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+/** @file
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+ Device driver for the Atmel ATSHA204A random number generator.
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+
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+ Copyright (c) 2018, Linaro Ltd. All rights reserved.<BR>
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+
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+ This program and the accompanying materials
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+ are licensed and made available under the terms and conditions of the BSD
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+ License which accompanies this distribution. The full text of the license may
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+ be found at http://opensource.org/licenses/bsd-license.php.
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+
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+ THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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+ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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+
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+**/
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+
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+#include "AtSha204aDriver.h"
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+
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+#include <Library/BaseMemoryLib.h>
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+#include <Library/DebugLib.h>
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+#include <Library/MemoryAllocationLib.h>
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+
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+#define MAX_RETRIES 5
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+
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+// Don't bother calculating the CRC for the immutable RANDOM opcode packet
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+#define OPCODE_COMMAND_PACKET_CRC 0xcd24
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+
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+/**
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+ Returns information about the random number generation implementation.
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+
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+ @param[in] This A pointer to the EFI_RNG_PROTOCOL instance.
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+ @param[in,out] AlgorithmListSize On input, the size in bytes of AlgorithmList
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+ On output with a return code of EFI_SUCCESS,
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+ the size in bytes of the data returned in
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+ AlgorithmList. On output with a return
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+ code of EFI_BUFFER_TOO_SMALL, the size of
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+ AlgorithmList required to obtain the list.
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+ @param[out] AlgorithmList A caller-allocated memory buffer filled by
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+ the driver with one EFI_RNG_ALGORITHM
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+ element for each supported RNG algorithm.
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+ The list must not change across multiple
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+ calls to the same driver. The first
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+ algorithm in the list is the default
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+ algorithm for the driver.
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+
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+ @retval EFI_SUCCESS The RNG algorithm list was returned
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+ successfully.
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+ @retval EFI_UNSUPPORTED The services is not supported by this driver
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+ @retval EFI_DEVICE_ERROR The list of algorithms could not be
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+ retrieved due to a hardware or firmware
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+ error.
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+ @retval EFI_INVALID_PARAMETER One or more of the parameters are incorrect.
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+ @retval EFI_BUFFER_TOO_SMALL The buffer RNGAlgorithmList is too small to
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+ hold the result.
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+
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+**/
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+STATIC
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+EFI_STATUS
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+EFIAPI
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+AtSha240aGetInfo (
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+ IN EFI_RNG_PROTOCOL *This,
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+ IN OUT UINTN *AlgorithmListSize,
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+ OUT EFI_RNG_ALGORITHM *AlgorithmList
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+)
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+{
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+ UINTN Size;
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+
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+ //
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+ // We only implement the raw algorithm
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+ //
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+ Size = sizeof (EFI_GUID);
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+
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+ if (*AlgorithmListSize < Size) {
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+ *AlgorithmListSize = Size;
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+ return EFI_BUFFER_TOO_SMALL;
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+ }
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+
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+ CopyGuid (AlgorithmList, &gEfiRngAlgorithmRaw);
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+ *AlgorithmListSize = Size;
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+
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+ return EFI_SUCCESS;
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+}
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+
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+
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+/**
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+ Produces and returns an RNG value using either the default or specified RNG
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+ algorithm.
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+
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+ @param[in] This A pointer to the EFI_RNG_PROTOCOL instance.
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+ @param[in] Algorithm A pointer to the EFI_RNG_ALGORITHM that
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+ identifies the RNG algorithm to use. May be
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+ NULL in which case the function will use its
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+ default RNG algorithm.
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+ @param[in] ValueLength The length in bytes of the memory buffer
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+ pointed to by RNGValue. The driver shall
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+ return exactly this numbers of bytes.
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+ @param[out] Value A caller-allocated memory buffer filled by the
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+ driver with the resulting RNG value.
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+
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+ @retval EFI_SUCCESS The RNG value was returned successfully.
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+ @retval EFI_UNSUPPORTED The algorithm specified by RNGAlgorithm is not
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+ supported by this driver.
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+ @retval EFI_DEVICE_ERROR An RNG value could not be retrieved due to a
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+ hardware or firmware error.
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+ @retval EFI_NOT_READY There is not enough random data available to
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+ satisfy the length requested by
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+ RNGValueLength.
