drivers/watchdog/rc32434_wdt.c

   1 /*
   2  *  IDT Interprise 79RC32434 watchdog driver
   3  *
   4  *  Copyright (C) 2006, Ondrej Zajicek <santiago@crfreenet.org>
   5  *  Copyright (C) 2008, Florian Fainelli <florian@openwrt.org>
   6  *
   7  *  based on
   8  *  SoftDog 0.05:       A Software Watchdog Device
   9  *
  10  *  (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  11  *                                      All Rights Reserved.
  12  *
  13  *  This program is free software; you can redistribute it and/or
  14  *  modify it under the terms of the GNU General Public License
  15  *  as published by the Free Software Foundation; either version
  16  *  2 of the License, or (at your option) any later version.
  17  *
  18  */
  19
  20 #include <linux/module.h>               /* For module specific items */
  21 #include <linux/moduleparam.h>          /* For new moduleparam's */
  22 #include <linux/types.h>                /* For standard types (like size_t) */
  23 #include <linux/errno.h>                /* For the -ENODEV/... values */
  24 #include <linux/kernel.h>               /* For printk/panic/... */
  25 #include <linux/fs.h>                   /* For file operations */
  26 #include <linux/miscdevice.h>           /* For MODULE_ALIAS_MISCDEV
  27                                                         (WATCHDOG_MINOR) */
  28 #include <linux/watchdog.h>             /* For the watchdog specific items */
  29 #include <linux/init.h>                 /* For __init/__exit/... */
  30 #include <linux/platform_device.h>      /* For platform_driver framework */
  31 #include <linux/spinlock.h>             /* For spin_lock/spin_unlock/... */
  32 #include <linux/uaccess.h>              /* For copy_to_user/put_user/... */
  33
  34 #include <asm/mach-rc32434/integ.h>     /* For the Watchdog registers */
  35
  36 #define PFX KBUILD_MODNAME ": "
  37
  38 #define VERSION "1.0"
  39
  40 static struct {
  41         unsigned long inuse;
  42         spinlock_t io_lock;
  43 } rc32434_wdt_device;
  44
  45 static struct integ __iomem *wdt_reg;
  46
  47 static int expect_close;
  48
  49 /* Board internal clock speed in Hz,
  50  * the watchdog timer ticks at. */
  51 extern unsigned int idt_cpu_freq;
  52
  53 /* translate wtcompare value to seconds and vice versa */
  54 #define WTCOMP2SEC(x)   (x / idt_cpu_freq)
  55 #define SEC2WTCOMP(x)   (x * idt_cpu_freq)
  56
  57 /* Use a default timeout of 20s. This should be
  58  * safe for CPU clock speeds up to 400MHz, as
  59  * ((2 ^ 32) - 1) / (400MHz / 2) = 21s.  */
  60 #define WATCHDOG_TIMEOUT 20
  61
  62 static int timeout = WATCHDOG_TIMEOUT;
  63 module_param(timeout, int, 0);
  64 MODULE_PARM_DESC(timeout, "Watchdog timeout value, in seconds (default="
  65                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  66
  67 static int nowayout = WATCHDOG_NOWAYOUT;
  68 module_param(nowayout, int, 0);
  69 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  70         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  71
  72 /* apply or and nand masks to data read from addr and write back */
  73 #define SET_BITS(addr, or, nand) \
  74         writel((readl(&addr) | or) & ~nand, &addr)
  75
  76 static int rc32434_wdt_set(int new_timeout)
  77 {
  78         int max_to = WTCOMP2SEC((u32)-1);
  79
  80         if (new_timeout < 0 || new_timeout > max_to) {
  81                 printk(KERN_ERR PFX "timeout value must be between 0 and %d",
  82                         max_to);
  83                 return -EINVAL;
  84         }
  85         timeout = new_timeout;
  86         spin_lock(&rc32434_wdt_device.io_lock);
  87         writel(SEC2WTCOMP(timeout), &wdt_reg->wtcompare);
  88         spin_unlock(&rc32434_wdt_device.io_lock);
  89
  90         return 0;
  91 }
  92
  93 static void rc32434_wdt_start(void)
  94 {
  95         u32 or, nand;
  96
  97         spin_lock(&rc32434_wdt_device.io_lock);
  98
  99         /* zero the counter before enabling */
 100         writel(0, &wdt_reg->wtcount);
 101
 102         /* don't generate a non-maskable interrupt,
 103          * do a warm reset instead */
 104         nand = 1 << RC32434_ERR_WNE;
