drivers/watchdog/txx9wdt.c

Source file repositories/reference/linux-study-clean/drivers/watchdog/txx9wdt.c

File Facts

System
Linux kernel
Corpus path
drivers/watchdog/txx9wdt.c
Extension
.c
Size
4427 bytes
Lines
173
Domain
Driver Families
Bucket
drivers/watchdog
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
/*
 * txx9wdt: A Hardware Watchdog Driver for TXx9 SoCs
 *
 * Copyright (C) 2007 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.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,

Annotation

Implementation Notes