[ARM] nommu: provide a way for correct control register value selection

Most MMU-based CPUs have a restriction on the setting of the data cache
enable and mmu enable bits in the control register, whereby if the data
cache is enabled, the MMU must also be enabled.  Enabling the data
cache without the MMU is an invalid combination.

However, there are CPUs where the data cache can be enabled without the
MMU.

In order to allow these CPUs to take advantage of that, provide a
method whereby each proc-*.S file defines the control regsiter value
for use with nommu (with the MMU disabled.)  Later on, when we add
support for enabling the MMU on these devices, we can adjust the
"crval" macro to also enable the data cache for nommu.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/proc-xsc3.S

@@ -426,23 +426,26 @@ __xsc3_setup:
 	orr	r0, r0, #(1 << 10)		@ enable L2 for LLR cache
 #endif
 	mcr	p15, 0, r0, c1, c0, 1		@ set auxiliary control reg
+
+	adr	r5, xsc3_crval
+	ldmia	r5, {r5, r6}
 	mrc	p15, 0, r0, c1, c0, 0		@ get control register
-	bic	r0, r0, #0x0002			@ .... .... .... ..A.
-	orr	r0, r0, #0x0005			@ .... .... .... .C.M
+	bic	r0, r0, r5			@ .... .... .... ..A.
+	orr	r0, r0, r6			@ .... .... .... .C.M
 #if BTB_ENABLE
-	bic	r0, r0, #0x0200			@ .... ..R. .... ....
-	orr	r0, r0, #0x3900			@ ..VI Z..S .... ....
-#else
-	bic	r0, r0, #0x0a00			@ .... Z.R. .... ....
-	orr	r0, r0, #0x3100			@ ..VI ...S .... ....
+	orr	r0, r0, #0x00000800		@ ..VI Z..S .... ....
 #endif
 #if L2_CACHE_ENABLE
-	orr 	r0, r0, #0x4000000		@ L2 enable
+	orr 	r0, r0, #0x04000000		@ L2 enable
 #endif
 	mov	pc, lr
 
 	.size	__xsc3_setup, . - __xsc3_setup
 
+	.type	xsc3_crval, #object
+xsc3_crval:
+	crval	clear=0x04003b02, mmuset=0x00003105, ucset=0x00001100
+
 	__INITDATA
 
 /*