linux/drivers/watchdog/sa1100_wdt.c
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   1/*
   2 *      Watchdog driver for the SA11x0/PXA2xx
   3 *
   4 *      (c) Copyright 2000 Oleg Drokin <green@crimea.edu>
   5 *          Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>
   6 *
   7 *      This program is free software; you can redistribute it and/or
   8 *      modify it under the terms of the GNU General Public License
   9 *      as published by the Free Software Foundation; either version
  10 *      2 of the License, or (at your option) any later version.
  11 *
  12 *      Neither Oleg Drokin nor iXcelerator.com admit liability nor provide
  13 *      warranty for any of this software. This material is provided
  14 *      "AS-IS" and at no charge.
  15 *
  16 *      (c) Copyright 2000           Oleg Drokin <green@crimea.edu>
  17 *
  18 *      27/11/2000 Initial release
  19 */
  20
  21#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  22
  23#include <linux/module.h>
  24#include <linux/moduleparam.h>
  25#include <linux/types.h>
  26#include <linux/kernel.h>
  27#include <linux/fs.h>
  28#include <linux/miscdevice.h>
  29#include <linux/watchdog.h>
  30#include <linux/init.h>
  31#include <linux/io.h>
  32#include <linux/bitops.h>
  33#include <linux/uaccess.h>
  34#include <linux/timex.h>
  35
  36#ifdef CONFIG_ARCH_PXA
  37#include <mach/regs-ost.h>
  38#endif
  39
  40#include <mach/reset.h>
  41#include <mach/hardware.h>
  42
  43static unsigned long oscr_freq;
  44static unsigned long sa1100wdt_users;
  45static unsigned int pre_margin;
  46static int boot_status;
  47
  48/*
  49 *      Allow only one person to hold it open
  50 */
  51static int sa1100dog_open(struct inode *inode, struct file *file)
  52{
  53        if (test_and_set_bit(1, &sa1100wdt_users))
  54                return -EBUSY;
  55
  56        /* Activate SA1100 Watchdog timer */
  57        writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
  58        writel_relaxed(OSSR_M3, OSSR);
  59        writel_relaxed(OWER_WME, OWER);
  60        writel_relaxed(readl_relaxed(OIER) | OIER_E3, OIER);
  61        return nonseekable_open(inode, file);
  62}
  63
  64/*
  65 * The watchdog cannot be disabled.
  66 *
  67 * Previous comments suggested that turning off the interrupt by
  68 * clearing OIER[E3] would prevent the watchdog timing out but this
  69 * does not appear to be true (at least on the PXA255).
  70 */
  71static int sa1100dog_release(struct inode *inode, struct file *file)
  72{
  73        pr_crit("Device closed - timer will not stop\n");
  74        clear_bit(1, &sa1100wdt_users);
  75        return 0;
  76}
  77
  78static ssize_t sa1100dog_write(struct file *file, const char __user *data,
  79                                                size_t len, loff_t *ppos)
  80{
  81        if (len)
  82                /* Refresh OSMR3 timer. */
  83                writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
  84        return len;
  85}
  86
  87static const struct watchdog_info ident = {
  88        .options        = WDIOF_CARDRESET | WDIOF_SETTIMEOUT
  89                                | WDIOF_KEEPALIVEPING,
  90        .identity       = "SA1100/PXA255 Watchdog",
  91        .firmware_version       = 1,
  92};
  93
  94static long sa1100dog_ioctl(struct file *file, unsigned int cmd,
  95                                                        unsigned long arg)
  96{
  97        int ret = -ENOTTY;
  98        int time;
  99        void __user *argp = (void __user *)arg;
 100        int __user *p = argp;
 101
 102        switch (cmd) {
 103        case WDIOC_GETSUPPORT:
 104                ret = copy_to_user(argp, &ident,
 105                                   sizeof(ident)) ? -EFAULT : 0;
 106                break;
 107
 108        case WDIOC_GETSTATUS:
 109                ret = put_user(0, p);
 110                break;
 111
 112        case WDIOC_GETBOOTSTATUS:
 113                ret = put_user(boot_status, p);
 114                break;
 115
 116        case WDIOC_KEEPALIVE:
 117                writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
 118                ret = 0;
 119                break;
 120
 121        case WDIOC_SETTIMEOUT:
 122                ret = get_user(time, p);
 123                if (ret)
 124                        break;
 125
 126                if (time <= 0 || (oscr_freq * (long long)time >= 0xffffffff)) {
 127                        ret = -EINVAL;
 128                        break;
 129                }
 130
 131                pre_margin = oscr_freq * time;
 132                writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
 133                /*fall through*/
 134
 135        case WDIOC_GETTIMEOUT:
 136                ret = put_user(pre_margin / oscr_freq, p);
 137                break;
 138        }
 139        return ret;
 140}
 141
 142static const struct file_operations sa1100dog_fops = {
 143        .owner          = THIS_MODULE,
 144        .llseek         = no_llseek,
 145        .write          = sa1100dog_write,
 146        .unlocked_ioctl = sa1100dog_ioctl,
 147        .open           = sa1100dog_open,
 148        .release        = sa1100dog_release,
 149};
 150
 151static struct miscdevice sa1100dog_miscdev = {
 152        .minor          = WATCHDOG_MINOR,
 153        .name           = "watchdog",
 154        .fops           = &sa1100dog_fops,
 155};
 156
 157static int margin __initdata = 60;              /* (secs) Default is 1 minute */
 158
 159static int __init sa1100dog_init(void)
 160{
 161        int ret;
 162
 163        oscr_freq = get_clock_tick_rate();
 164
 165        /*
 166         * Read the reset status, and save it for later.  If
 167         * we suspend, RCSR will be cleared, and the watchdog
 168         * reset reason will be lost.
 169         */
 170        boot_status = (reset_status & RESET_STATUS_WATCHDOG) ?
 171                                WDIOF_CARDRESET : 0;
 172        pre_margin = oscr_freq * margin;
 173
 174        ret = misc_register(&sa1100dog_miscdev);
 175        if (ret == 0)
 176                pr_info("SA1100/PXA2xx Watchdog Timer: timer margin %d sec\n",
 177                        margin);
 178        return ret;
 179}
 180
 181static void __exit sa1100dog_exit(void)
 182{
 183        misc_deregister(&sa1100dog_miscdev);
 184}
 185
 186module_init(sa1100dog_init);
 187module_exit(sa1100dog_exit);
 188
 189MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
 190MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
 191
 192module_param(margin, int, 0);
 193MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
 194
 195MODULE_LICENSE("GPL");
 196MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 197
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