[PATCH] Added Getentropy() support to beagle BSP

[Sebastian Huber]

On 15/03/18 05:56, Udit agarwal wrote:
>  c/src/lib/libbsp/arm/atsam/startup/getentropy-trng.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/c/src/lib/libbsp/arm/atsam/startup/getentropy-trng.c 
> b/c/src/lib/libbsp/arm/atsam/startup/getentropy-trng.c
> index 11e24dc..b26b6a8 100644
> --- a/c/src/lib/libbsp/arm/atsam/startup/getentropy-trng.c
> +++ b/c/src/lib/libbsp/arm/atsam/startup/getentropy-trng.c
> @@ -17,6 +17,8 @@
>  #include <string.h>
>  #include <rtems/sysinit.h>
>
> +static rtems_mutex atsam_trng_reg = 
> RTEMS_MUTEX_INITIALIZER("atsam_trng_reg");

Is this a register or a mutex?

> +
>  static void atsam_trng_enable(void)
>  {
>      PMC_EnablePeripheral(ID_TRNG);
> @@ -29,9 +31,12 @@ int getentropy(void *ptr, size_t n)
>          uint32_t random;
>          size_t copy;
>
> +        rtems_mutex_lock(&atsam_trng_reg);
>          while ((TRNG_GetStatus() & TRNG_ISR_DATRDY) == 0) {
>              /* wait */
>          }
> +
> +        rtems_mutex_unlock(&atsam_trng_reg);

Now the status register read is protected by a mutex.

>     random = TRNG_GetRandData();

Can you ensure that this read is correct in a multi-threaded application 
(the status register has the right value during the read)?

>
>          /*
> @@ -51,6 +56,7 @@ int getentropy(void *ptr, size_t n)
>          ptr += copy;
>      }
>
> +    rtems_mutex_destroy(&atsam_trng_reg);

Here  you destroy the mutex. What happens if you call getentropy() a 
second time?

> return 0;
>  }

-- 
Sebastian Huber, embedded brains GmbH

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