1 /* 2 * drivers/watchdog/ar7_wdt.c 3 * 4 * Copyright (C) 2007 Nicolas Thill <nico@openwrt.org> 5 * Copyright (c) 2005 Enrik Berkhan <Enrik.Berkhan@akk.org> 6 * 7 * Some code taken from: 8 * National Semiconductor SCx200 Watchdog support 9 * Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> 10 * 11 * This program is free software; you can redistribute it and/or modify 12 * it under the terms of the GNU General Public License as published by 13 * the Free Software Foundation; either version 2 of the License, or 14 * (at your option) any later version. 15 * 16 * This program is distributed in the hope that it will be useful, 17 * but WITHOUT ANY WARRANTY; without even the implied warranty of 18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 19 * GNU General Public License for more details. 20 * 21 * You should have received a copy of the GNU General Public License 22 * along with this program; if not, write to the Free Software 23 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 24 */ 25 26 #include <linux/module.h> 27 #include <linux/moduleparam.h> 28 #include <linux/errno.h> 29 #include <linux/init.h> 30 #include <linux/miscdevice.h> 31 #include <linux/watchdog.h> 32 #include <linux/notifier.h> 33 #include <linux/reboot.h> 34 #include <linux/fs.h> 35 #include <linux/ioport.h> 36 #include <linux/io.h> 37 #include <linux/uaccess.h> 38 39 #include <asm/addrspace.h> 40 #include <asm/ar7/ar7.h> 41 42 #define DRVNAME "ar7_wdt" 43 #define LONGNAME "TI AR7 Watchdog Timer" 44 45 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>"); 46 MODULE_DESCRIPTION(LONGNAME); 47 MODULE_LICENSE("GPL"); 48 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 49 50 static int margin = 60; 51 module_param(margin, int, 0); 52 MODULE_PARM_DESC(margin, "Watchdog margin in seconds"); 53 54 static int nowayout = WATCHDOG_NOWAYOUT; 55 module_param(nowayout, int, 0); 56 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close"); 57 58 #define READ_REG(x) readl((void __iomem *)&(x)) 59 #define WRITE_REG(x, v) writel((v), (void __iomem *)&(x)) 60 61 struct ar7_wdt { 62 u32 kick_lock; 63 u32 kick; 64 u32 change_lock; 65 u32 change; 66 u32 disable_lock; 67 u32 disable; 68 u32 prescale_lock; 69 u32 prescale; 70 }; 71 72 static struct semaphore open_semaphore; 73 static unsigned expect_close; 74 75 /* XXX currently fixed, allows max margin ~68.72 secs */ 76 #define prescale_value 0xffff 77 78 /* Offset of the WDT registers */ 79 static unsigned long ar7_regs_wdt; 80 /* Pointer to the remapped WDT IO space */ 81 static struct ar7_wdt *ar7_wdt; 82 static void ar7_wdt_get_regs(void) 83 { 84 u16 chip_id = ar7_chip_id(); 85 switch (chip_id) { 86 case AR7_CHIP_7100: 87 case AR7_CHIP_7200: 88 ar7_regs_wdt = AR7_REGS_WDT; 89 break; 90 default: 91 ar7_regs_wdt = UR8_REGS_WDT; 92 break; 93 } 94 } 95 96 97 static void ar7_wdt_kick(u32 value) 98 { 99 WRITE_REG(ar7_wdt->kick_lock, 0x5555); 100 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) { 101 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa); 102 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) { 103 WRITE_REG(ar7_wdt->kick, value); 104 return; 105 } 106 } 107 printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n"); 108 } 109 110 static void ar7_wdt_prescale(u32 value) 111 { 112 WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a); 113 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) { 114 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5); 115 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) { 116 WRITE_REG(ar7_wdt->prescale, value); 117 return; 118 } 119 } 120 printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n"); 121 } 122 123 static void ar7_wdt_change(u32 value) 124 { 125 WRITE_REG(ar7_wdt->change_lock, 0x6666); 126 if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) { 127 WRITE_REG(ar7_wdt->change_lock, 0xbbbb); 128 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) { 129 WRITE_REG(ar7_wdt->change, value); 130 return; 131 } 132 } 133 printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n"); 134 } 135 136 static void ar7_wdt_disable(u32 value) 137 { 138 WRITE_REG(ar7_wdt->disable_lock, 0x7777); 139 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) { 140 WRITE_REG(ar7_wdt->disable_lock, 0xcccc); 141 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) { 142 WRITE_REG(ar7_wdt->disable_lock, 0xdddd); 143 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) { 144 WRITE_REG(ar7_wdt->disable, value); 145 return; 146 } 147 } 148 } 149 printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n"); 150 } 151 152 static void ar7_wdt_update_margin(int new_margin) 153 { 154 u32 change; 155 156 change = new_margin * (ar7_vbus_freq() / prescale_value); 