summaryrefslogtreecommitdiff
path: root/arch/mips/cpu/xburst/start.S
blob: d2c064b0175b0c5368e5a7d183c9192bc6340b8e (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
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
/*
 *  Startup Code for MIPS32 XBURST CPU-core
 *
 *  Copyright (c) 2010 Xiangfu Liu <xiangfu@sharism.cc>
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

#include <config.h>
#include <version.h>
#include <asm/regdef.h>
#include <asm/mipsregs.h>
#include <asm/addrspace.h>
#include <asm/cacheops.h>

	.set noreorder

	.globl _start
	.text
_start:
	/* Initialize $gp */
	bal	1f
	 nop
	.word	_gp
1:
	lw	gp, 0(ra)

	/* Set up temporary stack */
	li	sp, CONFIG_SYS_SDRAM_BASE + CONFIG_SYS_INIT_SP_OFFSET

	la	t9, board_init_f
	jr	t9
	 nop

/*
 * void relocate_code (addr_sp, gd, addr_moni)
 *
 * This "function" does not return, instead it continues in RAM
 * after relocating the monitor code.
 *
 * a0 = addr_sp
 * a1 = gd
 * a2 = destination address
 */
	.globl	relocate_code
	.ent	relocate_code
relocate_code:
	move	sp, a0			# set new stack pointer

	li	t0, CONFIG_SYS_MONITOR_BASE
	sub	t6, a2, t0		# t6 <-- relocation offset

	la	t3, in_ram
	lw	t2, -12(t3)		# t2 <-- __image_copy_end
	move	t1, a2

	add	gp, t6			# adjust gp

	/*
	 * t0 = source address
	 * t1 = target address
	 * t2 = source end address
	 */
1:
	lw	t3, 0(t0)
	sw	t3, 0(t1)
	addu	t0, 4
	blt	t0, t2, 1b
	 addu	t1, 4

	/* If caches were enabled, we would have to flush them here. */

	/* flush d-cache */
	li	t0, KSEG0
	addi	t1, t0, CONFIG_SYS_DCACHE_SIZE
2:
	cache	INDEX_WRITEBACK_INV_D, 0(t0)
	bne	t0, t1, 2b
	 addi	t0, CONFIG_SYS_CACHELINE_SIZE

	sync

	/* flush i-cache */
	li	t0, KSEG0
	addi	t1, t0, CONFIG_SYS_ICACHE_SIZE
3:
	cache	INDEX_INVALIDATE_I, 0(t0)
	bne	t0, t1, 3b
	 addi	t0, CONFIG_SYS_CACHELINE_SIZE

	/* Invalidate BTB */
	mfc0	t0, CP0_CONFIG, 7
	nop
	ori	t0, 2
	mtc0	t0, CP0_CONFIG, 7
	nop

	/* Jump to where we've relocated ourselves */
	addi	t0, a2, in_ram - _start
	jr	t0
	 nop

	.word	__rel_dyn_end
	.word	__rel_dyn_start
	.word	__image_copy_end
	.word	_GLOBAL_OFFSET_TABLE_
	.word	num_got_entries

in_ram:
	/*
	 * Now we want to update GOT.
	 *
	 * GOT[0] is reserved. GOT[1] is also reserved for the dynamic object
	 * generated by GNU ld. Skip these reserved entries from relocation.
	 */
	lw	t3, -4(t0)		# t3 <-- num_got_entries
	lw	t4, -8(t0)		# t4 <-- _GLOBAL_OFFSET_TABLE_
	add	t4, t6			# t4 now holds relocated _G_O_T_
	addi	t4, t4, 8		# skipping first two entries
	li	t2, 2
1:
	lw	t1, 0(t4)
	beqz	t1, 2f
	 add	t1, t6
	sw	t1, 0(t4)
2:
	addi	t2, 1
	blt	t2, t3, 1b
	 addi	t4, 4

	/* Update dynamic relocations */
	lw	t1, -16(t0)		# t1 <-- __rel_dyn_start
	lw	t2, -20(t0)		# t2 <-- __rel_dyn_end

	b	2f			# skip first reserved entry
	 addi	t1, 8

1:
	lw	t3, -4(t1)		# t3 <-- relocation info

	sub	t3, 3
	bnez	t3, 2f			# skip non R_MIPS_REL32 entries
	 nop

	lw	t3, -8(t1)		# t3 <-- location to fix up in FLASH

	lw	t4, 0(t3)		# t4 <-- original pointer
	add	t4, t6			# t4 <-- adjusted pointer

	add	t3, t6			# t3 <-- location to fix up in RAM
	sw	t4, 0(t3)

2:
	blt	t1, t2, 1b
	 addi	t1, 8			# each rel.dyn entry is 8 bytes

	/*
	 * Clear BSS
	 *
	 * GOT is now relocated. Thus __bss_start and __bss_end can be
	 * accessed directly via $gp.
	 */
	la	t1, __bss_start		# t1 <-- __bss_start
	la	t2, __bss_end		# t2 <-- __bss_end

1:
	sw	zero, 0(t1)
	blt	t1, t2, 1b
	 addi	t1, 4

	move	a0, a1			# a0 <-- gd
	la	t9, board_init_r
	jr	t9
	 move	a1, a2

	.end	relocate_code