linux/drivers/watchdog/mtx-1_wdt.c
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   1/*
   2 *      Driver for the MTX-1 Watchdog.
   3 *
   4 *      (C) Copyright 2005 4G Systems <info@4g-systems.biz>,
   5 *                                                      All Rights Reserved.
   6 *                              http://www.4g-systems.biz
   7 *
   8 *      (C) Copyright 2007 OpenWrt.org, Florian Fainelli <florian@openwrt.org>
   9 *
  10 *      This program is free software; you can redistribute it and/or
  11 *      modify it under the terms of the GNU General Public License
  12 *      as published by the Free Software Foundation; either version
  13 *      2 of the License, or (at your option) any later version.
  14 *
  15 *      Neither Michael Stickel nor 4G Systems admit liability nor provide
  16 *      warranty for any of this software. This material is provided
  17 *      "AS-IS" and at no charge.
  18 *
  19 *      (c) Copyright 2005    4G Systems <info@4g-systems.biz>
  20 *
  21 *      Release 0.01.
  22 *      Author: Michael Stickel  michael.stickel@4g-systems.biz
  23 *
  24 *      Release 0.02.
  25 *      Author: Florian Fainelli florian@openwrt.org
  26 *              use the Linux watchdog/timer APIs
  27 *
  28 *      The Watchdog is configured to reset the MTX-1
  29 *      if it is not triggered for 100 seconds.
  30 *      It should not be triggered more often than 1.6 seconds.
  31 *
  32 *      A timer triggers the watchdog every 5 seconds, until
  33 *      it is opened for the first time. After the first open
  34 *      it MUST be triggered every 2..95 seconds.
  35 */
  36
  37#include <linux/module.h>
  38#include <linux/moduleparam.h>
  39#include <linux/types.h>
  40#include <linux/errno.h>
  41#include <linux/miscdevice.h>
  42#include <linux/fs.h>
  43#include <linux/init.h>
  44#include <linux/ioport.h>
  45#include <linux/timer.h>
  46#include <linux/completion.h>
  47#include <linux/jiffies.h>
  48#include <linux/watchdog.h>
  49#include <linux/platform_device.h>
  50#include <linux/io.h>
  51#include <linux/uaccess.h>
  52#include <linux/gpio.h>
  53
  54#include <asm/mach-au1x00/au1000.h>
  55
  56#define MTX1_WDT_INTERVAL       (5 * HZ)
  57
  58static int ticks = 100 * HZ;
  59
  60static struct {
  61        struct completion stop;
  62        spinlock_t lock;
  63        int running;
  64        struct timer_list timer;
  65        int queue;
  66        int default_ticks;
  67        unsigned long inuse;
  68        unsigned gpio;
  69        unsigned int gstate;
  70} mtx1_wdt_device;
  71
  72static void mtx1_wdt_trigger(unsigned long unused)
  73{
  74        spin_lock(&mtx1_wdt_device.lock);
  75        if (mtx1_wdt_device.running)
  76                ticks--;
  77
  78        /* toggle wdt gpio */
  79        mtx1_wdt_device.gstate = !mtx1_wdt_device.gstate;
  80        gpio_set_value(mtx1_wdt_device.gpio, mtx1_wdt_device.gstate);
  81
  82        if (mtx1_wdt_device.queue && ticks)
  83                mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
  84        else
  85                complete(&mtx1_wdt_device.stop);
  86        spin_unlock(&mtx1_wdt_device.lock);
  87}
  88
  89static void mtx1_wdt_reset(void)
  90{
  91        ticks = mtx1_wdt_device.default_ticks;
  92}
  93
  94
  95static void mtx1_wdt_start(void)
  96{
  97        unsigned long flags;
  98
  99        spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
 100        if (!mtx1_wdt_device.queue) {
 101                mtx1_wdt_device.queue = 1;
 102                mtx1_wdt_device.gstate = 1;
 103                gpio_set_value(mtx1_wdt_device.gpio, 1);
 104                mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
 105        }
 106        mtx1_wdt_device.running++;
 107        spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
 108}
 109
 110static int mtx1_wdt_stop(void)
 111{
 112        unsigned long flags;
 113
 114        spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
 115        if (mtx1_wdt_device.queue) {
 116                mtx1_wdt_device.queue = 0;
 117                mtx1_wdt_device.gstate = 0;
 118                gpio_set_value(mtx1_wdt_device.gpio, 0);
 119        }
 120        ticks = mtx1_wdt_device.default_ticks;
 121        spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
 122        return 0;
 123}
 124
 125/* Filesystem functions */
 126
 127static int mtx1_wdt_open(struct inode *inode, struct file *file)
 128{
 129        if (test_and_set_bit(0, &mtx1_wdt_device.inuse))
