nx2: run the guest counter at 31.25 MHz for Switch 2 titles

The Switch 2 counter runs at 31.25 MHz and its SDK converts ticks with
that constant: Mario Kart World's sdk builds 31,250,000 in
nn::os::GetSystemTickFrequency, TickManager::ConvertToTimeSpan and
TickManager::ConvertToTick (19.2 MHz appears nowhere). Eglantine counted
at the Switch 1 rate for every title, so every tick-based time in a
Switch 2 game was off by 1.63x: elapsed times read short, and a deadline
of one 60 Hz frame converted to ticks waited ~27 ms.

The wall clock now has a guest counter frequency, set at boot: 31.25 MHz
for Switch 2 programs, 19.2 MHz otherwise, EDEN_NX2_CNTFRQ=<Hz> to force
one. CNTPCT reads, CNTFRQ_EL0, svcGetSystemTick, thread tick counts and
the time services' tick conversions follow it, and the CNTPCT spin
detection keeps its ~1.7 us threshold.

Mario Kart World, title screen and attract demo, 180 s, same build:
frame times unchanged (17-19 ms once warm), process CPU time 848 s
instead of 930 s.

1 files changed, 6 insertions, 5 deletions

diff --git a/src/core/hle/service/psc/time/common.h b/src/core/hle/service/psc/time/common.h
index 2183fa72b8..6f7d2cb88b 100644
--- a/src/core/hle/service/psc/time/common.h
+++ b/src/core/hle/service/psc/time/common.h
@@ -134,12 +134,13 @@ struct OperationEvent : public Common::IntrusiveListBaseNode<OperationEvent> {
     Kernel::KEvent* m_event{};
 };
 
-constexpr inline std::chrono::nanoseconds ConvertToTimeSpan(s64 ticks) {
+inline std::chrono::nanoseconds ConvertToTimeSpan(s64 ticks) {
     constexpr auto one_second_ns{
         std::chrono::duration_cast<std::chrono::nanoseconds>(std::chrono::seconds(1)).count()};
 
-    constexpr s64 max{Common::WallClock::CNTFRQ *
-                      ((std::numeric_limits<s64>::max)() / one_second_ns)};
+    // The guest counter's frequency: 31.25 MHz for Switch 2 titles.
+    const s64 frequency{static_cast<s64>(Common::g_wall_clock.GetGuestCNTFRQ())};
+    const s64 max{frequency * ((std::numeric_limits<s64>::max)() / one_second_ns)};
 
     if (ticks > max) {
         return std::chrono::nanoseconds((std::numeric_limits<s64>::max)());
@@ -147,8 +148,8 @@ constexpr inline std::chrono::nanoseconds ConvertToTimeSpan(s64 ticks) {
         return std::chrono::nanoseconds((std::numeric_limits<s64>::min)());
     }
 
-    auto a{ticks / Common::WallClock::CNTFRQ * one_second_ns};
-    auto b{((ticks % Common::WallClock::CNTFRQ) * one_second_ns) / Common::WallClock::CNTFRQ};
+    auto a{ticks / frequency * one_second_ns};
+    auto b{((ticks % frequency) * one_second_ns) / frequency};
 
     return std::chrono::nanoseconds(a + b);
 }