sp805_wdt.c 7.49 KB
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/*
 * drivers/char/watchdog/sp805-wdt.c
 *
 * Watchdog driver for ARM SP805 watchdog module
 *
 * Copyright (C) 2010 ST Microelectronics
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 * Viresh Kumar <viresh.linux@gmail.com>
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 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2 or later. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/device.h>
#include <linux/resource.h>
#include <linux/amba/bus.h>
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
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#include <linux/pm.h>
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#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/watchdog.h>

/* default timeout in seconds */
#define DEFAULT_TIMEOUT		60

#define MODULE_NAME		"sp805-wdt"

/* watchdog register offsets and masks */
#define WDTLOAD			0x000
	#define LOAD_MIN	0x00000001
	#define LOAD_MAX	0xFFFFFFFF
#define WDTVALUE		0x004
#define WDTCONTROL		0x008
	/* control register masks */
	#define	INT_ENABLE	(1 << 0)
	#define	RESET_ENABLE	(1 << 1)
#define WDTINTCLR		0x00C
#define WDTRIS			0x010
#define WDTMIS			0x014
	#define INT_MASK	(1 << 0)
#define WDTLOCK			0xC00
	#define	UNLOCK		0x1ACCE551
	#define	LOCK		0x00000001

/**
 * struct sp805_wdt: sp805 wdt device structure
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 * @wdd: instance of struct watchdog_device
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 * @lock: spin lock protecting dev structure and io access
 * @base: base address of wdt
 * @clk: clock structure of wdt
 * @adev: amba device structure of wdt
 * @status: current status of wdt
 * @load_val: load value to be set for current timeout
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 */
struct sp805_wdt {
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	struct watchdog_device		wdd;
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	spinlock_t			lock;
	void __iomem			*base;
	struct clk			*clk;
	struct amba_device		*adev;
	unsigned int			load_val;
};

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static bool nowayout = WATCHDOG_NOWAYOUT;
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module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
		"Set to 1 to keep watchdog running after device release");
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/* This routine finds load value that will reset system in required timout */
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static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
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{
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	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
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	u64 load, rate;

	rate = clk_get_rate(wdt->clk);

	/*
	 * sp805 runs counter with given value twice, after the end of first
	 * counter it gives an interrupt and then starts counter again. If
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	 * interrupt already occurred then it resets the system. This is why
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	 * load is half of what should be required.
	 */
	load = div_u64(rate, 2) * timeout - 1;

	load = (load > LOAD_MAX) ? LOAD_MAX : load;
	load = (load < LOAD_MIN) ? LOAD_MIN : load;

	spin_lock(&wdt->lock);
	wdt->load_val = load;
	/* roundup timeout to closest positive integer value */
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	wdd->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
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	spin_unlock(&wdt->lock);
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	return 0;
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}

/* returns number of seconds left for reset to occur */
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static unsigned int wdt_timeleft(struct watchdog_device *wdd)
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{
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	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
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	u64 load, rate;

	rate = clk_get_rate(wdt->clk);

	spin_lock(&wdt->lock);
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	load = readl_relaxed(wdt->base + WDTVALUE);
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	/*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
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	if (!(readl_relaxed(wdt->base + WDTRIS) & INT_MASK))
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		load += wdt->load_val + 1;
	spin_unlock(&wdt->lock);

	return div_u64(load, rate);
}

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static int wdt_config(struct watchdog_device *wdd, bool ping)
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{
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	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
	int ret;

	if (!ping) {
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		ret = clk_prepare_enable(wdt->clk);
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		if (ret) {
			dev_err(&wdt->adev->dev, "clock enable fail");
			return ret;
		}
	}

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	spin_lock(&wdt->lock);

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	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
	writel_relaxed(wdt->load_val, wdt->base + WDTLOAD);
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	if (!ping) {
		writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
		writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base +
				WDTCONTROL);
	}
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	writel_relaxed(LOCK, wdt->base + WDTLOCK);
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	/* Flush posted writes. */
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	readl_relaxed(wdt->base + WDTLOCK);
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	spin_unlock(&wdt->lock);
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	return 0;
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}

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static int wdt_ping(struct watchdog_device *wdd)
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{
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	return wdt_config(wdd, true);
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}

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/* enables watchdog timers reset */
static int wdt_enable(struct watchdog_device *wdd)
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{
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	return wdt_config(wdd, false);
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}

