txx9wdt.c

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/*
 * txx9wdt: A Hardware Watchdog Driver for TXx9 SoCs
 *
 * Copyright (C) 2007 Atsushi Nemoto <[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/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <asm/txx9tmr.h>

#define WD_TIMER_CCD    7       /* 1/256 */
#define WD_TIMER_CLK    (clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
#define WD_MAX_TIMEOUT  ((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
#define TIMER_MARGIN    60      /* Default is 60 seconds */

static unsigned int timeout = TIMER_MARGIN; /* in seconds */
module_param(timeout, uint, 0);
MODULE_PARM_DESC(timeout,
    "Watchdog timeout in seconds. "
    "(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
    "default=" __MODULE_STRING(TIMER_MARGIN) ")");

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 struct txx9_tmr_reg __iomem *txx9wdt_reg;
static struct clk *txx9_imclk;
static DEFINE_SPINLOCK(txx9_lock);

static int txx9wdt_ping(struct watchdog_device *wdt_dev)
{
    spin_lock(&txx9_lock);
    __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
    spin_unlock(&txx9_lock);
    return 0;
}

static int txx9wdt_start(struct watchdog_device *wdt_dev)
{
    spin_lock(&txx9_lock);
    __raw_writel(WD_TIMER_CLK * wdt_dev->timeout, &txx9wdt_reg->cpra);
    __raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
    __raw_writel(0, &txx9wdt_reg->tisr);    /* clear pending interrupt */
    __raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
             &txx9wdt_reg->tcr);
    __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
    spin_unlock(&txx9_lock);
    return 0;
}

static int txx9wdt_stop(struct watchdog_device *wdt_dev)
{
    spin_lock(&txx9_lock);
    __raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
    __raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
             &txx9wdt_reg->tcr);
    spin_unlock(&txx9_lock);
    return 0;
}

static int txx9wdt_set_timeout(struct watchdog_device *wdt_dev,
                   unsigned int new_timeout)
{
    wdt_dev->timeout = new_timeout;
    txx9wdt_stop(wdt_dev);
    txx9wdt_start(wdt_dev);
    return 0;
}

static const struct watchdog_info txx9wdt_info = {
    .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
    .identity = "Hardware Watchdog for TXx9",
};

static const struct watchdog_ops txx9wdt_ops = {
    .owner = THIS_MODULE,
    .start = txx9wdt_start,
    .stop = txx9wdt_stop,
    .ping = txx9wdt_ping,
    .set_timeout = txx9wdt_set_timeout,
};

static struct watchdog_device txx9wdt = {
    .info = &txx9wdt_info,
    .ops = &txx9wdt_ops,
};

static int __init txx9wdt_probe(struct platform_device *dev)
{
    struct resource *res;
    int ret;

    txx9_imclk = clk_get(NULL, "imbus_clk");
    if (IS_ERR(txx9_imclk)) {
        ret = PTR_ERR(txx9_imclk);
        txx9_imclk = NULL;
        goto exit;
    }
    ret = clk_enable(txx9_imclk);
    if (ret) {
        clk_put(txx9_imclk);
        txx9_imclk = NULL;
        goto exit;
    }

    res = platform_get_resource(dev, IORESOURCE_MEM, 0);
    txx9wdt_reg = devm_request_and_ioremap(&dev->dev, res);
    if (!txx9wdt_reg) {
        ret = -EBUSY;
        goto exit;
    }

    if (timeout < 1 || timeout > WD_MAX_TIMEOUT)
        timeout = TIMER_MARGIN;
    txx9wdt.timeout = timeout;
    txx9wdt.min_timeout = 1;
    txx9wdt.max_timeout = WD_MAX_TIMEOUT;
    watchdog_set_nowayout(&txx9wdt, nowayout);

    ret = watchdog_register_device(&txx9wdt);
    if (ret)
        goto exit;

    pr_info("Hardware Watchdog Timer: timeout=%d sec (max %ld) (nowayout= %d)\n",
        timeout, WD_MAX_TIMEOUT, nowayout);

    return 0;
exit:
    if (txx9_imclk) {
        clk_disable(txx9_imclk);
        clk_put(txx9_imclk);
    }
    return ret;
}

static int __exit txx9wdt_remove(struct platform_device *dev)
{
    watchdog_unregister_device(&txx9wdt);
    clk_disable(txx9_imclk);
    clk_put(txx9_imclk);
    return 0;
}

static void txx9wdt_shutdown(struct platform_device *dev)
{
    txx9wdt_stop(&txx9wdt);
}

static struct platform_driver txx9wdt_driver = {
    .remove = __exit_p(txx9wdt_remove),
    .shutdown = txx9wdt_shutdown,
    .driver = {
        .name = "txx9wdt",
        .owner = THIS_MODULE,
    },
};

static int __init watchdog_init(void)
{
    return platform_driver_probe(&txx9wdt_driver, txx9wdt_probe);
}

static void __exit watchdog_exit(void)
{
    platform_driver_unregister(&txx9wdt_driver);
}

module_init(watchdog_init);
module_exit(watchdog_exit);

MODULE_DESCRIPTION("TXx9 Watchdog Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("platform:txx9wdt");