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f331b7313d
mahaf: now disabled on Win2k because we can't prevent the TLB bug there. removed the CopyPhysical API. wutil: allow querying windows version via number View: fix warning This was SVN commit r5169.
91 lines
2.4 KiB
C++
91 lines
2.4 KiB
C++
/**
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* =========================================================================
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* File : pmt.cpp
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* Project : 0 A.D.
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* Description : Timer implementation using ACPI PM timer
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* =========================================================================
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*/
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// license: GPL; see lib/license.txt
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#include "precompiled.h"
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#include "pmt.h"
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#include "lib/sysdep/win/win.h"
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#include "lib/sysdep/acpi.h"
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#include "lib/sysdep/win/mahaf.h"
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#include "lib/bits.h"
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#pragma pack(push,1)
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struct FADT
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{
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AcpiTable header;
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u8 unused[40];
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u32 pmTimerPortAddress;
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u8 unused2[32];
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u32 flags;
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};
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#pragma pack(pop)
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static const u32 TMR_VAL_EXT = BIT(8);
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//-----------------------------------------------------------------------------
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LibError CounterPMT::Activate()
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{
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if(!mahaf_Init())
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return ERR::FAIL; // NOWARN (no Administrator privileges)
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if(!acpi_Init())
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WARN_RETURN(ERR::FAIL);
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// (note: it's called FADT, but the signature is "FACP")
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const FADT* fadt = (const FADT*)acpi_GetTable("FACP");
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if(!fadt)
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WARN_RETURN(ERR::NO_SYS);
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m_portAddress = u16_from_larger(fadt->pmTimerPortAddress);
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return INFO::OK;
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}
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void CounterPMT::Shutdown()
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{
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acpi_Shutdown();
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mahaf_Shutdown();
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}
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bool CounterPMT::IsSafe() const
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{
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// the PMT has one issue: "Performance counter value may unexpectedly
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// leap forward" (Q274323). This happens on some buggy Pentium-era
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// systems under heavy PCI bus load. We are clever and observe that
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// the TSC implementation would be used on such systems (because it
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// has higher precedence and is safe on P5 CPUs), so the PMT is fine
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// in general.
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return true;
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}
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u64 CounterPMT::Counter() const
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{
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return mahaf_ReadPort32(m_portAddress);
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}
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/**
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* WHRT uses this to ensure the counter (running at nominal frequency)
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* doesn't overflow more than once during CALIBRATION_INTERVAL_MS.
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**/
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uint CounterPMT::CounterBits() const
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{
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// (see previous acpi_GetTable call)
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const FADT* fadt = (const FADT*)acpi_GetTable("FACP");
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debug_assert(fadt); // Activate made sure FADT is available
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const uint counterBits = (fadt->flags & TMR_VAL_EXT)? 32 : 24;
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return counterBits;
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}
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/**
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* initial measurement of the tick rate. not necessarily correct
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* (e.g. when using TSC: wcpu_ClockFrequency isn't exact).
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**/
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double CounterPMT::NominalFrequency() const
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{
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return (double)PMT_FREQ;
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}
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