xref: /openbmc/u-boot/arch/arm/cpu/arm720t/start.S (revision a79854a9) 
1/*
2 *  armboot - Startup Code for ARM720 CPU-core
3 *
4 *  Copyright (c) 2001	Marius Gröger <mag@sysgo.de>
5 *  Copyright (c) 2002	Alex Züpke <azu@sysgo.de>
6 *
7 * SPDX-License-Identifier:	GPL-2.0+
8 */
9
10#include <asm-offsets.h>
11#include <config.h>
12#include <version.h>
13#include <asm/hardware.h>
14
15/*
16 *************************************************************************
17 *
18 * Jump vector table as in table 3.1 in [1]
19 *
20 *************************************************************************
21 */
22
23
24.globl _start
25_start: b	reset
26	ldr	pc, _undefined_instruction
27	ldr	pc, _software_interrupt
28	ldr	pc, _prefetch_abort
29	ldr	pc, _data_abort
30	ldr	pc, _not_used
31	ldr	pc, _irq
32	ldr	pc, _fiq
33
34#ifdef CONFIG_SPL_BUILD
35_undefined_instruction: .word _undefined_instruction
36_software_interrupt:	.word _software_interrupt
37_prefetch_abort:	.word _prefetch_abort
38_data_abort:		.word _data_abort
39_not_used:		.word _not_used
40_irq:			.word _irq
41_fiq:			.word _fiq
42_pad:			.word 0x12345678 /* now 16*4=64 */
43#else
44_undefined_instruction: .word undefined_instruction
45_software_interrupt:	.word software_interrupt
46_prefetch_abort:	.word prefetch_abort
47_data_abort:		.word data_abort
48_not_used:		.word not_used
49_irq:			.word irq
50_fiq:			.word fiq
51_pad:			.word 0x12345678 /* now 16*4=64 */
52#endif	/* CONFIG_SPL_BUILD */
53
54	.balignl 16,0xdeadbeef
55
56
57/*
58 *************************************************************************
59 *
60 * Startup Code (reset vector)
61 *
62 * do important init only if we don't start from RAM!
63 * relocate armboot to ram
64 * setup stack
65 * jump to second stage
66 *
67 *************************************************************************
68 */
69
70.globl _TEXT_BASE
71_TEXT_BASE:
72#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_TEXT_BASE)
73	.word	CONFIG_SPL_TEXT_BASE
74#else
75	.word	CONFIG_SYS_TEXT_BASE
76#endif
77
78/*
79 * These are defined in the board-specific linker script.
80 * Subtracting _start from them lets the linker put their
81 * relative position in the executable instead of leaving
82 * them null.
83 */
84.globl _bss_start_ofs
85_bss_start_ofs:
86	.word __bss_start - _start
87
88.globl _bss_end_ofs
89_bss_end_ofs:
90	.word __bss_end - _start
91
92.globl _end_ofs
93_end_ofs:
94	.word _end - _start
95
96#ifdef CONFIG_USE_IRQ
97/* IRQ stack memory (calculated at run-time) */
98.globl IRQ_STACK_START
99IRQ_STACK_START:
100	.word	0x0badc0de
101
102/* IRQ stack memory (calculated at run-time) */
103.globl FIQ_STACK_START
104FIQ_STACK_START:
105	.word 0x0badc0de
106#endif
107
108/* IRQ stack memory (calculated at run-time) + 8 bytes */
109.globl IRQ_STACK_START_IN
110IRQ_STACK_START_IN:
111	.word	0x0badc0de
112
113/*
114 * the actual reset code
115 */
116
117reset:
118	/*
119	 * set the cpu to SVC32 mode
120	 */
121	mrs	r0,cpsr
122	bic	r0,r0,#0x1f
123	orr	r0,r0,#0xd3
124	msr	cpsr,r0
125
126	/*
127	 * we do sys-critical inits only at reboot,
128	 * not when booting from ram!
129	 */
130#ifndef CONFIG_SKIP_LOWLEVEL_INIT
131	bl	cpu_init_crit
132#endif
133
134	bl	_main
135
136/*------------------------------------------------------------------------------*/
137
138	.globl	c_runtime_cpu_setup
139c_runtime_cpu_setup:
140
141	mov	pc, lr
142
143/*
144 *************************************************************************
145 *
146 * CPU_init_critical registers
147 *
148 * setup important registers
149 * setup memory timing
150 *
151 *************************************************************************
152 */
153
154#ifndef CONFIG_SKIP_LOWLEVEL_INIT
155cpu_init_crit:
156
157	mov	ip, lr
158	/*
159	 * before relocating, we have to setup RAM timing
160	 * because memory timing is board-dependent, you will
161	 * find a lowlevel_init.S in your board directory.
