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/miscdevice.h> 32 #include <linux/platform_device.h> 33 #include <linux/watchdog.h> 34 #include <linux/fs.h> 35 #include <linux/ioport.h> 36 #include <linux/io.h> 37 #include <linux/uaccess.h> 38 #include <linux/clk.h> 39 40 #include <asm/addrspace.h> 41 #include <asm/mach-ar7/ar7.h> 42 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 49 static int margin = 60; 50 module_param(margin, int, 0); 51 MODULE_PARM_DESC(margin, "Watchdog margin in seconds"); 52 53 static bool nowayout = WATCHDOG_NOWAYOUT; 54 module_param(nowayout, bool, 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 unsigned expect_close; 73 static DEFINE_SPINLOCK(wdt_lock); 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 struct clk *vbus_clk; 84 85 static void ar7_wdt_kick(u32 value) 86 { 87 WRITE_REG(ar7_wdt->kick_lock, 0x5555); 88 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) { 89 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa); 90 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) { 91 WRITE_REG(ar7_wdt->kick, value); 92 return; 93 } 94 } 95 pr_err("failed to unlock WDT kick reg\n"); 96 } 97 98 static void ar7_wdt_prescale(u32 value) 99 { 100 WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a); 101 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) { 102 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5); 103 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) { 104 WRITE_REG(ar7_wdt->prescale, value); 105 return; 106 } 107 } 108 pr_err("failed to unlock WDT prescale reg\n"); 109 } 110 111 static void ar7_wdt_change(u32 value) 112 { 113 WRITE_REG(ar7_wdt->change_lock, 0x6666); 114 if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) { 115 WRITE_REG(ar7_wdt->change_lock, 0xbbbb); 116 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) { 117 WRITE_REG(ar7_wdt->change, value); 118 return; 119 } 120 } 121 pr_err("failed to unlock WDT change reg\n"); 122 } 123 124 static void ar7_wdt_disable(u32 value) 125 { 126 WRITE_REG(ar7_wdt->disable_lock, 0x7777); 127 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) { 128 WRITE_REG(ar7_wdt->disable_lock, 0xcccc); 129 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) { 130 WRITE_REG(ar7_wdt->disable_lock, 0xdddd); 131 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) { 132 WRITE_REG(ar7_wdt->disable, value); 133 return; 134 } 135 } 136 } 137 pr_err("failed to unlock WDT disable reg\n"); 138 } 139 140 static void ar7_wdt_update_margin(int new_margin) 141 { 142 u32 change; 143 u32 vbus_rate; 144 145 vbus_rate = clk_get_rate(vbus_clk); 146 change = new_margin * (vbus_rate / prescale_value); 147 if (change < 1) 148 change = 1; 149 if (change > 0xffff) 150 change = 0xffff; 151 ar7_wdt_change(change); 152 margin = change * prescale_value / vbus_rate; 153 pr_info("timer margin %d seconds (prescale %d, change %d, freq %d)\n", 154 margin, prescale_value, change, vbus_rate); 155 } 156 157 static void ar7_wdt_enable_wdt(void) 158 { 159 pr_debug("enabling watchdog timer\n"); 160 ar7_wdt_disable(1); 161 ar7_wdt_kick(1); 162 } 163 164 static void ar7_wdt_disable_wdt(void) 165 { 166 pr_debug("disabling watchdog timer\n"); 167 ar7_wdt_disable(0); 168 } 169 170 static int ar7_wdt_open(struct inode *inode, struct file *file) 171 { 172 /* only allow one at a time */ 173 if (test_and_set_bit(0, &wdt_is_open)) 174 return -EBUSY; 175 ar7_wdt_enable_wdt(); 176 expect_close = 0; 177 178 return nonseekable_open(inode, file); 