[edk2-devel] [edk2-platforms][PATCH 2/5] Silicon/Bcm283x: Add FIFO mode for RNG
Ard Biesheuvel via Groups.Io
ard.biesheuvel=linaro.org at groups.io
Wed Nov 27 12:44:14 UTC 2019
On Wed, 27 Nov 2019 at 13:37, Pete Batard <pete at akeo.ie> wrote:
>
> The Bcm283x Random Number Generator does not work in regular mode
> on the Bcm2711 powered Raspberry Pi 4. It does however work when
> using FIFO mode. So we add this new mode, which is governed by the
> use of the new PcdBcm283xRngUseFifo boolean PCD.
>
> Note that just as a Pi 4 doesn't seem to support regular mode, a
> Pi 3 doesn't seem to support FIFO mode, which is why we can't
> switch to simply using FIFO mode for both platforms.
>
> We also fix the register to which RNG_WARMUP_COUNT is written,
> which was incorrect.
>
At the risk of triggering another endless debate, could we /please/
not mix in trivial bugfixes with more complicated refactoring like
this?
> Signed-off-by: Pete Batard <pete at akeo.ie>
> ---
> Silicon/Broadcom/Bcm283x/Bcm283x.dec | 1 +
> Silicon/Broadcom/Bcm283x/Drivers/RngDxe/RngDxe.c | 96 +++++++++++++++-----
> Silicon/Broadcom/Bcm283x/Drivers/RngDxe/RngDxe.inf | 2 +
> 3 files changed, 74 insertions(+), 25 deletions(-)
>
> diff --git a/Silicon/Broadcom/Bcm283x/Bcm283x.dec b/Silicon/Broadcom/Bcm283x/Bcm283x.dec
> index 5b839b00d286..4a9be7b18c97 100644
> --- a/Silicon/Broadcom/Bcm283x/Bcm283x.dec
> +++ b/Silicon/Broadcom/Bcm283x/Bcm283x.dec
> @@ -21,3 +21,4 @@ [Guids]
>
> [PcdsFixedAtBuild.common]
> gBcm283xTokenSpaceGuid.PcdBcm283xRegistersAddress|0x0|UINT32|0x00000001
> + gBcm283xTokenSpaceGuid.PcdBcm283xRngUseFifo|0x0|BOOLEAN|0x00000002
> diff --git a/Silicon/Broadcom/Bcm283x/Drivers/RngDxe/RngDxe.c b/Silicon/Broadcom/Bcm283x/Drivers/RngDxe/RngDxe.c
> index 722815d32f06..462a21a6f3c3 100644
> --- a/Silicon/Broadcom/Bcm283x/Drivers/RngDxe/RngDxe.c
> +++ b/Silicon/Broadcom/Bcm283x/Drivers/RngDxe/RngDxe.c
> @@ -2,6 +2,7 @@
>
> This driver produces an EFI_RNG_PROTOCOL instance for the Broadcom 2836 RNG
>
> + Copyright (C) 2019, Pete Batard <pete at akeo.ie>
> Copyright (C) 2019, Linaro Ltd. All rights reserved.<BR>
>
> SPDX-License-Identifier: BSD-2-Clause-Patent
> @@ -12,6 +13,8 @@
> #include <Library/BaseMemoryLib.h>
> #include <Library/DebugLib.h>
> #include <Library/IoLib.h>
> +#include <Library/PcdLib.h>
> +#include <Library/TimerLib.h>
> #include <Library/UefiBootServicesTableLib.h>
>
> #include <IndustryStandard/Bcm2836.h>
> @@ -20,6 +23,8 @@
>
> #define RNG_WARMUP_COUNT 0x40000
> #define RNG_MAX_RETRIES 0x100 // arbitrary upper bound
> +#define RNG_FIFO_NUMVAL_MASK 0xff
> +#define RNG_STATUS_NUMVAL_SHIFT 24
>
> /**
> Returns information about the random number generation implementation.
> @@ -84,6 +89,54 @@ Bcm2836RngGetInfo (
> return EFI_SUCCESS;
> }
>
> +/**
> + Read a single random value, in either FIFO or regular mode.
> +
> + @param[in] Val A pointer to the 32-bit word that is to
> + be filled with a random value.
> +
> + @retval EFI_SUCCESS A random value was successfully read.
> + @retval EFI_NOT_READY The number of retries elapsed before a
> + random value was generated.
> +
> +**/
> +STATIC
> +EFI_STATUS
> +EFIAPI
> +Bcm2836RngReadValue (
> + IN OUT UINT32 *Val
> +)
> +{
> + UINT32 Avail;
> + UINT32 i;
> + BOOLEAN UseFifo = FixedPcdGetBool (PcdBcm283xRngUseFifo);
> +
> + ASSERT (Val != NULL);
> +
> + Avail = UseFifo ?
