xref: /openbmc/u-boot/arch/arm/cpu/arm720t/start.S (revision 70ad375e) 
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#ifdef CONFIG_USE_IRQ
71/* IRQ stack memory (calculated at run-time) */
72.globl IRQ_STACK_START
73IRQ_STACK_START:
74	.word	0x0badc0de
75
76/* IRQ stack memory (calculated at run-time) */
77.globl FIQ_STACK_START
78FIQ_STACK_START:
79	.word 0x0badc0de
80#endif
81
82/* IRQ stack memory (calculated at run-time) + 8 bytes */
83.globl IRQ_STACK_START_IN
84IRQ_STACK_START_IN:
85	.word	0x0badc0de
86
87/*
88 * the actual reset code
89 */
90
91reset:
92	/*
93	 * set the cpu to SVC32 mode
94	 */
95	mrs	r0,cpsr
96	bic	r0,r0,#0x1f
97	orr	r0,r0,#0xd3
98	msr	cpsr,r0
99
100	/*
101	 * we do sys-critical inits only at reboot,
102	 * not when booting from ram!
103	 */
104#ifndef CONFIG_SKIP_LOWLEVEL_INIT
105	bl	cpu_init_crit
106#endif
107
108	bl	_main
109
110/*------------------------------------------------------------------------------*/
111
112	.globl	c_runtime_cpu_setup
113c_runtime_cpu_setup:
114
115	mov	pc, lr
116
117/*
118 *************************************************************************
119 *
120 * CPU_init_critical registers
121 *
122 * setup important registers
123 * setup memory timing
124 *
125 *************************************************************************
126 */
127
128#ifndef CONFIG_SKIP_LOWLEVEL_INIT
129cpu_init_crit:
130
131	mov	ip, lr
132	/*
133	 * before relocating, we have to setup RAM timing
134	 * because memory timing is board-dependent, you will
135	 * find a lowlevel_init.S in your board directory.
136	 */
137	bl	lowlevel_init
138	mov	lr, ip
139
140	mov	pc, lr
141#endif /* CONFIG_SKIP_LOWLEVEL_INIT */
142
143
144#ifndef CONFIG_SPL_BUILD
145/*
146 *************************************************************************
147 *
148 * Interrupt handling
149 *
150 *************************************************************************
151 */
152
153@
154@ IRQ stack frame.
155@
156#define S_FRAME_SIZE	72
157
158#define S_OLD_R0	68
159#define S_PSR		64
160#define S_PC		60
161#define S_LR		56
162#define S_SP		52
163
164#define S_IP		48
165#define S_FP		44
166#define S_R10		40
167#define S_R9		36
168#define S_R8		32
169#define S_R7		28
170#define S_R6		24
171#define S_R5		20
172#define S_R4		16
173#define S_R3		12
174#define S_R2		8
175#define S_R1		4
176#define S_R0		0
177
178#define MODE_SVC 0x13
179#define I_BIT	 0x80
180
181/*
182 * use bad_save_user_regs for abort/prefetch/undef/swi ...
183 * use irq_save_user_regs / irq_restore_user_regs for IRQ/FIQ handling
184 */
185
186	.macro	bad_save_user_regs
187	sub	sp, sp, #S_FRAME_SIZE
188	stmia	sp, {r0 - r12}			@ Calling r0-r12
189	add	r8, sp, #S_PC
190
191	ldr	r2, IRQ_STACK_START_IN
192	ldmia	r2, {r2 - r4}			@ get pc, cpsr, old_r0
193	add	r0, sp, #S_FRAME_SIZE		@ restore sp_SVC
194
195	add	r5, sp, #S_SP
196	mov	r1, lr
197	stmia	r5, {r0 - r4}			@ save sp_SVC, lr_SVC, pc, cpsr, old_r
198	mov	r0, sp
199	.endm
200
201	.macro	irq_save_user_regs
202	sub	sp, sp, #S_FRAME_SIZE
203	stmia	sp, {r0 - r12}			@ Calling r0-r12
204	add	r8, sp, #S_PC
205	stmdb	r8, {sp, lr}^			@ Calling SP, LR
206	str	lr, [r8, #0]			@ Save calling PC
207	mrs	r6, spsr
208	str	r6, [r8, #4]			@ Save CPSR
209	str	r0, [r8, #8]			@ Save OLD_R0
210	mov	r0, sp
211	.endm
212
213	.macro	irq_restore_user_regs
214	ldmia	sp, {r0 - lr}^			@ Calling r0 - lr
215	mov	r0, r0
216	ldr	lr, [sp, #S_PC]			@ Get PC
217	add	sp, sp, #S_FRAME_SIZE
218	subs	pc, lr, #4			@ return & move spsr_svc into cpsr
219	.endm
220
221	.macro get_bad_stack
222	ldr	r13, IRQ_STACK_START_IN		@ setup our mode stack
223
224	str	lr, [r13]			@ save caller lr / spsr
225	mrs	lr, spsr
226	str	lr, [r13, #4]
227
228	mov	r13, #MODE_SVC			@ prepare SVC-Mode
229	msr	spsr_c, r13
230	mov	lr, pc
231	movs	pc, lr
232	.endm
233
234	.macro get_irq_stack			@ setup IRQ stack
235	ldr	sp, IRQ_STACK_START
236	.endm
237
238	.macro get_fiq_stack			@ setup FIQ stack
239	ldr	sp, FIQ_STACK_START
240	.endm
241
242/*
243 * exception handlers
244 */
245	.align	5
246undefined_instruction:
247	get_bad_stack
248	bad_save_user_regs
249	bl	do_undefined_instruction
250
251	.align	5
252software_interrupt:
253	get_bad_stack
254	bad_save_user_regs
255	bl	do_software_interrupt
256
257	.align	5
258prefetch_abort:
259	get_bad_stack
260	bad_save_user_regs
261	bl	do_prefetch_abort
262
263	.align	5
264data_abort:
265	get_bad_stack
266	bad_save_user_regs
267	bl	do_data_abort
268
269	.align	5
270not_used:
271	get_bad_stack
272	bad_save_user_regs
273	bl	do_not_used
274
275#ifdef CONFIG_USE_IRQ
276
277	.align	5
278irq:
279	get_irq_stack
280	irq_save_user_regs
281	bl	do_irq
282	irq_restore_user_regs
283
284	.align	5
285fiq:
286	get_fiq_stack
287	/* someone ought to write a more effiction fiq_save_user_regs */
288	irq_save_user_regs
289	bl	do_fiq
290	irq_restore_user_regs
291
292#else
293
294	.align	5
295irq:
296	get_bad_stack
297	bad_save_user_regs
298	bl	do_irq
299
300	.align	5
301fiq:
302	get_bad_stack
303	bad_save_user_regs
304	bl	do_fiq
305
306#endif
307#endif /* CONFIG_SPL_BUILD */
308