179 } 180 181 static int ar7_wdt_release(struct inode *inode, struct file *file) 182 { 183 if (!expect_close) 184 pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n"); 185 else if (!nowayout) 186 ar7_wdt_disable_wdt(); 187 clear_bit(0, &wdt_is_open); 188 return 0; 189 } 190 191 static ssize_t ar7_wdt_write(struct file *file, const char *data, 192 size_t len, loff_t *ppos) 193 { 194 /* check for a magic close character */ 195 if (len) { 196 size_t i; 197 198 spin_lock(&wdt_lock); 199 ar7_wdt_kick(1); 200 spin_unlock(&wdt_lock); 201 202 expect_close = 0; 203 for (i = 0; i < len; ++i) { 204 char c; 205 if (get_user(c, data + i)) 206 return -EFAULT; 207 if (c == 'V') 208 expect_close = 1; 209 } 210 211 } 212 return len; 213 } 214 215 static long ar7_wdt_ioctl(struct file *file, 216 unsigned int cmd, unsigned long arg) 217 { 218 static const struct watchdog_info ident = { 219 .identity = LONGNAME, 220 .firmware_version = 1, 221 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | 222 WDIOF_MAGICCLOSE), 223 }; 224 int new_margin; 225 226 switch (cmd) { 227 case WDIOC_GETSUPPORT: 228 if (copy_to_user((struct watchdog_info *)arg, &ident, 229 sizeof(ident))) 230 return -EFAULT; 231 return 0; 232 case WDIOC_GETSTATUS: 233 case WDIOC_GETBOOTSTATUS: 234 if (put_user(0, (int *)arg)) 235 return -EFAULT; 236 return 0; 237 case WDIOC_KEEPALIVE: 238 ar7_wdt_kick(1); 239 return 0; 240 case WDIOC_SETTIMEOUT: 241 if (get_user(new_margin, (int *)arg)) 242 return -EFAULT; 243 if (new_margin < 1) 244 return -EINVAL; 245 246 spin_lock(&wdt_lock); 247 ar7_wdt_update_margin(new_margin); 248 ar7_wdt_kick(1); 249 spin_unlock(&wdt_lock); 250 251 case WDIOC_GETTIMEOUT: 252 if (put_user(margin, (int *)arg)) 253 return -EFAULT; 254 return 0; 255 default: 256 return -ENOTTY; 257 } 258 } 259 260 static const struct file_operations ar7_wdt_fops = { 261 .owner = THIS_MODULE, 262 .write = ar7_wdt_write, 263 .unlocked_ioctl = ar7_wdt_ioctl, 264 .open = ar7_wdt_open, 265 .release = ar7_wdt_release, 266 .llseek = no_llseek, 267 }; 268 269 static struct miscdevice ar7_wdt_miscdev = { 270 .minor = WATCHDOG_MINOR, 271 .name = "watchdog", 272 .fops = &ar7_wdt_fops, 273 }; 274 275 static int ar7_wdt_probe(struct platform_device *pdev) 276 { 277 int rc; 278 279 ar7_regs_wdt = 280 platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs"); 281 ar7_wdt = devm_ioremap_resource(&pdev->dev, ar7_regs_wdt); 282 if (IS_ERR(ar7_wdt)) 283 return PTR_ERR(ar7_wdt); 284 285 vbus_clk = clk_get(NULL, "vbus"); 286 if (IS_ERR(vbus_clk)) { 287 pr_err("could not get vbus clock\n"); 288 return PTR_ERR(vbus_clk); 289 } 290 291 ar7_wdt_disable_wdt(); 292 ar7_wdt_prescale(prescale_value); 293 ar7_wdt_update_margin(margin); 294 295 rc = misc_register(&ar7_wdt_miscdev); 296 if (rc) { 297 pr_err("unable to register misc device\n"); 298 goto out; 299 } 300 return 0; 301 302 out: 303 clk_put(vbus_clk); 304 vbus_clk = NULL; 305 return rc; 306 } 307 308 static int ar7_wdt_remove(struct platform_device *pdev) 309 { 310 misc_deregister(&ar7_wdt_miscdev); 311 clk_put(vbus_clk); 312 vbus_clk = NULL; 313 return 0; 314 } 315 316 static void ar7_wdt_shutdown(struct platform_device *pdev) 317 { 318 if (!nowayout) 319 ar7_wdt_disable_wdt(); 320 } 321 322 static struct platform_driver ar7_wdt_driver = { 323 .probe = ar7_wdt_probe, 324 .remove = ar7_wdt_remove, 325 .shutdown = ar7_wdt_shutdown, 326 .driver = { 327 .name = "ar7_wdt", 328 }, 329 }; 330 331 module_platform_driver(ar7_wdt_driver); 332