> + (MmioRead32 (RNG_FIFO_COUNT) & RNG_FIFO_NUMVAL_MASK) :
> + (MmioRead32 (RNG_STATUS) >> RNG_STATUS_NUMVAL_SHIFT);
> +
> + //
> + // If we don't have a value ready, wait 1 us and retry.
> + //
> + for (i = 0; Avail < 1 && i < RNG_MAX_RETRIES; i++) {
> + MicroSecondDelay (1);
> + Avail = UseFifo ?
> + (MmioRead32 (RNG_FIFO_COUNT) & RNG_FIFO_NUMVAL_MASK) :
> + (MmioRead32 (RNG_STATUS) >> RNG_STATUS_NUMVAL_SHIFT);
> + }
> + if (Avail < 1) {
> + return EFI_NOT_READY;
> + }
> +
> + *Val = UseFifo ?
> + MmioRead32 (RNG_FIFO_DATA):
> + MmioRead32 (RNG_DATA);
> +
> + return EFI_SUCCESS;
> +}
> +
> /**
> Produces and returns an RNG value using either the default or specified RNG
> algorithm.
> @@ -123,9 +176,8 @@ Bcm2836RngGetRNG (
> OUT UINT8 *RNGValue
> )
> {
> - UINT32 Val;
> - UINT32 Num;
> - UINT32 Retries;
> + EFI_STATUS Status;
> + UINT32 Val;
>
> if (This == NULL || RNGValueLength == 0 || RNGValue == NULL) {
> return EFI_INVALID_PARAMETER;
> @@ -139,30 +191,24 @@ Bcm2836RngGetRNG (
> return EFI_UNSUPPORTED;
> }
>
> - while (RNGValueLength > 0) {
> - Retries = RNG_MAX_RETRIES;
> - do {
> - Num = MmioRead32 (RNG_STATUS) >> 24;
> - MemoryFence ();
> - } while (!Num && Retries-- > 0);
> -
> - if (!Num) {
> - return EFI_DEVICE_ERROR;
> + while (RNGValueLength >= sizeof (UINT32)) {
> + Status = Bcm2836RngReadValue (&Val);
> + if (EFI_ERROR (Status)) {
> + return Status;
> }
> + WriteUnaligned32 ((VOID *)RNGValue, Val);
> + RNGValue += sizeof (UINT32);
> + RNGValueLength -= sizeof (UINT32);
> + }
>
> - while (RNGValueLength >= sizeof (UINT32) && Num > 0) {
> - WriteUnaligned32 ((VOID *)RNGValue, MmioRead32 (RNG_DATA));
> - RNGValue += sizeof (UINT32);
> - RNGValueLength -= sizeof (UINT32);
> - Num--;
> + if (RNGValueLength > 0) {
> + Status = Bcm2836RngReadValue (&Val);
> + if (EFI_ERROR (Status)) {
> + return Status;
> }
> -
> - if (RNGValueLength > 0 && Num > 0) {
> - Val = MmioRead32 (RNG_DATA);
> - while (RNGValueLength--) {
> - *RNGValue++ = (UINT8)Val;
> - Val >>= 8;
> - }
> + while (RNGValueLength--) {
> + *RNGValue++ = (UINT8)Val;
> + Val >>= 8;
> }
> }
> return EFI_SUCCESS;
> @@ -190,7 +236,7 @@ Bcm2836RngEntryPoint (
> NULL);
> ASSERT_EFI_ERROR (Status);
>
> - MmioWrite32 (RNG_STATUS, RNG_WARMUP_COUNT);
> + MmioWrite32 (RNG_BIT_COUNT_THRESHOLD, RNG_WARMUP_COUNT);
> MmioWrite32 (RNG_CTRL, RNG_CTRL_ENABLE);
>
> return EFI_SUCCESS;
> diff --git a/Silicon/Broadcom/Bcm283x/Drivers/RngDxe/RngDxe.inf b/Silicon/Broadcom/Bcm283x/Drivers/RngDxe/RngDxe.inf
> index 8eb90de85cfd..31415231ae0b 100644
> --- a/Silicon/Broadcom/Bcm283x/Drivers/RngDxe/RngDxe.inf
> +++ b/Silicon/Broadcom/Bcm283x/Drivers/RngDxe/RngDxe.inf
> @@ -28,6 +28,7 @@ [LibraryClasses]
> DebugLib
> IoLib
> PcdLib
> + TimerLib
> UefiBootServicesTableLib
> UefiDriverEntryPoint
>
> @@ -39,6 +40,7 @@ [Guids]
>
> [FixedPcd]
> gBcm283xTokenSpaceGuid.PcdBcm283xRegistersAddress
> + gBcm283xTokenSpaceGuid.PcdBcm283xRngUseFifo
>
> [Depex]
> TRUE
> --
> 2.21.0.windows.1
>
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