libpayload/x86/delay: Make arch_ndelay call apic_delay if delay is long
This reduces power consumption on grunt by over 3W when sitting at the depthcharge recovery screen. BUG=b:109749762 TEST=Booted grunt in the recovery screen and made sure it continued to work. Change-Id: Id079c099ee4cf6a07724241af4400063f4551668 Signed-off-by: Raul E Rangel <rrangel@chromium.org> Reviewed-on: https://review.coreboot.org/28245 Reviewed-by: Martin Roth <martinroth@google.com> Reviewed-by: Richard Spiegel <richard.spiegel@silverbackltd.com> Reviewed-by: Julius Werner <jwerner@google.com> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
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@ -210,6 +210,8 @@ static void apic_init_timer(void)
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/* Set APIC init counter to MAX and count for 1 ms */
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apic_write32(APIC_TIMER_INIT_COUNT, UINT32_MAX);
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/* This is safe because apic_initialized() returns false so
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* arch_ndelay() falls back to a busy loop. */
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mdelay(1);
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ticks_per_ms =
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@ -28,6 +28,7 @@
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*/
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#include <libpayload.h>
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#include <arch/apic.h>
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/* The pause instruction can delay 10-140 CPU cycles, so avoid calling it when
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* getting close to finishing. Depending on the timer source, the timer can be
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@ -35,12 +36,23 @@
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* that the timer is running at the CPU frequency. */
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#define PAUSE_THRESHOLD_TICKS 150
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/* Let's assume APIC interrupts take at least 100us */
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#define APIC_INTERRUPT_LATENCY_NS (100 * NSECS_PER_USEC)
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void arch_ndelay(uint64_t ns)
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{
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uint64_t delta = ns * timer_hz() / NSECS_PER_SEC;
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uint64_t pause_delta = 0;
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uint64_t apic_us = 0;
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uint64_t start = timer_raw_value();
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if (ns > APIC_INTERRUPT_LATENCY_NS)
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apic_us = (ns - APIC_INTERRUPT_LATENCY_NS) / NSECS_PER_USEC;
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if (IS_ENABLED(CONFIG_LP_ENABLE_APIC) && apic_initialized() && apic_us)
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apic_delay(apic_us);
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if (delta > PAUSE_THRESHOLD_TICKS)
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pause_delta = delta - PAUSE_THRESHOLD_TICKS;
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