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 50 static int margin = 60; 51 module_param(margin, int, 0); 52 MODULE_PARM_DESC(margin, "Watchdog margin in seconds"); 53 54 static bool nowayout = WATCHDOG_NOWAYOUT; 55 module_param(nowayout, bool, 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 unsigned expect_close; 74 static DEFINE_SPINLOCK(wdt_lock); 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 pr_err("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 pr_err("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 pr_err("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 pr_err("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 pr_info("timer margin %d seconds (prescale %d, change %d, freq %d)\n", 155 margin, prescale_value, change, vbus_rate); 156 } 157 158 static void ar7_wdt_enable_wdt(void) 159 { 160 pr_debug("enabling watchdog timer\n"); 161 ar7_wdt_disable(1); 162 ar7_wdt_kick(1); 163 } 164 165 static void ar7_wdt_disable_wdt(void) 166 { 167 pr_debug("disabling watchdog timer\n"); 168 ar7_wdt_disable(0); 169 } 170 171 static int ar7_wdt_open(struct inode *inode, struct file *file) 172 { 173 /* only allow one at a time */ 174 if (test_and_set_bit(0, &wdt_is_open)) 175 return -EBUSY; 176 ar7_wdt_enable_wdt(); 177 expect_close = 0; 178 179 return nonseekable_open(inode, file); 180 } 181 182 static int ar7_wdt_release(struct inode *inode, struct file *file) 183 { 184 if (!expect_close) 185 pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n"); 186 else if (!nowayout) 187 ar7_wdt_disable_wdt(); 188 clear_bit(0, &wdt_is_open); 189 return 0; 190 } 191 192 static ssize_t ar7_wdt_write(struct file *file, const char *data, 193 size_t len, loff_t *ppos) 194 { 195 /* check for a magic close character */ 196 if (len) { 197 size_t i; 198 199 spin_lock(&wdt_lock); 200 ar7_wdt_kick(1); 201 spin_unlock(&wdt_lock); 202 203 expect_close = 0; 204 for (i = 0; i < len; ++i) { 205 char c; 206 if (get_user(c, data + i)) 207 return -EFAULT; 208 if (c == 'V') 209 expect_close = 1; 210 } 211 212 } 213 return len; 214 } 215 216 static long ar7_wdt_ioctl(struct file *file, 217 unsigned int cmd, unsigned long arg) 218 { 219 static const struct watchdog_info ident = { 220 .identity = LONGNAME, 221 .firmware_version = 1, 222 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | 223 WDIOF_MAGICCLOSE), 224 }; 225 int new_margin; 226 227 switch (cmd) { 228 case WDIOC_GETSUPPORT: 229 if (copy_to_user((struct watchdog_info *)arg, &ident, 230 sizeof(ident))) 231 return -EFAULT; 232 return 0; 233 case WDIOC_GETSTATUS: 234 case WDIOC_GETBOOTSTATUS: 235 if (put_user(0, (int *)arg)) 236 return -EFAULT; 237 return 0; 238 case WDIOC_KEEPALIVE: 239 ar7_wdt_kick(1); 240 return 0; 241 case WDIOC_SETTIMEOUT: 242 if (get_user(new_margin, (int *)arg)) 243 return -EFAULT; 244 if (new_margin < 1) 245 return -EINVAL; 246 247 spin_lock(&wdt_lock); 248 ar7_wdt_update_margin(new_margin); 249 ar7_wdt_kick(1); 250 spin_unlock(&wdt_lock); 251 252 case WDIOC_GETTIMEOUT: 253 if (put_user(margin, (int *)arg)) 254 return -EFAULT; 255 return 0; 256 default: 257 return -ENOTTY; 258 } 259 } 260 261 static const struct file_operations ar7_wdt_fops = { 262 .owner = THIS_MODULE, 263 .write = ar7_wdt_write, 264 .unlocked_ioctl = ar7_wdt_ioctl, 265 .open = ar7_wdt_open, 266 .release = ar7_wdt_release, 267 .llseek = no_llseek, 268 }; 269 270 static struct miscdevice ar7_wdt_miscdev = { 271 .minor = WATCHDOG_MINOR, 272 .name = "watchdog", 273 .fops = &ar7_wdt_fops, 274 }; 275 276 static int ar7_wdt_probe(struct platform_device *pdev) 277 { 278 int rc; 279 280 ar7_regs_wdt = 281 platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs"); 282 ar7_wdt = devm_ioremap_resource(&pdev->dev, ar7_regs_wdt); 283 if (IS_ERR(ar7_wdt)) 284 return PTR_ERR(ar7_wdt); 285 286 vbus_clk = clk_get(NULL, "vbus"); 287 if (IS_ERR(vbus_clk)) { 288 pr_err("could not get vbus clock\n"); 289 return PTR_ERR(vbus_clk); 290 } 291 292 ar7_wdt_disable_wdt(); 293 ar7_wdt_prescale(prescale_value); 294 ar7_wdt_update_margin(margin); 295 296 rc = misc_register(&ar7_wdt_miscdev); 297 if (rc) { 298 pr_err("unable to register misc device\n"); 299 goto out; 300 } 301 return 0; 302 303 out: 304 clk_put(vbus_clk); 305 vbus_clk = NULL; 306 return rc; 307 } 308 309 static int ar7_wdt_remove(struct platform_device *pdev) 310 { 311 misc_deregister(&ar7_wdt_miscdev); 312 clk_put(vbus_clk); 313 vbus_clk = NULL; 314 return 0; 315 } 316 317 static void ar7_wdt_shutdown(struct platform_device *pdev) 318 { 319 if (!nowayout) 320 ar7_wdt_disable_wdt(); 321 } 322 323 static struct platform_driver ar7_wdt_driver = { 324 .probe = ar7_wdt_probe, 325 .remove = ar7_wdt_remove, 326 .shutdown = ar7_wdt_shutdown, 327 .driver = { 328 .owner = THIS_MODULE, 329 .name = "ar7_wdt", 330 }, 331 }; 332 333 module_platform_driver(ar7_wdt_driver); 334