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

drivers/char/hw_random/meson-rng.c

+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);