xref: /openbmc/linux/drivers/watchdog/sbc_epx_c3.c (revision b6dfb247)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *	SBC EPX C3 0.1	A Hardware Watchdog Device for the Winsystems EPX-C3
4  *	single board computer
5  *
6  *	(c) Copyright 2006 Calin A. Culianu <calin@ajvar.org>, All Rights
7  *	Reserved.
8  *
9  *	based on softdog.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
10  */
11 
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 
14 #include <linux/module.h>
15 #include <linux/moduleparam.h>
16 #include <linux/types.h>
17 #include <linux/kernel.h>
18 #include <linux/fs.h>
19 #include <linux/mm.h>
20 #include <linux/miscdevice.h>
21 #include <linux/watchdog.h>
22 #include <linux/notifier.h>
23 #include <linux/reboot.h>
24 #include <linux/init.h>
25 #include <linux/ioport.h>
26 #include <linux/uaccess.h>
27 #include <linux/io.h>
28 
29 static int epx_c3_alive;
30 
31 #define WATCHDOG_TIMEOUT 1		/* 1 sec default timeout */
32 
33 static bool nowayout = WATCHDOG_NOWAYOUT;
34 module_param(nowayout, bool, 0);
35 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
36 					__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
37 
38 #define EPXC3_WATCHDOG_CTL_REG 0x1ee /* write 1 to enable, 0 to disable */
39 #define EPXC3_WATCHDOG_PET_REG 0x1ef /* write anything to pet once enabled */
40 
epx_c3_start(void)41 static void epx_c3_start(void)
42 {
43 	outb(1, EPXC3_WATCHDOG_CTL_REG);
44 }
45 
epx_c3_stop(void)46 static void epx_c3_stop(void)
47 {
48 
49 	outb(0, EPXC3_WATCHDOG_CTL_REG);
50 
51 	pr_info("Stopped watchdog timer\n");
52 }
53 
epx_c3_pet(void)54 static void epx_c3_pet(void)
55 {
56 	outb(1, EPXC3_WATCHDOG_PET_REG);
57 }
58 
59 /*
60  *	Allow only one person to hold it open
61  */
epx_c3_open(struct inode * inode,struct file * file)62 static int epx_c3_open(struct inode *inode, struct file *file)
63 {
64 	if (epx_c3_alive)
65 		return -EBUSY;
66 
67 	if (nowayout)
68 		__module_get(THIS_MODULE);
69 
70 	/* Activate timer */
71 	epx_c3_start();
72 	epx_c3_pet();
73 
74 	epx_c3_alive = 1;
75 	pr_info("Started watchdog timer\n");
76 
77 	return stream_open(inode, file);
78 }
79 
epx_c3_release(struct inode * inode,struct file * file)80 static int epx_c3_release(struct inode *inode, struct file *file)
81 {
82 	/* Shut off the timer.
