[PATCH v2 9/9] bsps/leon3: Use DSU time tag for GR712RC

[Martin Åberg]

OK, but please see the comment below.

On 2023-09-21 17:19, Sebastian Huber wrote:
> Update #4954.
> ---
>   bsps/sparc/leon3/start/cpucounter.c        | 62 ++++++++++++++++++++--
>   spec/build/bsps/sparc/leon3/grp.yml        |  2 +
>   spec/build/bsps/sparc/leon3/optdsubase.yml | 24 +++++++++
>   3 files changed, 84 insertions(+), 4 deletions(-)
>   create mode 100644 spec/build/bsps/sparc/leon3/optdsubase.yml
> 
> diff --git a/bsps/sparc/leon3/start/cpucounter.c b/bsps/sparc/leon3/start/cpucounter.c
> index db4f566021..35db839cd4 100644
> --- a/bsps/sparc/leon3/start/cpucounter.c
> +++ b/bsps/sparc/leon3/start/cpucounter.c
> @@ -77,7 +77,57 @@ RTEMS_ALIAS(_CPU_Counter_read) uint32_t _SPARC_Counter_read_ISR_disabled(void);
>   
>   #define LEON3_GET_TIMECOUNT_INIT leon3_timecounter_get_processor_up_counter
>   
> -#else /* !LEON3_HAS_ASR_22_23_UP_COUNTER */
> +#elif defined(LEON3_DSU_BASE)
> +
> +/*
> + * In general, using the Debug Support Unit (DSU) is not recommended.  Before
> + * you use it, check that it is available in flight models and that the time
> + * tag register is implemented in radiation hardened flip-flops.  For the
> + * GR712RC, this is the case.
> + */
> +
> +/* This value is specific to the GR712RC */
> +#define LEON3_DSU_TIME_TAG_ZERO_BITS 2

Yes the GR712RC is an exception in that the DSU timetag counter can be 
used. The comment (also in optdsubase.yml) is appropriate. 
Implementation is OK.

I would recommend to rework the symbol LEON3_DSU_BASE into something 
less generic, so that this is not activated by mistake. For example 
"LEON3_USE_GR712RC_DSU_COUNTER", or use an additional condition like "&& 
defined(RTEMS_BSP_GR712RC)". Another option would be to "#error" out if 
building a non-GR712RC BSP.


-- 
Best regards,

Martin Åberg
Software Engineer
Frontgrade Gaisler
martin.aberg at gaisler.com

Frontgrade Gaisler AB, Kungsgatan 12, SE-411 19 GÖTEBORG, Sweden.
+46 (0) 31 775 8650, www.gaisler.com