
95 ar7_wdt->prescale_lock = 0x5A5A;
96 if ((ar7_wdt->prescale_lock & 3) == 1) {
97 ar7_wdt->prescale_lock = 0xA5A5;
98 if ((ar7_wdt->prescale_lock & 3) == 3) {
99 ar7_wdt->prescale = value;
103 printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
106 static void ar7_wdt_change(u32 value)
108 volatile ar7_wdt_t *ar7_wdt = (ar7_wdt_t *)ioremap(AR7_REGS_WDT, sizeof(ar7_wdt_t));
110 ar7_wdt->change_lock = 0x6666;
111 if ((ar7_wdt->change_lock & 3) == 1) {
112 ar7_wdt->change_lock = 0xBBBB;
113 if ((ar7_wdt->change_lock & 3) == 3) {
114 ar7_wdt->change = value;
118 printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
121 static void ar7_wdt_disable(u32 value)
123 volatile ar7_wdt_t *ar7_wdt = (ar7_wdt_t *)ioremap(AR7_REGS_WDT, sizeof(ar7_wdt_t));
125 ar7_wdt->disable_lock = 0x7777;
126 if ((ar7_wdt->disable_lock & 3) == 1) {
127 ar7_wdt->disable_lock = 0xCCCC;
128 if ((ar7_wdt->disable_lock & 3) == 2) {
129 ar7_wdt->disable_lock = 0xDDDD;
130 if ((ar7_wdt->disable_lock & 3) == 3) {
131 ar7_wdt->disable = value;
136 printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
139 static void ar7_wdt_update_margin(int new_margin)
143 change = new_margin * (ar7_vbus_freq() / prescale_value);
144 if (change < 1) change = 1;
145 if (change > 0xFFFF) change = 0xFFFF;
146 ar7_wdt_change(change);
147 margin = change * prescale_value / ar7_vbus_freq();
148 printk(KERN_INFO DRVNAME
149 ": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
150 margin, prescale_value, change, ar7_vbus_freq());
153 static void ar7_wdt_enable_wdt(void)
155 printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
160 static void ar7_wdt_disable_wdt(void)
162 printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n");
166 static int ar7_wdt_open(struct inode *inode, struct file *file)
168 /* only allow one at a time */
169 if (down_trylock(&open_semaphore))
171 ar7_wdt_enable_wdt();
177 static int ar7_wdt_release(struct inode *inode, struct file *file)
180 printk(KERN_WARNING DRVNAME ": watchdog device closed unexpectedly, will not disable the watchdog timer\n");
181 } else if (!nowayout) {
182 ar7_wdt_disable_wdt();
189 static int ar7_wdt_notify_sys(struct notifier_block *this,
190 unsigned long code, void *unused)
192 if (code == SYS_HALT || code == SYS_POWER_OFF)
194 ar7_wdt_disable_wdt();
199 static struct notifier_block ar7_wdt_notifier =
201 .notifier_call = ar7_wdt_notify_sys
204 static ssize_t ar7_wdt_write(struct file *file, const char *data,
205 size_t len, loff_t *ppos)
207 if (ppos != &file->f_pos)
210 /* check for a magic close character */
217 for (i = 0; i < len; ++i) {
219 if (get_user(c, data+i))
229 static int ar7_wdt_ioctl(struct inode *inode, struct file *file,
230 unsigned int cmd, unsigned long arg)
232 static struct watchdog_info ident = {
233 .identity = LONGNAME,
234 .firmware_version = 1,
235 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING),
242 case WDIOC_GETSUPPORT:
243 if(copy_to_user((struct watchdog_info *)arg, &ident,
247 case WDIOC_GETSTATUS:
248 case WDIOC_GETBOOTSTATUS:
249 if (put_user(0, (int *)arg))
252 case WDIOC_KEEPALIVE:
255 case WDIOC_SETTIMEOUT:
256 if (get_user(new_margin, (int *)arg))
261 ar7_wdt_update_margin(new_margin);
264 case WDIOC_GETTIMEOUT:
265 if (put_user(margin, (int *)arg))
271 static struct file_operations ar7_wdt_fops = {
272 .owner = THIS_MODULE,
273 .write = ar7_wdt_write,
274 .ioctl = ar7_wdt_ioctl,
275 .open = ar7_wdt_open,
276 .release = ar7_wdt_release,
279 static struct miscdevice ar7_wdt_miscdev = {
280 .minor = WATCHDOG_MINOR,
282 .fops = &ar7_wdt_fops,
285 static int __init ar7_wdt_init(void)
289 if (!request_mem_region(AR7_REGS_WDT, sizeof(ar7_wdt_t), LONGNAME)) {
290 printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
294 ar7_wdt_disable_wdt();
295 ar7_wdt_prescale(prescale_value);
296 ar7_wdt_update_margin(margin);
298 sema_init(&open_semaphore, 1);
300 rc = misc_register(&ar7_wdt_miscdev);
302 printk(KERN_ERR DRVNAME ": unable to register misc device\n");
306 rc = register_reboot_notifier(&ar7_wdt_notifier);
308 printk(KERN_ERR DRVNAME ": unable to register reboot notifier\n");
314 misc_deregister(&ar7_wdt_miscdev);
316 release_mem_region(AR7_REGS_WDT, sizeof(ar7_wdt_t));
321 static void __exit ar7_wdt_cleanup(void)
323 unregister_reboot_notifier(&ar7_wdt_notifier);
324 misc_deregister(&ar7_wdt_miscdev);
325 release_mem_region(AR7_REGS_WDT, sizeof(ar7_wdt_t));
328 module_init(ar7_wdt_init);
329 module_exit(ar7_wdt_cleanup);