ath79_wdt.c

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/*
 * Atheros AR71XX/AR724X/AR913X built-in hardware watchdog timer.
 *
 * Copyright (C) 2008-2011 Gabor Juhos <[email protected]>
 * Copyright (C) 2008 Imre Kaloz <[email protected]>
 *
 * This driver was based on: drivers/watchdog/ixp4xx_wdt.c
 *  Author: Deepak Saxena <[email protected]>
 *  Copyright 2004 (c) MontaVista, Software, Inc.
 *
 * which again was based on sa1100 driver,
 *  Copyright (C) 2000 Oleg Drokin <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/bitops.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/types.h>
#include <linux/watchdog.h>
#include <linux/clk.h>
#include <linux/err.h>

#include <asm/mach-ath79/ath79.h>
#include <asm/mach-ath79/ar71xx_regs.h>

#define DRIVER_NAME "ath79-wdt"

#define WDT_TIMEOUT 15  /* seconds */

#define WDOG_CTRL_LAST_RESET    BIT(31)
#define WDOG_CTRL_ACTION_MASK   3
#define WDOG_CTRL_ACTION_NONE   0   /* no action */
#define WDOG_CTRL_ACTION_GPI    1   /* general purpose interrupt */
#define WDOG_CTRL_ACTION_NMI    2   /* NMI */
#define WDOG_CTRL_ACTION_FCR    3   /* full chip reset */

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
               "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

static int timeout = WDT_TIMEOUT;
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
              "(default=" __MODULE_STRING(WDT_TIMEOUT) "s)");

static unsigned long wdt_flags;

#define WDT_FLAGS_BUSY      0
#define WDT_FLAGS_EXPECT_CLOSE  1

static struct clk *wdt_clk;
static unsigned long wdt_freq;
static int boot_status;
static int max_timeout;

static inline void ath79_wdt_keepalive(void)
{
    ath79_reset_wr(AR71XX_RESET_REG_WDOG, wdt_freq * timeout);
    /* flush write */
    ath79_reset_rr(AR71XX_RESET_REG_WDOG);
}

static inline void ath79_wdt_enable(void)
{
    ath79_wdt_keepalive();
    ath79_reset_wr(AR71XX_RESET_REG_WDOG_CTRL, WDOG_CTRL_ACTION_FCR);
    /* flush write */
    ath79_reset_rr(AR71XX_RESET_REG_WDOG_CTRL);
}

static inline void ath79_wdt_disable(void)
{
    ath79_reset_wr(AR71XX_RESET_REG_WDOG_CTRL, WDOG_CTRL_ACTION_NONE);
    /* flush write */
    ath79_reset_rr(AR71XX_RESET_REG_WDOG_CTRL);
}

static int ath79_wdt_set_timeout(int val)
{
    if (val < 1 || val > max_timeout)
        return -EINVAL;

    timeout = val;
    ath79_wdt_keepalive();

    return 0;
}

static int ath79_wdt_open(struct inode *inode, struct file *file)
{
    if (test_and_set_bit(WDT_FLAGS_BUSY, &wdt_flags))
        return -EBUSY;

    clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);
    ath79_wdt_enable();

    return nonseekable_open(inode, file);
}

static int ath79_wdt_release(struct inode *inode, struct file *file)
{
    if (test_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags))
        ath79_wdt_disable();
    else {
        pr_crit("device closed unexpectedly, watchdog timer will not stop!\n");
        ath79_wdt_keepalive();
    }

    clear_bit(WDT_FLAGS_BUSY, &wdt_flags);
    clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);

    return 0;
}

static ssize_t ath79_wdt_write(struct file *file, const char *data,
                size_t len, loff_t *ppos)
{
    if (len) {
        if (!nowayout) {
            size_t i;

            clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags);

            for (i = 0; i != len; i++) {
                char c;

                if (get_user(c, data + i))
                    return -EFAULT;

                if (c == 'V')
                    set_bit(WDT_FLAGS_EXPECT_CLOSE,
                        &wdt_flags);
            }
        }

        ath79_wdt_keepalive();
    }

    return len;
}

static const struct watchdog_info ath79_wdt_info = {
    .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
                  WDIOF_MAGICCLOSE | WDIOF_CARDRESET,
    .firmware_version   = 0,
    .identity       = "ATH79 watchdog",
};

static long ath79_wdt_ioctl(struct file *file, unsigned int cmd,
                unsigned long arg)
{
    void __user *argp = (void __user *)arg;
    int __user *p = argp;
    int err;
    int t;