 105         or = 1 << RC32434_ERR_WRE;
 106
 107         /* reset the ERRCS timeout bit in case it's set */
 108         nand |= 1 << RC32434_ERR_WTO;
 109
 110         SET_BITS(wdt_reg->errcs, or, nand);
 111
 112         /* set the timeout (either default or based on module param) */
 113         rc32434_wdt_set(timeout);
 114
 115         /* reset WTC timeout bit and enable WDT */
 116         nand = 1 << RC32434_WTC_TO;
 117         or = 1 << RC32434_WTC_EN;
 118
 119         SET_BITS(wdt_reg->wtc, or, nand);
 120
 121         spin_unlock(&rc32434_wdt_device.io_lock);
 122         printk(KERN_INFO PFX "Started watchdog timer.\n");
 123 }
 124
 125 static void rc32434_wdt_stop(void)
 126 {
 127         spin_lock(&rc32434_wdt_device.io_lock);
 128
 129         /* Disable WDT */
 130         SET_BITS(wdt_reg->wtc, 0, 1 << RC32434_WTC_EN);
 131
 132         spin_unlock(&rc32434_wdt_device.io_lock);
 133         printk(KERN_INFO PFX "Stopped watchdog timer.\n");
 134 }
 135
 136 static void rc32434_wdt_ping(void)
 137 {
 138         spin_lock(&rc32434_wdt_device.io_lock);
 139         writel(0, &wdt_reg->wtcount);
 140         spin_unlock(&rc32434_wdt_device.io_lock);
 141 }
 142
 143 static int rc32434_wdt_open(struct inode *inode, struct file *file)
 144 {
 145         if (test_and_set_bit(0, &rc32434_wdt_device.inuse))
 146                 return -EBUSY;
 147
 148         if (nowayout)
 149                 __module_get(THIS_MODULE);
 150
 151         rc32434_wdt_start();
 152         rc32434_wdt_ping();
 153
 154         return nonseekable_open(inode, file);
 155 }
 156
 157 static int rc32434_wdt_release(struct inode *inode, struct file *file)
 158 {
 159         if (expect_close == 42) {
 160                 rc32434_wdt_stop();
 161                 module_put(THIS_MODULE);
 162         } else {
 163                 printk(KERN_CRIT PFX
 164                         "device closed unexpectedly. WDT will not stop!\n");
 165                 rc32434_wdt_ping();
 166         }
 167         clear_bit(0, &rc32434_wdt_device.inuse);
 168         return 0;
 169 }
 170
 171 static ssize_t rc32434_wdt_write(struct file *file, const char *data,
 172                                 size_t len, loff_t *ppos)
 173 {
 174         if (len) {
 175                 if (!nowayout) {
 176                         size_t i;
 177
 178                         /* In case it was set long ago */
 179                         expect_close = 0;
 180
 181                         for (i = 0; i != len; i++) {
 182                                 char c;
 183                                 if (get_user(c, data + i))
 184                                         return -EFAULT;
 185                                 if (c == 'V')
 186                                         expect_close = 42;
 187                         }
 188                 }
 189                 rc32434_wdt_ping();
 190                 return len;
 191         }
 192         return 0;
 193 }
 194
 195 static long rc32434_wdt_ioctl(struct file *file, unsigned int cmd,
 196                                 unsigned long arg)
 197 {
 198         void __user *argp = (void __user *)arg;
 199         int new_timeout;
 200         unsigned int value;
 201         static const struct watchdog_info ident = {
 202                 .options =              WDIOF_SETTIMEOUT |
 203                                         WDIOF_KEEPALIVEPING |
 204                                         WDIOF_MAGICCLOSE,
 205                 .identity =             "RC32434_WDT Watchdog",
 206         };
 207         switch (cmd) {
 208         case WDIOC_GETSUPPORT:
 209                 if (copy_to_user(argp, &ident, sizeof(ident)))
 210                         return -EFAULT;
 211                 break;
 212         case WDIOC_GETSTATUS:
 213         case WDIOC_GETBOOTSTATUS:
 214                 value = 0;
 215                 if (copy_to_user(argp, &value, sizeof(int)))
 216                         return -EFAULT;
 217                 break;
 218         case WDIOC_SETOPTIONS:
 219                 if (copy_from_user(&value, argp, sizeof(int)))
 220                         return -EFAULT;
 221                 switch (value) {
