1 /* drivers/char/watchdog/scx200_wdt.c 2 3 National Semiconductor SCx200 Watchdog support 4 5 Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> 6 7 Some code taken from: 8 National Semiconductor PC87307/PC97307 (ala SC1200) WDT driver 9 (c) Copyright 2002 Zwane Mwaikambo <zwane@commfireservices.com> 10 11 This program is free software; you can redistribute it and/or 12 modify it under the terms of the GNU General Public License as 13 published by the Free Software Foundation; either version 2 of the 14 License, or (at your option) any later version. 15 16 The author(s) of this software shall not be held liable for damages 17 of any nature resulting due to the use of this software. This 18 software is provided AS-IS with no warranties. */ 19 20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 21 22 #include <linux/module.h> 23 #include <linux/moduleparam.h> 24 #include <linux/init.h> 25 #include <linux/miscdevice.h> 26 #include <linux/watchdog.h> 27 #include <linux/notifier.h> 28 #include <linux/reboot.h> 29 #include <linux/fs.h> 30 #include <linux/ioport.h> 31 #include <linux/scx200.h> 32 #include <linux/uaccess.h> 33 #include <linux/io.h> 34 35 #define DEBUG 36 37 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>"); 38 MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver"); 39 MODULE_LICENSE("GPL"); 40 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 41 42 static int margin = 60; /* in seconds */ 43 module_param(margin, int, 0); 44 MODULE_PARM_DESC(margin, "Watchdog margin in seconds"); 45 46 static bool nowayout = WATCHDOG_NOWAYOUT; 47 module_param(nowayout, bool, 0); 48 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close"); 49 50 static u16 wdto_restart; 51 static char expect_close; 52 static unsigned long open_lock; 53 static DEFINE_SPINLOCK(scx_lock); 54 55 /* Bits of the WDCNFG register */ 56 #define W_ENABLE 0x00fa /* Enable watchdog */ 57 #define W_DISABLE 0x0000 /* Disable watchdog */ 58 59 /* The scaling factor for the timer, this depends on the value of W_ENABLE */ 60 #define W_SCALE (32768/1024) 61 62 static void scx200_wdt_ping(void) 63 { 64 spin_lock(&scx_lock); 65 outw(wdto_restart, scx200_cb_base + SCx200_WDT_WDTO); 66 spin_unlock(&scx_lock); 67 } 68 69 static void scx200_wdt_update_margin(void) 70 { 71 pr_info("timer margin %d seconds\n", margin); 72 wdto_restart = margin * W_SCALE; 73 } 74 75 static void scx200_wdt_enable(void) 76 { 77 pr_debug("enabling watchdog timer, wdto_restart = %d\n", wdto_restart); 78 79 spin_lock(&scx_lock); 80 outw(0, scx200_cb_base + SCx200_WDT_WDTO); 81 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS); 82 outw(W_ENABLE, scx200_cb_base + SCx200_WDT_WDCNFG); 83 spin_unlock(&scx_lock); 84 85 scx200_wdt_ping(); 86 } 87 88 static void scx200_wdt_disable(void) 89 { 90 pr_debug("disabling watchdog timer\n"); 91 92 spin_lock(&scx_lock); 93 outw(0, scx200_cb_base + SCx200_WDT_WDTO); 94 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS); 95 outw(W_DISABLE, scx200_cb_base + SCx200_WDT_WDCNFG); 96 spin_unlock(&scx_lock); 97 } 98 99 static int scx200_wdt_open(struct inode *inode, struct file *file) 100 { 101 /* only allow one at a time */ 102 if (test_and_set_bit(0, &open_lock)) 103 return -EBUSY; 104 scx200_wdt_enable(); 105 106 return nonseekable_open(inode, file); 107 } 108 109 static int scx200_wdt_release(struct inode *inode, struct file *file) 110 { 111 if (expect_close != 42) 112 pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n"); 113 else if (!nowayout) 114 scx200_wdt_disable(); 115 expect_close = 0; 116 clear_bit(0, &open_lock); 117 118 return 0; 119 } 120 121 static