[PATCH v2 3/9] bsps/leon3: Make GPTIMER fall back mandatory

[Martin Åberg]

Hello Sebastian,

My understanding is that with this patch, one GPTIMER subtimer is always 
allocated for the timecounter in uniprocessor configuration in the case 
of "use_gptimer".


Does this mean that the lower hardware requirement for all LEON3 systems 
is raised to require a GPTIMER with two available subtimers?
(Since the last hardware subtimer is typically dedicated to the watchdog 
function, three subtimers would in practice be needed.)


What are the implications when using RTEMS_MULTIPROCESSING together with 
"use_gptimer"?

In bsps/sparc/leon3/include/bsp/leon3.h, we have:
 >  #if defined(RTEMS_MULTIPROCESSING)
 >  #define LEON3_CLOCK_INDEX \
 >    ( rtems_configuration_get_user_multiprocessing_table() ? 
LEON3_Cpu_Index : 0 )
 >  #else
 >  #define LEON3_CLOCK_INDEX 0
 >  #endif

Can LEON3_COUNTER_GPTIMER_INDEX of CPU0 be equal to LEON3_CLOCK_INDEX of 
CPU1 here?


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



On 2023-09-21 17:19, Sebastian Huber wrote:
> Using the auto reload counter which generates the clock ticks for the
> timecounter or CPU counter is quite difficult and only works in
> uniprocessor configurations.
> 
> Update #4954.
> ---
>   bsps/sparc/leon3/clock/ckinit.c      | 35 ++--------------------------
>   bsps/sparc/leon3/include/bsp/leon3.h |  4 ----
>   bsps/sparc/leon3/start/cpucounter.c  |  2 +-
>   3 files changed, 3 insertions(+), 38 deletions(-)
> 
> diff --git a/bsps/sparc/leon3/clock/ckinit.c b/bsps/sparc/leon3/clock/ckinit.c
> index eea4649fa3..d800f01e4a 100644
> --- a/bsps/sparc/leon3/clock/ckinit.c
> +++ b/bsps/sparc/leon3/clock/ckinit.c
> @@ -69,19 +69,6 @@ static struct timecounter leon3_tc;
>   
>   static void leon3_tc_tick_default(void)
>   {
> -#if !defined(RTEMS_SMP)
> -  SPARC_Counter *counter;
> -  rtems_interrupt_level level;
> -
> -  counter = &_SPARC_Counter;
> -  rtems_interrupt_local_disable(level);
> -
> -  grlib_store_32(&LEON3_IrqCtrl_Regs->iclear, counter->pending_mask);
> -  counter->accumulated += counter->interval;
> -
> -  rtems_interrupt_local_enable(level);
> -#endif
> -
>     rtems_timecounter_tick();
>   }
>   
> @@ -238,29 +225,11 @@ static void leon3_clock_use_gptimer(
>     gptimer_timer *timer
>   )
>   {
> -#ifdef RTEMS_SMP
>     /*
> -   * The GR712RC for example has no timestamp unit in the interrupt
> -   * controller.  At least on SMP configurations we must use a second timer
> -   * in free running mode for the timecounter.  The timer is initialized by
> -   * leon3_counter_initialize().
> +   * As a fall back, use a second timer in free-running mode for the
> +   * timecounter.  The timer is initialized by leon3_counter_initialize().
>      */
>     tc->tc_get_timecount = _SPARC_Get_timecount_down;
> -#else
> -  SPARC_Counter *counter;
> -
> -  counter = &_SPARC_Counter;
> -  counter->read_isr_disabled = _SPARC_Counter_read_clock_isr_disabled;
> -  counter->read = _SPARC_Counter_read_clock;
> -  counter->counter_register = &timer->tcntval;
> -  counter->pending_register = &LEON3_IrqCtrl_Regs->ipend;
> -  counter->pending_mask = UINT32_C(1) << clkirq;
> -  counter->accumulated = rtems_configuration_get_microseconds_per_tick();
> -  counter->interval = rtems_configuration_get_microseconds_per_tick();
> -
> -  tc->tc_get_timecount = _SPARC_Get_timecount_clock;
> -#endif
> -
>     tc->tc_frequency = LEON3_GPTIMER_0_FREQUENCY_SET_BY_BOOT_LOADER,
>   
>     rtems_timecounter_install(tc);
> diff --git a/bsps/sparc/leon3/include/bsp/leon3.h b/bsps/sparc/leon3/include/bsp/leon3.h
> index fdb43b5817..84790b590f 100644
> --- a/bsps/sparc/leon3/include/bsp/leon3.h
> +++ b/bsps/sparc/leon3/include/bsp/leon3.h
> @@ -188,11 +188,7 @@ static inline uint32_t leon3_get_cpu_count( const irqamp *regs )
>    * @brief This constant defines the index of the GPTIMER timer used by the
>    *   CPU counter if the CPU counter uses the GPTIMER.
>    */
> -#if defined(RTEMS_SMP)
>   #define LEON3_COUNTER_GPTIMER_INDEX ( LEON3_CLOCK_INDEX + 1 )
> -#else
> -#define LEON3_COUNTER_GPTIMER_INDEX LEON3_CLOCK_INDEX
> -#endif
>   
>   /**
>    * @brief This constant defines the frequency set by the boot loader of the
> diff --git a/bsps/sparc/leon3/start/cpucounter.c b/bsps/sparc/leon3/start/cpucounter.c
> index a6db7677a3..374e43c9b1 100644
> --- a/bsps/sparc/leon3/start/cpucounter.c
> +++ b/bsps/sparc/leon3/start/cpucounter.c
> @@ -89,7 +89,7 @@ static void leon3_counter_use_gptimer(SPARC_Counter *counter, gptimer *gpt)
>     counter->read = _SPARC_Counter_read_down;
>     counter->counter_register = &timer->tcntval;
>   
> -  /* Make timer free running */
> +  /* Make timer free-running */
>     grlib_store_32(&timer->trldval, 0xffffffff);
>     grlib_store_32(&timer->tctrl, GPTIMER_TCTRL_EN | GPTIMER_TCTRL_RS);
>