162	 */
163	bl	lowlevel_init
164	mov	lr, ip
165
166	mov	pc, lr
167#endif /* CONFIG_SKIP_LOWLEVEL_INIT */
168
169
170#ifndef CONFIG_SPL_BUILD
171/*
172 *************************************************************************
173 *
174 * Interrupt handling
175 *
176 *************************************************************************
177 */
178
179@
180@ IRQ stack frame.
181@
182#define S_FRAME_SIZE	72
183
184#define S_OLD_R0	68
185#define S_PSR		64
186#define S_PC		60
187#define S_LR		56
188#define S_SP		52
189
190#define S_IP		48
191#define S_FP		44
192#define S_R10		40
193#define S_R9		36
194#define S_R8		32
195#define S_R7		28
196#define S_R6		24
197#define S_R5		20
198#define S_R4		16
199#define S_R3		12
200#define S_R2		8
201#define S_R1		4
202#define S_R0		0
203
204#define MODE_SVC 0x13
205#define I_BIT	 0x80
206
207/*
208 * use bad_save_user_regs for abort/prefetch/undef/swi ...
209 * use irq_save_user_regs / irq_restore_user_regs for IRQ/FIQ handling
210 */
211
212	.macro	bad_save_user_regs
213	sub	sp, sp, #S_FRAME_SIZE
214	stmia	sp, {r0 - r12}			@ Calling r0-r12
215	add	r8, sp, #S_PC
216
217	ldr	r2, IRQ_STACK_START_IN
218	ldmia	r2, {r2 - r4}			@ get pc, cpsr, old_r0
219	add	r0, sp, #S_FRAME_SIZE		@ restore sp_SVC
220
221	add	r5, sp, #S_SP
222	mov	r1, lr
223	stmia	r5, {r0 - r4}			@ save sp_SVC, lr_SVC, pc, cpsr, old_r
224	mov	r0, sp
225	.endm
226
227	.macro	irq_save_user_regs
228	sub	sp, sp, #S_FRAME_SIZE
229	stmia	sp, {r0 - r12}			@ Calling r0-r12
230	add	r8, sp, #S_PC
231	stmdb	r8, {sp, lr}^			@ Calling SP, LR
232	str	lr, [r8, #0]			@ Save calling PC
233	mrs	r6, spsr
234	str	r6, [r8, #4]			@ Save CPSR
235	str	r0, [r8, #8]			@ Save OLD_R0
236	mov	r0, sp
237	.endm
238
239	.macro	irq_restore_user_regs
240	ldmia	sp, {r0 - lr}^			@ Calling r0 - lr
241	mov	r0, r0
242	ldr	lr, [sp, #S_PC]			@ Get PC
243	add	sp, sp, #S_FRAME_SIZE
244	subs	pc, lr, #4			@ return & move spsr_svc into cpsr
245	.endm
246
247	.macro get_bad_stack
248	ldr	r13, IRQ_STACK_START_IN		@ setup our mode stack
249
250	str	lr, [r13]			@ save caller lr / spsr
251	mrs	lr, spsr
252	str	lr, [r13, #4]
253
254	mov	r13, #MODE_SVC			@ prepare SVC-Mode
255	msr	spsr_c, r13
256	mov	lr, pc
257	movs	pc, lr
258	.endm
259
260	.macro get_irq_stack			@ setup IRQ stack
261	ldr	sp, IRQ_STACK_START
262	.endm
263
264	.macro get_fiq_stack			@ setup FIQ stack
265	ldr	sp, FIQ_STACK_START
266	.endm
267
268/*
269 * exception handlers
270 */
271	.align	5
272undefined_instruction:
273	get_bad_stack
274	bad_save_user_regs
275	bl	do_undefined_instruction
276
277	.align	5
278software_interrupt:
279	get_bad_stack
280	bad_save_user_regs
281	bl	do_software_interrupt
282
283	.align	5
284prefetch_abort:
285	get_bad_stack
286	bad_save_user_regs
287	bl	do_prefetch_abort
288
289	.align	5
290data_abort:
291	get_bad_stack
292	bad_save_user_regs
293	bl	do_data_abort
294
295	.align	5
296not_used:
297	get_bad_stack
298	bad_save_user_regs
299	bl	do_not_used
300
301#ifdef CONFIG_USE_IRQ
302
303	.align	5
304irq:
305	get_irq_stack
306	irq_save_user_regs
307	bl	do_irq
308	irq_restore_user_regs
309
310	.align	5
311fiq:
312	get_fiq_stack
313	/* someone ought to write a more effiction fiq_save_user_regs */
314	irq_save_user_regs
315	bl	do_fiq
316	irq_restore_user_regs
317
318#else
319
320	.align	5
321irq:
322	get_bad_stack
323	bad_save_user_regs
324	bl	do_irq
325
326	.align	5
327fiq:
328	get_bad_stack
329	bad_save_user_regs
330	bl	do_fiq
331
332#endif
333#endif /* CONFIG_SPL_BUILD */
334