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 unsigned long wdt_is_open; 73 static spinlock_t wdt_lock; 74 static unsigned expect_close; 75 76 /* XXX currently fixed, allows max margin ~68.72 secs */ 77 #define prescale_value 0xffff 78 79 /* Offset of the WDT registers */ 80 static unsigned long ar7_regs_wdt; 81 /* Pointer to the remapped WDT IO space */ 82 static struct ar7_wdt *ar7_wdt; 83 static void ar7_wdt_get_regs(void) 84 { 85 u16 chip_id = ar7_chip_id(); 86 switch (chip_id) { 87 case AR7_CHIP_7100: 88 case AR7_CHIP_7200: 89 ar7_regs_wdt = AR7_REGS_WDT; 90 break; 91 default: 92 ar7_regs_wdt = UR8_REGS_WDT; 93 break; 94 } 95 } 96 97 98 static void ar7_wdt_kick(u32 value) 99 { 100 WRITE_REG(ar7_wdt->kick_lock, 0x5555); 101 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) { 102 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa); 103 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) { 104 WRITE_REG(ar7_wdt->kick, value); 105 return; 106 } 107 } 108 printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n"); 109 } 110 111 static void ar7_wdt_prescale(u32 value) 112 { 113 WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a); 114 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) { 115 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5); 116 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) { 117 WRITE_REG(ar7_wdt->prescale, value); 118 return; 119 } 120 } 121 printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n"); 122 } 123 124 static void ar7_wdt_change(u32 value) 125 { 126 WRITE_REG(ar7_wdt->change_lock, 0x6666); 127 if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) { 128 WRITE_REG(ar7_wdt->change_lock, 0xbbbb); 129 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) { 130 WRITE_REG(ar7_wdt->change, value); 131 return; 132 } 133 } 134 printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n"); 135 } 136 137 static void ar7_wdt_disable(u32 value) 138 { 139 WRITE_REG(ar7_wdt->disable_lock, 0x7777); 140 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) { 141 WRITE_REG(ar7_wdt->disable_lock, 0xcccc); 142 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) { 143 WRITE_REG(ar7_wdt->disable_lock, 0xdddd); 144 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) { 145 WRITE_REG(ar7_wdt->disable, value); 146 return; 147 } 148 } 149 } 150 printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n"); 151 } 152 153 static void ar7_wdt_update_margin(int new_margin) 154 { 155 u32 change; 156 157 change = new_margin * (ar7_vbus_freq() / prescale_value); 158 if (change < 1) 159 change = 1; 160 if (change > 0xffff) 161 change = 0xffff; 162 ar7_wdt_change(change); 163 margin = change * prescale_value / ar7_vbus_freq(); 164 printk(KERN_INFO DRVNAME 165 ": timer margin %d seconds (prescale %d, change %d, freq %d)\n", 166 margin, prescale_value, change, ar7_vbus_freq()); 167 } 168 169 static void ar7_wdt_enable_wdt(void) 170 { 171 printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n"); 172 ar7_wdt_disable(1); 173 ar7_wdt_kick(1); 174 } 175 176 static void ar7_wdt_disable_wdt(void) 177 { 178 printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n"); 179 ar7_wdt_disable(0); 180 } 181 182 static int ar7_wdt_open(struct inode *inode, struct file *file) 183 { 184 /* only allow one at a time */ 185 if (test_and_set_bit(0, &wdt_is_open)) 186 return -EBUSY; 187 ar7_wdt_enable_wdt(); 188 expect_close = 0; 189 190 return nonseekable_open(inode, file); 191 } 192 193 static int ar7_wdt_release(struct inode *inode, struct file *file) 194 { 195 if (!expect_close) 196 printk(KERN_WARNING DRVNAME 197 ": watchdog device closed unexpectedly," 198 "will not disable the