Re: [PATCH 2/6] timer: orion-timer: Add timer_get_boot_us() for BOOTSTAGE support

Hi Simon,

On 30.08.22 17:56, Simon Glass wrote:

Hi Stefan,

On Tue, 30 Aug 2022 at 06:08, Stefan Roese sr@denx.de wrote:

...

Adding Simon to Cc...

On 30.08.22 14:00, Michael Walle wrote:

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Am 2022-08-30 13:53, schrieb Stefan Roese:

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Add timer_get_boot_us() to support boards, that have CONFIG_BOOTSTAGE enabled, like pogo_v4.

Signed-off-by: Stefan Roese sr@denx.de

drivers/timer/orion-timer.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)

diff --git a/drivers/timer/orion-timer.c b/drivers/timer/orion-timer.c index 02ed138642b8..7e920eaeaa40 100644 --- a/drivers/timer/orion-timer.c +++ b/drivers/timer/orion-timer.c @@ -41,6 +41,28 @@ u64 notrace timer_early_get_count(void) } #endif

+#if CONFIG_IS_ENABLED(BOOTSTAGE) +ulong timer_get_boot_us(void) +{

• u64 ticks = 0;
• u32 rate = 1;
• u64 us;
• int ret;
• ret = dm_timer_init();
• if (!ret) {

•    /* The timer is available */
  

•    rate = timer_get_rate(gd->timer);
  

•    timer_get_count(gd->timer, &ticks);
  

• } else {

•    return 0;
  

• }
• us = (ticks * 1000) / rate;
• return us;

+} +#endif

This is duplicate code in almost all the timer drivers, shouldn't this be a (weak) default implementation in timer-uclass.c?

Yes. I was lazy and just copied this function and did not notice, that even more timer drivers have this function. Of course it makes sense to not duplicate code here, but have a common function for this. Frankly I don't even know why exactly this function is needed, as I did not look into BOOTSTAGE yet.

Simon, do we really need this function? Can't bootstage just use the "normal" timer functionality instead?

It is needed because bootstage is called before driver model is ready. In fact it can be used to time driver model things.

I see, makes sense. This brings up my next questions though, why isn't CONFIG_TIMER_EARLY enough in this case? AFAICT it's targeted exactly for this early (pre DM) bootstage. From drivers/timer/Kconfig:

config TIMER_EARLY bool "Allow timer to be used early in U-Boot" depends on TIMER # initr_bootstage() requires a timer and is called before initr_dm() # so only the early timer is available default y if X86 && BOOTSTAGE help In some cases the timer must be accessible before driver model is active. Examples include when using CONFIG_TRACE to trace U-Boot's execution before driver model is set up. Enable this option to use an early timer. These functions must be supported by your timer driver: timer_early_get_count() and timer_early_get_rate().

So again, do we really need timer_get_boot_us() or isn't it enough to select TIMER_EARLY when BOOTSTAGE is enabled?

Thanks, Stefan

The function here isn't that useful, since we cannot call dm_timer_init() before driver model is set up.

The timer_get_boot_us() function can by in a timer driver, but must exist outside the driver infrastructure. It must init the hard and then return the correct time. One driver model probes the timer driver, it must then continue on in that way.

Actually it looks like all the timers do this wrong. See arch/arm/mach-imx/syscounter.c or arch/arm/cpu/armv8/generic_timer.c for some ideas.

Thanks, Stefan