drm/radeon/rv740: fix backend setup
[linux-2.6.git] / drivers / watchdog / ixp2000_wdt.c
1 /*
2  * drivers/char/watchdog/ixp2000_wdt.c
3  *
4  * Watchdog driver for Intel IXP2000 network processors
5  *
6  * Adapted from the IXP4xx watchdog driver by Lennert Buytenhek.
7  * The original version carries these notices:
8  *
9  * Author: Deepak Saxena <dsaxena@plexity.net>
10  *
11  * Copyright 2004 (c) MontaVista, Software, Inc.
12  * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
13  *
14  * This file is licensed under  the terms of the GNU General Public
15  * License version 2. This program is licensed "as is" without any
16  * warranty of any kind, whether express or implied.
17  */
18
19 #include <linux/module.h>
20 #include <linux/moduleparam.h>
21 #include <linux/types.h>
22 #include <linux/kernel.h>
23 #include <linux/fs.h>
24 #include <linux/miscdevice.h>
25 #include <linux/watchdog.h>
26 #include <linux/init.h>
27 #include <linux/bitops.h>
28 #include <linux/uaccess.h>
29 #include <mach/hardware.h>
30
31 static int nowayout = WATCHDOG_NOWAYOUT;
32 static unsigned int heartbeat = 60;     /* (secs) Default is 1 minute */
33 static unsigned long wdt_status;
34 static spinlock_t wdt_lock;
35
36 #define WDT_IN_USE              0
37 #define WDT_OK_TO_CLOSE         1
38
39 static unsigned long wdt_tick_rate;
40
41 static void wdt_enable(void)
42 {
43         spin_lock(&wdt_lock);
44         ixp2000_reg_write(IXP2000_RESET0, *(IXP2000_RESET0) | WDT_RESET_ENABLE);
45         ixp2000_reg_write(IXP2000_TWDE, WDT_ENABLE);
46         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
47         ixp2000_reg_write(IXP2000_T4_CTL, TIMER_DIVIDER_256 | TIMER_ENABLE);
48         spin_unlock(&wdt_lock);
49 }
50
51 static void wdt_disable(void)
52 {
53         spin_lock(&wdt_lock);
54         ixp2000_reg_write(IXP2000_T4_CTL, 0);
55         spin_unlock(&wdt_lock);
56 }
57
58 static void wdt_keepalive(void)
59 {
60         spin_lock(&wdt_lock);
61         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
62         spin_unlock(&wdt_lock);
63 }
64
65 static int ixp2000_wdt_open(struct inode *inode, struct file *file)
66 {
67         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
68                 return -EBUSY;
69
70         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
71
72         wdt_enable();
73
74         return nonseekable_open(inode, file);
75 }
76
77 static ssize_t ixp2000_wdt_write(struct file *file, const char *data,
78                                                 size_t len, loff_t *ppos)
79 {
80         if (len) {
81                 if (!nowayout) {
82                         size_t i;
83
84                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
85
86                         for (i = 0; i != len; i++) {
87                                 char c;
88
89                                 if (get_user(c, data + i))
90                                         return -EFAULT;
91                                 if (c == 'V')
92                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
93                         }
94                 }
95                 wdt_keepalive();
96         }
97
98         return len;
99 }
100
101
102 static struct watchdog_info ident = {
103         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
104                                 WDIOF_KEEPALIVEPING,
105         .identity       = "IXP2000 Watchdog",
106 };
107
108 static long ixp2000_wdt_ioctl(struct file *file, unsigned int cmd,
109                                                         unsigned long arg)
110 {
111         int ret = -ENOTTY;
112         int time;
113
114         switch (cmd) {
115         case WDIOC_GETSUPPORT:
116                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
117                                    sizeof(ident)) ? -EFAULT : 0;
118                 break;
119
120         case WDIOC_GETSTATUS:
121                 ret = put_user(0, (int *)arg);
122                 break;
123
124         case WDIOC_GETBOOTSTATUS:
125                 ret = put_user(0, (int *)arg);
126                 break;
127
128         case WDIOC_KEEPALIVE:
129                 wdt_enable();
130                 ret = 0;
131                 break;
132
133         case WDIOC_SETTIMEOUT:
134                 ret = get_user(time, (int *)arg);
135                 if (ret)
136                         break;
137
138                 if (time <= 0 || time > 60) {
139                         ret = -EINVAL;
140                         break;
141                 }
142
143                 heartbeat = time;
144                 wdt_keepalive();
145                 /* Fall through */
146
147         case WDIOC_GETTIMEOUT:
148                 ret = put_user(heartbeat, (int *)arg);
149                 break;
150         }
151
152         return ret;
153 }
154
155 static int ixp2000_wdt_release(struct inode *inode, struct file *file)
156 {
157         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
158                 wdt_disable();
159         else
160                 printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
161                                         "timer will not stop\n");
162         clear_bit(WDT_IN_USE, &wdt_status);
163         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
164
165         return 0;
166 }
167
168
169 static const struct file_operations ixp2000_wdt_fops = {
170         .owner          = THIS_MODULE,
171         .llseek         = no_llseek,
172         .write          = ixp2000_wdt_write,
173         .unlocked_ioctl = ixp2000_wdt_ioctl,
174         .open           = ixp2000_wdt_open,
175         .release        = ixp2000_wdt_release,
176 };
177
178 static struct miscdevice ixp2000_wdt_miscdev = {
179         .minor          = WATCHDOG_MINOR,
180         .name           = "watchdog",
181         .fops           = &ixp2000_wdt_fops,
182 };
183
184 static int __init ixp2000_wdt_init(void)
185 {
186         if ((*IXP2000_PRODUCT_ID & 0x001ffef0) == 0x00000000) {
187                 printk(KERN_INFO "Unable to use IXP2000 watchdog due to IXP2800 erratum #25.\n");
188                 return -EIO;
189         }
190         wdt_tick_rate = (*IXP2000_T1_CLD * HZ) / 256;
191         spin_lock_init(&wdt_lock);
192         return misc_register(&ixp2000_wdt_miscdev);
193 }
194
195 static void __exit ixp2000_wdt_exit(void)
196 {
197         misc_deregister(&ixp2000_wdt_miscdev);
198 }
199
200 module_init(ixp2000_wdt_init);
201 module_exit(ixp2000_wdt_exit);
202
203 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
204 MODULE_DESCRIPTION("IXP2000 Network Processor Watchdog");
205
206 module_param(heartbeat, int, 0);
207 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
208
209 module_param(nowayout, int, 0);
210 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
211
212 MODULE_LICENSE("GPL");
213 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
214