最近工作需要在 UEFI? Shell 下Check EC Ram 的設定，發現手上只有 Windows 下的讀取工具(RW Everything)。于是研究了一下如何在Shell 讀取 EC Ram。

根據【參考1】讀取的流程如下：

Port 66 Commands

There are also some EC commands that use ports 0x66 and

0x62. Some of these are standard ACPI commands as defined in the external ACPI

spec, others are custom.

The port 66 protocol is essentially the standard ACPI EC

interface protocol.

1. Wait for port66.IBF = 0

2. Write command byte to port 66.

3. For each outgoing data or address byte:

3a. Wait for port66.IBF = 0

3b. Write data or address byte to port 62.

4. For each incoming data byte:

4a. Wait for port66.OBF = 1

4b. Read data byte from port 62.

5. If the command requires no data or address bytes, you can

determine when the command was accepted/executed by waiting for port66.IBF=0.

同時 ACPI 定義的通用 Command如下：

ACPI-defined port 66 commands

0x80 Read EC (write 0x80 to port 66, write address byte to

port 62, read data byte from port 62)

0x81 Write EC (write 0x81 to port 66, write address byte to

port 62, write data byte to port 62)

0x82 Burst Enable (write 0x82 to port 66, read data byte

from port 62 - the data byte is "burst ACK", value 0x90)

0x83 Burst Disable (write 0x83 to port 66, wait for

port66.IBF=0)

0x84 Query EC (i.e. read SCI event queue) (write 0x84 to

port 66, read data byte from port 62). When the data byte is 0, it means that

the SCI event queue is empty.

最終根據上述資料，編寫一個 Application 如下：

#include

#include

#include

#include

extern EFI_SYSTEM_TABLE *gST;

extern EFI_BOOT_SERVICES *gBS;

#define TIMEOUT 0xFFFF

#define ECCOMMAND 0x66

#define ECSTATUS 0x66

#define ECDATA 0x62

#define EC_S_OBF BIT0

#define EC_S_IBF BIT1

#define ECREADCMD 0x80

UINT8 MemBuffer[16][16];

void WaitIBF() {

UINT32 Status;

UINTN Count;

Count = 0;

Status = 0;

Status = IoRead8 (ECSTATUS);

while (((Status & EC_S_IBF) != 0)||(Count>TIMEOUT)) {

Status = IoRead8 (ECSTATUS);

Count++;

}

}

void WaitOBF() {

UINT32 Status;

UINTN Count;

Count = 0;

Status = 0;

Status = IoRead8 (ECSTATUS);

while (((Status & EC_S_OBF) == 0)||(Count>TIMEOUT)) {

Status = IoRead8 (ECSTATUS);

Count++;

}

}

UINT8 ReadECRam(UINT8 Index) {

WaitIBF(); //1

IoWrite8(ECCOMMAND,0x80);//2

WaitIBF(); //3a

IoWrite8(ECDATA, Index); //3b

WaitOBF(); //4a

return IoRead8(ECDATA); //4b

}

void GetData()

{

UINT8 i,j;

for (i=0;i<16;i++)

for (j=0;j<16;j++) {

MemBuffer[i][j]=ReadECRam(i*16+j);

}

}

void ShowData()

{

UINT8 i,j;

Print(L" ");

for (i=0;i<16;i++) Print(L"%02X ",i);

Print(L"\n");

for (i=0;i<16;i++) {

Print(L"%02X: ",i);

for (j=0;j<16;j++) {

Print(L"%02X ",MemBuffer[i][j]);

}

Print(L"\n");

}

Print(L"\n");

}

/***

Print a welcoming message.

Establishes the main structure of the application.

@retval 0 The application exited normally.

@retval Other An error occurred.

***/

INTN

EFIAPI

ShellAppMain (

IN UINTN Argc,

IN CHAR16 **Argv

)

{

EFI_INPUT_KEY Key;

Key.ScanCode=SCAN_NULL;

while (SCAN_UP!=Key.ScanCode)

{

gST->ConOut->ClearScreen(gST->ConOut);

GetData();

ShowData();

gST -> ConIn -> ReadKeyStroke(gST->ConIn,&Key);

Print(L"Press Arrow-Up to exit\n");

gBS->Stall(1000000UL);

}

return(0);

}

在實體機上運行結果如下(按向上鍵退出)：

源代碼和Application(X64)下載：

參考：

1. http://wiki.laptop.org/go/Ec_specification

總結

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