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 | |
41 | static void epx_c3_start(void) |
42 | { |
43 | outb(value: 1, EPXC3_WATCHDOG_CTL_REG); |
44 | } |
45 | |
46 | static void epx_c3_stop(void) |
47 | { |
48 | |
49 | outb(value: 0, EPXC3_WATCHDOG_CTL_REG); |
50 | |
51 | pr_info("Stopped watchdog timer\n" ); |
52 | } |
53 | |
54 | static void epx_c3_pet(void) |
55 | { |
56 | outb(value: 1, EPXC3_WATCHDOG_PET_REG); |
57 | } |
58 | |
59 | /* |
60 | * Allow only one person to hold it open |
61 | */ |
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, filp: file); |
78 | } |
79 | |
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 | |
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 | |
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(to: argp, from: &ident, n: 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 | |
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 | |
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(misc: &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 | |
204 | static void __exit watchdog_exit(void) |
205 | { |
206 | misc_deregister(misc: &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 | |