drivers/char/hw_random/meson-rng.c

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

File Facts

System
Linux kernel
Corpus path
drivers/char/hw_random/meson-rng.c
Extension
.c
Size
3526 bytes
Lines
153
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 meson_rng_priv {
	int (*read)(struct hwrng *rng, void *buf, size_t max, bool wait);
};

struct meson_rng_data {
	void __iomem *base;
	struct hwrng rng;
	struct device *dev;
};

static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
{
	struct meson_rng_data *data =
			container_of(rng, struct meson_rng_data, rng);

	*(u32 *)buf = readl_relaxed(data->base + RNG_DATA);

	return sizeof(u32);
}

static int meson_rng_wait_status(void __iomem *cfg_addr, int bit)
{
	u32 status = 0;
	int ret;

	ret = readl_relaxed_poll_timeout_atomic(cfg_addr,
						status, !(status & bit),
						10, 10000);
	if (ret)
		return -EBUSY;

	return 0;
}

static int meson_s4_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
{
	struct meson_rng_data *data =
			container_of(rng, struct meson_rng_data, rng);

	void __iomem *cfg_addr = data->base + RNG_S4_CFG;
	int err;

	writel_relaxed(readl_relaxed(cfg_addr) | SEED_READY_STS_BIT, cfg_addr);

	err = meson_rng_wait_status(cfg_addr, SEED_READY_STS_BIT);
	if (err) {
		dev_err(data->dev, "Seed isn't ready, try again\n");
		return err;
	}

	err = meson_rng_wait_status(cfg_addr, RUN_BIT);
	if (err) {
		dev_err(data->dev, "Can't get random number, try again\n");
		return err;
	}

	*(u32 *)buf = readl_relaxed(data->base + RNG_S4_DATA);

	return sizeof(u32);
}

static int meson_rng_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct meson_rng_data *data;
	struct clk *core_clk;
	const struct meson_rng_priv *priv;

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

	priv = device_get_match_data(&pdev->dev);
	if (!priv)
		return -ENODEV;

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

	core_clk = devm_clk_get_optional_enabled(dev, "core");
	if (IS_ERR(core_clk))
		return dev_err_probe(dev, PTR_ERR(core_clk),
				     "Failed to get core clock\n");

	data->rng.name = pdev->name;
	data->rng.read = priv->read;

	data->dev = &pdev->dev;

Annotation

Implementation Notes