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        err = copy_to_user(argp, &ath79_wdt_info,
                   sizeof(ath79_wdt_info)) ? -EFAULT : 0;
        break;

    case WDIOC_GETSTATUS:
        err = put_user(0, p);
        break;

    case WDIOC_GETBOOTSTATUS:
        err = put_user(boot_status, p);
        break;

    case WDIOC_KEEPALIVE:
        ath79_wdt_keepalive();
        err = 0;
        break;

    case WDIOC_SETTIMEOUT:
        err = get_user(t, p);
        if (err)
            break;

        err = ath79_wdt_set_timeout(t);
        if (err)
            break;

        /* fallthrough */
    case WDIOC_GETTIMEOUT:
        err = put_user(timeout, p);
        break;

    default:
        err = -ENOTTY;
        break;
    }

    return err;
}

static const struct file_operations ath79_wdt_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .write      = ath79_wdt_write,
    .unlocked_ioctl = ath79_wdt_ioctl,
    .open       = ath79_wdt_open,
    .release    = ath79_wdt_release,
};

static struct miscdevice ath79_wdt_miscdev = {
    .minor = WATCHDOG_MINOR,
    .name = "watchdog",
    .fops = &ath79_wdt_fops,
};

static int __devinit ath79_wdt_probe(struct platform_device *pdev)
{
    u32 ctrl;
    int err;

    wdt_clk = clk_get(&pdev->dev, "wdt");
    if (IS_ERR(wdt_clk))
        return PTR_ERR(wdt_clk);

    err = clk_enable(wdt_clk);
    if (err)
        goto err_clk_put;

    wdt_freq = clk_get_rate(wdt_clk);
    if (!wdt_freq) {
        err = -EINVAL;
        goto err_clk_disable;
    }

    max_timeout = (0xfffffffful / wdt_freq);
    if (timeout < 1 || timeout > max_timeout) {
        timeout = max_timeout;
        dev_info(&pdev->dev,
            "timeout value must be 0 < timeout < %d, using %d\n",
            max_timeout, timeout);
    }

    ctrl = ath79_reset_rr(AR71XX_RESET_REG_WDOG_CTRL);
    boot_status = (ctrl & WDOG_CTRL_LAST_RESET) ? WDIOF_CARDRESET : 0;

    err = misc_register(&ath79_wdt_miscdev);
    if (err) {
        dev_err(&pdev->dev,
            "unable to register misc device, err=%d\n", err);
        goto err_clk_disable;
    }

    return 0;

err_clk_disable:
    clk_disable(wdt_clk);
err_clk_put:
    clk_put(wdt_clk);
    return err;
}

static int __devexit ath79_wdt_remove(struct platform_device *pdev)
{
    misc_deregister(&ath79_wdt_miscdev);
    clk_disable(wdt_clk);
    clk_put(wdt_clk);
    return 0;
}

static void ath97_wdt_shutdown(struct platform_device *pdev)
{
    ath79_wdt_disable();
}

static struct platform_driver ath79_wdt_driver = {
    .remove     = __devexit_p(ath79_wdt_remove),
    .shutdown   = ath97_wdt_shutdown,
    .driver     = {
        .name   = DRIVER_NAME,
        .owner  = THIS_MODULE,
    },
};

static int __init ath79_wdt_init(void)
{
    return platform_driver_probe(&ath79_wdt_driver, ath79_wdt_probe);
}
module_init(ath79_wdt_init);

static void __exit ath79_wdt_exit(void)
{
    platform_driver_unregister(&ath79_wdt_driver);
}
module_exit(ath79_wdt_exit);

MODULE_DESCRIPTION("Atheros AR71XX/AR724X/AR913X hardware watchdog driver");
MODULE_AUTHOR("Gabor Juhos <[email protected]");
MODULE_AUTHOR("Imre Kaloz <[email protected]");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" DRIVER_NAME);
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);