xref: /openbmc/u-boot/arch/arm/cpu/arm926ejs/start.S (revision 901d0ea1) 
1/*
2 *  armboot - Startup Code for ARM926EJS CPU-core
3 *
4 *  Copyright (c) 2003  Texas Instruments
5 *
6 *  ----- Adapted for OMAP1610 OMAP730 from ARM925t code ------
7 *
8 *  Copyright (c) 2001	Marius Gröger <mag@sysgo.de>
9 *  Copyright (c) 2002	Alex Züpke <azu@sysgo.de>
10 *  Copyright (c) 2002	Gary Jennejohn <garyj@denx.de>
11 *  Copyright (c) 2003	Richard Woodruff <r-woodruff2@ti.com>
12 *  Copyright (c) 2003	Kshitij <kshitij@ti.com>
13 *  Copyright (c) 2010	Albert Aribaud <albert.u.boot@aribaud.net>
14 *
15 * SPDX-License-Identifier:	GPL-2.0+
16 */
17
18#include <asm-offsets.h>
19#include <config.h>
20#include <common.h>
21#include <version.h>
22
23/*
24 *************************************************************************
25 *
26 * Jump vector table as in table 3.1 in [1]
27 *
28 *************************************************************************
29 */
30
31
32#ifdef CONFIG_SYS_DV_NOR_BOOT_CFG
33.globl _start
34_start:
35.globl _NOR_BOOT_CFG
36_NOR_BOOT_CFG:
37	.word	CONFIG_SYS_DV_NOR_BOOT_CFG
38	b	reset
39#else
40.globl _start
41_start:
42	b	reset
43#endif
44#ifdef CONFIG_SPL_BUILD
45/* No exception handlers in preloader */
46	ldr	pc, _hang
47	ldr	pc, _hang
48	ldr	pc, _hang
49	ldr	pc, _hang
50	ldr	pc, _hang
51	ldr	pc, _hang
52	ldr	pc, _hang
53
54_hang:
55	.word	do_hang
56/* pad to 64 byte boundary */
57	.word	0x12345678
58	.word	0x12345678
59	.word	0x12345678
60	.word	0x12345678
61	.word	0x12345678
62	.word	0x12345678
63	.word	0x12345678
64#else
65	ldr	pc, _undefined_instruction
66	ldr	pc, _software_interrupt
67	ldr	pc, _prefetch_abort
68	ldr	pc, _data_abort
69	ldr	pc, _not_used
70	ldr	pc, _irq
71	ldr	pc, _fiq
72
73_undefined_instruction:
74	.word undefined_instruction
75_software_interrupt:
76	.word software_interrupt
77_prefetch_abort:
78	.word prefetch_abort
79_data_abort:
80	.word data_abort
81_not_used:
82	.word not_used
83_irq:
84	.word irq
85_fiq:
86	.word fiq
87
88#endif	/* CONFIG_SPL_BUILD */
89	.balignl 16,0xdeadbeef
90
91
92/*
93 *************************************************************************
94 *
95 * Startup Code (reset vector)
96 *
97 * do important init only if we don't start from memory!
98 * setup Memory and board specific bits prior to relocation.
99 * relocate armboot to ram
100 * setup stack
101 *
102 *************************************************************************
103 */
104
105.globl _TEXT_BASE
106_TEXT_BASE:
107#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_TEXT_BASE)
108	.word	CONFIG_SPL_TEXT_BASE
109#else
110	.word	CONFIG_SYS_TEXT_BASE
111#endif
112
113/*
114 * These are defined in the board-specific linker script.
115 * Subtracting _start from them lets the linker put their
116 * relative position in the executable instead of leaving
117 * them null.
