aboutsummaryrefslogtreecommitdiff
path: root/arch/arm/boot/compressed/head-shark.S
blob: 089c560e07f13947ed68ab446edcc9de40c30604 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
/* The head-file for the Shark
 * by Alexander Schulz
 *
 * Does the following:
 * - get the memory layout from firmware. This can only be done as long as the mmu
 *   is still on.
 * - switch the mmu off, so we have physical addresses
 * - copy the kernel to 0x08508000. This is done to have a fixed address where the
 *   C-parts (misc.c) are executed. This address must be known at compile-time,
 *   but the load-address of the kernel depends on how much memory is installed.
 * - Jump to this location.
 * - Set r8 with 0, r7 with the architecture ID for head.S
 */

#include <linux/linkage.h>

#include <asm/assembler.h>
	
		.section	".start", "ax"

		b	__beginning
	
__ofw_data:	.long	0				@ the number of memory blocks
		.space  128				@ (startaddr,size) ...
		.space  128				@ bootargs
		.align

__beginning:	mov	r4, r0				@ save the entry to the firmware

		mov	r0, #0xC0			@ disable irq and fiq
		mov	r1, r0
		mrs	r3, cpsr
		bic	r2, r3, r0
		eor	r2, r2, r1
		msr	cpsr_c, r2

		mov	r0, r4				@ get the Memory layout from firmware
		adr	r1, __ofw_data
		add	r2, r1, #4
		mov	lr, pc
		b	ofw_init
		mov	r1, #0

		adr	r2, __mmu_off			@ calculate physical address
		sub	r2, r2, #0xf0000000		@ openprom maps us at f000 virt, 0e50 phys
		adr	r0, __ofw_data
		ldr	r0, [r0, #4]
		add	r2, r2, r0
		add	r2, r2, #0x00500000

		mrc	p15, 0, r3, c1, c0
		bic	r3, r3, #0xC			@ Write Buffer and DCache
		bic	r3, r3, #0x1000			@ ICache
		mcr	p15, 0, r3, c1, c0		@ disabled

		mov	r0, #0
		mcr	p15, 0, r0, c7, c7		@ flush I,D caches on v4
		mcr	p15, 0, r0, c7, c10, 4		@ drain write buffer on v4
		mcr	p15, 0, r0, c8, c7		@ flush I,D TLBs on v4

		bic	r3, r3, #0x1			@ MMU
		mcr	p15, 0, r3, c1, c0		@ disabled

		mov	pc, r2

__copy_target:	.long	0x08507FFC
__copy_end:	.long	0x08607FFC
		
		.word	_start
		.word	__bss_start

		.align
__temp_stack:	.space 128

__mmu_off:
		adr	r0, __ofw_data			@ read the 1. entry of the memory map
		ldr	r0, [r0, #4]
		orr	r0, r0, #0x00600000
		sub	r0, r0, #4
	
		ldr	r1, __copy_end
		ldr	r3, __copy_target

/* r0 = 0x0e600000 (current end of kernelcode)
 * r3 = 0x08508000 (where it should begin)
 * r1 = 0x08608000 (end of copying area, 1MB)
 * The kernel is compressed, so 1 MB should be enough.
 * copy the kernel to the beginning of physical memory
 * We start from the highest address, so we can copy
 * from 0x08500000 to 0x08508000 if we have only 8MB
 */

/* As we get more 2.6-kernels it gets more and more
 * uncomfortable to be bound to kernel images of 1MB only.
 * So we add a loop here, to be able to copy some more.
 * Alexander Schulz 2005-07-17
 */

		mov	r4, #3				@ How many megabytes to copy


__MoveCode:	sub	r4, r4, #1
	
__Copy:		ldr	r2, [r0], #-4
		str	r2, [r1], #-4
		teq	r1, r3
		bne	__Copy

		/* The firmware maps us in blocks of 1 MB, the next block is
		   _below_ the last one. So our decrementing source pointer
		   ist right here, but the destination pointer must be increased
		   by 2 MB */
		add	r1, r1, #0x00200000
		add	r3, r3, #0x00100000

		teq	r4, #0
		bne	__MoveCode


		/* and jump to it */
		adr	r2, __go_on			@ where we want to jump
		adr	r0, __ofw_data			@ read the 1. entry of the memory map
		ldr	r0, [r0, #4]
		sub	r2, r2, r0			@ we are mapped add 0e50 now, sub that (-0e00)
		sub	r2, r2, #0x00500000		@ -0050
		ldr	r0, __copy_target		@ and add 0850 8000 instead
		add	r0, r0, #4
		add	r2, r2, r0
		mov	pc, r2				@ and jump there

__go_on:
		adr	sp, __temp_stack
		add	sp, sp, #128
		adr	r0, __ofw_data
		mov	lr, pc
		b	create_params
	
		mov	r8, #0
		mov	r7, #15