LXR linux/drivers/watchdog/sa1100

   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/clk.h>
  26#include <linux/types.h>
  27#include <linux/kernel.h>
  28#include <linux/fs.h>
  29#include <linux/miscdevice.h>
  30#include <linux/watchdog.h>
  31#include <linux/init.h>
  32#include <linux/io.h>
  33#include <linux/bitops.h>
  34#include <linux/uaccess.h>
  35#include <linux/timex.h>
  36
  37#ifdef CONFIG_ARCH_PXA
  38#include <mach/regs-ost.h>
  39#endif
  40
  41#include <mach/reset.h>
  42#include <mach/hardware.h>
  43
  44static unsigned long oscr_freq;
  45static unsigned long sa1100wdt_users;
  46static unsigned int pre_margin;
  47static int boot_status;
  48
  49/*
  50 *      Allow only one person to hold it open
  51 */
  52static int sa1100dog_open(struct inode *inode, struct file *file)
  53{
  54        if (test_and_set_bit(1, &sa1100wdt_users))
  55                return -EBUSY;
  56
  57        /* Activate SA1100 Watchdog timer */
  58        writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
  59        writel_relaxed(OSSR_M3, OSSR);
  60        writel_relaxed(OWER_WME, OWER);
  61        writel_relaxed(readl_relaxed(OIER) | OIER_E3, OIER);
  62        return nonseekable_open(inode, file);
  63}
  64
  65/*
  66 * The watchdog cannot be disabled.
  67 *
  68 * Previous comments suggested that turning off the interrupt by
  69 * clearing OIER[E3] would prevent the watchdog timing out but this
  70 * does not appear to be true (at least on the PXA255).
  71 */
  72static int sa1100dog_release(struct inode *inode, struct file *file)
  73{
  74        pr_crit("Device closed - timer will not stop\n");
  75        clear_bit(1, &sa1100wdt_users);
  76        return 0;
  77}
  78
  79static ssize_t sa1100dog_write(struct file *file, const char __user *data,
  80                                                size_t len, loff_t *ppos)
  81{
  82        if (len)
  83                /* Refresh OSMR3 timer. */
  84                writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
  85        return len;
  86}
  87
  88static const struct watchdog_info ident = {
  89        .options        = WDIOF_CARDRESET | WDIOF_SETTIMEOUT
  90                                | WDIOF_KEEPALIVEPING,
  91        .identity       = "SA1100/PXA255 Watchdog",
  92        .firmware_version       = 1,
  93};
  94
  95static long sa1100dog_ioctl(struct file *file, unsigned int cmd,
  96                                                        unsigned long arg)
  97{
  98        int ret = -ENOTTY;
  99        int time;
 100        void __user *argp = (void __user *)arg;
 101        int __user *p = argp;
 102
 103        switch (cmd) {
 104        case WDIOC_GETSUPPORT:
 105                ret = copy_to_user(argp, &ident,
 106                                   sizeof(ident)) ? -EFAULT : 0;
 107                break;
 108
 109        case WDIOC_GETSTATUS:
 110                ret = put_user(0, p);
 111                break;
 112
 113        case WDIOC_GETBOOTSTATUS:
 114                ret = put_user(boot_status, p);
 115                break;
 116
 117        case WDIOC_KEEPALIVE:
 118                writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
 119                ret = 0;
 120                break;
 121
 122        case WDIOC_SETTIMEOUT:
 123                ret = get_user(time, p);
 124                if (ret)
 125                        break;
 126
 127                if (time <= 0 || (oscr_freq * (long long)time >= 0xffffffff)) {
 128                        ret = -EINVAL;
 129                        break;
 130                }
 131
 132                pre_margin = oscr_freq * time;
 133                writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
 134                /*fall through*/
 135
 136        case WDIOC_GETTIMEOUT:
 137                ret = put_user(pre_margin / oscr_freq, p);
 138                break;
 139        }
 140        return ret;
 141}
 142
 143static const struct file_operations sa1100dog_fops = {
 144        .owner          = THIS_MODULE,
 145        .llseek         = no_llseek,
 146        .write          = sa1100dog_write,
 147        .unlocked_ioctl = sa1100dog_ioctl,
 148        .open           = sa1100dog_open,
 149        .release        = sa1100dog_release,
 150};
 151
 152static struct miscdevice sa1100dog_miscdev = {
 153        .minor          = WATCHDOG_MINOR,
 154        .name           = "watchdog",
 155        .fops           = &sa1100dog_fops,
 156};
 157
 158static int margin __initdata = 60;              /* (secs) Default is 1 minute */
 159static struct clk *clk;
 160
 161static int __init sa1100dog_init(void)
 162{
 163        int ret;
 164
 165        clk = clk_get(NULL, "OSTIMER0");
 166        if (IS_ERR(clk)) {
 167                pr_err("SA1100/PXA2xx Watchdog Timer: clock not found: %d\n",
 168                       (int) PTR_ERR(clk));
 169                return PTR_ERR(clk);
 170        }
 171
 172        ret = clk_prepare_enable(clk);
 173        if (ret) {
 174                pr_err("SA1100/PXA2xx Watchdog Timer: clock failed to prepare+enable: %d\n",
 175                       ret);
 176                goto err;
 177        }
 178
 179        oscr_freq = clk_get_rate(clk);
 180
 181        /*
 182         * Read the reset status, and save it for later.  If
 183         * we suspend, RCSR will be cleared, and the watchdog
 184         * reset reason will be lost.
 185         */
 186        boot_status = (reset_status & RESET_STATUS_WATCHDOG) ?
 187                                WDIOF_CARDRESET : 0;
 188        pre_margin = oscr_freq * margin;
 189
 190        ret = misc_register(&sa1100dog_miscdev);
 191        if (ret == 0) {
 192                pr_info("SA1100/PXA2xx Watchdog Timer: timer margin %d sec\n",
 193                        margin);
 194                return 0;
 195        }
 196
 197        clk_disable_unprepare(clk);
 198err:
 199        clk_put(clk);
 200        return ret;
 201}
 202
 203static void __exit sa1100dog_exit(void)
 204{
 205        misc_deregister(&sa1100dog_miscdev);
 206        clk_disable_unprepare(clk);
 207        clk_put(clk);
 208}
 209
 210module_init(sa1100dog_init);
 211module_exit(sa1100dog_exit);
 212
 213MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
 214MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
 215
 216module_param(margin, int, 0);
 217MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
 218
 219MODULE_LICENSE("GPL");
 220