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 #include <linux/clk.h> 38 39 #include <asm/addrspace.h> 40 #include <asm/mach-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 /* Resource of the WDT registers */ 80 static struct resource *ar7_regs_wdt; 81 /* Pointer to the remapped WDT IO space */ 82 static struct ar7_wdt *ar7_wdt; 83 84 static struct clk *vbus_clk; 85 86 static void ar7_wdt_kick(u32 value) 87 { 88 WRITE_REG(ar7_wdt->kick_lock, 0x5555); 89 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) { 90 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa); 91 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) { 92 WRITE_REG(ar7_wdt->kick, value); 93 return; 94 } 95 } 96 printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n"); 97 } 98 99 static void ar7_wdt_prescale(u32 value) 100 { 101 WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a); 102 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) { 103 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5); 104 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) { 105 WRITE_REG(ar7_wdt->prescale, value); 106 return; 107 } 108 } 109 printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n"); 110 } 111 112 static void ar7_wdt_change(u32 value) 113 { 114 WRITE_REG(ar7_wdt->change_lock, 0x6666); 115 if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) { 116 WRITE_REG(ar7_wdt->change_lock, 0xbbbb); 117 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) { 118 WRITE_REG(ar7_wdt->change, value); 119 return; 120 } 121 } 122 printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n"); 123 } 124 125 static void ar7_wdt_disable(u32 value) 126 { 127 WRITE_REG(ar7_wdt->disable_lock, 0x7777); 128 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) { 129 WRITE_REG(ar7_wdt->disable_lock, 0xcccc); 130 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) { 131 WRITE_REG(ar7_wdt->disable_lock, 0xdddd); 132 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) { 133 WRITE_REG(ar7_wdt->disable, value); 134 return; 135 } 136 } 137 } 138 printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n"); 139 } 140 141 static void ar7_wdt_update_margin(int new_margin) 142 { 143 u32 change; 144 u32 vbus_rate; 145 146 vbus_rate = clk_get_rate(vbus_clk); 147 change = new_margin * (vbus_rate / prescale_value); 148 if (change < 1) 149 change = 1; 150 if (change > 0xffff) 151 change = 0xffff; 152 ar7_wdt_change(change); 153 margin = change * prescale_value / vbus_rate; 154 printk(KERN_INFO DRVNAME 155 ": timer margin %d seconds (prescale %d, change %d, freq %d)\n", 156 margin, prescale_value, change, vbus_rate); 157 } 158 159 static void ar7_wdt_enable_wdt(void) 160 { 161 printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n"); 162 ar7_wdt_disable(1); 163 ar7_wdt_kick(1); 164 } 165 166 static void ar7_wdt_disable_wdt(void) 167 { 168 printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n"); 169 ar7_wdt_disable(0); 170 } 171 172 static int ar7_wdt_open(struct inode *inode, struct file *file) 173 { 174 /* only allow one at a time */ 175 if (test_and_set_bit(0, &wdt_is_open)) 176 return -EBUSY; 177 ar7_wdt_enable_wdt(); 178 expect_close = 0; 179 180 return nonseekable_open(inode, file); 181 } 182 183 static int ar7_wdt_release(struct inode *inode, struct file *file) 184 { 185 if (!expect_close) 186 printk(KERN_WARNING DRVNAME 187 ": watchdog device closed unexpectedly," 188 "will not disable the watchdog timer\n"); 189 else if (!nowayout) 190 ar7_wdt_disable_wdt(); 191 clear_bit(0, &wdt_is_open); 192 return 0; 193 } 194 195 static ssize_t ar7_wdt_write(struct file *file, const char *data, 196 size_t len, loff_t *ppos) 197 { 198 /* check for a magic close character */ 199 if (len) { 200 size_t i; 201 202 spin_lock(&wdt_lock); 203 ar7_wdt_kick(1); 204 spin_unlock(&wdt_lock); 205 206 expect_close = 0; 207 for (i = 0; i < len; ++i) { 208 char c; 209 if (get_user(c, data + i)) 210 return -EFAULT; 211 if (c == 'V') 212 expect_close = 1; 213 } 214 215 } 216 return len; 217 } 218 219 static long ar7_wdt_ioctl(struct file *file, 220 unsigned int cmd, unsigned long arg) 221 { 222 static const struct watchdog_info ident = { 223 .identity = LONGNAME, 224 .firmware_version = 1, 225 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | 226 WDIOF_MAGICCLOSE), 227 }; 228 int new_margin; 229 230 switch (cmd) { 231 case WDIOC_GETSUPPORT: 232 if (copy_to_user((struct watchdog_info *)arg, &ident, 233 sizeof(ident))) 234 return -EFAULT; 235 return 0; 236 case WDIOC_GETSTATUS: 237 case WDIOC_GETBOOTSTATUS: 238 if (put_user(0, (int *)arg)) 239 return -EFAULT; 240 return 0; 241 case WDIOC_KEEPALIVE: 242 ar7_wdt_kick(1); 243 return 0; 244 case WDIOC_SETTIMEOUT: 245 if (get_user(new_margin, (int *)arg)) 246 return -EFAULT; 247 if (new_margin < 1) 248 return -EINVAL; 249 250 spin_lock(&wdt_lock); 251 ar7_wdt_update_margin(new_margin); 252 ar7_wdt_kick(1); 253 spin_unlock(&wdt_lock); 254 255 case WDIOC_GETTIMEOUT: 256 if (put_user(margin, (int *)arg)) 257 return -EFAULT; 258 return 0; 259 default: 260 return -ENOTTY; 261 } 262 } 263 264 static const struct file_operations ar7_wdt_fops = { 265 .owner = THIS_MODULE, 266 .write = ar7_wdt_write, 267 .unlocked_ioctl = ar7_wdt_ioctl, 268 .open = ar7_wdt_open, 269 .release = ar7_wdt_release, 270 .llseek = no_llseek, 271 }; 272 273 static struct miscdevice ar7_wdt_miscdev = { 274 .minor = WATCHDOG_MINOR, 275 .name = "watchdog", 276 .fops = &ar7_wdt_fops, 277 }; 278 279 static int __devinit ar7_wdt_probe(struct platform_device *pdev) 280 { 281 int rc; 282 283 spin_lock_init(&wdt_lock); 284 285 ar7_regs_wdt = 286 platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs"); 287 if (!ar7_regs_wdt) { 288 printk(KERN_ERR DRVNAME ": could not get registers resource\n"); 289 rc = -ENODEV; 290 goto out; 291 } 292 293 if (!request_mem_region(ar7_regs_wdt->start, 294 resource_size(ar7_regs_wdt), LONGNAME)) { 295 printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n"); 296 rc = -EBUSY; 297 goto out; 298 } 299 300 ar7_wdt = ioremap(ar7_regs_wdt->start, resource_size(ar7_regs_wdt)); 301 if (!ar7_wdt) { 302 printk(KERN_ERR DRVNAME ": could not ioremap registers\n"); 303 rc = -ENXIO; 304 goto out_mem_region; 305 } 306 307 vbus_clk = clk_get(NULL, "vbus"); 308 if (IS_ERR(vbus_clk)) { 309 printk(KERN_ERR DRVNAME ": could not get vbus clock\n"); 310 rc = PTR_ERR(vbus_clk); 311 goto out_mem_region; 312 } 313 314 ar7_wdt_disable_wdt(); 315 ar7_wdt_prescale(prescale_value); 316 ar7_wdt_update_margin(margin); 317 318 rc = misc_register(&ar7_wdt_miscdev); 319 if (rc) { 320 printk(KERN_ERR DRVNAME ": unable to register misc device\n"); 321 goto out_alloc; 322 } 323 goto out; 324 325 out_alloc: 326 iounmap(ar7_wdt); 327 out_mem_region: 328 release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt)); 329 out: 330 return rc; 331 } 332 333 static int __devexit ar7_wdt_remove(struct platform_device *pdev) 334 { 335 misc_deregister(&ar7_wdt_miscdev); 336 iounmap(ar7_wdt); 337 release_mem_region(ar7_regs_wdt->start, resource_size(ar7_regs_wdt)); 338 339 return 0; 340 } 341 342 static void ar7_wdt_shutdown(struct platform_device *pdev) 343 { 344 if (!nowayout) 345 ar7_wdt_disable_wdt(); 346 } 347 348 static struct platform_driver ar7_wdt_driver = { 349 .probe = ar7_wdt_probe, 350 .remove = __devexit_p(ar7_wdt_remove), 351 .shutdown = ar7_wdt_shutdown, 352 .driver = { 353 .owner = THIS_MODULE, 354 .name = "ar7_wdt", 355 }, 356 }; 357 358 static int __init ar7_wdt_init(void) 359 { 360 return platform_driver_register(&ar7_wdt_driver); 361 } 362 363 static void __exit ar7_wdt_cleanup(void) 364 { 365 platform_driver_unregister(&ar7_wdt_driver); 366 } 367 368 module_init(ar7_wdt_init); 369 module_exit(ar7_wdt_cleanup); 370