[edk2-devel][PATCH v2 1/1] Platform/RPi/ConfigDxe: Improve CPU Frequency configuration

["Pete Batard" <pete@akeo.ie>]

Improve the CPU frequency settings of the platforms by:
- Adding a "Default" option that sets the frequency to the
  official default for each model/submodel.
- Adding a "Low" option, that sets the frequency to a fixed
  PCD, custom to each platform.
- Using fixed PCDs to set the maximum and default values for
  the custom frequency range, according to the overclocking
  capabilities of the platform.
- Ensuring that the firmware defaults to using the platform's
  default frequency, instead of a low arbitrary value.

Signed-off-by: Pete Batard <pete@akeo.ie>
---
 Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c      | 41 ++++++++++++--------
 Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf    |  5 +++
 Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.uni |  6 +--
 Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.vfr | 12 +++---
 Platform/RaspberryPi/RPi3/RPi3.dsc                      | 11 +++++-
 Platform/RaspberryPi/RPi4/RPi4.dsc                      | 11 +++++-
 Platform/RaspberryPi/RaspberryPi.dec                    |  3 ++
 7 files changed, 60 insertions(+), 29 deletions(-)

diff --git a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c
index b4b13b6798f9..1091e680ff85 100644
--- a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c
+++ b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c
@@ -24,6 +24,8 @@
 #include <Protocol/RpiFirmware.h>
 #include "ConfigDxeFormSetGuid.h"
 
+#define FREQ_1_MHZ 1000000
+
 extern UINT8 ConfigDxeHiiBin[];
 extern UINT8 ConfigDxeStrings[];
 
@@ -256,28 +258,35 @@ ApplyVariables (
   UINT32 Rate = 0;
   UINT64 SystemMemorySize;
 
-  if (CpuClock != 0) {
-    if (CpuClock == 2) {
-      /*
-       * Maximum: 1.2GHz on RPi 3, 1.4GHz on RPi 3B+, unless
-       * overridden with arm_freq=xxx in config.txt.
-       */
-      Status = mFwProtocol->GetMaxClockRate (RPI_MBOX_CLOCK_RATE_ARM, &Rate);
-      if (Status != EFI_SUCCESS) {
-        DEBUG ((DEBUG_ERROR, "Couldn't get the max CPU speed, leaving as is: %r\n", Status));
-      }
-    } else if (CpuClock == 3) {
-      Rate = CustomCpuClock * 1000000;
-    } else {
-      Rate = 600 * 1000000;
+  switch (CpuClock) {
+  case 0: // Low
+    Rate = FixedPcdGet32 (PcdCpuLowSpeedMHz) * FREQ_1_MHZ;
+    break;
+  case 1: // Default
+    /*
+     * What the Raspberry Pi Foundation calls "max clock rate" is really the default value
+     * from: https://www.raspberrypi.org/documentation/configuration/config-txt/overclocking.md
+     */
+    Status = mFwProtocol->GetMaxClockRate (RPI_MBOX_CLOCK_RATE_ARM, &Rate);
+    if (Status != EFI_SUCCESS) {
+      DEBUG ((DEBUG_ERROR, "Couldn't read default CPU speed %r\n", Status));
     }
+    break;
+  case 2: // Max
+    Rate = FixedPcdGet32 (PcdCpuMaxSpeedMHz) * FREQ_1_MHZ;
+    break;
+  case 3: // Custom
+    Rate = CustomCpuClock * FREQ_1_MHZ;
+    break;
   }
 
   if (Rate != 0) {
-    DEBUG ((DEBUG_INFO, "Setting CPU speed to %uHz\n", Rate));
+    DEBUG ((DEBUG_INFO, "Setting CPU speed to %u MHz\n", Rate / FREQ_1_MHZ));
     Status = mFwProtocol->SetClockRate (RPI_MBOX_CLOCK_RATE_ARM, Rate, 1);
     if (Status != EFI_SUCCESS) {
       DEBUG ((DEBUG_ERROR, "Couldn't set the CPU speed: %r\n", Status));
+    } else {
+      PcdSet32 (PcdCustomCpuClock, Rate / FREQ_1_MHZ);
     }
   }
 
@@ -285,7 +294,7 @@ ApplyVariables (
   if (Status != EFI_SUCCESS) {
     DEBUG ((DEBUG_ERROR, "Couldn't get the CPU speed: %r\n", Status));
   } else {
-    DEBUG ((DEBUG_INFO, "Current CPU speed is %uHz\n", Rate));
+    DEBUG ((DEBUG_INFO, "Current CPU speed is %u MHz\n", Rate / FREQ_1_MHZ));
   }
 
   if (mModelFamily >= 4 && PcdGet32 (PcdRamMoreThan3GB) != 0 &&
diff --git a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf
index 736d49df562b..57963baf9c90 100644
--- a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf
+++ b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf
@@ -57,6 +57,11 @@ [Protocols]
   gRaspberryPiFirmwareProtocolGuid      ## CONSUMES
   gRaspberryPiConfigAppliedProtocolGuid ## PRODUCES
 