 222                 case WDIOS_ENABLECARD:
 223                         rc32434_wdt_start();
 224                         break;
 225                 case WDIOS_DISABLECARD:
 226                         rc32434_wdt_stop();
 227                         break;
 228                 default:
 229                         return -EINVAL;
 230                 }
 231                 break;
 232         case WDIOC_KEEPALIVE:
 233                 rc32434_wdt_ping();
 234                 break;
 235         case WDIOC_SETTIMEOUT:
 236                 if (copy_from_user(&new_timeout, argp, sizeof(int)))
 237                         return -EFAULT;
 238                 if (rc32434_wdt_set(new_timeout))
 239                         return -EINVAL;
 240                 /* Fall through */
 241         case WDIOC_GETTIMEOUT:
 242                 return copy_to_user(argp, &timeout, sizeof(int));
 243         default:
 244                 return -ENOTTY;
 245         }
 246
 247         return 0;
 248 }
 249
 250 static const struct file_operations rc32434_wdt_fops = {
 251         .owner          = THIS_MODULE,
 252         .llseek         = no_llseek,
 253         .write          = rc32434_wdt_write,
 254         .unlocked_ioctl = rc32434_wdt_ioctl,
 255         .open           = rc32434_wdt_open,
 256         .release        = rc32434_wdt_release,
 257 };
 258
 259 static struct miscdevice rc32434_wdt_miscdev = {
 260         .minor  = WATCHDOG_MINOR,
 261         .name   = "watchdog",
 262         .fops   = &rc32434_wdt_fops,
 263 };
 264
 265 static char banner[] __devinitdata = KERN_INFO PFX
 266                 "Watchdog Timer version " VERSION ", timer margin: %d sec\n";
 267
 268 static int __devinit rc32434_wdt_probe(struct platform_device *pdev)
 269 {
 270         int ret;
 271         struct resource *r;
 272
 273         r = platform_get_resource_byname(pdev, IORESOURCE_MEM, "rb532_wdt_res");
 274         if (!r) {
 275                 printk(KERN_ERR PFX "failed to retrieve resources\n");
 276                 return -ENODEV;
 277         }
 278
 279         wdt_reg = ioremap_nocache(r->start, resource_size(r));
 280         if (!wdt_reg) {
 281                 printk(KERN_ERR PFX "failed to remap I/O resources\n");
 282                 return -ENXIO;
 283         }
 284
 285         spin_lock_init(&rc32434_wdt_device.io_lock);
 286
 287         /* Make sure the watchdog is not running */
 288         rc32434_wdt_stop();
 289
 290         /* Check that the heartbeat value is within it's range;
 291          * if not reset to the default */
 292         if (rc32434_wdt_set(timeout)) {
 293                 rc32434_wdt_set(WATCHDOG_TIMEOUT);
 294                 printk(KERN_INFO PFX
 295                         "timeout value must be between 0 and %d\n",
 296                         WTCOMP2SEC((u32)-1));
 297         }
 298
 299         ret = misc_register(&rc32434_wdt_miscdev);
 300         if (ret < 0) {
 301                 printk(KERN_ERR PFX "failed to register watchdog device\n");
 302                 goto unmap;
 303         }
 304
 305         printk(banner, timeout);
 306
 307         return 0;
 308
 309 unmap:
 310         iounmap(wdt_reg);
 311         return ret;
 312 }
 313
 314 static int __devexit rc32434_wdt_remove(struct platform_device *pdev)
 315 {
 316         misc_deregister(&rc32434_wdt_miscdev);
 317         iounmap(wdt_reg);
 318         return 0;
 319 }
 320
 321 static void rc32434_wdt_shutdown(struct platform_device *pdev)
 322 {
 323         rc32434_wdt_stop();
 324 }
 325
 326 static struct platform_driver rc32434_wdt_driver = {
 327         .probe          = rc32434_wdt_probe,
 328         .remove         = __devexit_p(rc32434_wdt_remove),
 329         .shutdown       = rc32434_wdt_shutdown,
 330         .driver         = {
 331                         .name = "rc32434_wdt",
 332         }
 333 };
 334
 335 module_platform_driver(rc32434_wdt_driver);
 336
 337 MODULE_AUTHOR("Ondrej Zajicek <santiago@crfreenet.org>,"
 338                 "Florian Fainelli <florian@openwrt.org>");
 339 MODULE_DESCRIPTION("Driver for the IDT RC32434 SoC watchdog");
 340 MODULE_LICENSE("GPL");
 341 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);