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/** @file
This driver produces an EFI_RNG_PROTOCOL instance for the AMD Seattle CCP
Copyright (C) 2016, Linaro Ltd. All rights reserved.<BR>
This program and the accompanying materials are licensed and made available
under the terms and conditions of the BSD License which accompanies this
distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
**/
#include <Library/BaseMemoryLib.h>
#include <Library/PcdLib.h>
#include <Library/IoLib.h>
#include <Protocol/Rng.h>
#define CCP_TRNG_OFFSET 0xc
#define CCP_TNRG_RETRIES 5
STATIC EFI_PHYSICAL_ADDRESS mCcpRngOutputReg;
STATIC EFI_HANDLE mHandle;
/**
Returns information about the random number generation implementation.
@param[in] This A pointer to the EFI_RNG_PROTOCOL
instance.
@param[in,out] RNGAlgorithmListSize On input, the size in bytes of
RNGAlgorithmList.
On output with a return code of
EFI_SUCCESS, the size in bytes of the
data returned in RNGAlgorithmList. On
output with a return code of
EFI_BUFFER_TOO_SMALL, the size of
RNGAlgorithmList required to obtain the
list.
@param[out] RNGAlgorithmList A caller-allocated memory buffer filled
by the driver with one EFI_RNG_ALGORITHM
element for each supported RNG algorithm.
The list must not change across multiple
calls to the same driver. The first
algorithm in the list is the default
algorithm for the driver.
@retval EFI_SUCCESS The RNG algorithm list was returned
successfully.
@retval EFI_UNSUPPORTED The services is not supported by this
driver.
@retval EFI_DEVICE_ERROR The list of algorithms could not be
retrieved due to a hardware or firmware
error.
@retval EFI_INVALID_PARAMETER One or more of the parameters are
incorrect.
@retval EFI_BUFFER_TOO_SMALL The buffer RNGAlgorithmList is too small
to hold the result.
**/
STATIC
EFI_STATUS
EFIAPI
StyxRngGetInfo (
IN EFI_RNG_PROTOCOL *This,
IN OUT UINTN *RNGAlgorithmListSize,
OUT EFI_RNG_ALGORITHM *RNGAlgorithmList
)
{
if (This == NULL || RNGAlgorithmListSize == NULL) {
return EFI_INVALID_PARAMETER;
}
if (*RNGAlgorithmListSize < sizeof (EFI_RNG_ALGORITHM)) {
*RNGAlgorithmListSize = sizeof (EFI_RNG_ALGORITHM);
return EFI_BUFFER_TOO_SMALL;
}
if (RNGAlgorithmList == NULL) {
return EFI_INVALID_PARAMETER;
}
*RNGAlgorithmListSize = sizeof (EFI_RNG_ALGORITHM);
CopyGuid (RNGAlgorithmList, &gEfiRngAlgorithmRaw);
return EFI_SUCCESS;
}
/**
Produces and returns an RNG value using either the default or specified RNG
algorithm.
@param[in] This A pointer to the EFI_RNG_PROTOCOL
instance.
@param[in] RNGAlgorithm A pointer to the EFI_RNG_ALGORITHM that
identifies the RNG algorithm to use. May
be NULL in which case the function will
use its default RNG algorithm.
@param[in] RNGValueLength The length in bytes of the memory buffer
pointed to by RNGValue. The driver shall
return exactly this numbers of bytes.
@param[out] RNGValue A caller-allocated memory buffer filled
by the driver with the resulting RNG
value.
@retval EFI_SUCCESS The RNG value was returned successfully.
@retval EFI_UNSUPPORTED The algorithm specified by RNGAlgorithm
is not supported by this driver.
@retval EFI_DEVICE_ERROR An RNG value could not be retrieved due
to a hardware or firmware error.
@retval EFI_NOT_READY There is not enough random data available
to satisfy the length requested by
RNGValueLength.
@retval EFI_INVALID_PARAMETER RNGValue is NULL or RNGValueLength is
zero.
**/
STATIC
EFI_STATUS
EFIAPI
StyxRngGetRNG (
IN EFI_RNG_PROTOCOL *This,
IN EFI_RNG_ALGORITHM *RNGAlgorithm, OPTIONAL
IN UINTN RNGValueLength,
OUT UINT8 *RNGValue
)
{
UINT32 Val;
UINT32 Retries;
UINT32 Loop;
if (This == NULL || RNGValueLength == 0 || RNGValue == NULL) {
return EFI_INVALID_PARAMETER;
}
//
// We only support the raw algorithm, so reject requests for anything else
//
if (RNGAlgorithm != NULL &&
!CompareGuid (RNGAlgorithm, &gEfiRngAlgorithmRaw)) {
return EFI_UNSUPPORTED;
}
do {
Retries = CCP_TNRG_RETRIES;
do {
Val = MmioRead32 (mCcpRngOutputReg);
} while (!Val && Retries-- > 0);
if (!Val) {
return EFI_DEVICE_ERROR;
}
for (Loop = 0; Loop < 4 && RNGValueLength > 0; Loop++, RNGValueLength--) {
*RNGValue++ = (UINT8)Val;
Val >>= 8;
}
} while (RNGValueLength > 0);
return EFI_SUCCESS;
}
STATIC EFI_RNG_PROTOCOL mStyxRngProtocol = {
StyxRngGetInfo,
StyxRngGetRNG
};
//
// Entry point of this driver.
//
EFI_STATUS
EFIAPI
StyxRngEntryPoint (
IN EFI_HANDLE ImageHandle,
IN EFI_SYSTEM_TABLE *SystemTable
)
{
mCcpRngOutputReg = PcdGet64 (PcdCCPBase) + CCP_TRNG_OFFSET;
return SystemTable->BootServices->InstallMultipleProtocolInterfaces (
&mHandle,
&gEfiRngProtocolGuid, &mStyxRngProtocol,
NULL
);
}
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