8.4.4.3. _LPI（低功耗空闲状态）

Package {
   Revision,            // Integer (WORD)
   LevelID,             // Integer (QWORD)
   Count,               // Integer (WORD)
   LPI[1],              // Package
   ...
   LPI[N]               // Package
   }

Package() {
   Min Residency,                 // Integer (DWORD)
   Worst case wakeup latency,     // Integer (DWORD)
   Flags,                         // Integer (DWORD)
   Arch. Context Lost Flags,      // Integer (DWORD)
   Residency Counter Frequency,   // Integer (DWORD)
   Enabled Parent State,          // Integer (DWORD)
   Entry Method,                  // Buffer (ResourceDescriptor) or
                                  // Integer (QWORD)
   Residency Counter Register     // Buffer (ResourceDescriptor)
   Usage Counter Register         // Buffer (ResourceDescriptor)
   State Name                     // String (ASCIIZ)
   }

StateX: MR = 100 us
StateY: MR = 1000 us
StateZ: MR = 800 us, power resource A must be OFF

Reg = SelectedLocalState(CurrentProcessor).EntryMethod
WCWL = SelectedLocalState(CurrentProcessor).WCWL
MR = SelectedLocalState(CurrentProcessor).MR

for level = Parent(CurrentProcessor) to system
   LocalState = SelectedLocalState(level)
   If LocalState == Run
      break
   EM = LocalState.EntryMethod
   WCWL = WCWL+ LocalState.WCWL
   MR = LocalState.MR
   If IsInteger(EM)
      Reg.Addr = Reg.Addr+ZeroExtend(EM)
   Else
      // Entry method here overrides any previous method
      Reg = EM
CompositeState.EntryMethod = Reg
CompositeState.WCWL=WCWL
CompositeState.MR=MR

Reg = SelectedLocalState(CurrentProcessor).EntryMethod
WCWL = SelectedLocalState(CurrentProcessor).WCWL
MR = SelectedLocalState(CurrentProcessor).MR

RegDecided = False
                      // Retrieve Level Index from Processor's \_LPI object
LastLevel = GetLevelIDOfLevel(CurrentProcessor)

for level = Parent(CurrentProcessor) to system
   LocalState = SelectedLocalState(level)

   If LocalState == Run
      break
   EM = LocalState.EntryMethod
   WCWL = WCWL+ LocalState.WCWL

      EM = LocalState.EntryMethod
      If IsInteger(EM)
         Reg.Addr = Reg.Addr+ZeroExtend(EM)
      Else
                      // Entry method is register
         Reg = EM

If IsProcessorLastInLevel(CurrentProcessor,level)
                      // If calling processor is last one to go idle in
                      // current level, retrieve Level Index from
                      // the container's \_LPI object
         LastLevel = GetLevelIDOfLevel(level)

Reg.Addr = Reg.Addr+LastLevel
CompositeState.EntryMethod = Reg
CompositeState.WCWL=WCWL
CompositeState.MR=MR

Device (SYSM) {                   // System level states
   Name (_HID, "ACPI0010")
   Name (_UID, 0)
   Name (_LPI,
      Package() {
         0,                       // Version
         0,                       // Level ID
         1,                       // Count

         Package () {             // Power gating state for system
            900,                  // Min residency (uS)
            400,                  // Wake latency (uS)
            0,                    // Enabled Parent State
            ...                   // (skipped fields). . .
            ResourceTemplate () {
                                  // Register Entry method
               Register(FFH,0x20,0x00,0x00000000DECEA5ED,0x3)
            },
            ...                   // (skipped fields). . .
         }
      )

