watchdog: nowayout is bool
[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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21 #include <linux/module.h>
22 #include <linux/moduleparam.h>
23 #include <linux/types.h>
24 #include <linux/timer.h>
25 #include <linux/kernel.h>
26 #include <linux/fs.h>
27 #include <linux/miscdevice.h>
28 #include <linux/watchdog.h>
29 #include <linux/init.h>
30 #include <linux/bitops.h>
31 #include <linux/uaccess.h>
32 #include <mach/hardware.h>
33
34 static bool nowayout = WATCHDOG_NOWAYOUT;
35 static unsigned int heartbeat = 60;     /* (secs) Default is 1 minute */
36 static unsigned long wdt_status;
37 static DEFINE_SPINLOCK(wdt_lock);
38
39 #define WDT_IN_USE              0
40 #define WDT_OK_TO_CLOSE         1
41
42 static unsigned long wdt_tick_rate;
43
44 static void wdt_enable(void)
45 {
46         spin_lock(&wdt_lock);
47         ixp2000_reg_write(IXP2000_RESET0, *(IXP2000_RESET0) | WDT_RESET_ENABLE);
48         ixp2000_reg_write(IXP2000_TWDE, WDT_ENABLE);
49         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
50         ixp2000_reg_write(IXP2000_T4_CTL, TIMER_DIVIDER_256 | TIMER_ENABLE);
51         spin_unlock(&wdt_lock);
52 }
53
54 static void wdt_disable(void)
55 {
56         spin_lock(&wdt_lock);
57         ixp2000_reg_write(IXP2000_T4_CTL, 0);
58         spin_unlock(&wdt_lock);
59 }
60
61 static void wdt_keepalive(void)
62 {
63         spin_lock(&wdt_lock);
64         ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
65         spin_unlock(&wdt_lock);
66 }
67
68 static int 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 ixp2000_wdt_write(struct file *file, const char *data,
81                                                 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 const struct watchdog_info ident = {
106         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
107                                 WDIOF_KEEPALIVEPING,
108         .identity       = "IXP2000 Watchdog",
109 };
110
111 static long ixp2000_wdt_ioctl(struct file *file, unsigned int cmd,
112                                                         unsigned long arg)
113 {
114         int ret = -ENOTTY;
115         int time;
116
117         switch (cmd) {
118         case WDIOC_GETSUPPORT:
119                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
120                                    sizeof(ident)) ? -EFAULT : 0;
121                 break;
122
123         case WDIOC_GETSTATUS:
124                 ret = put_user(0, (int *)arg);
125                 break;
126
127         case WDIOC_GETBOOTSTATUS:
128                 ret = put_user(0, (int *)arg);
129                 break;
130
131         case WDIOC_KEEPALIVE:
132                 wdt_enable();
133                 ret = 0;
134                 break;
135
136         case WDIOC_SETTIMEOUT:
137                 ret = get_user(time, (int *)arg);
138                 if (ret)
139                         break;
140
141                 if (time <= 0 || time > 60) {
142                         ret = -EINVAL;
143                         break;
144                 }
145
146                 heartbeat = time;
147                 wdt_keepalive();
148                 /* Fall through */
149
150         case WDIOC_GETTIMEOUT:
151                 ret = put_user(heartbeat, (int *)arg);
152                 break;
153         }
154
155         return ret;
156 }
157
158 static int ixp2000_wdt_release(struct inode *inode, struct file *file)
159 {
160         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
161                 wdt_disable();
162         else
163                 pr_crit("Device closed unexpectedly - timer will not stop\n");
164         clear_bit(WDT_IN_USE, &wdt_status);
165         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
166
167         return 0;
168 }
169
170
171 static const struct file_operations ixp2000_wdt_fops = {
172         .owner          = THIS_MODULE,
173         .llseek         = no_llseek,
174         .write          = ixp2000_wdt_write,
175         .unlocked_ioctl = ixp2000_wdt_ioctl,
176         .open           = ixp2000_wdt_open,
177         .release        = ixp2000_wdt_release,
178 };
179
180 static struct miscdevice ixp2000_wdt_miscdev = {
181         .minor          = WATCHDOG_MINOR,
182         .name           = "watchdog",
183         .fops           = &ixp2000_wdt_fops,
184 };
185
186 static int __init ixp2000_wdt_init(void)
187 {
188         if ((*IXP2000_PRODUCT_ID & 0x001ffef0) == 0x00000000) {
189                 pr_info("Unable to use IXP2000 watchdog due to IXP2800 erratum #25\n");
190                 return -EIO;
191         }
192         wdt_tick_rate = (*IXP2000_T1_CLD * HZ) / 256;
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, bool, 0);
211 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
212
213 MODULE_LICENSE("GPL");
214 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
215