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/platform_device.h> 32 #include <linux/watchdog.h> 33 #include <linux/fs.h> 34 #include <linux/ioport.h> 35 #include <linux/io.h> 36 #include <linux/uaccess.h> 37 38 #include <asm/addrspace.h> 39 #include <asm/mach-ar7/ar7.h> 40 41 #define DRVNAME "ar7_wdt" 42 #define LONGNAME "TI AR7 Watchdog Timer" 43 44 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>"); 45 MODULE_DESCRIPTION(LONGNAME); 46 MODULE_LICENSE("GPL"); 47 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 48 49 static int margin = 60; 50 module_param(margin, int, 0); 51 MODULE_PARM_DESC(margin, "Watchdog margin in seconds"); 52 53 static int nowayout = WATCHDOG_NOWAYOUT; 54 module_param(nowayout, int, 0); 55 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close"); 56 57 #define READ_REG(x) readl((void __iomem *)&(x)) 58 #define WRITE_REG(x, v) writel((v), (void __iomem *)&(x)) 59 60 struct ar7_wdt { 61 u32 kick_lock; 62 u32 kick; 63 u32 change_lock; 64 u32 change; 65 u32 disable_lock; 66 u32 disable; 67 u32 prescale_lock; 68 u32 prescale; 69 }; 70 71 static unsigned long wdt_is_open; 72 static spinlock_t wdt_lock; 73 static unsigned expect_close; 74 75 /* XXX currently fixed, allows max margin ~68.72 secs */ 76 #define prescale_value 0xffff 77 78 /* Resource of the WDT registers */ 79 static struct resource *ar7_regs_wdt; 80 /* Pointer to the remapped WDT IO space */ 81 static struct ar7_wdt *ar7_wdt; 82 83 static void ar7_wdt_kick(u32 value) 84 { 85 WRITE_REG(ar7_wdt->kick_lock, 0x5555); 86 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) { 87 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa); 88 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) { 89 WRITE_REG(ar7_wdt->kick, value); 90 return; 91 } 92 } 93 printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n"); 94 } 95 96 static void ar7_wdt_prescale(u32 value) 97 { 98 WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a); 99 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) { 100 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5); 101 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) { 102 WRITE_REG(ar7_wdt->prescale, value); 103 return; 104 } 105 } 106 printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n"); 107 } 108 109 static void ar7_wdt_change(u32 value) 110 { 111 WRITE_REG(ar7_wdt->change_lock, 0x6666); 112 if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) { 113 WRITE_REG(ar7_wdt->change_lock, 0xbbbb); 114 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) { 115 WRITE_REG(ar7_wdt->change, value); 116 return; 117 } 118 } 119 printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n"); 120 } 121 122 static void ar7_wdt_disable(u32 value) 123 { 124 WRITE_REG(ar7_wdt->disable_lock, 0x7777); 125 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) { 126 WRITE_REG(ar7_wdt->disable_lock, 0xcccc); 127 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) { 128 WRITE_REG(ar7_wdt->disable_lock, 0xdddd); 129 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) { 130 WRITE_REG(ar7_wdt->disable, value); 131 return; 132 } 133 } 134 } 135 printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n"); 136 } 137 138 static void ar7_wdt_update_margin(int new_margin) 139 { 140 u32 change; 141 142 change = new_margin * (ar7_vbus_freq() / prescale_value); 143 if (change < 1) 144 change = 1; 145 if (change > 0xffff) 146 change = 0xffff; 147 ar7_wdt_change(change); 148 margin = change * prescale_value / ar7_vbus_freq(); 149 printk(KERN_INFO DRVNAME 150 ": timer margin %d seconds (prescale %d, change %d, freq %d)\n", 151 margin, prescale_value, change, ar7_vbus_freq()); 152 } 153 154 static void ar7_wdt_enable_wdt(void) 155 { 156 printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n"); 157 ar7_wdt_disable(1); 158 ar7_wdt_kick(1); 159 } 160 161 static void ar7_wdt_disable_wdt(void) 162 { 163 printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n"); 164 ar7_wdt_disable(0); 165 } 166 167 static int ar7_wdt_open(struct inode *inode, struct file *file) 168 { 169 /* only allow one at a time */ 170 if (test_and_set_bit(0, &wdt_is_open)) 171 return -EBUSY; 172 ar7_wdt_enable_wdt(); 173 expect_close = 0; 174 175 return nonseekable_open(inode, file); 176 } 177 178 