Commit a5de196d authored by Alexey Romanov's avatar Alexey Romanov Committed by Herbert Xu
Browse files

hwrng: meson - add support for S4



For some Amlogic SOC's, mechanism to obtain random number
has been changed. For example, S4 now uses status bit waiting algo.

Signed-off-by: default avatarAlexey Romanov <avromanov@sberdevices.ru>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent b42ab1c6
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+77 −3
Original line number Diff line number Diff line
@@ -13,12 +13,23 @@
#include <linux/types.h>
#include <linux/of.h>
#include <linux/clk.h>
#include <linux/iopoll.h>

#define RNG_DATA	0x00
#define RNG_S4_DATA	0x08
#define RNG_S4_CFG	0x00

#define RUN_BIT		BIT(0)
#define SEED_READY_STS_BIT	BIT(31)

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)
@@ -31,16 +42,62 @@ static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
	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);
@@ -51,13 +108,30 @@ static int meson_rng_probe(struct platform_device *pdev)
				     "Failed to get core clock\n");

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

	data->dev = &pdev->dev;

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

static const struct meson_rng_priv meson_rng_priv = {
	.read = meson_rng_read,
};

static const struct meson_rng_priv meson_rng_priv_s4 = {
	.read = meson_s4_rng_read,
};

static const struct of_device_id meson_rng_of_match[] = {
	{ .compatible = "amlogic,meson-rng", },
	{
		.compatible = "amlogic,meson-rng",
		.data = (void *)&meson_rng_priv,
	},
	{
		.compatible = "amlogic,meson-s4-rng",
		.data = (void *)&meson_rng_priv_s4,
	},
	{},
};
MODULE_DEVICE_TABLE(of, meson_rng_of_match);