[edk2-platforms PATCH] Platform/RaspberryPi: Add 'clock-frequency' property for miniuart

["Adrien Thierry" <athierry@redhat.com>]

Describe the miniuart clock frequency in a _DSD property, so that it can
be read from the Linux driver.

The miniuart clock frequency is the core clock frequency on the
Raspberry Pi. It can be modified by the user using the 'core_freq'
property in the config.txt file. So, we fetch it from the underlying
Raspberry Pi firmware.

Signed-off-by: Adrien Thierry <athierry@redhat.com>
---
 Platform/RaspberryPi/AcpiTables/Uart.asl           | 14 ++++++++++++++
 Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c |  9 +++++++++
 .../RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf    |  1 +
 Platform/RaspberryPi/RPi3/RPi3.dsc                 |  5 +++++
 Platform/RaspberryPi/RPi4/RPi4.dsc                 |  5 +++++
 Platform/RaspberryPi/RaspberryPi.dec               |  1 +
 6 files changed, 35 insertions(+)

diff --git a/Platform/RaspberryPi/AcpiTables/Uart.asl b/Platform/RaspberryPi/AcpiTables/Uart.asl
index 974f06d3bc..ef5165be98 100644
--- a/Platform/RaspberryPi/AcpiTables/Uart.asl
+++ b/Platform/RaspberryPi/AcpiTables/Uart.asl
@@ -77,6 +77,20 @@ Device (URTM)
     MEMORY32SETBASE (RBUF, RMEM, RBAS, BCM2836_MINI_UART_OFFSET)
     Return (^RBUF)
   }
+
+  //
+  // Mini Uart Clock Rate will be dynamically updated during boot
+  // 0x4D 0x55 0x43 0x52 0xC 0x1000000 (Value must be > 16777215)
+  //
+  Name (MUCR, 0x1000000)
+
+  Name (_DSD, Package ()
+  {
+    ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), Package ()
+    {
+      Package (2) { "clock-frequency", MUCR },
+    }
+  })
 }
 
 //
diff --git a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c
index 415d99fadb..3dcf2bac0d 100644
--- a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c
+++ b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c
@@ -44,6 +44,7 @@ STATIC RASPBERRY_PI_FIRMWARE_PROTOCOL *mFwProtocol;
 STATIC UINT32 mModelFamily = 0;
 STATIC UINT32 mModelInstalledMB = 0;
 STATIC UINT32 mModelRevision = 0;
+STATIC UINT32 mCoreClockRate = 0;
 
 STATIC EFI_MAC_ADDRESS  mMacAddress;
 
@@ -798,6 +799,7 @@ STATIC CONST AML_NAME_OP_REPLACE SsdtEmmcNameOpReplace[] = {
 
 STATIC CONST AML_NAME_OP_REPLACE DsdtNameOpReplace[] = {
   { "URIU", PcdToken (PcdUartInUse) },
+  { "MUCR", PcdToken (PcdMiniUartClockRate) },
   { }
 };
 
@@ -944,6 +946,13 @@ ConfigInitialize (
     DEBUG ((DEBUG_INFO, "Current Raspberry Pi revision %x\n", mModelRevision));
   }
 
+  Status = mFwProtocol->GetClockRate (RPI_MBOX_CLOCK_RATE_CORE, &mCoreClockRate);
+  if (Status != EFI_SUCCESS) {
+    DEBUG ((DEBUG_ERROR, "Couldn't get the Raspberry Pi core clock rate: %r\n", Status));
+  } else {
+    PcdSet32S (PcdMiniUartClockRate, mCoreClockRate);
+  }
+
   Status = SetupVariables ();
   if (Status != EFI_SUCCESS) {
     DEBUG ((DEBUG_ERROR, "Couldn't not setup NV vars: %r\n", Status));
diff --git a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf
index e6e22ad82e..6f6e8f42ac 100644
--- a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf
+++ b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf
@@ -95,6 +95,7 @@
   gRaspberryPiTokenSpaceGuid.PcdFanTemp
   gRaspberryPiTokenSpaceGuid.PcdUartInUse
   gRaspberryPiTokenSpaceGuid.PcdXhciPci
+  gRaspberryPiTokenSpaceGuid.PcdMiniUartClockRate
 
 [Depex]
   gPcdProtocolGuid AND gRaspberryPiFirmwareProtocolGuid
diff --git a/Platform/RaspberryPi/RPi3/RPi3.dsc b/Platform/RaspberryPi/RPi3/RPi3.dsc
index 6ab5d1ae6d..6dc48dc233 100644
--- a/Platform/RaspberryPi/RPi3/RPi3.dsc
+++ b/Platform/RaspberryPi/RPi3/RPi3.dsc
@@ -561,6 +561,11 @@
   #
   gRaspberryPiTokenSpaceGuid.PcdUartInUse|1
 
+  #
+  # Mini-UART clock rate
+  #
+  gRaspberryPiTokenSpaceGuid.PcdMiniUartClockRate|250000000
+
 ################################################################################
 #
 # Components Section - list of all EDK II Modules needed by this Platform
diff --git a/Platform/RaspberryPi/RPi4/RPi4.dsc b/Platform/RaspberryPi/RPi4/RPi4.dsc
index 44ed60ab2f..a9c0c36bb1 100644
--- a/Platform/RaspberryPi/RPi4/RPi4.dsc
+++ b/Platform/RaspberryPi/RPi4/RPi4.dsc
@@ -580,6 +580,11 @@
   #
   gRaspberryPiTokenSpaceGuid.PcdUartInUse|0
 
+  #
+  # Mini-UART clock rate
+  #
+  gRaspberryPiTokenSpaceGuid.PcdMiniUartClockRate|500000000
+
 ################################################################################
 #
 # Components Section - list of all EDK II Modules needed by this Platform
diff --git a/Platform/RaspberryPi/RaspberryPi.dec b/Platform/RaspberryPi/RaspberryPi.dec
index 797be59274..17b6061a05 100644
--- a/Platform/RaspberryPi/RaspberryPi.dec
+++ b/Platform/RaspberryPi/RaspberryPi.dec
@@ -72,3 +72,4 @@
   gRaspberryPiTokenSpaceGuid.PcdMmcEnableDma|0|UINT32|0x0000001F
   gRaspberryPiTokenSpaceGuid.PcdUartInUse|1|UINT32|0x00000021
   gRaspberryPiTokenSpaceGuid.PcdXhciPci|0|UINT32|0x00000022
+  gRaspberryPiTokenSpaceGuid.PcdMiniUartClockRate|0|UINT32|0x00000023
-- 
2.17.1