It works with the old firmware as well.

sâm., 3 apr. 2021, 10:36 Ard Biesheuvel <ardb@kernel.org> a scris:

> On Fri, 2 Apr 2021 at 19:52, Mario Bălănică <mariobalanica02@gmail.com>
> wrote:
> >
> > The baud rate divisor calculation for mini UART on BCM2711 is the same
> > as on older models since this commit:
> > https://github.com/raspberrypi/firmware/commit/1e5456a
> >
> > Signed-off-by: Mario Bălănică <mariobalanica02@gmail.com>
>
> Doesn't this make the new build incompatible with the old firmware? Is
> there a way to support both?
>
>
> > ---
> >  Platform/RaspberryPi/Library/DualSerialPortLib/DualSerialPortLib.c   |
> 15 +++------------
> >  Platform/RaspberryPi/Library/PlatformLib/AArch64/RaspberryPiHelper.S |
> 4 ----
> >  Platform/RaspberryPi/RPi4/RPi4.dsc                                   |
> 6 ++++--
> >  3 files changed, 7 insertions(+), 18 deletions(-)
> >
> > diff --git
> a/Platform/RaspberryPi/Library/DualSerialPortLib/DualSerialPortLib.c
> b/Platform/RaspberryPi/Library/DualSerialPortLib/DualSerialPortLib.c
> > index 5e83bbf022eb..d2f983bf0a9f 100644
> > --- a/Platform/RaspberryPi/Library/DualSerialPortLib/DualSerialPortLib.c
> > +++ b/Platform/RaspberryPi/Library/DualSerialPortLib/DualSerialPortLib.c
> > @@ -34,25 +34,16 @@ SerialPortGetDivisor (
> >    UINT32  SerialBaudRate
> >  )
> >  {
> > -  UINT64              BaseClockRate;
> > +  UINT32              BaseClockRate;
> >    UINT32              Divisor;
> >
> > -  //
> > -  // On the Raspberry Pi, the clock to use for the 16650-compatible UART
> > -  // is the base clock divided by the 12.12 fixed point VPU clock
> divisor.
> > -  //
> > -  BaseClockRate = (UINT64)PcdGet32 (PcdSerialClockRate);
> > -#if (RPI_MODEL == 4)
> > -  Divisor = MmioRead32(BCM2836_CM_BASE + BCM2836_CM_VPU_CLOCK_DIVISOR)
> & 0xFFFFFF;
> > -  if (Divisor != 0)
> > -    BaseClockRate = (BaseClockRate << 12) / Divisor;
> > -#endif
> > +  BaseClockRate = PcdGet32 (PcdSerialClockRate);
> >
> >    //
> >    // As per the BCM2xxx datasheets:
> >    // baudrate = system_clock_freq / (8 * (divisor + 1)).
> >    //
> > -  Divisor = (UINT32)BaseClockRate / (SerialBaudRate * 8);
> > +  Divisor = BaseClockRate / (SerialBaudRate * 8);
> >    if (Divisor != 0) {
> >      Divisor--;
> >    }
> > diff --git
> a/Platform/RaspberryPi/Library/PlatformLib/AArch64/RaspberryPiHelper.S
> b/Platform/RaspberryPi/Library/PlatformLib/AArch64/RaspberryPiHelper.S
> > index 58351e4fb8cc..7008aaf8aa4c 100644
> > ---
> a/Platform/RaspberryPi/Library/PlatformLib/AArch64/RaspberryPiHelper.S
> > +++
> b/Platform/RaspberryPi/Library/PlatformLib/AArch64/RaspberryPiHelper.S
> > @@ -85,13 +85,11 @@ ASM_FUNC (ArmPlatformPeiBootAction)
> >      adr     x2, mBoardRevision
> >      str     w0, [x2]
> >
> > -#if (RPI_MODEL == 3)
> >      run     .Lclkinfo_buffer
> >
> >      ldr     w0, .Lfrequency
> >      adr     x2, _gPcd_BinaryPatch_PcdSerialClockRate
> >      str     w0, [x2]
> > -#endif
> >
> >      ret
> >
> > @@ -135,7 +133,6 @@ ASM_FUNC (ArmPlatformPeiBootAction)
> >      .long   0                           // end tag
> >      .set    .Lrevinfo_size, . - .Lrevinfo_buffer
> >
> > -#if (RPI_MODEL == 3)
> >      .align  4
> >  .Lclkinfo_buffer:
> >      .long   .Lclkinfo_size
> > @@ -148,7 +145,6 @@ ASM_FUNC (ArmPlatformPeiBootAction)
> >      .long   0                           // frequency
> >      .long   0                           // end tag
> >      .set    .Lclkinfo_size, . - .Lclkinfo_buffer
> > -#endif
> >
> >  //UINTN
> >  //ArmPlatformGetPrimaryCoreMpId (
> > diff --git a/Platform/RaspberryPi/RPi4/RPi4.dsc
> b/Platform/RaspberryPi/RPi4/RPi4.dsc
> > index 2c05c31118d2..ff802d8347ea 100644
> > --- a/Platform/RaspberryPi/RPi4/RPi4.dsc
> > +++ b/Platform/RaspberryPi/RPi4/RPi4.dsc
> > @@ -429,7 +429,6 @@ [PcdsFixedAtBuild.common]
> >    gArmPlatformTokenSpaceGuid.PL011UartClkInHz|48000000
> >    gEfiMdeModulePkgTokenSpaceGuid.PcdSerialUseMmio|TRUE
> >    gEfiMdeModulePkgTokenSpaceGuid.PcdSerialRegisterStride|4
> > -  gEfiMdeModulePkgTokenSpaceGuid.PcdSerialClockRate|1000000000
> >    gEfiMdeModulePkgTokenSpaceGuid.PcdSerialFifoControl|0x27
> >    gEfiMdeModulePkgTokenSpaceGuid.PcdSerialExtendedTxFifoSize|8
> >    gEfiMdePkgTokenSpaceGuid.PcdUartDefaultBaudRate|115200
> > @@ -465,6 +464,9 @@ [PcdsFixedAtBuild.common]
> >    gEfiMdeModulePkgTokenSpaceGuid.PcdFirmwareVendor|L"EDK2"
> >    gEfiMdeModulePkgTokenSpaceGuid.PcdSetNxForStack|TRUE
> >
> > +[PcdsPatchableInModule]
> > +  gEfiMdeModulePkgTokenSpaceGuid.PcdSerialClockRate|500000000
> > +
> >  [PcdsDynamicHii.common.DEFAULT]
> >
> >    #
> > @@ -621,7 +623,7 @@ [Components.common]
> >    MdeModulePkg/Universal/Console/TerminalDxe/TerminalDxe.inf
> >    MdeModulePkg/Universal/SerialDxe/SerialDxe.inf {
> >      <LibraryClasses>
> > -
> SerialPortLib|Platform/RaspberryPi/Library/DualSerialPortLib/DualSerialPortLib.inf
> > +
> SerialPortLib|Platform/RaspberryPi/Library/DualSerialPortLib/DualSerialPortDxeLib.inf
> >    }
> >    Platform/RaspberryPi/Drivers/DisplayDxe/DisplayDxe.inf
> >    EmbeddedPkg/Drivers/ConsolePrefDxe/ConsolePrefDxe.inf
> > --
> > 2.29.2.windows.2
> >
>