powerpc: Change interrupt disable implemetation

Instead of SPRG0 (= special purpose register 272) use the new global
symbol _PPC_INTERRUPT_DISABLE_MASK to store the interrupt disable mask.
The benefit is that it is now possible to disable interrupts without
further run-time initialization in boot_card().

At least on Freescale e500 cores this leads also to a faster execution
since the mfmsr and mfspr instruction require four cycles to complete.
The instructions to load the mask value can execute while the mfmsr is
in progress.

1 files changed, 1 insertions, 5 deletions

diff --git a/c/src/lib/libbsp/powerpc/score603e/startup/bspstart.c b/c/src/lib/libbsp/powerpc/score603e/startup/bspstart.c
index 3519a59f3b..8caf955835 100644
--- a/c/src/lib/libbsp/powerpc/score603e/startup/bspstart.c
+++ b/c/src/lib/libbsp/powerpc/score603e/startup/bspstart.c
@@ -194,11 +194,7 @@ void bsp_start( void )
   /*
    * Initialize default raw exception handlers.
    */
-  ppc_exc_initialize(
-    PPC_INTERRUPT_DISABLE_MASK_DEFAULT,
-    intrStackStart,
-    intrStackSize
-  );
+  ppc_exc_initialize(intrStackStart, intrStackSize);
 
   msr_value = 0x2030;
   _CPU_MSR_SET( msr_value );