Alexey Romanov (avromanov@xxxxxxxxxxxxxx) wrote:
> 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: Alexey Romanov <avromanov@xxxxxxxxxxxxxx>
> ---
> drivers/char/hw_random/meson-rng.c | 77 ++++++++++++++++++++++++++++--
> 1 file changed, 74 insertions(+), 3 deletions(-)
> diff --git a/drivers/char/hw_random/meson-rng.c b/drivers/char/hw_random/meson-rng.c
> index a4eb8e35f13d..c6d7349630a1 100644
> --- a/drivers/char/hw_random/meson-rng.c
> +++ b/drivers/char/hw_random/meson-rng.c
> @@ -14,19 +14,65 @@
> #include <linux/of.h>
> #include <linux/clk.h>
> -#define RNG_DATA 0x00
> +struct meson_rng_priv {
> + bool check_status_bit;
> + unsigned int data_offset;
> + unsigned int cfg_offset;
> +};
> struct meson_rng_data {
> void __iomem *base;
> struct hwrng rng;
> + struct device *dev;
> + const struct meson_rng_priv *priv;
> };
> +#define RUN_BIT 0
> +#define SEED_READY_STS_BIT 31
> +#define RETRY_CNT 100
> +
> +static int meson_rng_wait_status(void __iomem *cfg_addr, int bit)
> +{
> + u32 status;
> + u32 cnt = 0;
> +
> + do {
> + status = readl_relaxed(cfg_addr) & BIT(bit);
> + cpu_relax();
> + } while (status && (cnt++ < RETRY_CNT));
> +
Could you use readl_relaxed_poll_timeout here instead of open coding the
loop?
> + if (status)
> + return -EBUSY;
> +
> + return 0;
> +}
> +
> 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);
> + const struct meson_rng_priv *priv = data->priv;
> +
> + if (priv->check_status_bit) {
> + void __iomem *cfg_addr = data->base + priv->cfg_offset;
> + int err;
> +
> + writel_relaxed(readl_relaxed(cfg_addr) | BIT(SEED_READY_STS_BIT), cfg_addr);
> - *(u32 *)buf = readl_relaxed(data->base + RNG_DATA);
> + 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 + priv->data_offset);
> return sizeof(u32);
> }
> @@ -41,6 +87,10 @@ static int meson_rng_probe(struct platform_device *pdev)
> if (!data)
> return -ENOMEM;
> + data->priv = device_get_match_data(&pdev->dev);
> + if (!data->priv)
> + return -ENODEV;
> +
> data->base = devm_platform_ioremap_resource(pdev, 0);
> if (IS_ERR(data->base))
> return PTR_ERR(data->base);
> @@ -53,11 +103,32 @@ static int meson_rng_probe(struct platform_device *pdev)
> data->rng.name = pdev->name;
> data->rng.read = meson_rng_read;
> + data->dev = &pdev->dev;
> +
> return devm_hwrng_register(dev, &data->rng);
> }
> +static const struct meson_rng_priv meson_rng_priv = {
> + .check_status_bit = false,
> + .data_offset = 0x0,
> + .cfg_offset = 0x0,
> +};
> +
> +static const struct meson_rng_priv meson_rng_priv_s4 = {
> + .check_status_bit = true,
> + .data_offset = 0x8,
> + .cfg_offset = 0x0,
> +};
> +
> 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-rng-s4",
> + .data = (void *)&meson_rng_priv_s4,
> + },
> {},
> };
> MODULE_DEVICE_TABLE(of, meson_rng_of_match);
> --
> 2.38.1
