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1 office 1 /*
2 * ADM5120_WDT 0.01: Infineon ADM5120 SoC watchdog driver
3 * Copyright (c) Ondrej Zajicek <santiago@crfreenet.org>, 2007
4 *
5 * based on
6 *
7 * RC32434_WDT 0.01: IDT Interprise 79RC32434 watchdog driver
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version
12 * 2 of the License, or (at your option) any later version.
13 *
14 */
15 #include <linux/module.h>
16 #include <linux/types.h>
17 #include <linux/fs.h>
18 #include <linux/miscdevice.h>
19 #include <linux/watchdog.h>
20 #include <linux/irq.h>
21  
22 #include <asm/bootinfo.h>
23  
24 #include <asm/mach-adm5120/adm5120_info.h>
25 #include <asm/mach-adm5120/adm5120_defs.h>
26 #include <asm/mach-adm5120/adm5120_switch.h>
27  
28 #define DEFAULT_TIMEOUT 15 /* (secs) Default is 15 seconds */
29 #define MAX_TIMEOUT 327
30 /* Max is 327 seconds, counter is 15-bit integer, step is 10 ms */
31  
32 #define NAME "adm5120_wdt"
33 #define VERSION "0.1"
34  
35 static int expect_close;
36 static int access;
37 static unsigned int timeout = DEFAULT_TIMEOUT;
38  
39 static int nowayout = WATCHDOG_NOWAYOUT;
40 module_param(nowayout, int, 0);
41 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
42 MODULE_LICENSE("GPL");
43  
44  
45 static inline void wdt_set_timeout(void)
46 {
47 u32 val = (1 << 31) | (((timeout * 100) & 0x7FFF) << 16);
48 SW_WRITE_REG(SWITCH_REG_WDOG0, val);
49 }
50  
51 /*
52 It looks like WDOG0-register-write don't modify counter,
53 but WDOG0-register-read resets counter.
54 */
55  
56 static inline void wdt_reset_counter(void)
57 {
58 SW_READ_REG(SWITCH_REG_WDOG0);
59 }
60  
61 static inline void wdt_disable(void)
62 {
63 SW_WRITE_REG(SWITCH_REG_WDOG0, 0x7FFF0000);
64 }
65  
66  
67  
68 static int wdt_open(struct inode *inode, struct file *file)
69 {
70 /* Allow only one person to hold it open */
71 if (access)
72 return -EBUSY;
73  
74 if (nowayout)
75 __module_get(THIS_MODULE);
76  
77 /* Activate timer */
78 wdt_reset_counter();
79 wdt_set_timeout();
80 printk(KERN_INFO NAME ": enabling watchdog timer\n");
81 access = 1;
82 return 0;
83 }
84  
85 static int wdt_release(struct inode *inode, struct file *file)
86 {
87 /*
88 * Shut off the timer.
89 * Lock it in if it's a module and we set nowayout
90 */
91 if (expect_close && (nowayout == 0)) {
92 wdt_disable();
93 printk(KERN_INFO NAME ": disabling watchdog timer\n");
94 module_put(THIS_MODULE);
95 } else
96 printk(KERN_CRIT NAME ": device closed unexpectedly. WDT will not stop!\n");
97  
98 access = 0;
99 return 0;
100 }
101  
102 static ssize_t wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
103 {
104 /* Refresh the timer. */
105 if (len) {
106 if (!nowayout) {
107 size_t i;
108  
109 /* In case it was set long ago */
110 expect_close = 0;
111  
112 for (i = 0; i != len; i++) {
113 char c;
114 if (get_user(c, data + i))
115 return -EFAULT;
116 if (c == 'V')
117 expect_close = 1;
118 }
119 }
120 wdt_reset_counter();
121 return len;
122 }
123 return 0;
124 }
125  
126 static long wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
127 {
128 int new_timeout;
129 static struct watchdog_info ident = {
130 .options = WDIOF_SETTIMEOUT |
131 WDIOF_KEEPALIVEPING |
132 WDIOF_MAGICCLOSE,
133 .firmware_version = 0,
134 .identity = "ADM5120_WDT Watchdog",
135 };
136 switch (cmd) {
137 default:
138 return -ENOTTY;
139 case WDIOC_GETSUPPORT:
140 if (copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)))
141 return -EFAULT;
142 return 0;
143 case WDIOC_GETSTATUS:
144 case WDIOC_GETBOOTSTATUS:
145 return put_user(0, (int *)arg);
146 case WDIOC_KEEPALIVE:
147 wdt_reset_counter();
148 return 0;
149 case WDIOC_SETTIMEOUT:
150 if (get_user(new_timeout, (int *)arg))
151 return -EFAULT;
152 if (new_timeout < 1)
153 return -EINVAL;
154 if (new_timeout > MAX_TIMEOUT)
155 return -EINVAL;
156 timeout = new_timeout;
157 wdt_set_timeout();
158 /* Fall */
159 case WDIOC_GETTIMEOUT:
160 return put_user(timeout, (int *)arg);
161 }
162 }
163  
164 static const struct file_operations wdt_fops = {
165 .owner = THIS_MODULE,
166 .llseek = no_llseek,
167 .write = wdt_write,
168 .unlocked_ioctl = wdt_ioctl,
169 .open = wdt_open,
170 .release = wdt_release,
171 };
172  
173 static struct miscdevice wdt_miscdev = {
174 .minor = WATCHDOG_MINOR,
175 .name = "watchdog",
176 .fops = &wdt_fops,
177 };
178  
179 static char banner[] __initdata = KERN_INFO NAME ": Watchdog Timer version " VERSION "\n";
180  
181 static int __init watchdog_init(void)
182 {
183 int ret;
184  
185 ret = misc_register(&wdt_miscdev);
186  
187 if (ret)
188 return ret;
189  
190 wdt_disable();
191 printk(banner);
192  
193 return 0;
194 }
195  
196 static void __exit watchdog_exit(void)
197 {
198 misc_deregister(&wdt_miscdev);
199 }
200  
201 module_init(watchdog_init);
202 module_exit(watchdog_exit);