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/* disables watchdog timers reset */
static int wdt_disable(struct watchdog_device *wdd)
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{
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	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
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	spin_lock(&wdt->lock);
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	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
	writel_relaxed(0, wdt->base + WDTCONTROL);
	writel_relaxed(LOCK, wdt->base + WDTLOCK);
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	/* Flush posted writes. */
	readl_relaxed(wdt->base + WDTLOCK);
	spin_unlock(&wdt->lock);
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	clk_disable_unprepare(wdt->clk);
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	return 0;
}

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static const struct watchdog_info wdt_info = {
	.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
	.identity = MODULE_NAME,
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};

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static const struct watchdog_ops wdt_ops = {
	.owner		= THIS_MODULE,
	.start		= wdt_enable,
	.stop		= wdt_disable,
	.ping		= wdt_ping,
	.set_timeout	= wdt_setload,
	.get_timeleft	= wdt_timeleft,
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};

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static int
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sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
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{
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	struct sp805_wdt *wdt;
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	int ret = 0;

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	if (!devm_request_mem_region(&adev->dev, adev->res.start,
				resource_size(&adev->res), "sp805_wdt")) {
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		dev_warn(&adev->dev, "Failed to get memory region resource\n");
		ret = -ENOENT;
		goto err;
	}

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	wdt = devm_kzalloc(&adev->dev, sizeof(*wdt), GFP_KERNEL);
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	if (!wdt) {
		dev_warn(&adev->dev, "Kzalloc failed\n");
		ret = -ENOMEM;
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		goto err;
	}

	wdt->base = devm_ioremap(&adev->dev, adev->res.start,
			resource_size(&adev->res));
	if (!wdt->base) {
		ret = -ENOMEM;
		dev_warn(&adev->dev, "ioremap fail\n");
		goto err;
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	}

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	wdt->clk = devm_clk_get(&adev->dev, NULL);
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	if (IS_ERR(wdt->clk)) {
		dev_warn(&adev->dev, "Clock not found\n");
		ret = PTR_ERR(wdt->clk);
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		goto err;
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	}

	wdt->adev = adev;
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	wdt->wdd.info = &wdt_info;
	wdt->wdd.ops = &wdt_ops;

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	spin_lock_init(&wdt->lock);
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	watchdog_set_nowayout(&wdt->wdd, nowayout);
	watchdog_set_drvdata(&wdt->wdd, wdt);
	wdt_setload(&wdt->wdd, DEFAULT_TIMEOUT);
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	ret = watchdog_register_device(&wdt->wdd);
	if (ret) {
		dev_err(&adev->dev, "watchdog_register_device() failed: %d\n",
				ret);
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		goto err;
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	}
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	amba_set_drvdata(adev, wdt);
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	dev_info(&adev->dev, "registration successful\n");
	return 0;

err:
	dev_err(&adev->dev, "Probe Failed!!!\n");
	return ret;
}

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static int sp805_wdt_remove(struct amba_device *adev)
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{
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	struct sp805_wdt *wdt = amba_get_drvdata(adev);

	watchdog_unregister_device(&wdt->wdd);
	amba_set_drvdata(adev, NULL);
	watchdog_set_drvdata(&wdt->wdd, NULL);
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	return 0;
}

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static int __maybe_unused sp805_wdt_suspend(struct device *dev)
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{
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	struct sp805_wdt *wdt = dev_get_drvdata(dev);

	if (watchdog_active(&wdt->wdd))
		return wdt_disable(&wdt->wdd);
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	return 0;
}

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static int __maybe_unused sp805_wdt_resume(struct device *dev)
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{
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	struct sp805_wdt *wdt = dev_get_drvdata(dev);
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	if (watchdog_active(&wdt->wdd))
		return wdt_enable(&wdt->wdd);
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	return 0;
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}

static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops, sp805_wdt_suspend,
		sp805_wdt_resume);

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static struct amba_id sp805_wdt_ids[] = {
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	{
		.id	= 0x00141805,
		.mask	= 0x00ffffff,
	},
	{ 0, 0 },
};

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MODULE_DEVICE_TABLE(amba, sp805_wdt_ids);

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static struct amba_driver sp805_wdt_driver = {
	.drv = {
		.name	= MODULE_NAME,
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		.pm	= &sp805_wdt_dev_pm_ops,
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	},
	.id_table	= sp805_wdt_ids,
	.probe		= sp805_wdt_probe,
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	.remove = sp805_wdt_remove,
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};

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module_amba_driver(sp805_wdt_driver);
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MODULE_AUTHOR("Viresh Kumar <viresh.linux@gmail.com>");
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MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
MODULE_LICENSE("GPL");