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acrn-kernel/drivers/watchdog/tegra_wdt.c

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/*
* Copyright (c) 2014, NVIDIA CORPORATION. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
/* minimum and maximum watchdog trigger timeout, in seconds */
#define MIN_WDT_TIMEOUT 1
#define MAX_WDT_TIMEOUT 255
/*
* Base of the WDT registers, from the timer base address. There are
* actually 5 watchdogs that can be configured (by pairing with an available
* timer), at bases 0x100 + (WDT ID) * 0x20, where WDT ID is 0 through 4.
* This driver only configures the first watchdog (WDT ID 0).
*/
#define WDT_BASE 0x100
#define WDT_ID 0
/*
* Register base of the timer that's selected for pairing with the watchdog.
* This driver arbitrarily uses timer 5, which is currently unused by
* other drivers (in particular, the Tegra clocksource driver). If this
* needs to change, take care that the new timer is not used by the
* clocksource driver.
*/
#define WDT_TIMER_BASE 0x60
#define WDT_TIMER_ID 5
/* WDT registers */
#define WDT_CFG 0x0
#define WDT_CFG_PERIOD_SHIFT 4
#define WDT_CFG_PERIOD_MASK 0xff
#define WDT_CFG_INT_EN (1 << 12)
#define WDT_CFG_PMC2CAR_RST_EN (1 << 15)
#define WDT_STS 0x4
#define WDT_STS_COUNT_SHIFT 4
#define WDT_STS_COUNT_MASK 0xff
#define WDT_STS_EXP_SHIFT 12
#define WDT_STS_EXP_MASK 0x3
#define WDT_CMD 0x8
#define WDT_CMD_START_COUNTER (1 << 0)
#define WDT_CMD_DISABLE_COUNTER (1 << 1)
#define WDT_UNLOCK (0xc)
#define WDT_UNLOCK_PATTERN (0xc45a << 0)
/* Timer registers */
#define TIMER_PTV 0x0
#define TIMER_EN (1 << 31)
#define TIMER_PERIODIC (1 << 30)
struct tegra_wdt {
struct watchdog_device wdd;
void __iomem *wdt_regs;
void __iomem *tmr_regs;
};
#define WDT_HEARTBEAT 120
static int heartbeat = WDT_HEARTBEAT;
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat,
"Watchdog heartbeats in seconds. (default = "
__MODULE_STRING(WDT_HEARTBEAT) ")");
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 tegra_wdt_start(struct watchdog_device *wdd)
{
struct tegra_wdt *wdt = watchdog_get_drvdata(wdd);
u32 val;
/*
* This thing has a fixed 1MHz clock. Normally, we would set the
* period to 1 second by writing 1000000ul, but the watchdog system
* reset actually occurs on the 4th expiration of this counter,
* so we set the period to 1/4 of this amount.
*/
val = 1000000ul / 4;
val |= (TIMER_EN | TIMER_PERIODIC);
writel(val, wdt->tmr_regs + TIMER_PTV);
/*
* Set number of periods and start counter.
*
* Interrupt handler is not required for user space
* WDT accesses, since the caller is responsible to ping the
* WDT to reset the counter before expiration, through ioctls.
*/
val = WDT_TIMER_ID |
(wdd->timeout << WDT_CFG_PERIOD_SHIFT) |
WDT_CFG_PMC2CAR_RST_EN;
writel(val, wdt->wdt_regs + WDT_CFG);
writel(WDT_CMD_START_COUNTER, wdt->wdt_regs + WDT_CMD);
return 0;
}
static int tegra_wdt_stop(struct watchdog_device *wdd)
{
struct tegra_wdt *wdt = watchdog_get_drvdata(wdd);
writel(WDT_UNLOCK_PATTERN, wdt->wdt_regs + WDT_UNLOCK);
writel(WDT_CMD_DISABLE_COUNTER, wdt->wdt_regs + WDT_CMD);
writel(0, wdt->tmr_regs + TIMER_PTV);
return 0;
}
static int tegra_wdt_ping(struct watchdog_device *wdd)
{
struct tegra_wdt *wdt = watchdog_get_drvdata(wdd);
writel(WDT_CMD_START_COUNTER, wdt->wdt_regs + WDT_CMD);
return 0;
}
static int tegra_wdt_set_timeout(struct watchdog_device *wdd,
unsigned int timeout)
{
wdd->timeout = timeout;
if (watchdog_active(wdd)) {
tegra_wdt_stop(wdd);
return tegra_wdt_start(wdd);
}
return 0;
}
static unsigned int tegra_wdt_get_timeleft(struct watchdog_device *wdd)
{
struct tegra_wdt *wdt = watchdog_get_drvdata(wdd);
u32 val;
int count;
int exp;
val = readl(wdt->wdt_regs + WDT_STS);
/* Current countdown (from timeout) */
count = (val >> WDT_STS_COUNT_SHIFT) & WDT_STS_COUNT_MASK;
/* Number of expirations (we are waiting for the 4th expiration) */
exp = (val >> WDT_STS_EXP_SHIFT) & WDT_STS_EXP_MASK;
/*
* The entire thing is divided by 4 because we are ticking down 4 times
* faster due to needing to wait for the 4th expiration.
