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/** @file
Acpi Helper
Copyright (c) 2017 - 2021, Arm Limited. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
// Module specific include files.
#include <Library/AcpiHelperLib.h>
/** Convert a hex number to its ASCII code.
@param [in] Hex Hex number to convert.
Must be 0 <= x < 16.
@return The ASCII code corresponding to x.
-1 if error.
**/
UINT8
EFIAPI
AsciiFromHex (
IN UINT8 Hex
)
{
if (Hex < 10) {
return (UINT8)(Hex + '0');
}
if (Hex < 16) {
return (UINT8)(Hex - 10 + 'A');
}
ASSERT (FALSE);
return (UINT8)-1;
}
/** Convert an ASCII char representing an hexadecimal number
to its integer value.
@param [in] Char Char to convert.
Must be between '0'-'9' or 'A'-'F' or 'a'-'f'.
@return The corresponding integer (between 0-16).
-1 if error.
**/
UINT8
EFIAPI
HexFromAscii (
IN CHAR8 Char
)
{
if ((Char >= '0') && (Char <= '9')) {
return (UINT8)(Char - '0');
}
if ((Char >= 'A') && (Char <= 'F')) {
return (UINT8)(Char - 'A' + 10);
}
if ((Char >= 'a') && (Char <= 'f')) {
return (UINT8)(Char - 'a' + 10);
}
ASSERT (FALSE);
return (UINT8)-1;
}
/** Check if a HID is a valid PNP ID.
@param [in] Hid The Hid to validate.
@retval TRUE The Hid is a valid PNP ID.
@retval FALSE The Hid is not a valid PNP ID.
**/
BOOLEAN
IsValidPnpId (
IN CONST CHAR8 * Hid
)
{
UINTN Index;
if (AsciiStrLen (Hid) != 7) {
return FALSE;
}
// A valid PNP ID must be of the form "AAA####"
// where A is an uppercase letter and # is a hex digit.
for (Index = 0; Index < 3; Index++) {
if (!IS_UPPER_CHAR (Hid[Index])) {
return FALSE;
}
}
for (Index = 3; Index < 7; Index++) {
if (!IS_UPPER_HEX (Hid[Index])) {
return FALSE;
}
}
return TRUE;
}
/** Check if a HID is a valid ACPI ID.
@param [in] Hid The Hid to validate.
@retval TRUE The Hid is a valid ACPI ID.
@retval FALSE The Hid is not a valid ACPI ID.
**/
BOOLEAN
IsValidAcpiId (
IN CONST CHAR8 * Hid
)
{
UINTN Index;
if (AsciiStrLen (Hid) != 8) {
return FALSE;
}
// A valid ACPI ID must be of the form "NNNN####"
// where N is an uppercase letter or a digit ('0'-'9')
// and # is a hex digit.
for (Index = 0; Index < 4; Index++) {
if (!(IS_UPPER_CHAR (Hid[Index]) || IS_DIGIT (Hid[Index]))) {
return FALSE;
}
}
for (Index = 4; Index < 8; Index++) {
if (!IS_UPPER_HEX (Hid[Index])) {
return FALSE;
}
}
return TRUE;
}
/** Convert a EisaId string to its compressed UINT32 equivalent.
Cf. ACPI 6.4 specification, s19.3.4 "ASL Macros": "Eisaid"
@param [in] EisaIdStr Input EisaId string.
@param [out] EisaIdInt Output EisaId UINT32 (compressed).
@retval EFI_SUCCESS The function completed successfully.
@retval EFI_INVALID_PARAMETER Invalid parameter.
**/
EFI_STATUS
EFIAPI
AmlGetEisaIdFromString (
IN CONST CHAR8 * EisaIdStr,
OUT UINT32 * EisaIdInt
)
{
if ((EisaIdStr == NULL) ||
(!IsValidPnpId (EisaIdStr)) ||
(EisaIdInt == NULL)) {
ASSERT (0);
return EFI_INVALID_PARAMETER;
}
/* Cf. ACPI 6.4 specification, s19.3.4 "ASL Macros": "Eisaid"
Converts and compresses the 7-character text argument into its corresponding
4-byte numeric EISA ID encoding (Integer). This can be used when declaring
IDs for devices that are EISA IDs.
The algorithm used to convert the TextID is as shown in the following
example:
Starting with a seven character input string "PNP0303", we want to create
a DWordConst. This string contains a three character manufacturer code
"PNP", a three character hex product identifier "030", and a one character
revision identifier "3".
The compressed manufacturer code is created as follows:
1) Find hex ASCII value for each letter
2) Subtract 40h from each ASCII value
3) Retain 5 least significant bits for each letter and discard remaining
0's:
Byte 0:
Bit 7: reserved (0)
Bit 6-2: 1st character of compressed mfg code "P"
Bit 1-0: Upper 2 bits of 2nd character of mfg code "N"
Byte 1:
Bit 7-5: Lower 3 bits of 2nd character of mfg code "N"
Bit 4-0: 3rd character of mfg code "P"
Byte 2:
Bit 7-4: 1st hex digit of product number "0"
Bit 3-0: 2nd hex digit of product number "3"
Byte 3:
Bit 7-4: 3rd hex digit of product number "0"
Bit 3-0: 4th hex digit of product number "3"
*/
*EisaIdInt = SwapBytes32 (
((EisaIdStr[0] - 0x40) << 26) |
((EisaIdStr[1] - 0x40) << 21) |
((EisaIdStr[2] - 0x40) << 16) |
(HexFromAscii (EisaIdStr[3]) << 12) |
(HexFromAscii (EisaIdStr[4]) << 8) |
(HexFromAscii (EisaIdStr[5]) << 4) |
(HexFromAscii (EisaIdStr[6]))
);
return EFI_SUCCESS;
}
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