Some SoCs like Exynos850 might require the SSS bus clock (PCLK) to be
enabled in order to access TRNG registers. Add and handle the optional
PCLK clock accordingly to make it possible.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
---
Changes in v2:
  - Used devm_clk_get_optional_enabled() to avoid calling
    clk_prepare_enable() for PCLK

 drivers/char/hw_random/exynos-trng.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/char/hw_random/exynos-trng.c b/drivers/char/hw_random/exynos-trng.c
index 91c210d80a3d..99a0b271ffb7 100644
--- a/drivers/char/hw_random/exynos-trng.c
+++ b/drivers/char/hw_random/exynos-trng.c
@@ -47,7 +47,8 @@
 struct exynos_trng_dev {
 	struct device	*dev;
 	void __iomem	*mem;
-	struct clk	*clk;
+	struct clk	*clk;	/* operating clock */
+	struct clk	*pclk;	/* bus clock */
 	struct hwrng	rng;
 };
 
@@ -141,6 +142,13 @@ static int exynos_trng_probe(struct platform_device *pdev)
 		goto err_clock;
 	}
 
+	trng->pclk = devm_clk_get_optional_enabled(&pdev->dev, "pclk");
+	if (IS_ERR(trng->pclk)) {
+		ret = dev_err_probe(&pdev->dev, PTR_ERR(trng->pclk),
+				    "Could not get pclk");
+		goto err_clock;
+	}
+
 	ret = devm_hwrng_register(&pdev->dev, &trng->rng);
 	if (ret) {
 		dev_err(&pdev->dev, "Could not register hwrng device.\n");
-- 
2.39.2

Hi Sam,

On Wed, 19 Jun 2024 at 02:15, Sam Protsenko <semen.protsenko@linaro.org> wrote:
>
> Some SoCs like Exynos850 might require the SSS bus clock (PCLK) to be
> enabled in order to access TRNG registers. Add and handle the optional
> PCLK clock accordingly to make it possible.
>
> Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
> ---
> Changes in v2:
>   - Used devm_clk_get_optional_enabled() to avoid calling
>     clk_prepare_enable() for PCLK
>

Reviewed-by: Anand Moon <linux.amoon@gmail.com>

Thanks

-Anand

On 18/06/2024 22:45, Sam Protsenko wrote:
> Some SoCs like Exynos850 might require the SSS bus clock (PCLK) to be
> enabled in order to access TRNG registers. Add and handle the optional
> PCLK clock accordingly to make it possible.
> 
> Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
> ---

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof