Merge master.kernel.org:/pub/scm/linux/kernel/git/jejb/scsi-for-linus-2.6
[linux-2.6] / drivers / char / watchdog / ixp2000_wdt.c
1 /*
2  * drivers/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/config.h>
20 #include <linux/module.h>
21 #include <linux/moduleparam.h>
22 #include <linux/types.h>
23 #include <linux/kernel.h>
24 #include <linux/fs.h>
25 #include <linux/miscdevice.h>
26 #include <linux/watchdog.h>
27 #include <linux/init.h>
28 #include <linux/bitops.h>
29
30 #include <asm/hardware.h>
31 #include <asm/uaccess.h>
32
33 #ifdef CONFIG_WATCHDOG_NOWAYOUT
34 static int nowayout = 1;
35 #else
36 static int nowayout = 0;
37 #endif
38 static unsigned int heartbeat = 60;     /* (secs) Default is 1 minute */
39 static unsigned long wdt_status;
40
41 #define WDT_IN_USE              0
42 #define WDT_OK_TO_CLOSE         1
43
44 static unsigned long wdt_tick_rate;
45
46 static void
47 wdt_enable(void)
48 {
49         ixp2000_reg_write(IXP2000_RESET0, *(IXP2000_RESET0) | WDT_RESET_ENABLE);
50         ixp2000_reg_write(IXP2000_TWDE, WDT_ENABLE);
51         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
52         ixp2000_reg_write(IXP2000_T4_CTL, TIMER_DIVIDER_256 | TIMER_ENABLE);
53 }
54
55 static void
56 wdt_disable(void)
57 {
58         ixp2000_reg_write(IXP2000_T4_CTL, 0);
59 }
60
61 static void
62 wdt_keepalive(void)
63 {
64         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
65 }
66
67 static int
68 ixp2000_wdt_open(struct inode *inode, struct file *file)
69 {
70         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
71                 return -EBUSY;
72
73         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
74
75         wdt_enable();
76
77         return nonseekable_open(inode, file);
78 }
79
80 static ssize_t
81 ixp2000_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
82 {
83         if (len) {
84                 if (!nowayout) {
85                         size_t i;
86
87                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
88
89                         for (i = 0; i != len; i++) {
90                                 char c;
91
92                                 if (get_user(c, data + i))
93                                         return -EFAULT;
94                                 if (c == 'V')
95                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
96                         }
97                 }
98                 wdt_keepalive();
99         }
100
101         return len;
102 }
103
104
105 static struct watchdog_info ident = {
106         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
107                                 WDIOF_KEEPALIVEPING,
108         .identity       = "IXP2000 Watchdog",
109 };
110
111 static int
112 ixp2000_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
113                         unsigned long arg)
114 {
115         int ret = -ENOIOCTLCMD;
116         int time;
117
118         switch (cmd) {
119         case WDIOC_GETSUPPORT:
120                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
121                                    sizeof(ident)) ? -EFAULT : 0;
122                 break;
123
124         case WDIOC_GETSTATUS:
125                 ret = put_user(0, (int *)arg);
126                 break;
127
128         case WDIOC_GETBOOTSTATUS:
129                 ret = put_user(0, (int *)arg);
130                 break;
131
132         case WDIOC_SETTIMEOUT:
133                 ret = get_user(time, (int *)arg);
134                 if (ret)
135                         break;
136
137                 if (time <= 0 || time > 60) {
138                         ret = -EINVAL;
139                         break;
140                 }
141
142                 heartbeat = time;
143                 wdt_keepalive();
144                 /* Fall through */
145
146         case WDIOC_GETTIMEOUT:
147                 ret = put_user(heartbeat, (int *)arg);
148                 break;
149
150         case WDIOC_KEEPALIVE:
151                 wdt_enable();
152                 ret = 0;
153                 break;
154         }
155
156         return ret;
157 }
158
159 static int
160 ixp2000_wdt_release(struct inode *inode, struct file *file)
161 {
162         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
163                 wdt_disable();
164         } else {
165                 printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
166                                         "timer will not stop\n");
167         }
168
169         clear_bit(WDT_IN_USE, &wdt_status);
170         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
171
172         return 0;
173 }
174
175
176 static struct file_operations ixp2000_wdt_fops =
177 {
178         .owner          = THIS_MODULE,
179         .llseek         = no_llseek,
180         .write          = ixp2000_wdt_write,
181         .ioctl          = ixp2000_wdt_ioctl,
182         .open           = ixp2000_wdt_open,
183         .release        = ixp2000_wdt_release,
184 };
185
186 static struct miscdevice ixp2000_wdt_miscdev =
187 {
188         .minor          = WATCHDOG_MINOR,
189         .name           = "IXP2000 Watchdog",
190         .fops           = &ixp2000_wdt_fops,
191 };
192
193 static int __init ixp2000_wdt_init(void)
194 {
195         if ((*IXP2000_PRODUCT_ID & 0x001ffef0) == 0x00000000) {
196                 printk(KERN_INFO "Unable to use IXP2000 watchdog due to IXP2800 erratum #25.\n");
197                 return -EIO;
198         }
199
200         wdt_tick_rate = (*IXP2000_T1_CLD * HZ) / 256;
201
202         return misc_register(&ixp2000_wdt_miscdev);
203 }
204
205 static void __exit ixp2000_wdt_exit(void)
206 {
207         misc_deregister(&ixp2000_wdt_miscdev);
208 }
209
210 module_init(ixp2000_wdt_init);
211 module_exit(ixp2000_wdt_exit);
212
213 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net">);
214 MODULE_DESCRIPTION("IXP2000 Network Processor Watchdog");
215
216 module_param(heartbeat, int, 0);
217 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
218
219 module_param(nowayout, int, 0);
220 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
221
222 MODULE_LICENSE("GPL");
223 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
224