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 #include <linux/module.h> 17 #include <linux/moduleparam.h> 18 #include <linux/types.h> 19 #include <linux/kernel.h> 20 #include <linux/fs.h> 21 #include <linux/mm.h> 22 #include <linux/miscdevice.h> 23 #include <linux/watchdog.h> 24 #include <linux/notifier.h> 25 #include <linux/reboot.h> 26 #include <linux/init.h> 27 #include <linux/ioport.h> 28 #include <linux/uaccess.h> 29 #include <linux/io.h> 30 31 #define PFX "epx_c3: " 32 static int epx_c3_alive; 33 34 #define WATCHDOG_TIMEOUT 1 /* 1 sec default timeout */ 35 36 static int nowayout = WATCHDOG_NOWAYOUT; 37 module_param(nowayout, int, 0); 38 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 39 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 40 41 #define EPXC3_WATCHDOG_CTL_REG 0x1ee /* write 1 to enable, 0 to disable */ 42 #define EPXC3_WATCHDOG_PET_REG 0x1ef /* write anything to pet once enabled */ 43 44 static void epx_c3_start(void) 45 { 46 outb(1, EPXC3_WATCHDOG_CTL_REG); 47 } 48 49 static void epx_c3_stop(void) 50 { 51 52 outb(0, EPXC3_WATCHDOG_CTL_REG); 53 54 printk(KERN_INFO PFX "Stopped watchdog timer.\n"); 55 } 56 57 static void epx_c3_pet(void) 58 { 59 outb(1, EPXC3_WATCHDOG_PET_REG); 60 } 61 62 /* 63 * Allow only one person to hold it open 64 */ 65 static int epx_c3_open(struct inode *inode, struct file *file) 66 { 67 if (epx_c3_alive) 68 return -EBUSY; 69 70 if (nowayout) 71 __module_get(THIS_MODULE); 72 73 /* Activate timer */ 74 epx_c3_start(); 75 epx_c3_pet(); 76 77 epx_c3_alive = 1; 78 printk(KERN_INFO "Started watchdog timer.\n"); 79 80 return nonseekable_open(inode, file); 81 } 82 83 static int epx_c3_release(struct inode *inode, struct file *file) 84 { 85 /* Shut off the timer. 86 * Lock it in if it's a module and we defined ...NOWAYOUT */ 87 if (!nowayout) 88 epx_c3_stop(); /* Turn the WDT off */ 89 90 epx_c3_alive = 0; 91 92 return 0; 93 } 94 95 static ssize_t epx_c3_write(struct file *file, const char __user *data, 96 size_t len, loff_t *ppos) 97 { 98 /* Refresh the timer. */ 99 if (len) 100 epx_c3_pet(); 101 return len; 102 } 103 104 static long epx_c3_ioctl(struct file *file, unsigned int cmd, 105 unsigned long arg) 106 { 107 int options, retval = -EINVAL; 108 int __user *argp = (void __user *)arg; 109 static const struct watchdog_info ident = { 110 .options = WDIOF_KEEPALIVEPING, 111 .firmware_version = 0, 112 .identity = "Winsystems EPX-C3 H/W Watchdog", 113 }; 114 115 switch (cmd) { 116 case WDIOC_GETSUPPORT: 117 if (copy_to_user(argp, &ident, sizeof(ident))) 118 return -EFAULT; 119 return 0; 120 case WDIOC_GETSTATUS: 121 case WDIOC_GETBOOTSTATUS: 122 return put_user(0, argp); 123 case WDIOC_SETOPTIONS: 124 if (get_user(options, argp)) 125 return -EFAULT; 126 127 if (options & WDIOS_DISABLECARD) { 128 epx_c3_stop(); 129 retval = 0; 130 } 131 132 if (options & WDIOS_ENABLECARD) { 133 epx_c3_start(); 134 retval = 0; 135 } 136 137 return retval; 138 case WDIOC_KEEPALIVE: 139 epx_c3_pet(); 140 return 0; 141 case WDIOC_GETTIMEOUT: 142 return put_user(WATCHDOG_TIMEOUT, argp); 143 default: 144 return -ENOTTY; 145 } 146 } 147 148 static int epx_c3_notify_sys(struct notifier_block *this, unsigned long code, 149 void *unused) 150 { 151 if (code == SYS_DOWN || code == SYS_HALT) 152 epx_c3_stop(); /* Turn the WDT off */ 153 154 return NOTIFY_DONE; 155 } 156 157 static const struct file_operations epx_c3_fops = { 158 .owner = THIS_MODULE, 159 .llseek = no_llseek, 160 .write = epx_c3_write, 161 .unlocked_ioctl = epx_c3_ioctl, 162 .open = epx_c3_open, 163 .release = epx_c3_release, 164 }; 165 166 static struct miscdevice epx_c3_miscdev = { 167 .minor = WATCHDOG_MINOR, 168 .name = "watchdog", 169 .fops = &epx_c3_fops, 170 }; 171 172 static struct notifier_block epx_c3_notifier = { 173 .notifier_call = epx_c3_notify_sys, 174 }; 175 176 static const char banner[] __initdata = KERN_INFO PFX 177 "Hardware Watchdog Timer for Winsystems EPX-C3 SBC: 0.1\n"; 178 179 static int __init watchdog_init(void) 180 { 181 int ret; 182 183 if (!request_region(EPXC3_WATCHDOG_CTL_REG, 2, "epxc3_watchdog")) 184 return -EBUSY; 185 186 ret = register_reboot_notifier(&epx_c3_notifier); 187 if (ret) { 188 printk(KERN_ERR PFX "cannot register reboot notifier " 189 "(err=%d)\n", ret); 190 goto out; 191 } 192 193 ret = misc_register(&epx_c3_miscdev); 194 if (ret) { 195 printk(KERN_ERR PFX "cannot register miscdev on minor=%d " 196 "(err=%d)\n", WATCHDOG_MINOR, ret); 197 unregister_reboot_notifier(&epx_c3_notifier); 198 goto out; 199 } 200 201 printk(banner); 202 203 return 0; 204 205 out: 206 release_region(EPXC3_WATCHDOG_CTL_REG, 2); 207 return ret; 208 } 209 210 static void __exit watchdog_exit(void) 211 { 212 misc_deregister(&epx_c3_miscdev); 213 unregister_reboot_notifier(&epx_c3_notifier); 214 release_region(EPXC3_WATCHDOG_CTL_REG, 2); 215 } 216 217 module_init(watchdog_init); 218 module_exit(watchdog_exit); 219 220 MODULE_AUTHOR("Calin A. Culianu <calin@ajvar.org>"); 221 MODULE_DESCRIPTION("Hardware Watchdog Device for Winsystems EPX-C3 SBC. " 222 "Note that there is no way to probe for this device -- " 223 "so only use it if you are *sure* you are runnning on this specific " 224 "SBC system from Winsystems! It writes to IO ports 0x1ee and 0x1ef!"); 225 MODULE_LICENSE("GPL"); 226 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 227