drivers/watchdog/ar7_wdt.c

   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);