ARMv7: Document the PRRR and NMRR registers setting
This patch adds a comment to the proc-v7.S file for the setting of the
PRRR and NMRR registers. It also sets the PRRR[13:12] bits to 0
(corresponding to the reserved TEX[0]CB encoding 110) to be consistent
with the documentation.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index 095b69f..0a8ffd3 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -219,8 +219,36 @@
mov r10, #0x1f @ domains 0, 1 = manager
mcr p15, 0, r10, c3, c0, 0 @ load domain access register
#endif
- ldr r5, =0xff0aa1a8
- ldr r6, =0x40e040e0
+ /*
+ * Memory region attributes with SCTLR.TRE=1
+ *
+ * n = TEX[0],C,B
+ * TR = PRRR[2n+1:2n] - memory type
+ * IR = NMRR[2n+1:2n] - inner cacheable property
+ * OR = NMRR[2n+17:2n+16] - outer cacheable property
+ *
+ * n TR IR OR
+ * UNCACHED 000 00
+ * BUFFERABLE 001 10 00 00
+ * WRITETHROUGH 010 10 10 10
+ * WRITEBACK 011 10 11 11
+ * reserved 110
+ * WRITEALLOC 111 10 01 01
+ * DEV_SHARED 100 01
+ * DEV_NONSHARED 100 01
+ * DEV_WC 001 10
+ * DEV_CACHED 011 10
+ *
+ * Other attributes:
+ *
+ * DS0 = PRRR[16] = 0 - device shareable property
+ * DS1 = PRRR[17] = 1 - device shareable property
+ * NS0 = PRRR[18] = 0 - normal shareable property
+ * NS1 = PRRR[19] = 1 - normal shareable property
+ * NOS = PRRR[24+n] = 1 - not outer shareable
+ */
+ ldr r5, =0xff0a81a8 @ PRRR
+ ldr r6, =0x40e040e0 @ NMRR
mcr p15, 0, r5, c10, c2, 0 @ write PRRR
mcr p15, 0, r6, c10, c2, 1 @ write NMRR
adr r5, v7_crval