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 #include <linux/io.h>                   /* For devm_ioremap_nocache */
  36
  37 #include <asm/mach-rc32434/integ.h>     /* For the Watchdog registers */
  38
  39 #define VERSION "1.0"
  40
  41 static struct {
  42         unsigned long inuse;
  43         spinlock_t io_lock;
  44 } rc32434_wdt_device;
  45
  46 static struct integ __iomem *wdt_reg;
  47
  48 static int expect_close;
  49
  50 /* Board internal clock speed in Hz,
  51  * the watchdog timer ticks at. */
  52 extern unsigned int idt_cpu_freq;
  53
  54 /* translate wtcompare value to seconds and vice versa */
  55 #define WTCOMP2SEC(x)   (x / idt_cpu_freq)
  56 #define SEC2WTCOMP(x)   (x * idt_cpu_freq)
  57
  58 /* Use a default timeout of 20s. This should be
  59  * safe for CPU clock speeds up to 400MHz, as
  60  * ((2 ^ 32) - 1) / (400MHz / 2) = 21s.  */
  61 #define WATCHDOG_TIMEOUT 20
  62
  63 static int timeout = WATCHDOG_TIMEOUT;
  64 module_param(timeout, int, 0);
  65 MODULE_PARM_DESC(timeout, "Watchdog timeout value, in seconds (default="
  66                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  67
  68 static bool nowayout = WATCHDOG_NOWAYOUT;
  69 module_param(nowayout, bool, 0);
  70 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  71         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  72
  73 /* apply or and nand masks to data read from addr and write back */
  74 #define SET_BITS(addr, or, nand) \
  75         writel((readl(&addr) | or) & ~nand, &addr)
  76
  77 static int rc32434_wdt_set(int new_timeout)
  78 {
  79         int max_to = WTCOMP2SEC((u32)-1);
  80
  81         if (new_timeout < 0 || new_timeout > max_to) {
  82                 pr_err("timeout value must be between 0 and %d\n", 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         pr_info("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         pr_info("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                 pr_crit("device closed unexpectedly. WDT will not stop!\n");
 164                 rc32434_wdt_ping();
 165         }
 166         clear_bit(0, &rc32434_wdt_device.inuse);
 167         return 0;
 168 }
 169
 170 static ssize_t rc32434_wdt_write(struct file *file, const char *data,
 171                                 size_t len, loff_t *ppos)
 172 {
 173         if (len) {
 174                 if (!nowayout) {
 175                         size_t i;
 176
 177                         /* In case it was set long ago */
 178                         expect_close = 0;
 179
 180                         for (i = 0; i != len; i++) {
 181                                 char c;
 182                                 if (get_user(c, data + i))
 183                                         return -EFAULT;
 184                                 if (c == 'V')
 185                                         expect_close = 42;
 186                         }
 187                 }
 188                 rc32434_wdt_ping();
 189                 return len;
 190         }
 191         return 0;
 192 }
 193
 194 static long rc32434_wdt_ioctl(struct file *file, unsigned int cmd,
 195                                 unsigned long arg)
 196 {
 197         void __user *argp = (void __user *)arg;
 198         int new_timeout;
 199         unsigned int value;
 200         static const struct watchdog_info ident = {
 201                 .options =              WDIOF_SETTIMEOUT |
 202                                         WDIOF_KEEPALIVEPING |
 203                                         WDIOF_MAGICCLOSE,
 204                 .identity =             "RC32434_WDT Watchdog",
 205         };
 206         switch (cmd) {
 207         case WDIOC_GETSUPPORT:
 208                 if (copy_to_user(argp, &ident, sizeof(ident)))
 209                         return -EFAULT;
 210                 break;
 211         case WDIOC_GETSTATUS:
 212         case WDIOC_GETBOOTSTATUS:
 213                 value = 0;
 214                 if (copy_to_user(argp, &value, sizeof(int)))
 215                         return -EFAULT;
 216                 break;
