ARM: proc: add definition of cpu_reset for ARMv6 and ARMv7 cores

This patch adds simple definitions of cpu_reset for ARMv6 and ARMv7
cores, which disable the MMU via the SCTLR.
Signed-off-by: NWill Deacon <will.deacon@arm.com>

arch/arm/mm/proc-v6.S

@@ -56,6 +56,11 @@ ENTRY(cpu_v6_proc_fin)
  */
 	.align	5
 ENTRY(cpu_v6_reset)
+	mrc	p15, 0, r1, c1, c0, 0		@ ctrl register
+	bic	r1, r1, #0x1			@ ...............m
+	mcr	p15, 0, r1, c1, c0, 0		@ disable MMU
+	mov	r1, #0
+	mcr	p15, 0, r1, c7, c5, 4		@ ISB
 	mov	pc, r0
 
 /*

arch/arm/mm/proc-v7.S

@@ -58,9 +58,16 @@ ENDPROC(cpu_v7_proc_fin)
  *	to what would be the reset vector.
  *
  *	- loc   - location to jump to for soft reset
+ *
+ *	This code must be executed using a flat identity mapping with
+ *      caches disabled.
  */
 	.align	5
 ENTRY(cpu_v7_reset)
+	mrc	p15, 0, r1, c1, c0, 0		@ ctrl register
+	bic	r1, r1, #0x1			@ ...............m
+	mcr	p15, 0, r1, c1, c0, 0		@ disable MMU
+	isb
 	mov	pc, r0
 ENDPROC(cpu_v7_reset)