drivers/watchdog/renesas_wwdt.c

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

File Facts

System
Linux kernel
Corpus path
drivers/watchdog/renesas_wwdt.c
Extension
.c
Size
4084 bytes
Lines
164
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 wwdt_priv {
	void __iomem *base;
	struct watchdog_device wdev;
};

static int wwdt_start(struct watchdog_device *wdev)
{
	struct wwdt_priv *priv = container_of(wdev, struct wwdt_priv, wdev);

	writeb(WDTA0RUN | WDTA0_KEY, priv->base + WDTA0WDTE);
	return 0;
}

static const struct watchdog_info wwdt_ident = {
	.options = WDIOF_KEEPALIVEPING | WDIOF_ALARMONLY,
	.identity = "Renesas Window Watchdog",
};

static const struct watchdog_ops wwdt_ops = {
	.owner = THIS_MODULE,
	.start = wwdt_start,
};

static irqreturn_t wwdt_error_irq(int irq, void *dev_id)
{
	struct device *dev = dev_id;

	dev_warn(dev, "Watchdog timed out\n");
	return IRQ_HANDLED;
}

static irqreturn_t wwdt_pretimeout_irq(int irq, void *dev_id)
{
	struct watchdog_device *wdev = dev_id;

	watchdog_notify_pretimeout(wdev);
	return IRQ_HANDLED;
}

static int wwdt_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct wwdt_priv *priv;
	struct watchdog_device *wdev;
	struct clk *clk;
	unsigned long rate;
	unsigned int interval, window_size;
	int ret;
	u8 val;

	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	priv->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(priv->base))
		return PTR_ERR(priv->base);

	clk = devm_clk_get(dev, "cnt");
	if (IS_ERR(clk))
		return PTR_ERR(clk);

	rate = clk_get_rate(clk);
	if (!rate)
		return -EINVAL;

	wdev = &priv->wdev;

	val = readb(priv->base + WDTA0WDTE);
	if (val & WDTA0RUN)
		set_bit(WDOG_HW_RUNNING, &wdev->status);

	val = readb(priv->base + WDTA0MD);
	interval = 1 << (9 + WDTA0OVF(val));
	/* size of the closed(!) window per mille */
	window_size = 250 * (3 - WDTA0WS(val));

	wdev->info = &wwdt_ident;
	wdev->ops = &wwdt_ops;
	wdev->parent = dev;
	wdev->min_hw_heartbeat_ms = window_size * interval / rate;
	wdev->max_hw_heartbeat_ms = 1000 * interval / rate;
	wdev->timeout = DIV_ROUND_UP(wdev->max_hw_heartbeat_ms, 1000);
	watchdog_set_nowayout(wdev, true);

	if (!(val & WDTA0ERM)) {
		ret = platform_get_irq_byname(pdev, "error");
		if (ret < 0)
			return ret;

Annotation

Implementation Notes