drivers/char/hw_random/pic32-rng.c

Source file repositories/reference/linux-study-clean/drivers/char/hw_random/pic32-rng.c

File Facts

System
Linux kernel
Corpus path
drivers/char/hw_random/pic32-rng.c
Extension
.c
Size
2889 bytes
Lines
121
Domain
Driver Families
Bucket
drivers/char
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 pic32_rng {
	void __iomem	*base;
	struct hwrng	rng;
};

/*
 * The TRNG can generate up to 24Mbps. This is a timeout that should be safe
 * enough given the instructions in the loop and that the TRNG may not always
 * be at maximum rate.
 */
#define RNG_TIMEOUT 500

static int pic32_rng_init(struct hwrng *rng)
{
	struct pic32_rng *priv = container_of(rng, struct pic32_rng, rng);

	/* enable TRNG in enhanced mode */
	writel(TRNGEN | TRNGMOD, priv->base + RNGCON);
	return 0;
}

static int pic32_rng_read(struct hwrng *rng, void *buf, size_t max,
			  bool wait)
{
	struct pic32_rng *priv = container_of(rng, struct pic32_rng, rng);
	u64 *data = buf;
	u32 t;
	unsigned int timeout = RNG_TIMEOUT;

	do {
		t = readl(priv->base + RNGRCNT) & RCNT_MASK;
		if (t == 64) {
			/* TRNG value comes through the seed registers */
			*data = ((u64)readl(priv->base + RNGSEED2) << 32) +
				readl(priv->base + RNGSEED1);
			return 8;
		}
	} while (wait && --timeout);

	return -EIO;
}

static void pic32_rng_cleanup(struct hwrng *rng)
{
	struct pic32_rng *priv = container_of(rng, struct pic32_rng, rng);

	writel(0, priv->base + RNGCON);
}

static int pic32_rng_probe(struct platform_device *pdev)
{
	struct pic32_rng *priv;
	struct clk *clk;

	priv = devm_kzalloc(&pdev->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_enabled(&pdev->dev, NULL);
	if (IS_ERR(clk))
		return PTR_ERR(clk);

	priv->rng.name = pdev->name;
	priv->rng.init = pic32_rng_init;
	priv->rng.read = pic32_rng_read;
	priv->rng.cleanup = pic32_rng_cleanup;

	return devm_hwrng_register(&pdev->dev, &priv->rng);
}

static const struct of_device_id pic32_rng_of_match[] __maybe_unused = {
	{ .compatible	= "microchip,pic32mzda-rng", },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, pic32_rng_of_match);

static struct platform_driver pic32_rng_driver = {
	.probe		= pic32_rng_probe,
	.driver		= {
		.name	= "pic32-rng",
		.of_match_table = pic32_rng_of_match,
	},
};

module_platform_driver(pic32_rng_driver);

Annotation

Implementation Notes