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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 27 28 #include <linux/module.h> 29 #include <linux/moduleparam.h> 30 #include <linux/errno.h> 31 #include <linux/init.h> 32 #include <linux/miscdevice.h> 33 #include <linux/platform_device.h> 34 #include <linux/watchdog.h> 35 #include <linux/fs.h> 36 #include <linux/ioport.h> 37 #include <linux/io.h> 38 #include <linux/uaccess.h> 39 #include <linux/clk.h> 40 41 #include <asm/addrspace.h> 42 #include <asm/mach-ar7/ar7.h> 43 44 #define LONGNAME "TI AR7 Watchdog Timer" 45 46 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>"); 47 MODULE_DESCRIPTION(LONGNAME); 48 MODULE_LICENSE("GPL"); 49 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 50 51 static int margin = 60; 52 module_param(margin, int, 0); 53 MODULE_PARM_DESC(margin, "Watchdog margin in seconds"); 54 55 static bool nowayout = WATCHDOG_NOWAYOUT; 56 module_param(nowayout, bool, 0); 57 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close"); 58 59 #define READ_REG(x) readl((void __iomem *)&(x)) 60 #define WRITE_REG(x, v) writel((v), (void __iomem *)&(x)) 61 62 struct ar7_wdt { 63 u32 kick_lock; 64 u32 kick; 65 u32 change_lock; 66 u32 change; 67 u32 disable_lock; 68 u32 disable; 69 u32 prescale_lock; 70 u32 prescale; 71 }; 72 73 static unsigned long wdt_is_open; 74 static unsigned expect_close; 75 static DEFINE_SPINLOCK(wdt_lock); 76 77 /* XXX currently fixed, allows max margin ~68.72 secs */ 78 #define prescale_value 0xffff 79 80 /* Resource of the WDT registers */ 81 static struct resource *ar7_regs_wdt; 82 /* Pointer to the remapped WDT IO space */ 83 static struct ar7_wdt *ar7_wdt; 84 85 static struct clk *vbus_clk; 86 87 static void ar7_wdt_kick(u32 value) 88 { 89 WRITE_REG(ar7_wdt->kick_lock, 0x5555); 90 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) { 91 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa); 92 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) { 93 WRITE_REG(ar7_wdt->kick, value); 94 return; 95 } 96 } 97 pr_err("failed to unlock WDT kick reg\n"); 98 } 99 100 static void ar7_wdt_prescale(u32 value) 101 { 102 WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a); 103 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) { 104 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5); 105 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) { 106 WRITE_REG(ar7_wdt->prescale, value); 107 return; 108 } 109 } 110 pr_err("failed to unlock WDT prescale reg\n"); 111 } 112 113 static void ar7_wdt_change(u32 value) 114 { 115 WRITE_REG(ar7_wdt->change_lock, 0x6666); 116 if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) { 117 WRITE_REG(ar7_wdt->change_lock, 0xbbbb); 118 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) { 119 WRITE_REG(ar7_wdt->change, value); 120 return; 121 } 122 } 123 pr_err("failed to unlock WDT change reg\n"); 124 } 125 126 static void ar7_wdt_disable(u32 value) 127 { 128 WRITE_REG(ar7_wdt->disable_lock, 0x7777); 129 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) { 130 WRITE_REG(ar7_wdt->disable_lock, 0xcccc); 131 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) { 132 WRITE_REG(ar7_wdt->disable_lock, 0xdddd); 133 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) { 134 WRITE_REG(ar7_wdt->disable, value); 135 return; 136 } 137 } 138 } 139 pr_err("failed to unlock WDT disable reg\n"); 140 } 141 142 static void ar7_wdt_update_margin(int new_margin) 143 { 144 u32 change; 145 u32 vbus_rate; 146 147 vbus_rate = clk_get_rate(vbus_clk); 148 change = new_margin * (vbus_rate / prescale_value); 149 if (change < 1) 150 change = 1; 151 if (change > 0xffff) 152 change = 0xffff; 153 ar7_wdt_change(change); 154 margin = change * prescale_value / vbus_rate; 155 pr_info("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 pr_debug("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 pr_debug("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 pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n"); 187 else if (!nowayout) 188 ar7_wdt_disable_wdt(); 189 clear_bit(0, &wdt_is_open); 190 return 0; 191 } 192 193 static ssize_t ar7_wdt_write(struct file *file, const char *data, 194 size_t len, loff_t *ppos) 195 { 196 /* check for a magic close character */ 197 if (len) { 198 size_t i; 199 200 spin_lock(&wdt_lock); 201 ar7_wdt_kick(1); 202 spin_unlock(&wdt_lock); 203 204 expect_close = 0; 205 for (i = 0; i < len; ++i) { 206 char c; 207 if (get_user(c, data + i)) 208 return -EFAULT; 209 if (c == 'V') 210 expect_close = 1; 211 } 212 213 } 214 return len; 215 } 216 217 static long ar7_wdt_ioctl(struct file *file, 218 unsigned int cmd, unsigned long arg) 219 { 220 static const struct watchdog_info ident = { 221 .identity = LONGNAME, 222 .firmware_version = 1, 223 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | 224 WDIOF_MAGICCLOSE), 225 }; 226 int new_margin; 227 228 switch (cmd) { 229 case WDIOC_GETSUPPORT: 230 if (copy_to_user((struct watchdog_info *)arg, &ident, 231 sizeof(ident))) 232 return -EFAULT; 233 return 0; 234 case WDIOC_GETSTATUS: 235 case WDIOC_GETBOOTSTATUS: 236 if (put_user(0, (int *)arg)) 237 return -EFAULT; 238 return 0; 239 case WDIOC_KEEPALIVE: 240 ar7_wdt_kick(1); 241 return 0; 242 case WDIOC_SETTIMEOUT: 243 if (get_user(new_margin, (int *)arg)) 244 return -EFAULT; 245 if (new_margin < 1) 246 return -EINVAL; 247 248 spin_lock(&wdt_lock); 249 ar7_wdt_update_margin(new_margin); 250 ar7_wdt_kick(1); 251 spin_unlock(&wdt_lock); 252 253 case WDIOC_GETTIMEOUT: 254 if (put_user(margin, (int *)arg)) 255 return -EFAULT; 256 return 0; 257 default: 258 return -ENOTTY; 259 } 260 } 261 262 static const struct file_operations ar7_wdt_fops = { 263 .owner = THIS_MODULE, 264 .write = ar7_wdt_write, 265 .unlocked_ioctl = ar7_wdt_ioctl, 266 .open = ar7_wdt_open, 267 .release = ar7_wdt_release, 268 .llseek = no_llseek, 269 }; 270 271 static struct miscdevice ar7_wdt_miscdev = { 272 .minor = WATCHDOG_MINOR, 273 .name = "watchdog", 274 .fops = &ar7_wdt_fops, 275 }; 276 277 static int ar7_wdt_probe(struct platform_device *pdev) 278 { 279 int rc; 280 281 ar7_regs_wdt = 282 platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs"); 283 if (!ar7_regs_wdt) { 284 pr_err("could not get registers resource\n"); 285 return -ENODEV; 286 } 287 288 ar7_wdt = devm_request_and_ioremap(&pdev->dev, ar7_regs_wdt); 289 if (!ar7_wdt) { 290 pr_err("could not ioremap registers\n"); 291 return -ENXIO; 292 } 293 294 vbus_clk = clk_get(NULL, "vbus"); 295 if (IS_ERR(vbus_clk)) { 296 pr_err("could not get vbus clock\n"); 297 return PTR_ERR(vbus_clk); 298 } 299 300 ar7_wdt_disable_wdt(); 301 ar7_wdt_prescale(prescale_value); 302 ar7_wdt_update_margin(margin); 303 304 rc = misc_register(&ar7_wdt_miscdev); 305 if (rc) { 306 pr_err("unable to register misc device\n"); 307 goto out; 308 } 309 return 0; 310 311 out: 312 clk_put(vbus_clk); 313 vbus_clk = NULL; 314 return rc; 315 } 316 317 static int ar7_wdt_remove(struct platform_device *pdev) 318 { 319 misc_deregister(&ar7_wdt_miscdev); 320 clk_put(vbus_clk); 321 vbus_clk = NULL; 322 return 0; 323 } 324 325 static void ar7_wdt_shutdown(struct platform_device *pdev) 326 { 327 if (!nowayout) 328 ar7_wdt_disable_wdt(); 329 } 330 331 static struct platform_driver ar7_wdt_driver = { 332 .probe = ar7_wdt_probe, 333 .remove = ar7_wdt_remove, 334 .shutdown = ar7_wdt_shutdown, 335 .driver = { 336 .owner = THIS_MODULE, 337 .name = "ar7_wdt", 338 }, 339 }; 340 341 module_platform_driver(ar7_wdt_driver); 342