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