/** @file
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Device driver for the Atmel ATSHA204A random number generator.
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Copyright (c) 2018, Linaro Ltd. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#include "AtSha204aDriver.h"
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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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#define MAX_RETRIES 5
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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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Returns information about the random number generation implementation.
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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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@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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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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// We only implement the raw algorithm
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//
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Size = sizeof (EFI_GUID);
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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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CopyGuid (AlgorithmList, &gEfiRngAlgorithmRaw);
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*AlgorithmListSize = Size;
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return EFI_SUCCESS;
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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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@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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@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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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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if (Algorithm != NULL && !CompareGuid (Algorithm, &gEfiRngAlgorithmRaw)) {
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return EFI_UNSUPPORTED;
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}
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AtSha204a = ATSHA204A_DEV_FROM_THIS (This);
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Request.OperationCount = 1;
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Request.Operation.Flags = 0;
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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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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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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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gBS->Stall (2500); // wait 2.5 ms for wake to complete
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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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gBS->Stall (50 * 1000); // 50 ms max execution time for RANDOM opcode
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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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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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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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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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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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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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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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// 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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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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return EFI_SUCCESS;
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ErrorCloseProtocol:
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gBS->CloseProtocol (ControllerHandle, &gEfiI2cIoProtocolGuid,
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DriverBindingHandle, ControllerHandle);
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ErrorFreeDev:
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gBS->FreePool (AtSha204a);
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return Status;
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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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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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AtSha204a = ATSHA204A_DEV_FROM_THIS (Rng);
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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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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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gBS->FreePool (AtSha204a);
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return EFI_SUCCESS;
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}
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