[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, 7 insertions, 9 deletions

diff --git a/arch/arm/mm/proc-xscale.S b/arch/arm/mm/proc-xscale.S
index 29bcc4dd6517..1ad0c880c80c 100644
--- a/arch/arm/mm/proc-xscale.S
+++ b/arch/arm/mm/proc-xscale.S
@@ -475,11 +475,12 @@ __xscale_setup:
         orr     r0, r0, #1 << 6                 @ cp6 for IOP3xx and Bulverde
         orr     r0, r0, #1 << 13                @ Its undefined whether this
         mcr     p15, 0, r0, c15, c1, 0          @ affects USR or SVC modes
+
+        adr     r5, xscale_crval
+        ldmia   r5, {r5, r6}
         mrc     p15, 0, r0, c1, c0, 0           @ get control register
-        ldr     r5, xscale_cr1_clear
         bic     r0, r0, r5
-        ldr     r5, xscale_cr1_set
-        orr     r0, r0, r5
+        orr     r0, r0, r6
         mov     pc, lr
         .size   __xscale_setup, . - __xscale_setup
 
@@ -489,12 +490,9 @@ __xscale_setup:
          * ..11 1.01 .... .101
          * 
          */
-        .type   xscale_cr1_clear, #object
-        .type   xscale_cr1_set, #object
-xscale_cr1_clear:
-        .word   0x3b07
-xscale_cr1_set:
-        .word   0x3905
+        .type   xscale_crval, #object
+xscale_crval:
+        crval   clear=0x00003b07, mmuset=0x00003905, ucset=0x00001900
 
         __INITDATA