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/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         ar7_wdt = devm_ioremap_resource(&pdev->dev, ar7_regs_wdt);
 284         if (IS_ERR(ar7_wdt))
 285                 return PTR_ERR(ar7_wdt);
 286
 287         vbus_clk = clk_get(NULL, "vbus");
 288         if (IS_ERR(vbus_clk)) {
 289                 pr_err("could not get vbus clock\n");
 290                 return PTR_ERR(vbus_clk);
 291         }
 292
 293         ar7_wdt_disable_wdt();
 294         ar7_wdt_prescale(prescale_value);
 295         ar7_wdt_update_margin(margin);
 296
 297         rc = misc_register(&ar7_wdt_miscdev);
 298         if (rc) {
 299                 pr_err("unable to register misc device\n");
 300                 goto out;
 301         }
 302         return 0;
 303
 304 out:
 305         clk_put(vbus_clk);
 306         vbus_clk = NULL;
 307         return rc;
 308 }
 309
 310 static int ar7_wdt_remove(struct platform_device *pdev)
 311 {
 312         misc_deregister(&ar7_wdt_miscdev);
 313         clk_put(vbus_clk);
 314         vbus_clk = NULL;
 315         return 0;
 316 }
 317
 318 static void ar7_wdt_shutdown(struct platform_device *pdev)
 319 {
 320         if (!nowayout)
 321                 ar7_wdt_disable_wdt();
 322 }
 323
 324 static struct platform_driver ar7_wdt_driver = {
 325         .probe = ar7_wdt_probe,
 326         .remove = ar7_wdt_remove,
 327         .shutdown = ar7_wdt_shutdown,
 328         .driver = {
 329                 .owner = THIS_MODULE,
 330                 .name = "ar7_wdt",
 331         },
 332 };
 333
 334 module_platform_driver(ar7_wdt_driver);