xref: /openbmc/linux/drivers/watchdog/sbc_epx_c3.c (revision 8c0b9ee8)
1 /*
2  *	SBC EPX C3 0.1	A Hardware Watchdog Device for the Winsystems EPX-C3
3  *	single board computer
4  *
5  *	(c) Copyright 2006 Calin A. Culianu <calin@ajvar.org>, All Rights
6  *	Reserved.
7  *
8  *	This program is free software; you can redistribute it and/or
9  *	modify it under the terms of the GNU General Public License
10  *	as published by the Free Software Foundation; either version
11  *	2 of the License, or (at your option) any later version.
12  *
13  *	based on softdog.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
14  */
15 
16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
17 
18 #include <linux/module.h>
19 #include <linux/moduleparam.h>
20 #include <linux/types.h>
21 #include <linux/kernel.h>
22 #include <linux/fs.h>
23 #include <linux/mm.h>
24 #include <linux/miscdevice.h>
25 #include <linux/watchdog.h>
26 #include <linux/notifier.h>
27 #include <linux/reboot.h>
28 #include <linux/init.h>
29 #include <linux/ioport.h>
30 #include <linux/uaccess.h>
31 #include <linux/io.h>
32 
33 static int epx_c3_alive;
34 
35 #define WATCHDOG_TIMEOUT 1		/* 1 sec default timeout */
36 
37 static bool nowayout = WATCHDOG_NOWAYOUT;
38 module_param(nowayout, bool, 0);
39 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
40 					__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
41 
42 #define EPXC3_WATCHDOG_CTL_REG 0x1ee /* write 1 to enable, 0 to disable */
43 #define EPXC3_WATCHDOG_PET_REG 0x1ef /* write anything to pet once enabled */
44 
45 static void epx_c3_start(void)
46 {
47 	outb(1, EPXC3_WATCHDOG_CTL_REG);
48 }
49 
50 static void epx_c3_stop(void)
51 {
52 
53 	outb(0, EPXC3_WATCHDOG_CTL_REG);
54 
55 	pr_info("Stopped watchdog timer\n");
56 }
57 
58 static void epx_c3_pet(void)
59 {
60 	outb(1, EPXC3_WATCHDOG_PET_REG);
61 }
62 
63 /*
64  *	Allow only one person to hold it open
65  */
66 static int epx_c3_open(struct inode *inode, struct file *file)
67 {
68 	if (epx_c3_alive)
69 		return -EBUSY;
70 
71 	if (nowayout)
72 		__module_get(THIS_MODULE);
73 
74 	/* Activate timer */
75 	epx_c3_start();
76 	epx_c3_pet();
77 
78 	epx_c3_alive = 1;
79 	pr_info("Started watchdog timer\n");
80 
81 	return nonseekable_open(inode, file);
82 }
83 
84 static int epx_c3_release(struct inode *inode, struct file *file)
85 {
86 	/* Shut off the timer.