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+ @retval EFI_INVALID_PARAMETER RNGValue is NULL or RNGValueLength is zero.
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+
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+**/
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+STATIC
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+EFI_STATUS
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+EFIAPI
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+AtSha240aGetRNG (
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+ IN EFI_RNG_PROTOCOL *This,
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+ IN EFI_RNG_ALGORITHM *Algorithm OPTIONAL,
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+ IN UINTN ValueLength,
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+ OUT UINT8 *Value
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+)
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+{
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+ EFI_STATUS Status;
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+ ATSHA204A_DEV *AtSha204a;
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+ ATSHA204A_I2C_RNG_COMMAND Command;
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+ ATSHA204A_I2C_RNG_RESULT Result;
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+ I2C_RNG_REQUEST Request;
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+ I2C_RNG_REQUEST Response;
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+ UINTN Retries;
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+
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+ if (Algorithm != NULL && !CompareGuid (Algorithm, &gEfiRngAlgorithmRaw)) {
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+ return EFI_UNSUPPORTED;
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+ }
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+
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+ AtSha204a = ATSHA204A_DEV_FROM_THIS (This);
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+
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+ Request.OperationCount = 1;
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+ Request.Operation.Flags = 0;
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+
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+ Command.Command = ATSHA204A_COMMAND;
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+ Command.Count = sizeof (Command) - 1;
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+ Command.Opcode = ATSHA204A_OPCODE_RANDOM;
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+ Command.Param1 = 0;
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+ Command.Param2 = 0;
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+ Command.Crc = OPCODE_COMMAND_PACKET_CRC;
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+
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+ Response.OperationCount = 1;
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+ Response.Operation.Flags = I2C_FLAG_READ;
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+ Response.Operation.LengthInBytes = sizeof (Result);
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+ Response.Operation.Buffer = (VOID *)&Result;
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+
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+ Retries = 0;
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+ while (ValueLength > 0) {
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+ //
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+ // The AtSha204a will go back to sleep right in the middle of a transaction
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+ // if it does not complete in ~1.3 seconds. So send the wake sequence for
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+ // each iteration, which consists of a dummy write to slave address 0x0.
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+ //
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+ Request.Operation.LengthInBytes = 0;
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+ Status = AtSha204a->I2cIo->QueueRequest (AtSha204a->I2cIo, 1, NULL,
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+ (VOID *)&Request, NULL);
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+ DEBUG ((DEBUG_INFO, "%a: wake AtSha204a: I2cIo->QueueRequest() - %r\n",
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+ __FUNCTION__, Status));
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+
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+ gBS->Stall (2500); // wait 2.5 ms for wake to complete
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+
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+ Request.Operation.LengthInBytes = sizeof (Command);
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+ Request.Operation.Buffer = (VOID *)&Command;
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+ Status = AtSha204a->I2cIo->QueueRequest (AtSha204a->I2cIo, 0, NULL,
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+ (VOID *)&Request, NULL);
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+ if (EFI_ERROR (Status)) {
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+ if (++Retries <= MAX_RETRIES) {
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+ continue;
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+ }
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+ DEBUG ((DEBUG_ERROR, "%a: I2C request transfer failed, Status == %r\n",
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+ __FUNCTION__, Status));
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+ return EFI_DEVICE_ERROR;
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+ }
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+
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+ gBS->Stall (50 * 1000); // 50 ms max execution time for RANDOM opcode
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+
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+ Status = AtSha204a->I2cIo->QueueRequest (AtSha204a->I2cIo, 0, NULL,
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+ (VOID *)&Response, NULL);
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+ if (EFI_ERROR (Status)) {
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+ if (++Retries <= MAX_RETRIES) {
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+ continue;
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+ }
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+ DEBUG ((DEBUG_ERROR, "%a: I2C response transfer failed, Status == %r\n",
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+ __FUNCTION__, Status));
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+ return EFI_DEVICE_ERROR;
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+ }
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+
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+ if (Result.Count < sizeof (Result)) {
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+ //
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+ // Incomplete packet received, most likely due to an error. Retry.