83 	 * Lock it in if it's a module and we defined ...NOWAYOUT */
84 	if (!nowayout)
85 		epx_c3_stop();		/* Turn the WDT off */
86 
87 	epx_c3_alive = 0;
88 
89 	return 0;
90 }
91 
epx_c3_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)92 static ssize_t epx_c3_write(struct file *file, const char __user *data,
93 			size_t len, loff_t *ppos)
94 {
95 	/* Refresh the timer. */
96 	if (len)
97 		epx_c3_pet();
98 	return len;
99 }
100 
epx_c3_ioctl(struct file * file,unsigned int cmd,unsigned long arg)101 static long epx_c3_ioctl(struct file *file, unsigned int cmd,
102 						unsigned long arg)
103 {
104 	int options, retval = -EINVAL;
105 	int __user *argp = (void __user *)arg;
106 	static const struct watchdog_info ident = {
107 		.options		= WDIOF_KEEPALIVEPING,
108 		.firmware_version	= 0,
109 		.identity		= "Winsystems EPX-C3 H/W Watchdog",
110 	};
111 
112 	switch (cmd) {
113 	case WDIOC_GETSUPPORT:
114 		if (copy_to_user(argp, &ident, sizeof(ident)))
115 			return -EFAULT;
116 		return 0;
117 	case WDIOC_GETSTATUS:
118 	case WDIOC_GETBOOTSTATUS:
119 		return put_user(0, argp);
120 	case WDIOC_SETOPTIONS:
121 		if (get_user(options, argp))
122 			return -EFAULT;
123 
124 		if (options & WDIOS_DISABLECARD) {
125 			epx_c3_stop();
126 			retval = 0;
127 		}
128 
129 		if (options & WDIOS_ENABLECARD) {
130 			epx_c3_start();
131 			retval = 0;
132 		}
133 
134 		return retval;
135 	case WDIOC_KEEPALIVE:
136 		epx_c3_pet();
137 		return 0;
138 	case WDIOC_GETTIMEOUT:
139 		return put_user(WATCHDOG_TIMEOUT, argp);
140 	default:
141 		return -ENOTTY;
142 	}
143 }
144 
epx_c3_notify_sys(struct notifier_block * this,unsigned long code,void * unused)145 static int epx_c3_notify_sys(struct notifier_block *this, unsigned long code,
146 				void *unused)
147 {
148 	if (code == SYS_DOWN || code == SYS_HALT)
149 		epx_c3_stop();		/* Turn the WDT off */
150 
151 	return NOTIFY_DONE;
152 }
153 
154 static const struct file_operations epx_c3_fops = {
155 	.owner		= THIS_MODULE,
156 	.llseek		= no_llseek,
157 	.write		= epx_c3_write,
158 	.unlocked_ioctl	= epx_c3_ioctl,
159 	.compat_ioctl	= compat_ptr_ioctl,
160 	.open		= epx_c3_open,
161 	.release	= epx_c3_release,
162 };
163 
164 static struct miscdevice epx_c3_miscdev = {
165 	.minor		= WATCHDOG_MINOR,
166 	.name		= "watchdog",
167 	.fops		= &epx_c3_fops,
168 };
169 
170 static struct notifier_block epx_c3_notifier = {
171 	.notifier_call = epx_c3_notify_sys,
172 };
173 
watchdog_init(void)174 static int __init watchdog_init(void)
175 {
176 	int ret;
177 
178 	if (!request_region(EPXC3_WATCHDOG_CTL_REG, 2, "epxc3_watchdog"))
179 		return -EBUSY;
180 
181 	ret = register_reboot_notifier(&epx_c3_notifier);
182 	if (ret) {
183 		pr_err("cannot register reboot notifier (err=%d)\n", ret);
184 		goto out;
185 	}
186 
187 	ret = misc_register(&epx_c3_miscdev);
188 	if (ret) {
189 		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
190 		       WATCHDOG_MINOR, ret);
191 		unregister_reboot_notifier(&epx_c3_notifier);
192 		goto out;
193 	}
194 
195 	pr_info("Hardware Watchdog Timer for Winsystems EPX-C3 SBC: 0.1\n");
196 
197 	return 0;
198 
199 out:
200 	release_region(EPXC3_WATCHDOG_CTL_REG, 2);
201 	return ret;
202 }
203 
watchdog_exit(void)204 static void __exit watchdog_exit(void)
205 {
206 	misc_deregister(&epx_c3_miscdev);
207 	unregister_reboot_notifier(&epx_c3_notifier);
208 	release_region(EPXC3_WATCHDOG_CTL_REG, 2);
209 }
210 
211 module_init(watchdog_init);
212 module_exit(watchdog_exit);
213 
214 MODULE_AUTHOR("Calin A. Culianu <calin@ajvar.org>");
215 MODULE_DESCRIPTION("Hardware Watchdog Device for Winsystems EPX-C3 SBC.  "
216 	"Note that there is no way to probe for this device -- "
217 	"so only use it if you are *sure* you are running on this specific "
218 	"SBC system from Winsystems!  It writes to IO ports 0x1ee and 0x1ef!");
219 MODULE_LICENSE("GPL");
220