drivers/watchdog/bcm2835_wdt.c

Source file repositories/reference/linux-study-clean/drivers/watchdog/bcm2835_wdt.c

File Facts

System
Linux kernel
Corpus path
drivers/watchdog/bcm2835_wdt.c
Extension
.c
Size
6529 bytes
Lines
238
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

struct bcm2835_wdt {
	void __iomem		*base;
	spinlock_t		lock;
};

static unsigned int heartbeat;
static bool nowayout = WATCHDOG_NOWAYOUT;

static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt)
{
	uint32_t cur;

	cur = readl(wdt->base + PM_RSTC);

	return !!(cur & PM_RSTC_WRCFG_FULL_RESET);
}

static int bcm2835_wdt_start(struct watchdog_device *wdog)
{
	struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
	uint32_t cur;
	unsigned long flags;

	spin_lock_irqsave(&wdt->lock, flags);

	writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
				PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
	cur = readl_relaxed(wdt->base + PM_RSTC);
	writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
		  PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);

	spin_unlock_irqrestore(&wdt->lock, flags);

	return 0;
}

static int bcm2835_wdt_stop(struct watchdog_device *wdog)
{
	struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);

	writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
	return 0;
}

static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
{
	struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);

	uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
	return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
}

static void __bcm2835_restart(struct bcm2835_wdt *wdt)
{
	u32 val;

	/* use a timeout of 10 ticks (~150us) */
	writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
	val = readl_relaxed(wdt->base + PM_RSTC);
	val &= PM_RSTC_WRCFG_CLR;
	val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
	writel_relaxed(val, wdt->base + PM_RSTC);

	/* No sleeping, possibly atomic. */
	mdelay(1);
}

static int bcm2835_restart(struct watchdog_device *wdog,
			   unsigned long action, void *data)
{
	struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);

	__bcm2835_restart(wdt);

	return 0;
}

static const struct watchdog_ops bcm2835_wdt_ops = {
	.owner =	THIS_MODULE,
	.start =	bcm2835_wdt_start,
	.stop =		bcm2835_wdt_stop,
	.get_timeleft =	bcm2835_wdt_get_timeleft,
	.restart =	bcm2835_restart,
};

static const struct watchdog_info bcm2835_wdt_info = {
	.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
			WDIOF_KEEPALIVEPING,
	.identity =	"Broadcom BCM2835 Watchdog timer",
};

Annotation

Implementation Notes