Re: [PATCH v2 2/2] hwrng: msm - Add support for prng v2

Stanimir Varbanov
2018-06-19T12:11:33Z

Hi Vinod,

On 06/19/2018 12:54 PM, Vinod Koul wrote:
> Qcom 8996 and later chips support prng v2 which requires to
> implement only .read callback for hwrng.
>
> This version of chip has multiple Execution Environments (EE) and
> secure world is typically responsible for configuring the prng.
>
> Add driver data for qcom,prng as 0 and qcom,prng-v2 as 1 and use
> that to skip initialization and cleanup routines.
>
> Signed-off-by: Vinod Koul <vkoul@kernel.org>
> ---
> drivers/char/hw_random/msm-rng.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/char/hw_random/msm-rng.c b/drivers/char/hw_random/msm-rng.c
> index 841fee845ec9..4676520e1f16 100644
> --- a/drivers/char/hw_random/msm-rng.c
> +++ b/drivers/char/hw_random/msm-rng.c
> @@ -17,6 +17,7 @@
> #include <linux/io.h>
> #include <linux/module.h>
> #include <linux/of.h>
> +#include <linux/of_device.h>
> #include <linux/platform_device.h>
>
> /* Device specific register offsets */
> @@ -131,6 +132,7 @@ static int msm_rng_probe(struct platform_device *pdev)
> {
> struct resource *res;
> struct msm_rng *rng;
> + unsigned int skip_init;
> int ret;
>
> rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
> @@ -149,9 +151,12 @@ static int msm_rng_probe(struct platform_device *pdev)
> return PTR_ERR(rng->clk);
>
> rng->hwrng.name = KBUILD_MODNAME,
> - rng->hwrng.init = msm_rng_init,
> - rng->hwrng.cleanup = msm_rng_cleanup,
> - rng->hwrng.read = msm_rng_read,
> + rng->hwrng.read = msm_rng_read;
> + skip_init = (unsigned long)of_device_get_match_data(&pdev->dev);

skip_init is unsigned int, despite I think you don't need to cast it.

> + if (!skip_init) {
> + rng->hwrng.init = msm_rng_init;
> + rng->hwrng.cleanup = msm_rng_cleanup;
> + }
>
> ret = devm_hwrng_register(&pdev->dev, &rng->hwrng);
> if (ret) {
> @@ -163,7 +168,8 @@ static int msm_rng_probe(struct platform_device *pdev)
> }
>
> static const struct of_device_id msm_rng_of_match[] = {
> - { .compatible = "qcom,prng", },
> + { .compatible = "qcom,prng", .data = (void *)0},
> + { .compatible = "qcom,prng-v2", .data = (void *)1},

No need to cast. IMO it'd be better to create defines for these numbers:

#define PRNG_V1 0
#define PRNG_V2 1

--
regards,
Stan