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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  21
  22 #include <linux/module.h>               /* For module specific items */
  23 #include <linux/moduleparam.h>          /* For new moduleparam's */
  24 #include <linux/types.h>                /* For standard types (like size_t) */
  25 #include <linux/errno.h>                /* For the -ENODEV/... values */
  26 #include <linux/kernel.h>               /* For printk/panic/... */
  27 #include <linux/fs.h>                   /* For file operations */
  28 #include <linux/miscdevice.h>           /* For MODULE_ALIAS_MISCDEV
  29                                                         (WATCHDOG_MINOR) */
  30 #include <linux/watchdog.h>             /* For the watchdog specific items */
  31 #include <linux/init.h>                 /* For __init/__exit/... */
  32 #include <linux/platform_device.h>      /* For platform_driver framework */
  33 #include <linux/spinlock.h>             /* For spin_lock/spin_unlock/... */
  34 #include <linux/uaccess.h>              /* For copy_to_user/put_user/... */
  35
  36 #include <asm/mach-rc32434/integ.h>     /* For the Watchdog registers */
  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 bool nowayout = WATCHDOG_NOWAYOUT;
  68 module_param(nowayout, bool, 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                 pr_err("timeout value must be between 0 and %d\n", max_to);
  82                 return -EINVAL;
  83         }
  84         timeout = new_timeout;
  85         spin_lock(&rc32434_wdt_device.io_lock);
  86         writel(SEC2WTCOMP(timeout), &wdt_reg->wtcompare);
  87         spin_unlock(&rc32434_wdt_device.io_lock);
  88
  89         return 0;
  90 }
  91
  92 static void rc32434_wdt_start(void)
  93 {
  94         u32 or, nand;
  95
  96         spin_lock(&rc32434_wdt_device.io_lock);
  97
  98         /* zero the counter before enabling */
  99         writel(0, &wdt_reg->wtcount);
 100
 101         /* don't generate a non-maskable interrupt,
 102          * do a warm reset instead */
 103         nand = 1 << RC32434_ERR_WNE;
 104         or = 1 << RC32434_ERR_WRE;
 105
 106         /* reset the ERRCS timeout bit in case it's set */
 107         nand |= 1 << RC32434_ERR_WTO;
 108
 109         SET_BITS(wdt_reg->errcs, or, nand);
 110
 111         /* set the timeout (either default or based on module param) */
 112         rc32434_wdt_set(timeout);
 113
 114         /* reset WTC timeout bit and enable WDT */
 115         nand = 1 << RC32434_WTC_TO;
 116         or = 1 << RC32434_WTC_EN;
 117
 118         SET_BITS(wdt_reg->wtc, or, nand);
 119
 120         spin_unlock(&rc32434_wdt_device.io_lock);
 121         pr_info("Started watchdog timer\n");
 122 }
 123
 124 static void rc32434_wdt_stop(void)
 125 {
 126         spin_lock(&rc32434_wdt_device.io_lock);
 127
 128         /* Disable WDT */
 129         SET_BITS(wdt_reg->wtc, 0, 1 << RC32434_WTC_EN);
 130
 131         spin_unlock(&rc32434_wdt_device.io_lock);
 132         pr_info("Stopped watchdog timer\n");
 133 }
 134
 135 static void rc32434_wdt_ping(void)
 136 {
 137         spin_lock(&rc32434_wdt_device.io_lock);
 138         writel(0, &wdt_reg->wtcount);
 139         spin_unlock(&rc32434_wdt_device.io_lock);
 140 }
 141
 142 static int rc32434_wdt_open(struct inode *inode, struct file *file)
 143 {
 144         if (test_and_set_bit(0, &rc32434_wdt_device.inuse))
 145                 return -EBUSY;
 146
 147         if (nowayout)
 148                 __module_get(THIS_MODULE);
 149
 150         rc32434_wdt_start();
 151         rc32434_wdt_ping();
 152
 153         return nonseekable_open(inode, file);
 154 }
 155
 156 static int rc32434_wdt_release(struct inode *inode, struct file *file)
 157 {
 158         if (expect_close == 42) {
 159                 rc32434_wdt_stop();
 160                 module_put(THIS_MODULE);
 161         } else {
 162                 pr_crit("device closed unexpectedly. WDT will not stop!\n");
 163                 rc32434_wdt_ping();
 164         }
 165         clear_bit(0, &rc32434_wdt_device.inuse);
 166         return 0;
 167 }
 168
 169 static ssize_t rc32434_wdt_write(struct file *file, const char *data,
 170                                 size_t len, loff_t *ppos)
 171 {
 172         if (len) {
 173                 if (!nowayout) {
 174                         size_t i;
 175
 176                         /* In case it was set long ago */
 177                         expect_close = 0;
 178
 179                         for (i = 0; i != len; i++) {
 180                                 char c;
 181                                 if (get_user(c, data + i))
 182                                         return -EFAULT;
 183                                 if (c == 'V')
 184                                         expect_close = 42;
 185                         }
 186                 }
 187                 rc32434_wdt_ping();
 188                 return len;
 189         }
 190         return 0;
 191 }
 192
 193 static long rc32434_wdt_ioctl(struct file *file, unsigned int cmd,
 194                                 unsigned long arg)
 195 {
 196         void __user *argp = (void __user *)arg;
 197         int new_timeout;
 198         unsigned int value;
 199         static const struct watchdog_info ident = {
 200                 .options =              WDIOF_SETTIMEOUT |
 201                                         WDIOF_KEEPALIVEPING |
 202                                         WDIOF_MAGICCLOSE,
 203                 .identity =             "RC32434_WDT Watchdog",
 204         };
 205         switch (cmd) {
 206         case WDIOC_GETSUPPORT:
 207                 if (copy_to_user(argp, &ident, sizeof(ident)))
 208                         return -EFAULT;
 209                 break;
 210         case WDIOC_GETSTATUS:
 211         case WDIOC_GETBOOTSTATUS:
 212                 value = 0;
 213                 if (copy_to_user(argp, &value, sizeof(int)))
 214                         return -EFAULT;
 215                 break;
 216         case WDIOC_SETOPTIONS:
 217                 if (copy_from_user(&value, argp, sizeof(int)))
 218                         return -EFAULT;
 219                 switch (value) {
 220                 case WDIOS_ENABLECARD:
 221                         rc32434_wdt_start();
 222                         break;
 223                 case WDIOS_DISABLECARD:
 224                         rc32434_wdt_stop();
 225                         break;
 226                 default:
 227                         return -EINVAL;
 228                 }
 229                 break;
 230         case WDIOC_KEEPALIVE:
 231                 rc32434_wdt_ping();
 232                 break;
 233         case WDIOC_SETTIMEOUT:
 234                 if (copy_from_user(&new_timeout, argp, sizeof(int)))
 235                         return -EFAULT;
 236                 if (rc32434_wdt_set(new_timeout))
 237                         return -EINVAL;
 238                 /* Fall through */
 239         case WDIOC_GETTIMEOUT:
 240                 return copy_to_user(argp, &timeout, sizeof(int));
 241         default:
 242                 return -ENOTTY;
 243         }
 244
 245         return 0;
 246 }
 247
 248 static const struct file_operations rc32434_wdt_fops = {
 249         .owner          = THIS_MODULE,
 250         .llseek         = no_llseek,
 251         .write          = rc32434_wdt_write,
 252         .unlocked_ioctl = rc32434_wdt_ioctl,
 253         .open           = rc32434_wdt_open,
 254         .release        = rc32434_wdt_release,
 255 };
 256
 257 static struct miscdevice rc32434_wdt_miscdev = {
 258         .minor  = WATCHDOG_MINOR,
 259         .name   = "watchdog",
 260         .fops   = &rc32434_wdt_fops,
 261 };
 262
 263 static int rc32434_wdt_probe(struct platform_device *pdev)
 264 {
 265         int ret;
 266         struct resource *r;
 267
 268         r = platform_get_resource_byname(pdev, IORESOURCE_MEM, "rb532_wdt_res");
 269         if (!r) {
 270                 pr_err("failed to retrieve resources\n");
 271                 return -ENODEV;
 272         }
 273
 274         wdt_reg = ioremap_nocache(r->start, resource_size(r));
 275         if (!wdt_reg) {
 276                 pr_err("failed to remap I/O resources\n");
 277                 return -ENXIO;
 278         }
 279
 280         spin_lock_init(&rc32434_wdt_device.io_lock);
 281
 282         /* Make sure the watchdog is not running */
 283         rc32434_wdt_stop();
 284
 285         /* Check that the heartbeat value is within it's range;
 286          * if not reset to the default */
 287         if (rc32434_wdt_set(timeout)) {
 288                 rc32434_wdt_set(WATCHDOG_TIMEOUT);
 289                 pr_info("timeout value must be between 0 and %d\n",
 290                         WTCOMP2SEC((u32)-1));
 291         }
 292
 293         ret = misc_register(&rc32434_wdt_miscdev);
 294         if (ret < 0) {
 295                 pr_err("failed to register watchdog device\n");
 296                 goto unmap;
 297         }
 298
 299         pr_info("Watchdog Timer version " VERSION ", timer margin: %d sec\n",
 300                 timeout);
 301
 302         return 0;
 303
 304 unmap:
 305         iounmap(wdt_reg);
 306         return ret;
 307 }
 308
 309 static int rc32434_wdt_remove(struct platform_device *pdev)
 310 {
 311         misc_deregister(&rc32434_wdt_miscdev);
 312         iounmap(wdt_reg);
 313         return 0;
 314 }
 315
 316 static void rc32434_wdt_shutdown(struct platform_device *pdev)
 317 {
 318         rc32434_wdt_stop();
 319 }
 320
 321 static struct platform_driver rc32434_wdt_driver = {
 322         .probe          = rc32434_wdt_probe,
 323         .remove         = rc32434_wdt_remove,
 324         .shutdown       = rc32434_wdt_shutdown,
 325         .driver         = {
 326                         .name = "rc32434_wdt",
 327         }
 328 };
 329
 330 module_platform_driver(rc32434_wdt_driver);
 331
 332 MODULE_AUTHOR("Ondrej Zajicek <santiago@crfreenet.org>,"
 333                 "Florian Fainelli <florian@openwrt.org>");
 334 MODULE_DESCRIPTION("Driver for the IDT RC32434 SoC watchdog");
 335 MODULE_LICENSE("GPL");
 336 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);