1 /*++ 2 3 Copyright (c) 1999 - 2014, Intel Corporation. All rights reserved 4 5 This program and the accompanying materials are licensed and made available under 7 the terms and conditions of the BSD License that accompanies this distribution. 9 The full text of the license may be found at 11 http://opensource.org/licenses/bsd-license.php. 13 15 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 17 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 19 21 23 24 Module Name: 25 26 SmmIo.c 27 28 Abstract: 29 30 SMM I/O access utility implementation file, for Ia32 31 32 --*/ 33 34 // 35 // Include files 36 // 37 #include "Library/StallSmmLib.h" 38 #include "Pi/PiSmmCis.h" 39 #include "PiDxe.h" 40 #include <Library/IoLib.h> 41 #include <Library/PcdLib.h> 42 #include "PchAccess.h" 43 44 /** 45 Delay for at least the request number of microseconds. 46 Timer used is ACPI time counter, which has 1us granularity. 47 48 @param Microseconds Number of microseconds to delay. 49 50 @retval None 51 52 **/ 53 VOID 54 SmmStall ( 55 IN UINTN Microseconds 56 ) 57 { 58 UINTN Ticks; 59 UINTN Counts; 60 UINTN CurrentTick; 61 UINTN OriginalTick; 62 UINTN RemainingTick; 63 UINT16 AcpiBaseAddr; 64 65 if (Microseconds == 0) { 66 return; 67 } 68 69 AcpiBaseAddr = PchLpcPciCfg16 (R_PCH_LPC_ACPI_BASE) & B_PCH_LPC_ACPI_BASE_BAR; 70 71 OriginalTick = IoRead32 (AcpiBaseAddr + R_PCH_ACPI_PM1_TMR); 72 CurrentTick = OriginalTick; 73 74 // 75 // The timer frequency is 3.579545 MHz, so 1 ms corresponds 3.58 clocks 76 // 77 Ticks = Microseconds * 358 / 100 + OriginalTick + 1; 78 79 // 80 // The loops needed by timer overflow 81 // 82 Counts = Ticks / V_PCH_ACPI_PM1_TMR_MAX_VAL; 83 84 // 85 // Remaining clocks within one loop 86 // 87 RemainingTick = Ticks % V_PCH_ACPI_PM1_TMR_MAX_VAL; 88 89 // 90 // not intend to use TMROF_STS bit of register PM1_STS, because this adds extra 91 // one I/O operation, and maybe generate SMI 92 // 93 while ((Counts != 0) || (RemainingTick > CurrentTick)) { 94 CurrentTick = IoRead32 (AcpiBaseAddr + R_PCH_ACPI_PM1_TMR); 95 // 96 // Check if timer overflow 97 // 98 if (CurrentTick < OriginalTick) { 99 Counts--; 100 } 101 OriginalTick = CurrentTick; 102 } 103 } 104
