powerpc/85xx:Fix MSR[DE] bit in MSR to support debugger

Debugging of e500 and e500v1 processer requires MSR[DE] bit to be set always.
Where MSR = Machine State register

Make sure of MSR[DE] bit is set uniformaly across the different execution
address space i.e. AS0 and AS1.

Signed-off-by: Radu Lazarescu <radu.lazarescu@freescale.com>
Signed-off-by: Catalin Udma <catalin.udma@freescale.com>
Signed-off-by: Marius Grigoras <marius.grigoras@freescale.com>
Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>

arch/powerpc/cpu/mpc85xx/cpu_init.c

@@ -537,7 +537,7 @@ void arch_preboot_os(void)
 	 * disabled by the time we get called.
 	 */
 	msr = mfmsr();
-	msr &= ~(MSR_ME|MSR_CE|MSR_DE);
+	msr &= ~(MSR_ME|MSR_CE);
 	mtmsr(msr);
 
 	setup_ivors();

arch/powerpc/cpu/mpc85xx/start.S

@@ -82,6 +82,9 @@
 	.globl _start_e500
 
 _start_e500:
+/* Enable debug exception */
+	li	r1,MSR_DE
+	mtmsr 	r1
 
 #if defined(CONFIG_SECURE_BOOT) && defined(CONFIG_E500MC)
 	/* ISBC uses L2 as stack.
@@ -733,8 +736,8 @@ create_init_ram_area:
 	msync
 	tlbwe
 
-	lis	r6,MSR_IS|MSR_DS@h
-	ori	r6,r6,MSR_IS|MSR_DS@l
+	lis	r6,MSR_IS|MSR_DS|MSR_DE@h
+	ori	r6,r6,MSR_IS|MSR_DS|MSR_DE@l
 	lis	r7,switch_as@h
 	ori	r7,r7,switch_as@l