Messages in this thread Patch in this message | | | Subject | [PATCH v4 1/7] arm/dt: Make __vet_atags also accept a dtb image | From | Grant Likely <> | Date | Tue, 22 Feb 2011 19:22:08 -0700 |
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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
Signed-off-by: Grant Likely <grant.likely@secretlab.ca> --- arch/arm/kernel/head-common.S | 24 ++++++++++++++++++------ arch/arm/kernel/head.S | 8 ++++---- 2 files changed, 22 insertions(+), 10 deletions(-)
diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S index c84b57d..854bd22 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 diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S index 64af186..5bad500 100644 --- a/arch/arm/kernel/head.S +++ b/arch/arm/kernel/head.S @@ -66,7 +66,7 @@ * * 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). @@ -89,7 +89,7 @@ ENTRY(stext) beq __error_p @ yes, error 'p' /* - * r1 = machine no, r2 = atags, + * r1 = machine no, r2 = atags or dtb, * r9 = cpuid, r10 = procinfo */ bl __vet_atags @@ -347,7 +347,7 @@ __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 @@ -384,7 +384,7 @@ 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 *
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