;; @file
;  Provide FSP API entry points.
;
; Copyright (c) 2022, Intel Corporation. All rights reserved.<BR>
; SPDX-License-Identifier: BSD-2-Clause-Patent
;;

    SECTION .text

%include    "PushPopRegsNasm.inc"

;
; Following are fixed PCDs
;
extern   ASM_PFX(PcdGet8 (PcdFspHeapSizePercentage))

struc FSPM_UPD_COMMON_FSP24
    ; FSP_UPD_HEADER {
    .FspUpdHeader:              resd  8
    ; }
    ; FSPM_ARCH2_UPD {
    .Revision:                  resb  1
    .Reserved:                  resb  3
    .Length                     resd  1
    .NvsBufferPtr               resq  1
    .StackBase:                 resq  1
    .StackSize:                 resq  1
    .BootLoaderTolumSize:       resd  1
    .BootMode:                  resd  1
    .FspEventHandler            resq  1
    .Reserved1:                 resb 16
    ; }
    .size:
endstruc

;
; Following functions will be provided in C
;
extern ASM_PFX(SecStartup)
extern ASM_PFX(FspApiCommon)

;
; Following functions will be provided in PlatformSecLib
;
extern ASM_PFX(AsmGetFspBaseAddress)
extern ASM_PFX(AsmGetFspInfoHeader)

FSP_HEADER_IMGBASE_OFFSET    EQU   1Ch
FSP_HEADER_CFGREG_OFFSET     EQU   24h

;----------------------------------------------------------------------------
; FspMemoryInit API
;
; This FSP API is called after TempRamInit and initializes the memory.
;
;----------------------------------------------------------------------------
global ASM_PFX(FspMemoryInitApi)
ASM_PFX(FspMemoryInitApi):
  mov    rax,  3 ; FSP_API_INDEX.FspMemoryInitApiIndex
  jmp    ASM_PFX(FspApiCommon)

;----------------------------------------------------------------------------
; TempRamExitApi API
;
; This API tears down temporary RAM
;
;----------------------------------------------------------------------------
global ASM_PFX(TempRamExitApi)
ASM_PFX(TempRamExitApi):
  mov    rax,  4 ; FSP_API_INDEX.TempRamExitApiIndex
  jmp    ASM_PFX(FspApiCommon)

;----------------------------------------------------------------------------
; FspApiCommonContinue API
;
; This is the FSP API common entry point to resume the FSP execution
;
;----------------------------------------------------------------------------
global ASM_PFX(FspApiCommonContinue)
ASM_PFX(FspApiCommonContinue):
  ;
  ; RAX holds the API index
  ; Push RDX and RCX to form CONTEXT_STACK_64
  ;
  push   rdx    ; Push a QWORD data for stack alignment
  push   rdx    ; Push API Parameter2 on stack
  push   rcx    ; Push API Parameter1 on stack

  ;
  ; FspMemoryInit API setup the initial stack frame
  ;

  ;
  ; Place holder to store the FspInfoHeader pointer
  ;
  push   rax

  ;
  ; Update the FspInfoHeader pointer
  ;
  push   rax
  call   ASM_PFX(AsmGetFspInfoHeader)
  mov    [rsp + 8], rax
  pop    rax

  ;
  ; Create a Task Frame in the stack for the Boot Loader
  ;
  pushfq
  cli
  PUSHA_64

  ; Reserve 16 bytes for IDT save/restore
  sub     rsp, 16
  sidt    [rsp]

  ;  Get Stackbase and StackSize from FSPM_UPD Param
  mov    rdx, rcx                                ; Put FSPM_UPD Param to rdx
  cmp    rdx, 0
  jnz    FspStackSetup

  ; Get UPD default values if FspmUpdDataPtr (ApiParam1) is null
  xchg   rbx, rax
  call   ASM_PFX(AsmGetFspInfoHeader)
  mov    edx, [rax + FSP_HEADER_IMGBASE_OFFSET]
  add    edx, [rax + FSP_HEADER_CFGREG_OFFSET]
  xchg   rbx, rax

FspStackSetup:
  mov    cl, [rdx + FSPM_UPD_COMMON_FSP24.Revision]
  cmp    cl, 3
  jae    FspmUpdCommonFsp24

  mov    rax, 08000000000000002h                 ; RETURN_INVALID_PARAMETER
  sub    rsp, 0b8h
  ret

FspmUpdCommonFsp24:
  ;
  ; StackBase = temp memory base, StackSize = temp memory size
  ;
  mov    rdi, [rdx + FSPM_UPD_COMMON_FSP24.StackBase]
  mov    ecx, [rdx + FSPM_UPD_COMMON_FSP24.StackSize]