 130                return -EBUSY;
 131        return nonseekable_open(inode, file);
 132}
 133
 134
 135static int mtx1_wdt_release(struct inode *inode, struct file *file)
 136{
 137        clear_bit(0, &mtx1_wdt_device.inuse);
 138        return 0;
 139}
 140
 141static long mtx1_wdt_ioctl(struct file *file, unsigned int cmd,
 142                                                        unsigned long arg)
 143{
 144        void __user *argp = (void __user *)arg;
 145        int __user *p = (int __user *)argp;
 146        unsigned int value;
 147        static const struct watchdog_info ident = {
 148                .options = WDIOF_CARDRESET,
 149                .identity = "MTX-1 WDT",
 150        };
 151
 152        switch (cmd) {
 153        case WDIOC_GETSUPPORT:
 154                if (copy_to_user(argp, &ident, sizeof(ident)))
 155                        return -EFAULT;
 156                break;
 157        case WDIOC_GETSTATUS:
 158        case WDIOC_GETBOOTSTATUS:
 159                put_user(0, p);
 160                break;
 161        case WDIOC_SETOPTIONS:
 162                if (get_user(value, p))
 163                        return -EFAULT;
 164                if (value & WDIOS_ENABLECARD)
 165                        mtx1_wdt_start();
 166                else if (value & WDIOS_DISABLECARD)
 167                        mtx1_wdt_stop();
 168                else
 169                        return -EINVAL;
 170                return 0;
 171        case WDIOC_KEEPALIVE:
 172                mtx1_wdt_reset();
 173                break;
 174        default:
 175                return -ENOTTY;
 176        }
 177        return 0;
 178}
 179
 180
 181static ssize_t mtx1_wdt_write(struct file *file, const char *buf,
 182                                                size_t count, loff_t *ppos)
 183{
 184        if (!count)
 185                return -EIO;
 186        mtx1_wdt_reset();
 187        return count;
 188}
 189
 190static const struct file_operations mtx1_wdt_fops = {
 191        .owner          = THIS_MODULE,
 192        .llseek         = no_llseek,
 193        .unlocked_ioctl = mtx1_wdt_ioctl,
 194        .open           = mtx1_wdt_open,
 195        .write          = mtx1_wdt_write,
 196        .release        = mtx1_wdt_release,
 197};
 198
 199
 200static struct miscdevice mtx1_wdt_misc = {
 201        .minor  = WATCHDOG_MINOR,
 202        .name   = "watchdog",
 203        .fops   = &mtx1_wdt_fops,
 204};
 205
 206
 207static int __devinit mtx1_wdt_probe(struct platform_device *pdev)
 208{
 209        int ret;
 210
 211        mtx1_wdt_device.gpio = pdev->resource[0].start;
 212        ret = gpio_request_one(mtx1_wdt_device.gpio,
 213                                GPIOF_OUT_INIT_HIGH, "mtx1-wdt");
 214        if (ret < 0) {
 215                dev_err(&pdev->dev, "failed to request gpio");
 216                return ret;
 217        }
 218
 219        spin_lock_init(&mtx1_wdt_device.lock);
 220        init_completion(&mtx1_wdt_device.stop);
 221        mtx1_wdt_device.queue = 0;
 222        clear_bit(0, &mtx1_wdt_device.inuse);
 223        setup_timer(&mtx1_wdt_device.timer, mtx1_wdt_trigger, 0L);
 224        mtx1_wdt_device.default_ticks = ticks;
 225
 226        ret = misc_register(&mtx1_wdt_misc);
 227        if (ret < 0) {
 228                dev_err(&pdev->dev, "failed to register\n");
 229                return ret;
 230        }
 231        mtx1_wdt_start();
 232        dev_info(&pdev->dev, "MTX-1 Watchdog driver\n");
 233        return 0;
 234}
 235
 236static int __devexit mtx1_wdt_remove(struct platform_device *pdev)
 237{
 238        /* FIXME: do we need to lock this test ? */
 239        if (mtx1_wdt_device.queue) {
 240                mtx1_wdt_device.queue = 0;
 241                wait_for_completion(&mtx1_wdt_device.stop);
 242        }
 243
 244        gpio_free(mtx1_wdt_device.gpio);
 245        misc_deregister(&mtx1_wdt_misc);
 246        return 0;
 247}
 248
 249static struct platform_driver mtx1_wdt_driver = {
 250        .probe = mtx1_wdt_probe,
 251        .remove = __devexit_p(mtx1_wdt_remove),
 252        .driver.name = "mtx1-wdt",
 253        .driver.owner = THIS_MODULE,
 254};
 255
 256module_platform_driver(mtx1_wdt_driver);
 257
 258MODULE_AUTHOR("Michael Stickel, Florian Fainelli");
 259MODULE_DESCRIPTION("Driver for the MTX-1 watchdog");
 260MODULE_LICENSE("GPL");
 261MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 262MODULE_ALIAS("platform:mtx1-wdt");
 263
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