118 */
119.globl _bss_start_ofs
120_bss_start_ofs:
121	.word __bss_start - _start
122
123.globl _bss_end_ofs
124_bss_end_ofs:
125	.word __bss_end - _start
126
127.globl _end_ofs
128_end_ofs:
129	.word _end - _start
130
131#ifdef CONFIG_USE_IRQ
132/* IRQ stack memory (calculated at run-time) */
133.globl IRQ_STACK_START
134IRQ_STACK_START:
135	.word	0x0badc0de
136
137/* IRQ stack memory (calculated at run-time) */
138.globl FIQ_STACK_START
139FIQ_STACK_START:
140	.word 0x0badc0de
141#endif
142
143/* IRQ stack memory (calculated at run-time) + 8 bytes */
144.globl IRQ_STACK_START_IN
145IRQ_STACK_START_IN:
146	.word	0x0badc0de
147
148/*
149 * the actual reset code
150 */
151
152reset:
153	/*
154	 * set the cpu to SVC32 mode
155	 */
156	mrs	r0,cpsr
157	bic	r0,r0,#0x1f
158	orr	r0,r0,#0xd3
159	msr	cpsr,r0
160
161	/*
162	 * we do sys-critical inits only at reboot,
163	 * not when booting from ram!
164	 */
165#ifndef CONFIG_SKIP_LOWLEVEL_INIT
166	bl	cpu_init_crit
167#endif
168
169	bl	_main
170
171/*------------------------------------------------------------------------------*/
172
173	.globl	c_runtime_cpu_setup
174c_runtime_cpu_setup:
175
176	bx	lr
177
178/*
179 *************************************************************************
180 *
181 * CPU_init_critical registers
182 *
183 * setup important registers
184 * setup memory timing
185 *
186 *************************************************************************
187 */
188#ifndef CONFIG_SKIP_LOWLEVEL_INIT
189cpu_init_crit:
190	/*
191	 * flush D cache before disabling it
192	 */
193	mov	r0, #0
194flush_dcache:
195	mrc	p15, 0, r15, c7, c10, 3
196	bne	flush_dcache
197
198	mcr	p15, 0, r0, c8, c7, 0	/* invalidate TLB */
199	mcr	p15, 0, r0, c7, c5, 0	/* invalidate I Cache */
200
201	/*
202	 * disable MMU and D cache
203	 * enable I cache if CONFIG_SYS_ICACHE_OFF is not defined
204	 */
205	mrc	p15, 0, r0, c1, c0, 0
206	bic	r0, r0, #0x00000300	/* clear bits 9:8 (---- --RS) */
207	bic	r0, r0, #0x00000087	/* clear bits 7, 2:0 (B--- -CAM) */
208#ifdef CONFIG_SYS_EXCEPTION_VECTORS_HIGH
209	orr	r0, r0, #0x00002000	/* set bit 13 (--V- ----) */
210#else
211	bic	r0, r0, #0x00002000	/* clear bit 13 (--V- ----) */
212#endif
213	orr	r0, r0, #0x00000002	/* set bit 2 (A) Align */
214#ifndef CONFIG_SYS_ICACHE_OFF
215	orr	r0, r0, #0x00001000	/* set bit 12 (I) I-Cache */
216#endif
217	mcr	p15, 0, r0, c1, c0, 0
218
219	/*
220	 * Go setup Memory and board specific bits prior to relocation.
221	 */
222	mov	ip, lr		/* perserve link reg across call */
223	bl	lowlevel_init	/* go setup pll,mux,memory */
224	mov	lr, ip		/* restore link */
225	mov	pc, lr		/* back to my caller */
226#endif /* CONFIG_SKIP_LOWLEVEL_INIT */
227
228#ifndef CONFIG_SPL_BUILD
229/*
230 *************************************************************************
231 *
232 * Interrupt handling
233 *
234 *************************************************************************
235 */
236
237@
238@ IRQ stack frame.
239@
240#define S_FRAME_SIZE	72
241
242#define S_OLD_R0	68
243#define S_PSR		64
244#define S_PC		60
245#define S_LR		56
246#define S_SP		52
247
248#define S_IP		48
249#define S_FP		44
250#define S_R10		40
251#define S_R9		36
252#define S_R8		32
253#define S_R7		28
254#define S_R6		24
255#define S_R5		20
256#define S_R4		16
257#define S_R3		12
258#define S_R2		8
259#define S_R1		4
260#define S_R0		0
261
262#define MODE_SVC 0x13
263#define I_BIT	 0x80
264
265/*
266 * use bad_save_user_regs for abort/prefetch/undef/swi ...
