[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>

1 files changed, 6 insertions, 9 deletions

diff --git a/arch/arm/mm/proc-arm922.S b/arch/arm/mm/proc-arm922.S
index 33dae4929f09..0d237693d0a4 100644
--- a/arch/arm/mm/proc-arm922.S
+++ b/arch/arm/mm/proc-arm922.S
@@ -395,11 +395,11 @@ __arm922_setup:
 #ifdef CONFIG_MMU
 	mcr	p15, 0, r0, c8, c7		@ invalidate I,D TLBs on v4
 #endif
+	adr	r5, arm922_crval
+	ldmia	r5, {r5, r6}
 	mrc	p15, 0, r0, c1, c0		@ get control register v4
-	ldr	r5, arm922_cr1_clear
 	bic	r0, r0, r5
-	ldr	r5, arm922_cr1_set
-	orr	r0, r0, r5
+	orr	r0, r0, r6
 	mov	pc, lr
 	.size	__arm922_setup, . - __arm922_setup
 
@@ -409,12 +409,9 @@ __arm922_setup:
 	 * ..11 0001 ..11 0101
 	 * 
 	 */
-	.type	arm922_cr1_clear, #object
-	.type	arm922_cr1_set, #object
-arm922_cr1_clear:
-	.word	0x3f3f
-arm922_cr1_set:
-	.word	0x3135
+	.type	arm922_crval, #object
+arm922_crval:
+	crval	clear=0x00003f3f, mmuset=0x00003135, ucset=0x00001130
 
 	__INITDATA