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+ //
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+ if (++Retries <= MAX_RETRIES) {
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+ continue;
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+ }
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+ DEBUG ((DEBUG_WARN, "%a: incomplete packet received\n", __FUNCTION__));
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+ return EFI_DEVICE_ERROR;
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+ }
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+
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+ gBS->CopyMem (Value, Result.Result, MIN (ValueLength,
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+ ATSHA204A_OUTPUT_SIZE));
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+ if (ValueLength < ATSHA204A_OUTPUT_SIZE) {
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+ break;
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+ }
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+
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+ Value += ATSHA204A_OUTPUT_SIZE;
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+ ValueLength -= ATSHA204A_OUTPUT_SIZE;
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+ Retries = 0;
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+ }
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+ return EFI_SUCCESS;
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+}
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+
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+EFI_STATUS
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+AtSha204aInit (
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+ IN EFI_HANDLE DriverBindingHandle,
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+ IN EFI_HANDLE ControllerHandle
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+ )
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+{
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+ EFI_STATUS Status;
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+ ATSHA204A_DEV *AtSha204a;
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+
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+ Status = gBS->AllocatePool (EfiBootServicesData, sizeof (ATSHA204A_DEV),
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+ (VOID **) &AtSha204a);
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+ if (EFI_ERROR (Status)) {
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+ return EFI_OUT_OF_RESOURCES;
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+ }
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+
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+ AtSha204a->Signature = ATSHA204A_DEV_SIGNATURE;
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+ AtSha204a->Rng.GetInfo = AtSha240aGetInfo;
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+ AtSha204a->Rng.GetRNG = AtSha240aGetRNG;
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+
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+ //
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+ // Open I2C I/O Protocol
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+ //
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+ Status = gBS->OpenProtocol (ControllerHandle,
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+ &gEfiI2cIoProtocolGuid,
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+ (VOID **)&AtSha204a->I2cIo,
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+ DriverBindingHandle,
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+ ControllerHandle,
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+ EFI_OPEN_PROTOCOL_BY_DRIVER);
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+ if (EFI_ERROR (Status)) {
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+ goto ErrorFreeDev;
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+ }
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+
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+ Status = gBS->InstallProtocolInterface (&ControllerHandle,
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+ &gEfiRngProtocolGuid,
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+ EFI_NATIVE_INTERFACE,
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+ &AtSha204a->Rng);
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+ if (EFI_ERROR (Status)) {
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+ DEBUG ((DEBUG_ERROR,
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+ "Failed to install RNG protocol interface (Status == %r)\n",
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+ Status));
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+ goto ErrorCloseProtocol;
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+ }
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+
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+ return EFI_SUCCESS;
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+
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+ErrorCloseProtocol:
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+ gBS->CloseProtocol (ControllerHandle, &gEfiI2cIoProtocolGuid,
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+ DriverBindingHandle, ControllerHandle);
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+
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+ErrorFreeDev:
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+ gBS->FreePool (AtSha204a);
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+
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+ return Status;
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+}
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+
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+EFI_STATUS
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+AtSha204aRelease (
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+ IN EFI_HANDLE DriverBindingHandle,
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+ IN EFI_HANDLE ControllerHandle
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+ )
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+{
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+ EFI_RNG_PROTOCOL *Rng;
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+ ATSHA204A_DEV *AtSha204a;
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+ EFI_STATUS Status;
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+
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+ Status = gBS->HandleProtocol (ControllerHandle,
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+ &gEfiRngProtocolGuid,
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+ (VOID **)&Rng);
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+ ASSERT_EFI_ERROR (Status);
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+ if (EFI_ERROR (Status)) {
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+ return Status;
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+ }
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+
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+ AtSha204a = ATSHA204A_DEV_FROM_THIS (Rng);
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+
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+ Status = gBS->UninstallProtocolInterface (ControllerHandle,
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+ &gEfiRngProtocolGuid,
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+ Rng);
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+ ASSERT_EFI_ERROR (Status);
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+ if (EFI_ERROR (Status)) {
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+ return Status;
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+ }
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+
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+ Status = gBS->CloseProtocol (ControllerHandle,
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+ &gEfiI2cIoProtocolGuid,
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+ DriverBindingHandle,
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+ ControllerHandle);
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+ ASSERT_EFI_ERROR (Status);
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+ if (EFI_ERROR (Status)) {
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+ return Status;
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+ }
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+
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+ gBS->FreePool (AtSha204a);
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+
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+ return EFI_SUCCESS;
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+}
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