*/
return (((3 - exp) * wdd->timeout) + count) / 4;
}
static const struct watchdog_info tegra_wdt_info = {
.options = WDIOF_SETTIMEOUT |
WDIOF_MAGICCLOSE |
WDIOF_KEEPALIVEPING,
.firmware_version = 0,
.identity = "Tegra Watchdog",
};
static struct watchdog_ops tegra_wdt_ops = {
.owner = THIS_MODULE,
.start = tegra_wdt_start,
.stop = tegra_wdt_stop,
.ping = tegra_wdt_ping,
.set_timeout = tegra_wdt_set_timeout,
.get_timeleft = tegra_wdt_get_timeleft,
};
static int tegra_wdt_probe(struct platform_device *pdev)
{
struct watchdog_device *wdd;
struct tegra_wdt *wdt;
struct resource *res;
void __iomem *regs;
int ret;
/* This is the timer base. */
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
regs = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(regs))
return PTR_ERR(regs);
/*
* Allocate our watchdog driver data, which has the
* struct watchdog_device nested within it.
*/
wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
if (!wdt)
return -ENOMEM;
/* Initialize struct tegra_wdt. */
wdt->wdt_regs = regs + WDT_BASE;
wdt->tmr_regs = regs + WDT_TIMER_BASE;
/* Initialize struct watchdog_device. */
wdd = &wdt->wdd;
wdd->timeout = heartbeat;
wdd->info = &tegra_wdt_info;
wdd->ops = &tegra_wdt_ops;
wdd->min_timeout = MIN_WDT_TIMEOUT;
wdd->max_timeout = MAX_WDT_TIMEOUT;
wdd->parent = &pdev->dev;
watchdog_set_drvdata(wdd, wdt);
watchdog_set_nowayout(wdd, nowayout);
ret = watchdog_register_device(wdd);
if (ret) {
dev_err(&pdev->dev,
"failed to register watchdog device\n");
return ret;
}
platform_set_drvdata(pdev, wdt);
dev_info(&pdev->dev,
"initialized (heartbeat = %d sec, nowayout = %d)\n",
heartbeat, nowayout);
return 0;
}
static int tegra_wdt_remove(struct platform_device *pdev)
{
struct tegra_wdt *wdt = platform_get_drvdata(pdev);
tegra_wdt_stop(&wdt->wdd);
watchdog_unregister_device(&wdt->wdd);
dev_info(&pdev->dev, "removed wdt\n");
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int tegra_wdt_runtime_suspend(struct device *dev)
{
struct tegra_wdt *wdt = dev_get_drvdata(dev);
if (watchdog_active(&wdt->wdd))
tegra_wdt_stop(&wdt->wdd);
return 0;
}
static int tegra_wdt_runtime_resume(struct device *dev)
{
struct tegra_wdt *wdt = dev_get_drvdata(dev);
if (watchdog_active(&wdt->wdd))
tegra_wdt_start(&wdt->wdd);
return 0;
}
#endif
static const struct of_device_id tegra_wdt_of_match[] = {
{ .compatible = "nvidia,tegra30-timer", },
{ },
};
MODULE_DEVICE_TABLE(of, tegra_wdt_of_match);
static const struct dev_pm_ops tegra_wdt_pm_ops = {
SET_SYSTEM_SLEEP_PM_OPS(tegra_wdt_runtime_suspend,
tegra_wdt_runtime_resume)
};
static struct platform_driver tegra_wdt_driver = {
.probe = tegra_wdt_probe,
.remove = tegra_wdt_remove,
.driver = {
.name = "tegra-wdt",
.pm = &tegra_wdt_pm_ops,
.of_match_table = tegra_wdt_of_match,
},
};
module_platform_driver(tegra_wdt_driver);
MODULE_AUTHOR("NVIDIA Corporation");
MODULE_DESCRIPTION("Tegra Watchdog Driver");
MODULE_LICENSE("GPL v2");
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