267 * use irq_save_user_regs / irq_restore_user_regs for IRQ/FIQ handling
268 */
269
270	.macro	bad_save_user_regs
271	@ carve out a frame on current user stack
272	sub	sp, sp, #S_FRAME_SIZE
273	stmia	sp, {r0 - r12}	@ Save user registers (now in svc mode) r0-r12
274	ldr	r2, IRQ_STACK_START_IN
275	@ get values for "aborted" pc and cpsr (into parm regs)
276	ldmia	r2, {r2 - r3}
277	add	r0, sp, #S_FRAME_SIZE		@ grab pointer to old stack
278	add	r5, sp, #S_SP
279	mov	r1, lr
280	stmia	r5, {r0 - r3}	@ save sp_SVC, lr_SVC, pc, cpsr
281	mov	r0, sp		@ save current stack into r0 (param register)
282	.endm
283
284	.macro	irq_save_user_regs
285	sub	sp, sp, #S_FRAME_SIZE
286	stmia	sp, {r0 - r12}			@ Calling r0-r12
287	@ !!!! R8 NEEDS to be saved !!!! a reserved stack spot would be good.
288	add	r8, sp, #S_PC
289	stmdb	r8, {sp, lr}^		@ Calling SP, LR
290	str	lr, [r8, #0]		@ Save calling PC
291	mrs	r6, spsr
292	str	r6, [r8, #4]		@ Save CPSR
293	str	r0, [r8, #8]		@ Save OLD_R0
294	mov	r0, sp
295	.endm
296
297	.macro	irq_restore_user_regs
298	ldmia	sp, {r0 - lr}^			@ Calling r0 - lr
299	mov	r0, r0
300	ldr	lr, [sp, #S_PC]			@ Get PC
301	add	sp, sp, #S_FRAME_SIZE
302	subs	pc, lr, #4		@ return & move spsr_svc into cpsr
303	.endm
304
305	.macro get_bad_stack
306	ldr	r13, IRQ_STACK_START_IN		@ setup our mode stack
307
308	str	lr, [r13]	@ save caller lr in position 0 of saved stack
309	mrs	lr, spsr	@ get the spsr
310	str	lr, [r13, #4]	@ save spsr in position 1 of saved stack
311	mov	r13, #MODE_SVC	@ prepare SVC-Mode
312	@ msr	spsr_c, r13
313	msr	spsr, r13	@ switch modes, make sure moves will execute
314	mov	lr, pc		@ capture return pc
315	movs	pc, lr		@ jump to next instruction & switch modes.
316	.endm
317
318	.macro get_irq_stack			@ setup IRQ stack
319	ldr	sp, IRQ_STACK_START
320	.endm
321
322	.macro get_fiq_stack			@ setup FIQ stack
323	ldr	sp, FIQ_STACK_START
324	.endm
325#endif	/* CONFIG_SPL_BUILD */
326
327/*
328 * exception handlers
329 */
330#ifdef CONFIG_SPL_BUILD
331	.align	5
332do_hang:
333	ldr	sp, _TEXT_BASE			/* switch to abort stack */
3341:
335	bl	1b				/* hang and never return */
336#else	/* !CONFIG_SPL_BUILD */
337	.align  5
338undefined_instruction:
339	get_bad_stack
340	bad_save_user_regs
341	bl	do_undefined_instruction
342
343	.align	5
344software_interrupt:
345	get_bad_stack
346	bad_save_user_regs
347	bl	do_software_interrupt
348
349	.align	5
350prefetch_abort:
351	get_bad_stack
352	bad_save_user_regs
353	bl	do_prefetch_abort
354
355	.align	5
356data_abort:
357	get_bad_stack
358	bad_save_user_regs
359	bl	do_data_abort
360
361	.align	5
362not_used:
363	get_bad_stack
364	bad_save_user_regs
365	bl	do_not_used
366
367#ifdef CONFIG_USE_IRQ
368
369	.align	5
370irq:
371	get_irq_stack
372	irq_save_user_regs
373	bl	do_irq
374	irq_restore_user_regs
375
376	.align	5
377fiq:
378	get_fiq_stack
379	/* someone ought to write a more effiction fiq_save_user_regs */
380	irq_save_user_regs
381	bl	do_fiq
382	irq_restore_user_regs
383
384#else
385
386	.align	5
387irq:
388	get_bad_stack
389	bad_save_user_regs
390	bl	do_irq
391
392	.align	5
393fiq:
394	get_bad_stack
395	bad_save_user_regs
396	bl	do_fiq
397
398#endif
399#endif	/* CONFIG_SPL_BUILD */
400