+[FixedPcd]
+  gRaspberryPiTokenSpaceGuid.PcdCpuLowSpeedMHz
+  gRaspberryPiTokenSpaceGuid.PcdCpuDefSpeedMHz
+  gRaspberryPiTokenSpaceGuid.PcdCpuMaxSpeedMHz
+
 [Pcd]
   gBcm27xxTokenSpaceGuid.PcdBcm27xxRegistersAddress
   gBcm283xTokenSpaceGuid.PcdBcm283xRegistersAddress
diff --git a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.uni b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.uni
index 77eda96d8136..046c75f9bfab 100644
--- a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.uni
+++ b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.uni
@@ -22,13 +22,13 @@
 
 #string STR_CHIPSET_CLOCK_CPU_PROMPT #language en-US "CPU Clock"
 #string STR_CHIPSET_CLOCK_CPU_HELP   #language en-US "CPU Speed"
-#string STR_CHIPSET_CLOCK_CPU_NA     #language en-US "Don't Override"
-#string STR_CHIPSET_CLOCK_CPU_600MHZ #language en-US "Min (600MHz)"
+#string STR_CHIPSET_CLOCK_CPU_LOW    #language en-US "Low"
+#string STR_CHIPSET_CLOCK_CPU_DEF    #language en-US "Default"
 #string STR_CHIPSET_CLOCK_CPU_MAX    #language en-US "Max"
 #string STR_CHIPSET_CLOCK_CPU_CUSTOM #language en-US "Custom"
 
 #string STR_CHIPSET_CUSTOM_CPU_CLOCK_PROMPT #language en-US "CPU Clock Rate (MHz)"
-#string STR_CHIPSET_CUSTOM_CPU_CLOCK_HELP   #language en-US "Adjust the CPU speed.\nMin value: 100 MHz\nMax value: 1600 MHz\n\nWarning: Overclocking can make the system unbootable!"
+#string STR_CHIPSET_CUSTOM_CPU_CLOCK_HELP   #language en-US "Manually set the CPU Speed\n\nWarning: Overclocking can make the system unbootable!"
 
 /*
  * Advanced configuration.
diff --git a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.vfr b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.vfr
index 9c2fd64a8e27..bab96885b78c 100644
--- a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.vfr
+++ b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.vfr
@@ -53,8 +53,8 @@ typedef struct {
 
 typedef struct {
   /*
-   * 0 - don't change the clock rate.
-   * 1 - 600MHz.
+   * 0 - low.
+   * 1 - default.
    * 2 - maximum.
    * 3 - custom.
    */
@@ -253,8 +253,8 @@ formset
             prompt      = STRING_TOKEN(STR_CHIPSET_CLOCK_CPU_PROMPT),
             help        = STRING_TOKEN(STR_CHIPSET_CLOCK_CPU_HELP),
             flags       = NUMERIC_SIZE_4 | INTERACTIVE | RESET_REQUIRED,
-            option text = STRING_TOKEN(STR_CHIPSET_CLOCK_CPU_NA), value = 0, flags = DEFAULT;
-            option text = STRING_TOKEN(STR_CHIPSET_CLOCK_CPU_600MHZ), value = 1, flags = 0;
+            option text = STRING_TOKEN(STR_CHIPSET_CLOCK_CPU_LOW), value = 0, flags = 0;
+            option text = STRING_TOKEN(STR_CHIPSET_CLOCK_CPU_DEF), value = 1, flags = DEFAULT;
             option text = STRING_TOKEN(STR_CHIPSET_CLOCK_CPU_MAX), value = 2, flags = 0;
             option text = STRING_TOKEN(STR_CHIPSET_CLOCK_CPU_CUSTOM), value = 3, flags = 0;
         endoneof;
@@ -265,8 +265,8 @@ formset
               help    = STRING_TOKEN(STR_CHIPSET_CUSTOM_CPU_CLOCK_HELP),
               flags   = DISPLAY_UINT_DEC | NUMERIC_SIZE_4 | INTERACTIVE | RESET_REQUIRED,
               minimum = 100,
-              maximum = 1600,
-              default = 600,
+              maximum = FixedPcdGet32 (PcdCpuMaxSpeedMHz),
+              default = FixedPcdGet32 (PcdCpuDefSpeedMHz),
           endnumeric;
         endif;
     endform;
diff --git a/Platform/RaspberryPi/RPi3/RPi3.dsc b/Platform/RaspberryPi/RPi3/RPi3.dsc
index 91d5738afbc6..d92f5cc1863d 100644
--- a/Platform/RaspberryPi/RPi3/RPi3.dsc
+++ b/Platform/RaspberryPi/RPi3/RPi3.dsc
@@ -396,6 +396,13 @@ [PcdsFixedAtBuild.common]
   gEfiMdePkgTokenSpaceGuid.PcdUartDefaultBaudRate|115200
   gEfiMdePkgTokenSpaceGuid.PcdUartDefaultReceiveFifoDepth|0
 