      Device (CLU0) {             // Package0 state
         Name (_HID, "ACPI0010")
         Name (_UID, 1)
         Name (_LPI,
            Package() {
               0,                 // Version
               0,                 // Level ID
               2,                 // Count
               Package () {       // Retention state for Cluster
                  40,             // Min residency (uS)
                  20,             // Wake latency (uS)
                  ...             // (skipped fields). . .
                  0,              // System must be running
                  0,              // Integer Entry method
                  ...             // (skipped fields). . .
                  },
               Package () {       // Power Gating state for Cluster
                  100,            // Min residency (uS)
                  80,             // Wake latency (uS)
                  ...             // (skipped fields). . .
                  1,              // System may power down
                  0x1020000,      // Integer Entry method
                  ...             // (skipped fields). . .
                  }
               }
            )
         Name(PLPI,
            Package() {
               0,                 // Version
               0,                 // Level ID
               2,                 // Count
               Package () {       // Retention state for CPU
                  40,             // Min residency (uS)
                  20,             // Wake latency (uS)
                  ...             // (skipped fields). . .
                  1,              // Parent node can be
                                  // in retention or running
                  ResourceTemplate () {
                                  // Register Entry method
                     Register(FFH,
                        0x20,0x00,
                        0x000000000000DEAF,0x3),
                     }
                  ...             // (skipped fields). . .
                  },
               Package () {       // Power Gating state for CPU
                  100,            // Min residency (uS)
                  80,             // Wake latency (uS)
                  ...             // (skipped fields). . .
                  2,              // Parent node can be in any state
                  ResourceTemplate () {
                                  // Register Entry method
                     Register(FFH,
                        0x20,0x00,
                        0x0000000000000DEAD,0x3),
                     }
                  ...             // (skipped fields). . .
                  }
               }
            )
         Device (CPU0) {          // Core0
               Name (_HID, "ACPI0007")
               Method (_LPI, 0, NotSerialized)
            {
                  return(PLPI)
            }
         }
         Device (CPU1) { // Core1
               Name (_HID, "ACPI0007")
               Method (_LPI, 0, NotSerialized)
            {
                  return(PLPI)
            }
         }
   }                              // end of NOD0
   Device (CLU1) {                // Package1 state
         Name (_HID, "ACPI0010")
         Name (_UID, 2)
      ....
   }
} // End of SYM

ResourceTemplate() {Register {(SystemMemory, 0, 0, 0, 0)}}

PowerResource(PWRA,0,0) {...}
PowerResource(PWRB,0,0) {...}
PowerResource(PWRC,0,0) {...}
PowerResource(PWRD,0,0) {...}
PowerResource(PWRE,0,1) {...}

Device (FOO) {
   Name(_S0W, 4) //Device in D3Cold can wake system from S0-idle
   Name(_PR0,Package(){PWRA, PWRB, PWRC})
   Name(_PR2,Package(){PWRA, PWRB})
   Name(_PR3,Package(){PWRA})
   Name(_PRE,Package(){PWRD})
   Name(_PRW,Package(){0, 0, PWRD} // PWRD must be ON for FOO to wake system
}

Device (BAR) {
   Name(_S0W, 3) // Device in D3Hot can wake system from S0-idle
   Name(_PR0,Package(){PWRA, PWRB})
   Name(_PR3,Package(){PWRC})
   Name(_PRW,Package(){PWRC}) // PWRC must be ON for BAR to wake system

}
Device (BAH) {
   Name(_S0W, 0) // This device can only wake the system from
                            // S0-idle if it is in D0
   Name(_PR0,Package(){PWRA, PWRB, PWRC})
}
Device (SYM) {
   Name(_RDI,
      Package() {
         0,                              // Version
         Package(){}                     // Local State 1 is Shallow;
                                         // Devices FOO, BAR and BAH can wake
                                         // the system if enabled for wake
         Package(){PWRA, PWRB}           // RDI for Local State 2. State is deeper
                                         // Device BAH cannot wake the system if this
                                         // state is used, as it needs PWRA and PWRB
                                         // to be able to wake the system
         Package(){PWRA, PWRB, PWRC}     // RDI for Local State 3.
                                         // Devices BAH and BAR cannot wake
                                         // the system, BAH needs PWRA, PWRB
                                         // and PWRC, and BAR needs PWRC
                                         // for all devices
      Package(){PWRA, PWRB, PWRC, PWRD}  // None of the devices listed
                                         // above could wake the system
      })
   ...