87 	 * Lock it in if it's a module and we defined ...NOWAYOUT */
88 	if (!nowayout)
89 		epx_c3_stop();		/* Turn the WDT off */
90 
91 	epx_c3_alive = 0;
92 
93 	return 0;
94 }
95 
96 static ssize_t epx_c3_write(struct file *file, const char __user *data,
97 			size_t len, loff_t *ppos)
98 {
99 	/* Refresh the timer. */
100 	if (len)
101 		epx_c3_pet();
102 	return len;
103 }
104 
105 static long epx_c3_ioctl(struct file *file, unsigned int cmd,
106 						unsigned long arg)
107 {
108 	int options, retval = -EINVAL;
109 	int __user *argp = (void __user *)arg;
110 	static const struct watchdog_info ident = {
111 		.options		= WDIOF_KEEPALIVEPING,
112 		.firmware_version	= 0,
113 		.identity		= "Winsystems EPX-C3 H/W Watchdog",
114 	};
115 
116 	switch (cmd) {
117 	case WDIOC_GETSUPPORT:
118 		if (copy_to_user(argp, &ident, sizeof(ident)))
119 			return -EFAULT;
120 		return 0;
121 	case WDIOC_GETSTATUS:
122 	case WDIOC_GETBOOTSTATUS:
123 		return put_user(0, argp);
124 	case WDIOC_SETOPTIONS:
125 		if (get_user(options, argp))
126 			return -EFAULT;
127 
128 		if (options & WDIOS_DISABLECARD) {
129 			epx_c3_stop();
130 			retval = 0;
131 		}
132 
133 		if (options & WDIOS_ENABLECARD) {
134 			epx_c3_start();
135 			retval = 0;
136 		}
137 
138 		return retval;
139 	case WDIOC_KEEPALIVE:
140 		epx_c3_pet();
141 		return 0;
142 	case WDIOC_GETTIMEOUT:
143 		return put_user(WATCHDOG_TIMEOUT, argp);
144 	default:
145 		return -ENOTTY;
146 	}
147 }
148 
149 static int epx_c3_notify_sys(struct notifier_block *this, unsigned long code,
150 				void *unused)
151 {
152 	if (code == SYS_DOWN || code == SYS_HALT)
153 		epx_c3_stop();		/* Turn the WDT off */
154 
155 	return NOTIFY_DONE;
156 }
157 
158 static const struct file_operations epx_c3_fops = {
159 	.owner		= THIS_MODULE,
160 	.llseek		= no_llseek,
161 	.write		= epx_c3_write,
162 	.unlocked_ioctl	= epx_c3_ioctl,
163 	.open		= epx_c3_open,
164 	.release	= epx_c3_release,
165 };
166 
167 static struct miscdevice epx_c3_miscdev = {
168 	.minor		= WATCHDOG_MINOR,
169 	.name		= "watchdog",
170 	.fops		= &epx_c3_fops,
171 };
172 
173 static struct notifier_block epx_c3_notifier = {
174 	.notifier_call = epx_c3_notify_sys,
175 };
176 
177 static int __init watchdog_init(void)
178 {
179 	int ret;
180 
181 	if (!request_region(EPXC3_WATCHDOG_CTL_REG, 2, "epxc3_watchdog"))
182 		return -EBUSY;
183 
184 	ret = register_reboot_notifier(&epx_c3_notifier);
185 	if (ret) {
186 		pr_err("cannot register reboot notifier (err=%d)\n", ret);
187 		goto out;
188 	}
189 
190 	ret = misc_register(&epx_c3_miscdev);
191 	if (ret) {
192 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
193 		       WATCHDOG_MINOR, ret);
194 		unregister_reboot_notifier(&epx_c3_notifier);
195 		goto out;
196 	}
197 
198 	pr_info("Hardware Watchdog Timer for Winsystems EPX-C3 SBC: 0.1\n");
199 
200 	return 0;
201 
202 out:
203 	release_region(EPXC3_WATCHDOG_CTL_REG, 2);
204 	return ret;
205 }
206 
207 static void __exit watchdog_exit(void)
208 {
209 	misc_deregister(&epx_c3_miscdev);
210 	unregister_reboot_notifier(&epx_c3_notifier);
211 	release_region(EPXC3_WATCHDOG_CTL_REG, 2);
212 }
213 
214 module_init(watchdog_init);
215 module_exit(watchdog_exit);
216 
217 MODULE_AUTHOR("Calin A. Culianu <calin@ajvar.org>");
218 MODULE_DESCRIPTION("Hardware Watchdog Device for Winsystems EPX-C3 SBC.  "
219 	"Note that there is no way to probe for this device -- "
220 	"so only use it if you are *sure* you are running on this specific "
221 	"SBC system from Winsystems!  It writes to IO ports 0x1ee and 0x1ef!");
222 MODULE_LICENSE("GPL");
223