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