summaryrefslogtreecommitdiffstats
path: root/arch/arm/kernel/head-common.S
diff options
context:
space:
mode:
authorGrant Likely <grant.likely@secretlab.ca>2011-04-28 14:27:20 -0600
committerGrant Likely <grant.likely@secretlab.ca>2011-05-11 15:12:32 +0200
commit4c2896e88d976d0e5b2213c64cde885f5677fa2b (patch)
treed5573124e35cb3b81b7ac56fb4d7708eacf4991d /arch/arm/kernel/head-common.S
parent7ee4b98eca42c1ff1df7dcf443dac07f0a2ea93d (diff)
downloadlinux-4c2896e88d976d0e5b2213c64cde885f5677fa2b.tar.gz
linux-4c2896e88d976d0e5b2213c64cde885f5677fa2b.tar.bz2
linux-4c2896e88d976d0e5b2213c64cde885f5677fa2b.zip
arm/dt: Make __vet_atags also accept a dtb image
The dtb is passed to the kernel via register r2, which is the same method that is used to pass an atags pointer. This patch modifies __vet_atags to not clear r2 when it encounters a dtb image. v2: fixed bugs pointed out by Nicolas Pitre Tested-by: Tony Lindgren <tony@atomide.com> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Diffstat (limited to 'arch/arm/kernel/head-common.S')
-rw-r--r--arch/arm/kernel/head-common.S24
1 files changed, 18 insertions, 6 deletions
diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S
index c84b57d27d07..854bd22380d3 100644
--- a/arch/arm/kernel/head-common.S
+++ b/arch/arm/kernel/head-common.S
@@ -15,6 +15,12 @@
#define ATAG_CORE_SIZE ((2*4 + 3*4) >> 2)
#define ATAG_CORE_SIZE_EMPTY ((2*4) >> 2)
+#ifdef CONFIG_CPU_BIG_ENDIAN
+#define OF_DT_MAGIC 0xd00dfeed
+#else
+#define OF_DT_MAGIC 0xedfe0dd0 /* 0xd00dfeed in big-endian */
+#endif
+
/*
* Exception handling. Something went wrong and we can't proceed. We
* ought to tell the user, but since we don't have any guarantee that
@@ -28,20 +34,26 @@
/* Determine validity of the r2 atags pointer. The heuristic requires
* that the pointer be aligned, in the first 16k of physical RAM and
- * that the ATAG_CORE marker is first and present. Future revisions
+ * that the ATAG_CORE marker is first and present. If CONFIG_OF_FLATTREE
+ * is selected, then it will also accept a dtb pointer. Future revisions
* of this function may be more lenient with the physical address and
* may also be able to move the ATAGS block if necessary.
*
* Returns:
- * r2 either valid atags pointer, or zero
+ * r2 either valid atags pointer, valid dtb pointer, or zero
* r5, r6 corrupted
*/
__vet_atags:
tst r2, #0x3 @ aligned?
bne 1f
- ldr r5, [r2, #0] @ is first tag ATAG_CORE?
- cmp r5, #ATAG_CORE_SIZE
+ ldr r5, [r2, #0]
+#ifdef CONFIG_OF_FLATTREE
+ ldr r6, =OF_DT_MAGIC @ is it a DTB?
+ cmp r5, r6
+ beq 2f
+#endif
+ cmp r5, #ATAG_CORE_SIZE @ is first tag ATAG_CORE?
cmpne r5, #ATAG_CORE_SIZE_EMPTY
bne 1f
ldr r5, [r2, #4]
@@ -49,7 +61,7 @@ __vet_atags:
cmp r5, r6
bne 1f
- mov pc, lr @ atag pointer is ok
+2: mov pc, lr @ atag/dtb pointer is ok
1: mov r2, #0
mov pc, lr
@@ -61,7 +73,7 @@ ENDPROC(__vet_atags)
*
* r0 = cp#15 control register
* r1 = machine ID
- * r2 = atags pointer
+ * r2 = atags/dtb pointer
* r9 = processor ID
*/
__INIT