+  #
+  # Fixed CPU settings.
+  #
+  gRaspberryPiTokenSpaceGuid.PcdCpuLowSpeedMHz|600
+  gRaspberryPiTokenSpaceGuid.PcdCpuDefSpeedMHz|1200
+  gRaspberryPiTokenSpaceGuid.PcdCpuMaxSpeedMHz|1500
+
   ## Default Terminal Type
   ## 0-PCANSI, 1-VT100, 2-VT00+, 3-UTF8, 4-TTYTERM
   gEfiMdePkgTokenSpaceGuid.PcdDefaultTerminalType|4
@@ -412,8 +419,8 @@ [PcdsDynamicHii.common.DEFAULT]
   # Clock overrides.
   #
 
-  gRaspberryPiTokenSpaceGuid.PcdCpuClock|L"CpuClock"|gConfigDxeFormSetGuid|0x0|0
-  gRaspberryPiTokenSpaceGuid.PcdCustomCpuClock|L"CustomCpuClock"|gConfigDxeFormSetGuid|0x0|600
+  gRaspberryPiTokenSpaceGuid.PcdCpuClock|L"CpuClock"|gConfigDxeFormSetGuid|0x0|1
+  gRaspberryPiTokenSpaceGuid.PcdCustomCpuClock|L"CustomCpuClock"|gConfigDxeFormSetGuid|0x0|gRaspberryPiTokenSpaceGuid.PcdCpuDefSpeedMHz
 
   #
   # SD-related.
diff --git a/Platform/RaspberryPi/RPi4/RPi4.dsc b/Platform/RaspberryPi/RPi4/RPi4.dsc
index 2e98c3e16b91..aabf3566360f 100644
--- a/Platform/RaspberryPi/RPi4/RPi4.dsc
+++ b/Platform/RaspberryPi/RPi4/RPi4.dsc
@@ -435,6 +435,13 @@ [PcdsFixedAtBuild.common]
   gArmTokenSpaceGuid.PcdGicDistributorBase|0xFF841000
   gArmTokenSpaceGuid.PcdGicInterruptInterfaceBase|0xFF842000
 
+  #
+  # Fixed CPU settings.
+  #
+  gRaspberryPiTokenSpaceGuid.PcdCpuLowSpeedMHz|800
+  gRaspberryPiTokenSpaceGuid.PcdCpuDefSpeedMHz|1500
+  gRaspberryPiTokenSpaceGuid.PcdCpuMaxSpeedMHz|2200
+
   ## Default Terminal Type
   ## 0-PCANSI, 1-VT100, 2-VT00+, 3-UTF8, 4-TTYTERM
   gEfiMdePkgTokenSpaceGuid.PcdDefaultTerminalType|4
@@ -451,8 +458,8 @@ [PcdsDynamicHii.common.DEFAULT]
   # Clock overrides.
   #
 
-  gRaspberryPiTokenSpaceGuid.PcdCpuClock|L"CpuClock"|gConfigDxeFormSetGuid|0x0|0
-  gRaspberryPiTokenSpaceGuid.PcdCustomCpuClock|L"CustomCpuClock"|gConfigDxeFormSetGuid|0x0|600
+  gRaspberryPiTokenSpaceGuid.PcdCpuClock|L"CpuClock"|gConfigDxeFormSetGuid|0x0|1
+  gRaspberryPiTokenSpaceGuid.PcdCustomCpuClock|L"CustomCpuClock"|gConfigDxeFormSetGuid|0x0|gRaspberryPiTokenSpaceGuid.PcdCpuDefSpeedMHz
 
   #
   # SD-related.
diff --git a/Platform/RaspberryPi/RaspberryPi.dec b/Platform/RaspberryPi/RaspberryPi.dec
index 1355cdee0534..b51eefeb09fb 100644
--- a/Platform/RaspberryPi/RaspberryPi.dec
+++ b/Platform/RaspberryPi/RaspberryPi.dec
@@ -44,6 +44,9 @@ [PcdsFixedAtBuild.common]
   gRaspberryPiTokenSpaceGuid.PcdNvStorageFtwWorkingBase|0x0|UINT32|0x00000007
   gRaspberryPiTokenSpaceGuid.PcdExtendedMemoryBase|0x0|UINT32|0x00000008
   gRaspberryPiTokenSpaceGuid.PcdFdtSize|0x10000|UINT32|0x00000009
+  gRaspberryPiTokenSpaceGuid.PcdCpuLowSpeedMHz|600|UINT32|0x0000000a
+  gRaspberryPiTokenSpaceGuid.PcdCpuDefSpeedMHz|800|UINT32|0x0000000b
+  gRaspberryPiTokenSpaceGuid.PcdCpuMaxSpeedMHz|1000|UINT32|0x0000000c
 
 [PcdsFixedAtBuild, PcdsPatchableInModule, PcdsDynamic, PcdsDynamicEx]
   gRaspberryPiTokenSpaceGuid.PcdCpuClock|0|UINT32|0x0000000d
-- 
2.21.0.windows.1