157 if (change < 1) change = 1; 158 if (change > 0xffff) change = 0xffff; 159 ar7_wdt_change(change); 160 margin = change * prescale_value / ar7_vbus_freq(); 161 printk(KERN_INFO DRVNAME 162 ": timer margin %d seconds (prescale %d, change %d, freq %d)\n", 163 margin, prescale_value, change, ar7_vbus_freq()); 164 } 165 166 static void ar7_wdt_enable_wdt(void) 167 { 168 printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n"); 169 ar7_wdt_disable(1); 170 ar7_wdt_kick(1); 171 } 172 173 static void ar7_wdt_disable_wdt(void) 174 { 175 printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n"); 176 ar7_wdt_disable(0); 177 } 178 179 static int ar7_wdt_open(struct inode *inode, struct file *file) 180 { 181 /* only allow one at a time */ 182 if (down_trylock(&open_semaphore)) 183 return -EBUSY; 184 ar7_wdt_enable_wdt(); 185 expect_close = 0; 186 187 return nonseekable_open(inode, file); 188 } 189 190 static int ar7_wdt_release(struct inode *inode, struct file *file) 191 { 192 if (!expect_close) 193 printk(KERN_WARNING DRVNAME 194 ": watchdog device closed unexpectedly," 195 "will not disable the watchdog timer\n"); 196 else if (!nowayout) 197 ar7_wdt_disable_wdt(); 198 199 up(&open_semaphore); 200 201 return 0; 202 } 203 204 static int ar7_wdt_notify_sys(struct notifier_block *this, 205 unsigned long code, void *unused) 206 { 207 if (code == SYS_HALT || code == SYS_POWER_OFF) 208 if (!nowayout) 209 ar7_wdt_disable_wdt(); 210 211 return NOTIFY_DONE; 212 } 213 214 static struct notifier_block ar7_wdt_notifier = { 215 .notifier_call = ar7_wdt_notify_sys 216 }; 217 218 static ssize_t ar7_wdt_write(struct file *file, const char *data, 219 size_t len, loff_t *ppos) 220 { 221 /* check for a magic close character */ 222 if (len) { 223 size_t i; 224 225 ar7_wdt_kick(1); 226 227 expect_close = 0; 228 for (i = 0; i < len; ++i) { 229 char c; 230 if (get_user(c, data+i)) 231 return -EFAULT; 232 if (c == 'V') 233 expect_close = 1; 234 } 235 236 } 237 return len; 238 } 239 240 static int ar7_wdt_ioctl(struct inode *inode, struct file *file, 241 unsigned int cmd, unsigned long arg) 242 { 243 static struct watchdog_info ident = { 244 .identity = LONGNAME, 245 .firmware_version = 1, 246 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING), 247 }; 248 int new_margin; 249 250 switch (cmd) { 251 default: 252 return -ENOTTY; 253 case WDIOC_GETSUPPORT: 254 if (copy_to_user((struct watchdog_info *)arg, &ident, 255 sizeof(ident))) 256 return -EFAULT; 257 return 0; 258 case WDIOC_GETSTATUS: 259 case WDIOC_GETBOOTSTATUS: 260 if (put_user(0, (int *)arg)) 261 return -EFAULT; 262 return 0; 263 case WDIOC_KEEPALIVE: 264 ar7_wdt_kick(1); 265 return 0; 266 case WDIOC_SETTIMEOUT: 267 if (get_user(new_margin, (int *)arg)) 268 return -EFAULT; 269 if (new_margin < 1) 270 return -EINVAL; 271 272 ar7_wdt_update_margin(new_margin); 273 ar7_wdt_kick(1); 274 275 case WDIOC_GETTIMEOUT: 276 if (put_user(margin, (int *)arg)) 277 return -EFAULT; 278 return 0; 279 } 280 } 281 282 static const struct file_operations ar7_wdt_fops = { 283 .owner = THIS_MODULE, 284 .write = ar7_wdt_write, 285 .ioctl = ar7_wdt_ioctl, 286 .open = ar7_wdt_open, 287 .release = ar7_wdt_release, 288 }; 289 290 static struct miscdevice ar7_wdt_miscdev = { 291 .minor = WATCHDOG_MINOR, 292 .name = "watchdog", 293 .fops = &ar7_wdt_fops, 294 }; 295 296 static int __init ar7_wdt_init(void) 297 { 298 int rc; 299 300 ar7_wdt_get_regs(); 301 302 if (!request_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt), 303 LONGNAME)) { 304 printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n"); 305 return -EBUSY; 306 } 307 308 ar7_wdt = (struct ar7_wdt *) 309 ioremap(ar7_regs_wdt, sizeof(struct ar7_wdt)); 310 311 ar7_wdt_disable_wdt(); 312 ar7_wdt_prescale(prescale_value); 313 ar7_wdt_update_margin(margin); 314 315 sema_init(&open_semaphore, 1); 316 317 rc = register_reboot_notifier(&ar7_wdt_notifier); 318 if (rc) { 319 printk(KERN_ERR DRVNAME 320 ": unable to register reboot notifier\n"); 321 goto out_alloc; 322 } 323 324 rc = misc_register(&ar7_wdt_miscdev); 325 if (rc) { 326 printk(KERN_ERR DRVNAME ": unable to register misc device\n"); 327 goto out_register; 328 } 329 goto out; 330 331 out_register: 332 unregister_reboot_notifier(&ar7_wdt_notifier); 333 out_alloc: 334 iounmap(ar7_wdt); 335 release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt)); 336 out: 337 return rc; 338 } 339 340 static void __exit ar7_wdt_cleanup(void) 341 { 342 misc_deregister(&ar7_wdt_miscdev); 343 unregister_reboot_notifier(&ar7_wdt_notifier); 344 iounmap(ar7_wdt); 345 release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt)); 346 } 347 348 module_init(ar7_wdt_init); 349 module_exit(ar7_wdt_cleanup); 350