ArmPkg/ArmGicDxe: Replace CpuArch registration event with DEPEX

Instead of relying on a protocol notification event to register the core IRQ
interrupt handler with CPU arch protocol once it becomes available, use
a DEPEX to ensure that the GIC driver is not dispatched at all until the
CPU arch protocol has turned up.

This will allow the GIC driver to use other CPU arch protocol methods,
such as the ones needed to map the GIC MMIO regions at driver startup.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

ArmPkg/Drivers/ArmGicDxe/ArmGicCommonDxe.c

@@ -18,6 +18,7 @@ EFI_EVENT  EfiExitBootServicesEvent = (EFI_EVENT)NULL;
 UINTN  mGicNumInterrupts = 0;
 
 HARDWARE_INTERRUPT_HANDLER  *gRegisteredInterruptHandlers = NULL;
+EFI_CPU_ARCH_PROTOCOL       *gCpuArch;
 
 /**
   Calculate GICD_ICFGRn base address and corresponding bit
@@ -98,55 +99,6 @@ RegisterInterruptSource (
   }
 }
 
-STATIC VOID  *mCpuArchProtocolNotifyEventRegistration;
-
-STATIC
-VOID
-EFIAPI
-CpuArchEventProtocolNotify (
-  IN  EFI_EVENT  Event,
-  IN  VOID       *Context
-  )
-{
-  EFI_CPU_ARCH_PROTOCOL  *Cpu;
-  EFI_STATUS             Status;
-
-  // Get the CPU protocol that this driver requires.
-  Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **)&Cpu);
-  if (EFI_ERROR (Status)) {
-    return;
-  }
-
-  // Unregister the default exception handler.
-  Status = Cpu->RegisterInterruptHandler (Cpu, ARM_ARCH_EXCEPTION_IRQ, NULL);
-  if (EFI_ERROR (Status)) {
-    DEBUG ((
-      DEBUG_ERROR,
-      "%a: Cpu->RegisterInterruptHandler() - %r\n",
-      __func__,
-      Status
-      ));
-    return;
-  }
-
-  // Register to receive interrupts
-  Status = Cpu->RegisterInterruptHandler (
-                  Cpu,
-                  ARM_ARCH_EXCEPTION_IRQ,
-                  Context
-                  );
-  if (EFI_ERROR (Status)) {
-    DEBUG ((
-      DEBUG_ERROR,
-      "%a: Cpu->RegisterInterruptHandler() - %r\n",
-      __func__,
-      Status
-      ));
-  }
-
-  gBS->CloseEvent (Event);
-}
-
 EFI_STATUS
 InstallAndRegisterInterruptService (
   IN EFI_HARDWARE_INTERRUPT_PROTOCOL   *InterruptProtocol,
@@ -159,12 +111,24 @@ InstallAndRegisterInterruptService (
   CONST UINTN  RihArraySize =
     (sizeof (HARDWARE_INTERRUPT_HANDLER) * mGicNumInterrupts);
 
+  // Locate the CPU arch protocol - cannot fail because of DEPEX
+  Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **)&gCpuArch);
+  ASSERT_EFI_ERROR (Status);
+
   // Initialize the array for the Interrupt Handlers
   gRegisteredInterruptHandlers = AllocateZeroPool (RihArraySize);
   if (gRegisteredInterruptHandlers == NULL) {
     return EFI_OUT_OF_RESOURCES;
   }
 
+  // Register to receive interrupts
+  Status = gCpuArch->RegisterInterruptHandler (gCpuArch, ARM_ARCH_EXCEPTION_IRQ, InterruptHandler);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_ERROR, "%a: Cpu->RegisterInterruptHandler() - %r\n", __func__, Status));
+    FreePool (gRegisteredInterruptHandlers);
+    return Status;
+  }
+
   Status = gBS->InstallMultipleProtocolInterfaces (
                   &gHardwareInterruptHandle,
                   &gHardwareInterruptProtocolGuid,
@@ -177,17 +141,6 @@ InstallAndRegisterInterruptService (
     return Status;
   }
 
-  //
-  // Install the interrupt handler as soon as the CPU arch protocol appears.
-  //
-  EfiCreateProtocolNotifyEvent (
-    &gEfiCpuArchProtocolGuid,
-    TPL_CALLBACK,
-    CpuArchEventProtocolNotify,
-    InterruptHandler,
-    &mCpuArchProtocolNotifyEventRegistration
-    );
-
   // Register for an ExitBootServicesEvent
   Status = gBS->CreateEvent (
                   EVT_SIGNAL_EXIT_BOOT_SERVICES,

ArmPkg/Drivers/ArmGicDxe/ArmGicDxe.h

@@ -23,6 +23,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 
 extern UINTN                       mGicNumInterrupts;
 extern HARDWARE_INTERRUPT_HANDLER  *gRegisteredInterruptHandlers;
+extern EFI_CPU_ARCH_PROTOCOL       *gCpuArch;
 
 // Common API
 EFI_STATUS

ArmPkg/Drivers/ArmGicDxe/ArmGicDxe.inf

@@ -51,7 +51,7 @@
 [Protocols]
   gHardwareInterruptProtocolGuid  ## PRODUCES
   gHardwareInterrupt2ProtocolGuid ## PRODUCES
-  gEfiCpuArchProtocolGuid         ## CONSUMES ## NOTIFY
+  gEfiCpuArchProtocolGuid         ## CONSUMES
 
 [Pcd.common]
   gArmTokenSpaceGuid.PcdGicDistributorBase
@@ -59,4 +59,4 @@
   gArmTokenSpaceGuid.PcdGicInterruptInterfaceBase
 
 [Depex]
-  TRUE
+  gEfiCpuArchProtocolGuid

ArmPkg/Drivers/ArmGicDxe/ArmGicV2Dxe.inf

@@ -41,11 +41,11 @@
 [Protocols]
   gHardwareInterruptProtocolGuid  ## PRODUCES
   gHardwareInterrupt2ProtocolGuid ## PRODUCES
-  gEfiCpuArchProtocolGuid         ## CONSUMES ## NOTIFY
+  gEfiCpuArchProtocolGuid         ## CONSUMES
 
 [Pcd.common]
   gArmTokenSpaceGuid.PcdGicDistributorBase
   gArmTokenSpaceGuid.PcdGicInterruptInterfaceBase
 
 [Depex]
-  TRUE
+  gEfiCpuArchProtocolGuid

ArmPkg/Drivers/ArmGicDxe/ArmGicV3Dxe.inf

@@ -47,11 +47,11 @@
 [Protocols]
   gHardwareInterruptProtocolGuid  ## PRODUCES
   gHardwareInterrupt2ProtocolGuid ## PRODUCES
-  gEfiCpuArchProtocolGuid         ## CONSUMES ## NOTIFY
+  gEfiCpuArchProtocolGuid         ## CONSUMES
 
 [Pcd.common]
   gArmTokenSpaceGuid.PcdGicDistributorBase
   gArmTokenSpaceGuid.PcdGicRedistributorsBase
 
 [Depex]
-  TRUE
+  gEfiCpuArchProtocolGuid