  ;
  ; Keep using bootloader stack if heap size % is 0
  ;
  mov    rbx, ASM_PFX(PcdGet8 (PcdFspHeapSizePercentage))
  mov    bl,  BYTE [rbx]
  cmp    bl,  0
  jz     SkipStackSwitch

  ;
  ; Set up a dedicated temp ram stack for FSP if FSP heap size % doesn't equal 0
  ;
  add    rdi, rcx
  ;
  ; Switch to new FSP stack
  ;
  xchg   rdi, rsp                                ; Exchange rdi and rsp, rdi will be assigned to the current rsp pointer and rsp will be Stack base + Stack size

SkipStackSwitch:
  ;
  ; If heap size % is 0:
  ;   EDI is FSPM_UPD_COMMON_FSP24.StackBase and will hold ESP later (boot loader stack pointer)
  ;   ECX is FSPM_UPD_COMMON_FSP24.StackSize
  ;   ESP is boot loader stack pointer (no stack switch)
  ;   BL  is 0 to indicate no stack switch (EBX will hold FSPM_UPD_COMMON_FSP24.StackBase later)
  ;
  ; If heap size % is not 0
  ;   EDI is boot loader stack pointer
  ;   ECX is FSPM_UPD_COMMON_FSP24.StackSize
  ;   ESP is new stack (FSPM_UPD_COMMON_FSP24.StackBase + FSPM_UPD_COMMON_FSP24.StackSize)
  ;   BL  is NOT 0 to indicate stack has switched
  ;
  cmp    bl, 0
  jnz    StackHasBeenSwitched

  mov    rbx, rdi                                ; Put FSPM_UPD_COMMON_FSP24.StackBase to rbx as temp memory base
  mov    rdi, rsp                                ; Put boot loader stack pointer to rdi
  jmp    StackSetupDone

StackHasBeenSwitched:
  mov    rbx, rsp                                ; Put Stack base + Stack size in ebx
  sub    rbx, rcx                                ; Stack base + Stack size - Stack size as temp memory base

StackSetupDone:

  ;
  ; Per X64 calling convention, make sure RSP is 16-byte aligned.
  ;
  mov    rdx, rsp
  and    rdx, 0fh
  sub    rsp, rdx

  ;
  ; Pass the API Idx to SecStartup
  ;
  push   rax

  ;
  ; Pass the BootLoader stack to SecStartup
  ;
  push   rdi

  ;
  ; Pass BFV into the PEI Core
  ; It uses relative address to calculate the actual boot FV base
  ; For FSP implementation with single FV, PcdFspBootFirmwareVolumeBase and
  ; PcdFspAreaBaseAddress are the same. For FSP with multiple FVs,
  ; they are different. The code below can handle both cases.
  ;
  call    ASM_PFX(AsmGetFspBaseAddress)
  mov    r8, rax

  ;
  ; Pass entry point of the PEI core
  ;
  call   ASM_PFX(AsmGetPeiCoreOffset)
  lea    r9,  [r8 + rax]

  ;
  ; Pass stack base and size into the PEI Core
  ;
  mov    rcx,  rcx
  mov    rdx,  rbx

  ;
  ; Pass Control into the PEI Core
  ; RCX = SizeOfRam, RDX = TempRamBase, R8 = BFV, R9 = PeiCoreEntry, Last 1 Stack = BL stack, Last 2 Stack = API index
  ; According to X64 calling convention, caller has to allocate 32 bytes as a shadow store on call stack right before
  ; calling the function.
  ;
  sub    rsp, 20h
  call   ASM_PFX(SecStartup)
  add    rsp, 20h
exit:
  ret

global ASM_PFX(FspPeiCoreEntryOff)
ASM_PFX(FspPeiCoreEntryOff):
   ;
   ; This value will be patched by the build script
   ;
   DD    0x12345678

global ASM_PFX(AsmGetPeiCoreOffset)
ASM_PFX(AsmGetPeiCoreOffset):
   push  rbx
   mov   rbx, ASM_PFX(FspPeiCoreEntryOff)
   mov   eax, dword[ebx]
   pop   rbx
   ret

;----------------------------------------------------------------------------
; TempRamInit API
;
; Empty function for WHOLEARCHIVE build option
;
;----------------------------------------------------------------------------
global ASM_PFX(TempRamInitApi)
ASM_PFX(TempRamInitApi):
  jmp $
  ret

;----------------------------------------------------------------------------
; Module Entrypoint API
;----------------------------------------------------------------------------
global ASM_PFX(_ModuleEntryPoint)
ASM_PFX(_ModuleEntryPoint):
  jmp $

