CoCalc -- head-shark.S

GitHub Repository: awilliam/linux-vfio
Path: blob/master/arch/arm/boot/compressed/head-shark.S
¹⁰⁸¹⁹ views
1
/* The head-file for the Shark
2
 * by Alexander Schulz
3
 *
4
 * Does the following:
5
 * - get the memory layout from firmware. This can only be done as long as the mmu
6
 *   is still on.
7
 * - switch the mmu off, so we have physical addresses
8
 * - copy the kernel to 0x08508000. This is done to have a fixed address where the
9
 *   C-parts (misc.c) are executed. This address must be known at compile-time,
10
 *   but the load-address of the kernel depends on how much memory is installed.
11
 * - Jump to this location.
12
 * - Set r8 with 0, r7 with the architecture ID for head.S
13
 */
14

15
#include <linux/linkage.h>
16

17
#include <asm/assembler.h>
18
	
19
		.section	".start", "ax"
20

21
		b	__beginning
22
	
23
__ofw_data:	.long	0				@ the number of memory blocks
24
		.space  128				@ (startaddr,size) ...
25
		.space  128				@ bootargs
26
		.align
27

28
__beginning:	mov	r4, r0				@ save the entry to the firmware
29

30
		mov	r0, #0xC0			@ disable irq and fiq
31
		mov	r1, r0
32
		mrs	r3, cpsr
33
		bic	r2, r3, r0
34
		eor	r2, r2, r1
35
		msr	cpsr_c, r2
36

37
		mov	r0, r4				@ get the Memory layout from firmware
38
		adr	r1, __ofw_data
39
		add	r2, r1, #4
40
		mov	lr, pc
41
		b	ofw_init
42
		mov	r1, #0
43

44
		adr	r2, __mmu_off			@ calculate physical address
45
		sub	r2, r2, #0xf0000000		@ openprom maps us at f000 virt, 0e50 phys
46
		adr	r0, __ofw_data
47
		ldr	r0, [r0, #4]
48
		add	r2, r2, r0
49
		add	r2, r2, #0x00500000
50

51
		mrc	p15, 0, r3, c1, c0
52
		bic	r3, r3, #0xC			@ Write Buffer and DCache
53
		bic	r3, r3, #0x1000			@ ICache
54
		mcr	p15, 0, r3, c1, c0		@ disabled
55

56
		mov	r0, #0
57
		mcr	p15, 0, r0, c7, c7		@ flush I,D caches on v4
58
		mcr	p15, 0, r0, c7, c10, 4		@ drain write buffer on v4
59
		mcr	p15, 0, r0, c8, c7		@ flush I,D TLBs on v4
60

61
		bic	r3, r3, #0x1			@ MMU
62
		mcr	p15, 0, r3, c1, c0		@ disabled
63

64
		mov	pc, r2
65

66
__copy_target:	.long	0x08507FFC
67
__copy_end:	.long	0x08607FFC
68
		
69
		.word	_start
70
		.word	__bss_start
71

72
		.align
73
__temp_stack:	.space 128
74

75
__mmu_off:
76
		adr	r0, __ofw_data			@ read the 1. entry of the memory map
77
		ldr	r0, [r0, #4]
78
		orr	r0, r0, #0x00600000
79
		sub	r0, r0, #4
80
	
81
		ldr	r1, __copy_end
82
		ldr	r3, __copy_target
83

84
/* r0 = 0x0e600000 (current end of kernelcode)
85
 * r3 = 0x08508000 (where it should begin)
86
 * r1 = 0x08608000 (end of copying area, 1MB)
87
 * The kernel is compressed, so 1 MB should be enough.
88
 * copy the kernel to the beginning of physical memory
89
 * We start from the highest address, so we can copy
90
 * from 0x08500000 to 0x08508000 if we have only 8MB
91
 */
92

93
/* As we get more 2.6-kernels it gets more and more
94
 * uncomfortable to be bound to kernel images of 1MB only.
95
 * So we add a loop here, to be able to copy some more.
96
 * Alexander Schulz 2005-07-17
97
 */
98

99
		mov	r4, #3				@ How many megabytes to copy
100

101

102
__MoveCode:	sub	r4, r4, #1
103
	
104
__Copy:		ldr	r2, [r0], #-4
105
		str	r2, [r1], #-4
106
		teq	r1, r3
107
		bne	__Copy
108

109
		/* The firmware maps us in blocks of 1 MB, the next block is
110
		   _below_ the last one. So our decrementing source pointer
111
		   ist right here, but the destination pointer must be increased
112
		   by 2 MB */
113
		add	r1, r1, #0x00200000
114
		add	r3, r3, #0x00100000
115

116
		teq	r4, #0
117
		bne	__MoveCode
118

119

120
		/* and jump to it */
121
		adr	r2, __go_on			@ where we want to jump
122
		adr	r0, __ofw_data			@ read the 1. entry of the memory map
123
		ldr	r0, [r0, #4]
124
		sub	r2, r2, r0			@ we are mapped add 0e50 now, sub that (-0e00)
125
		sub	r2, r2, #0x00500000		@ -0050
126
		ldr	r0, __copy_target		@ and add 0850 8000 instead
127
		add	r0, r0, #4
128
		add	r2, r2, r0
129
		mov	pc, r2				@ and jump there
130

131
__go_on:
132
		adr	sp, __temp_stack
133
		add	sp, sp, #128
134
		adr	r0, __ofw_data
135
		mov	lr, pc
136
		b	create_params
137
	
138
		mov	r8, #0
139
		mov	r7, #15
140

141
Product

Resources

Company