int scx200_wdt_notify_sys(struct notifier_block *this, 122 unsigned long code, void *unused) 123 { 124 if (code == SYS_HALT || code == SYS_POWER_OFF) 125 if (!nowayout) 126 scx200_wdt_disable(); 127 128 return NOTIFY_DONE; 129 } 130 131 static struct notifier_block scx200_wdt_notifier = { 132 .notifier_call = scx200_wdt_notify_sys, 133 }; 134 135 static ssize_t scx200_wdt_write(struct file *file, const char __user *data, 136 size_t len, loff_t *ppos) 137 { 138 /* check for a magic close character */ 139 if (len) { 140 size_t i; 141 142 scx200_wdt_ping(); 143 144 expect_close = 0; 145 for (i = 0; i < len; ++i) { 146 char c; 147 if (get_user(c, data + i)) 148 return -EFAULT; 149 if (c == 'V') 150 expect_close = 42; 151 } 152 153 return len; 154 } 155 156 return 0; 157 } 158 159 static long scx200_wdt_ioctl(struct file *file, unsigned int cmd, 160 unsigned long arg) 161 { 162 void __user *argp = (void __user *)arg; 163 int __user *p = argp; 164 static const struct watchdog_info ident = { 165 .identity = "NatSemi SCx200 Watchdog", 166 .firmware_version = 1, 167 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | 168 WDIOF_MAGICCLOSE, 169 }; 170 int new_margin; 171 172 switch (cmd) { 173 case WDIOC_GETSUPPORT: 174 if (copy_to_user(argp, &ident, sizeof(ident))) 175 return -EFAULT; 176 return 0; 177 case WDIOC_GETSTATUS: 178 case WDIOC_GETBOOTSTATUS: 179 if (put_user(0, p)) 180 return -EFAULT; 181 return 0; 182 case WDIOC_KEEPALIVE: 183 scx200_wdt_ping(); 184 return 0; 185 case WDIOC_SETTIMEOUT: 186 if (get_user(new_margin, p)) 187 return -EFAULT; 188 if (new_margin < 1) 189 return -EINVAL; 190 margin = new_margin; 191 scx200_wdt_update_margin(); 192 scx200_wdt_ping(); 193 case WDIOC_GETTIMEOUT: 194 if (put_user(margin, p)) 195 return -EFAULT; 196 return 0; 197 default: 198 return -ENOTTY; 199 } 200 } 201 202 static const struct file_operations scx200_wdt_fops = { 203 .owner = THIS_MODULE, 204 .llseek = no_llseek, 205 .write = scx200_wdt_write, 206 .unlocked_ioctl = scx200_wdt_ioctl, 207 .open = scx200_wdt_open, 208 .release = scx200_wdt_release, 209 }; 210 211 static struct miscdevice scx200_wdt_miscdev = { 212 .minor = WATCHDOG_MINOR, 213 .name = "watchdog", 214 .fops = &scx200_wdt_fops, 215 }; 216 217 static int __init scx200_wdt_init(void) 218 { 219 int r; 220 221 pr_debug("NatSemi SCx200 Watchdog Driver\n"); 222 223 /* check that we have found the configuration block */ 224 if (!scx200_cb_present()) 225 return -ENODEV; 226 227 if (!request_region(scx200_cb_base + SCx200_WDT_OFFSET, 228 SCx200_WDT_SIZE, 229 "NatSemi SCx200 Watchdog")) { 230 pr_warn("watchdog I/O region busy\n"); 231 return -EBUSY; 232 } 233 234 scx200_wdt_update_margin(); 235 scx200_wdt_disable(); 236 237 r = register_reboot_notifier(&scx200_wdt_notifier); 238 if (r) { 239 pr_err("unable to register reboot notifier\n"); 240 release_region(scx200_cb_base + SCx200_WDT_OFFSET, 241 SCx200_WDT_SIZE); 242 return r; 243 } 244 245 r = misc_register(&scx200_wdt_miscdev); 246 if (r) { 247 unregister_reboot_notifier(&scx200_wdt_notifier); 248 release_region(scx200_cb_base + SCx200_WDT_OFFSET, 249 SCx200_WDT_SIZE); 250 return r; 251 } 252 253 return 0; 254 } 255 256 static void __exit scx200_wdt_cleanup(void) 257 { 258 misc_deregister(&scx200_wdt_miscdev); 259 unregister_reboot_notifier(&scx200_wdt_notifier); 260 release_region(scx200_cb_base + SCx200_WDT_OFFSET, 261 SCx200_WDT_SIZE); 262 } 263 264 module_init(scx200_wdt_init); 265 module_exit(scx200_wdt_cleanup); 266 267 /* 268 Local variables: 269 compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules" 270 c-basic-offset: 8 271 End: 272 */ 273