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Commit 9d20fdd5 authored by Bill Gatliff's avatar Bill Gatliff Committed by Russell King
Browse files

[ARM] 4423/1: add ATAGS support 



Examines the ATAGS pointer (r2) at boot, and interprets
a nonzero value as a reference to an ATAGS structure. A
suitable ATAGS structure replaces the kernel's command line.

Signed-off-by: default avatarBill Gatliff <bgat@billgatliff.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 7d09e854

arch/arm/kernel/head-common.S

+37 −3
Original line number Diff line number Diff line
@@ -20,7 +20,8 @@ __switch_data: 
	.long	_end				@ r7

	.long	processor_id			@ r4

	.long	__machine_arch_type		@ r5

	.long	cr_alignment			@ r6

	.long	__atags_pointer			@ r6

	.long	cr_alignment			@ r7

	.long	init_thread_union + THREAD_START_SP @ sp



/*
@@ -29,6 +30,7 @@ __switch_data: 
 *

 *  r0  = cp#15 control register

 *  r1  = machine ID

 *  r2  = atags pointer

 *  r9  = processor ID

 */

	.type	__mmap_switched, %function
@@ -47,11 +49,12 @@ __mmap_switched: 
	strcc	fp, [r6],#4

	bcc	1b



	ldmia	r3, {r4, r5, r6, sp}

	ldmia	r3, {r4, r5, r6, r7, sp}

	str	r9, [r4]			@ Save processor ID

	str	r1, [r5]			@ Save machine type

	str	r2, [r6]			@ Save atags pointer

	bic	r4, r0, #CR_A			@ Clear 'A' bit

	stmia	r6, {r0, r4}			@ Save control register values

	stmia	r7, {r0, r4}			@ Save control register values

	b	start_kernel



/*
@@ -215,3 +218,34 @@ ENTRY(lookup_machine_type) 
	bl	__lookup_machine_type

	mov	r0, r5

	ldmfd	sp!, {r4 - r6, pc}



/* 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

 * of this function may be more lenient with the physical address and

 * may also be able to move the ATAGS block if necessary.

 *

 * r8  = machinfo

 *

 * Returns:

 *  r2 either valid atags pointer, or zero

 *  r5, r6 corrupted

 */



	.type	__vet_atags, %function

__vet_atags:

	tst	r2, #0x3			@ aligned?

	bne	1f



	ldr	r5, [r2, #0]			@ is first tag ATAG_CORE?

	subs	r5, r5, #ATAG_CORE_SIZE

	bne	1f

	ldr	r5, [r2, #4]

	ldr	r6, =ATAG_CORE

	cmp	r5, r6

	bne	1f



	mov	pc, lr				@ atag pointer is ok



1:	mov	r2, #0

	mov	pc, lr

arch/arm/kernel/head.S

+6 −1
Original line number Diff line number Diff line
@@ -29,6 +29,10 @@ 
#define KERNEL_RAM_VADDR	(PAGE_OFFSET + TEXT_OFFSET)

#define KERNEL_RAM_PADDR	(PHYS_OFFSET + TEXT_OFFSET)



#define ATAG_CORE 0x54410001

#define ATAG_CORE_SIZE ((2*4 + 3*4) >> 2)





/*

 * swapper_pg_dir is the virtual address of the initial page table.

 * We place the page tables 16K below KERNEL_RAM_VADDR.  Therefore, we must
@@ -61,7 +65,7 @@ 
 *

 * 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.

 * r1 = machine nr, r2 = atags pointer.

 *

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

 * 0xc0008000, you call this at __pa(0xc0008000).
@@ -85,6 +89,7 @@ ENTRY(stext) 
	bl	__lookup_machine_type		@ r5=machinfo

	movs	r8, r5				@ invalid machine (r5=0)?

	beq	__error_a			@ yes, error 'a'

	bl	__vet_atags

	bl	__create_page_tables



	/*

arch/arm/kernel/setup.c

+5 −1
Original line number Diff line number Diff line
@@ -63,6 +63,8 @@ unsigned int processor_id; 
unsigned int __machine_arch_type;

EXPORT_SYMBOL(__machine_arch_type);



unsigned int __atags_pointer __initdata;



unsigned int system_rev;

EXPORT_SYMBOL(system_rev);
@@ -780,7 +782,9 @@ void __init setup_arch(char **cmdline_p) 
	if (mdesc->soft_reboot)

		reboot_setup("s");



	if (mdesc->boot_params)

	if (__atags_pointer)

		tags = phys_to_virt(__atags_pointer);

	else if (mdesc->boot_params)

		tags = phys_to_virt(mdesc->boot_params);



	/*