brcm63xx: add working lzma-loader and use it for initramfs
[openwrt/svn-archive/archive.git] / target / linux / brcm63xx / image / lzma-loader / src / head.S
1 /*
2 * LZMA compressed kernel loader for Atheros AR7XXX/AR9XXX based boards
3 *
4 * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
5 *
6 * Some parts of this code was based on the OpenWrt specific lzma-loader
7 * for the BCM47xx and ADM5120 based boards:
8 * Copyright (C) 2004 Manuel Novoa III (mjn3@codepoet.org)
9 * Copyright (C) 2005 by Oleg I. Vdovikin <oleg@cs.msu.su>
10 *
11 * This program is free software; you can redistribute it and/or modify it
12 * under the terms of the GNU General Public License version 2 as published
13 * by the Free Software Foundation.
14 */
15
16 #include <asm/asm.h>
17 #include <asm/regdef.h>
18 #include "cp0regdef.h"
19 #include "cacheops.h"
20 #include "config.h"
21
22 #define KSEG0 0x80000000
23
24 .macro ehb
25 sll zero, 3
26 .endm
27
28 .text
29
30 LEAF(startup)
31 .set noreorder
32 .set mips32
33
34 mtc0 zero, CP0_WATCHLO # clear watch registers
35 mtc0 zero, CP0_WATCHHI
36 mtc0 zero, CP0_CAUSE # clear before writing status register
37
38 mfc0 t0, CP0_STATUS
39 li t1, 0x1000001f
40 or t0, t1
41 xori t0, 0x1f
42 mtc0 t0, CP0_STATUS
43 ehb
44
45 mtc0 zero, CP0_COUNT
46 mtc0 zero, CP0_COMPARE
47 ehb
48
49 la t0, __reloc_label # get linked address of label
50 bal __reloc_label # branch and link to label to
51 nop # get actual address
52 __reloc_label:
53 subu t0, ra, t0 # get reloc_delta
54
55 beqz t0, __reloc_done # if delta is 0 we are in the right place
56 nop
57
58 /* Copy our code to the right place */
59 la t1, _code_start # get linked address of _code_start
60 la t2, _code_end # get linked address of _code_end
61 addu t0, t0, t1 # calculate actual address of _code_start
62
63 __reloc_copy:
64 lw t3, 0(t0)
65 sw t3, 0(t1)
66 add t1, 4
67 blt t1, t2, __reloc_copy
68 add t0, 4
69
70 /* flush cache */
71 la t0, _code_start
72 la t1, _code_end
73
74 li t2, ~(CONFIG_CACHELINE_SIZE - 1)
75 and t0, t2
76 and t1, t2
77 li t2, CONFIG_CACHELINE_SIZE
78
79 b __flush_check
80 nop
81
82 __flush_line:
83 cache Hit_Writeback_Inv_D, 0(t0)
84 cache Hit_Invalidate_I, 0(t0)
85 add t0, t2
86
87 __flush_check:
88 bne t0, t1, __flush_line
89 nop
90
91 sync
92
93 __reloc_done:
94
95 /* clear bss */
96 la t0, _bss_start
97 la t1, _bss_end
98 b __bss_check
99 nop
100
101 __bss_fill:
102 sw zero, 0(t0)
103 addi t0, 4
104
105 __bss_check:
106 bne t0, t1, __bss_fill
107 nop
108
109 /* Setup new "C" stack */
110 la sp, _stack
111
112 /* jump to the decompressor routine */
113 la t0, loader_main
114 jr t0
115 nop
116
117 .set reorder
118 END(startup)