watchdog timer\n"); 199 else if (!nowayout) 200 ar7_wdt_disable_wdt(); 201 clear_bit(0, &wdt_is_open); 202 return 0; 203 } 204 205 static int ar7_wdt_notify_sys(struct notifier_block *this, 206 unsigned long code, void *unused) 207 { 208 if (code == SYS_HALT || code == SYS_POWER_OFF) 209 if (!nowayout) 210 ar7_wdt_disable_wdt(); 211 212 return NOTIFY_DONE; 213 } 214 215 static struct notifier_block ar7_wdt_notifier = { 216 .notifier_call = ar7_wdt_notify_sys, 217 }; 218 219 static ssize_t ar7_wdt_write(struct file *file, const char *data, 220 size_t len, loff_t *ppos) 221 { 222 /* check for a magic close character */ 223 if (len) { 224 size_t i; 225 226 spin_lock(&wdt_lock); 227 ar7_wdt_kick(1); 228 spin_unlock(&wdt_lock); 229 230 expect_close = 0; 231 for (i = 0; i < len; ++i) { 232 char c; 233 if (get_user(c, data + i)) 234 return -EFAULT; 235 if (c == 'V') 236 expect_close = 1; 237 } 238 239 } 240 return len; 241 } 242 243 static long ar7_wdt_ioctl(struct file *file, 244 unsigned int cmd, unsigned long arg) 245 { 246 static struct watchdog_info ident = { 247 .identity = LONGNAME, 248 .firmware_version = 1, 249 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING), 250 }; 251 int new_margin; 252 253 switch (cmd) { 254 case WDIOC_GETSUPPORT: 255 if (copy_to_user((struct watchdog_info *)arg, &ident, 256 sizeof(ident))) 257 return -EFAULT; 258 return 0; 259 case WDIOC_GETSTATUS: 260 case WDIOC_GETBOOTSTATUS: 261 if (put_user(0, (int *)arg)) 262 return -EFAULT; 263 return 0; 264 case WDIOC_KEEPALIVE: 265 ar7_wdt_kick(1); 266 return 0; 267 case WDIOC_SETTIMEOUT: 268 if (get_user(new_margin, (int *)arg)) 269 return -EFAULT; 270 if (new_margin < 1) 271 return -EINVAL; 272 273 spin_lock(&wdt_lock); 274 ar7_wdt_update_margin(new_margin); 275 ar7_wdt_kick(1); 276 spin_unlock(&wdt_lock); 277 278 case WDIOC_GETTIMEOUT: 279 if (put_user(margin, (int *)arg)) 280 return -EFAULT; 281 return 0; 282 default: 283 return -ENOTTY; 284 } 285 } 286 287 static const struct file_operations ar7_wdt_fops = { 288 .owner = THIS_MODULE, 289 .write = ar7_wdt_write, 290 .unlocked_ioctl = ar7_wdt_ioctl, 291 .open = ar7_wdt_open, 292 .release = ar7_wdt_release, 293 }; 294 295 static struct miscdevice ar7_wdt_miscdev = { 296 .minor = WATCHDOG_MINOR, 297 .name = "watchdog", 298 .fops = &ar7_wdt_fops, 299 }; 300 301 static int __init ar7_wdt_init(void) 302 { 303 int rc; 304 305 spin_lock_init(&wdt_lock); 306 307 ar7_wdt_get_regs(); 308 309 if (!request_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt), 310 LONGNAME)) { 311 printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n"); 312 return -EBUSY; 313 } 314 315 ar7_wdt = (struct ar7_wdt *) 316 ioremap(ar7_regs_wdt, sizeof(struct ar7_wdt)); 317 318 ar7_wdt_disable_wdt(); 319 ar7_wdt_prescale(prescale_value); 320 ar7_wdt_update_margin(margin); 321 322 rc = register_reboot_notifier(&ar7_wdt_notifier); 323 if (rc) { 324 printk(KERN_ERR DRVNAME 325 ": unable to register reboot notifier\n"); 326 goto out_alloc; 327 } 328 329 rc = misc_register(&ar7_wdt_miscdev); 330 if (rc) { 331 printk(KERN_ERR DRVNAME ": unable to register misc device\n"); 332 goto out_register; 333 } 334 goto out; 335 336 out_register: 337 unregister_reboot_notifier(&ar7_wdt_notifier); 338 out_alloc: 339 iounmap(ar7_wdt); 340 release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt)); 341 out: 342 return rc; 343 } 344 345 static void __exit ar7_wdt_cleanup(void) 346 { 347 misc_deregister(&ar7_wdt_miscdev); 348 unregister_reboot_notifier(&ar7_wdt_notifier); 349 iounmap(ar7_wdt); 350 release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt)); 351 } 352 353 module_init(ar7_wdt_init); 354 module_exit(ar7_wdt_cleanup); 355