static int ar7_wdt_release(struct inode *inode, struct file *file) 179 { 180 if (!expect_close) 181 printk(KERN_WARNING DRVNAME 182 ": watchdog device closed unexpectedly," 183 "will not disable the watchdog timer\n"); 184 else if (!nowayout) 185 ar7_wdt_disable_wdt(); 186 clear_bit(0, &wdt_is_open); 187 return 0; 188 } 189 190 static ssize_t ar7_wdt_write(struct file *file, const char *data, 191 size_t len, loff_t *ppos) 192 { 193 /* check for a magic close character */ 194 if (len) { 195 size_t i; 196 197 spin_lock(&wdt_lock); 198 ar7_wdt_kick(1); 199 spin_unlock(&wdt_lock); 200 201 expect_close = 0; 202 for (i = 0; i < len; ++i) { 203 char c; 204 if (get_user(c, data + i)) 205 return -EFAULT; 206 if (c == 'V') 207 expect_close = 1; 208 } 209 210 } 211 return len; 212 } 213 214 static long ar7_wdt_ioctl(struct file *file, 215 unsigned int cmd, unsigned long arg) 216 { 217 static struct watchdog_info ident = { 218 .identity = LONGNAME, 219 .firmware_version = 1, 220 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | 221 WDIOF_MAGICCLOSE), 222 }; 223 int new_margin; 224 225 switch (cmd) { 226 case WDIOC_GETSUPPORT: 227 if (copy_to_user((struct watchdog_info *)arg, &ident, 228 sizeof(ident))) 229 return -EFAULT; 230 return 0; 231 case WDIOC_GETSTATUS: 232 case WDIOC_GETBOOTSTATUS: 233 if (put_user(0, (int *)arg)) 234 return -EFAULT; 235 return 0; 236 case WDIOC_KEEPALIVE: 237 ar7_wdt_kick(1); 238 return 0; 239 case WDIOC_SETTIMEOUT: 240 if (get_user(new_margin, (int *)arg)) 241 return -EFAULT; 242 if (new_margin < 1) 243 return -EINVAL; 244 245 spin_lock(&wdt_lock); 246 ar7_wdt_update_margin(new_margin); 247 ar7_wdt_kick(1); 248 spin_unlock(&wdt_lock); 249 250 case WDIOC_GETTIMEOUT: 251 if (put_user(margin, (int *)arg)) 252 return -EFAULT; 253 return 0; 254 default: 255 return -ENOTTY; 256 } 257 } 258 259 static const struct file_operations ar7_wdt_fops = { 260 .owner = THIS_MODULE, 261 .write = ar7_wdt_write, 262 .unlocked_ioctl = ar7_wdt_ioctl, 263 .open = ar7_wdt_open, 264 .release = ar7_wdt_release, 265 }; 266 267 static struct miscdevice ar7_wdt_miscdev = { 268 .minor = WATCHDOG_MINOR, 269 .name = "watchdog", 270 .fops = &ar7_wdt_fops, 271 }; 272 273 static int __devinit ar7_wdt_probe(struct platform_device *pdev) 274 { 275 int rc; 276 277 spin_lock_init(&wdt_lock); 278 279 ar7_regs_wdt = 280 platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs"); 281 if (!ar7_regs_wdt) { 282 printk(KERN_ERR DRVNAME ": could not get registers resource\n"); 283 rc = -ENODEV; 284 goto out; 285 } 286 287 if (!request_mem_region(ar7_regs_wdt->start, 288 resource_size(ar7_regs_wdt), LONGNAME)) { 289 printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n"); 290 rc = -EBUSY; 291 goto out; 292 } 293 294 ar7_wdt = ioremap(ar7_regs_wdt->start, resource_size(ar7_regs_wdt)); 295 if (!ar7_wdt) { 296 printk(KERN_ERR DRVNAME ": could not ioremap registers\n"); 297 rc = -ENXIO; 298 goto out_mem_region; 299 } 300 301 ar7_wdt_disable_wdt(); 302 ar7_wdt_prescale(prescale_value); 303 ar7_wdt_update_margin(margin); 304 305 rc = misc_register(&ar7_wdt_miscdev); 306 if (rc) { 307 printk(KERN_ERR DRVNAME ": unable to register misc device\n"); 308 goto out_alloc; 309 } 310 goto out; 311 312 out_alloc: 313 iounmap(ar7_wdt); 314 out_mem_region: 315 release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt)); 316 out: 317 return rc; 318 } 319 320 static int __devexit ar7_wdt_remove(struct platform_device *pdev) 321 { 322 misc_deregister(&ar7_wdt_miscdev); 323 iounmap(ar7_wdt); 324 release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt)); 325 326 return 0; 327 } 328 329 static void ar7_wdt_shutdown(struct platform_device *pdev) 330 { 331 if (!nowayout) 332 ar7_wdt_disable_wdt(); 333 } 334 335 static struct platform_driver ar7_wdt_driver = { 336 .probe = ar7_wdt_probe, 337 .remove = __devexit_p(ar7_wdt_remove), 338 .shutdown = ar7_wdt_shutdown, 339 .driver = { 340 .owner = THIS_MODULE, 341 .name = "ar7_wdt", 342 }, 343 }; 344 345 static int __init ar7_wdt_init(void) 346 { 347 return platform_driver_register(&ar7_wdt_driver); 348 } 349 350 static void __exit ar7_wdt_cleanup(void) 351 { 352 platform_driver_unregister(&ar7_wdt_driver); 353 } 354 355 module_init(ar7_wdt_init); 356 module_exit(ar7_wdt_cleanup); 357