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Commit 4c2896e8 authored by Grant Likely's avatar Grant Likely
Browse files

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: default avatarTony Lindgren <tony@atomide.com>
Signed-off-by: default avatarGrant Likely <grant.likely@secretlab.ca>
parent 7ee4b98e

arch/arm/kernel/head-common.S

+18 −6
Original line number Diff line number Diff line
@@ -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

arch/arm/kernel/head.S

+4 −4
Original line number Diff line number Diff line
@@ -59,7 +59,7 @@ 
 *

 * This is normally called from the decompressor code.  The requirements

 * are: MMU = off, D-cache = off, I-cache = dont care, r0 = 0,

 * r1 = machine nr, r2 = atags pointer.

 * r1 = machine nr, r2 = atags or dtb pointer.

 *

 * This code is mostly position independent, so if you link the kernel at

 * 0xc0008000, you call this at __pa(0xc0008000).
@@ -91,7 +91,7 @@ ENTRY(stext) 
#endif



	/*

	 * r1 = machine no, r2 = atags,

	 * r1 = machine no, r2 = atags or dtb,

	 * r8 = phys_offset, r9 = cpuid, r10 = procinfo

	 */

	bl	__vet_atags
@@ -339,7 +339,7 @@ __secondary_data: 
 *

 *  r0  = cp#15 control register

 *  r1  = machine ID

 *  r2  = atags pointer

 *  r2  = atags or dtb pointer

 *  r4  = page table pointer

 *  r9  = processor ID

 *  r13 = *virtual* address to jump to upon completion
@@ -376,7 +376,7 @@ ENDPROC(__enable_mmu) 
 *

 *  r0  = cp#15 control register

 *  r1  = machine ID

 *  r2  = atags pointer

 *  r2  = atags or dtb pointer

 *  r9  = processor ID

 *  r13 = *virtual* address to jump to upon completion

 *