 217         case WDIOC_SETOPTIONS:
 218                 if (copy_from_user(&value, argp, sizeof(int)))
 219                         return -EFAULT;
 220                 switch (value) {
 221                 case WDIOS_ENABLECARD:
 222                         rc32434_wdt_start();
 223                         break;
 224                 case WDIOS_DISABLECARD:
 225                         rc32434_wdt_stop();
 226                         break;
 227                 default:
 228                         return -EINVAL;
 229                 }
 230                 break;
 231         case WDIOC_KEEPALIVE:
 232                 rc32434_wdt_ping();
 233                 break;
 234         case WDIOC_SETTIMEOUT:
 235                 if (copy_from_user(&new_timeout, argp, sizeof(int)))
 236                         return -EFAULT;
 237                 if (rc32434_wdt_set(new_timeout))
 238                         return -EINVAL;
 239                 /* Fall through */
 240         case WDIOC_GETTIMEOUT:
 241                 return copy_to_user(argp, &timeout, sizeof(int));
 242         default:
 243                 return -ENOTTY;
 244         }
 245
 246         return 0;
 247 }
 248
 249 static const struct file_operations rc32434_wdt_fops = {
 250         .owner          = THIS_MODULE,
 251         .llseek         = no_llseek,
 252         .write          = rc32434_wdt_write,
 253         .unlocked_ioctl = rc32434_wdt_ioctl,
 254         .open           = rc32434_wdt_open,
 255         .release        = rc32434_wdt_release,
 256 };
 257
 258 static struct miscdevice rc32434_wdt_miscdev = {
 259         .minor  = WATCHDOG_MINOR,
 260         .name   = "watchdog",
 261         .fops   = &rc32434_wdt_fops,
 262 };
 263
 264 static int rc32434_wdt_probe(struct platform_device *pdev)
 265 {
 266         int ret;
 267         struct resource *r;
 268
 269         r = platform_get_resource_byname(pdev, IORESOURCE_MEM, "rb532_wdt_res");
 270         if (!r) {
 271                 pr_err("failed to retrieve resources\n");
 272                 return -ENODEV;
 273         }
 274
 275         wdt_reg = devm_ioremap_nocache(&pdev->dev, r->start, resource_size(r));
 276         if (!wdt_reg) {
 277                 pr_err("failed to remap I/O resources\n");
 278                 return -ENXIO;
 279         }
 280
 281         spin_lock_init(&rc32434_wdt_device.io_lock);
 282
 283         /* Make sure the watchdog is not running */
 284         rc32434_wdt_stop();
 285
 286         /* Check that the heartbeat value is within it's range;
 287          * if not reset to the default */
 288         if (rc32434_wdt_set(timeout)) {
 289                 rc32434_wdt_set(WATCHDOG_TIMEOUT);
 290                 pr_info("timeout value must be between 0 and %d\n",
 291                         WTCOMP2SEC((u32)-1));
 292         }
 293
 294         ret = misc_register(&rc32434_wdt_miscdev);
 295         if (ret < 0) {
 296                 pr_err("failed to register watchdog device\n");
 297                 return ret;
 298         }
 299
 300         pr_info("Watchdog Timer version " VERSION ", timer margin: %d sec\n",
 301                 timeout);
 302
 303         return 0;
 304 }
 305
 306 static int rc32434_wdt_remove(struct platform_device *pdev)
 307 {
 308         misc_deregister(&rc32434_wdt_miscdev);
 309         return 0;
 310 }
 311
 312 static void rc32434_wdt_shutdown(struct platform_device *pdev)
 313 {
 314         rc32434_wdt_stop();
 315 }
 316
 317 static struct platform_driver rc32434_wdt_driver = {
 318         .probe          = rc32434_wdt_probe,
 319         .remove         = rc32434_wdt_remove,
 320         .shutdown       = rc32434_wdt_shutdown,
 321         .driver         = {
 322                         .name = "rc32434_wdt",
 323         }
 324 };
 325
 326 module_platform_driver(rc32434_wdt_driver);
 327
 328 MODULE_AUTHOR("Ondrej Zajicek <santiago@crfreenet.org>,"
 329                 "Florian Fainelli <florian@openwrt.org>");
 330 MODULE_DESCRIPTION("Driver for the IDT RC32434 SoC watchdog");
 331 MODULE_LICENSE("GPL");
 332 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);