xref: /openbmc/u-boot/arch/arm/cpu/armv7/start.S (revision a2ac1b3a) 
1/*
2 * armboot - Startup Code for OMAP3530/ARM Cortex CPU-core
3 *
4 * Copyright (c) 2004	Texas Instruments <r-woodruff2@ti.com>
5 *
6 * Copyright (c) 2001	Marius Gröger <mag@sysgo.de>
7 * Copyright (c) 2002	Alex Züpke <azu@sysgo.de>
8 * Copyright (c) 2002	Gary Jennejohn <garyj@denx.de>
9 * Copyright (c) 2003	Richard Woodruff <r-woodruff2@ti.com>
10 * Copyright (c) 2003	Kshitij <kshitij@ti.com>
11 * Copyright (c) 2006-2008 Syed Mohammed Khasim <x0khasim@ti.com>
12 *
13 * See file CREDITS for list of people who contributed to this
14 * project.
15 *
16 * This program is free software; you can redistribute it and/or
17 * modify it under the terms of the GNU General Public License as
18 * published by the Free Software Foundation; either version 2 of
19 * the License, or (at your option) any later version.
20 *
21 * This program is distributed in the hope that it will be useful,
22 * but WITHOUT ANY WARRANTY; without even the implied warranty of
23 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
24 * GNU General Public License for more details.
25 *
26 * You should have received a copy of the GNU General Public License
27 * along with this program; if not, write to the Free Software
28 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
29 * MA 02111-1307 USA
30 */
31
32#include <asm-offsets.h>
33#include <config.h>
34#include <version.h>
35#include <asm/system.h>
36#include <linux/linkage.h>
37
38.globl _start
39_start: b	reset
40	ldr	pc, _undefined_instruction
41	ldr	pc, _software_interrupt
42	ldr	pc, _prefetch_abort
43	ldr	pc, _data_abort
44	ldr	pc, _not_used
45	ldr	pc, _irq
46	ldr	pc, _fiq
47#ifdef CONFIG_SPL_BUILD
48_undefined_instruction: .word _undefined_instruction
49_software_interrupt:	.word _software_interrupt
50_prefetch_abort:	.word _prefetch_abort
51_data_abort:		.word _data_abort
52_not_used:		.word _not_used
53_irq:			.word _irq
54_fiq:			.word _fiq
55_pad:			.word 0x12345678 /* now 16*4=64 */
56#else
57_undefined_instruction: .word undefined_instruction
58_software_interrupt:	.word software_interrupt
59_prefetch_abort:	.word prefetch_abort
60_data_abort:		.word data_abort
61_not_used:		.word not_used
62_irq:			.word irq
63_fiq:			.word fiq
64_pad:			.word 0x12345678 /* now 16*4=64 */
65#endif	/* CONFIG_SPL_BUILD */
66
67.global _end_vect
68_end_vect:
69
70	.balignl 16,0xdeadbeef
71/*************************************************************************
72 *
73 * Startup Code (reset vector)
74 *
75 * do important init only if we don't start from memory!
76 * setup Memory and board specific bits prior to relocation.
77 * relocate armboot to ram
78 * setup stack
79 *
80 *************************************************************************/
81
82.globl _TEXT_BASE
83_TEXT_BASE:
84	.word	CONFIG_SYS_TEXT_BASE
85
86/*
87 * These are defined in the board-specific linker script.
88 */
89.globl _bss_start_ofs
90_bss_start_ofs:
91	.word __bss_start - _start
92
93.global	_image_copy_end_ofs
94_image_copy_end_ofs:
95	.word 	__image_copy_end - _start
96
97.globl _bss_end_ofs
98_bss_end_ofs:
99	.word __bss_end__ - _start
100
101.globl _end_ofs
102_end_ofs:
103	.word _end - _start
104
105#ifdef CONFIG_USE_IRQ
106/* IRQ stack memory (calculated at run-time) */
107.globl IRQ_STACK_START
108IRQ_STACK_START:
109	.word	0x0badc0de
110
111/* IRQ stack memory (calculated at run-time) */
112.globl FIQ_STACK_START
113FIQ_STACK_START:
114	.word 0x0badc0de
115#endif
116
117/* IRQ stack memory (calculated at run-time) + 8 bytes */
118.globl IRQ_STACK_START_IN
119IRQ_STACK_START_IN:
120	.word	0x0badc0de
121
122/*
123 * the actual reset code
124 */
125
126reset:
127	bl	save_boot_params
128	/*
129	 * set the cpu to SVC32 mode
130	 */
131	mrs	r0, cpsr
132	bic	r0, r0, #0x1f
133	orr	r0, r0, #0xd3
134	msr	cpsr,r0
135
136/*
137 * Setup vector:
138 * (OMAP4 spl TEXT_BASE is not 32 byte aligned.
139 * Continue to use ROM code vector only in OMAP4 spl)
140 */
141#if !(defined(CONFIG_OMAP44XX) && defined(CONFIG_SPL_BUILD))
142	/* Set V=0 in CP15 SCTRL register - for VBAR to point to vector */
143	mrc	p15, 0, r0, c1, c0, 0	@ Read CP15 SCTRL Register
144	bic	r0, #CR_V		@ V = 0
145	mcr	p15, 0, r0, c1, c0, 0	@ Write CP15 SCTRL Register
146
147	/* Set vector address in CP15 VBAR register */
148	ldr	r0, =_start
149	mcr	p15, 0, r0, c12, c0, 0	@Set VBAR
150#endif
151
152	/* the mask ROM code should have PLL and others stable */
153#ifndef CONFIG_SKIP_LOWLEVEL_INIT
154	bl	cpu_init_cp15
155	bl	cpu_init_crit
156#endif
157
158/* Set stackpointer in internal RAM to call board_init_f */
159call_board_init_f:
160	ldr	sp, =(CONFIG_SYS_INIT_SP_ADDR)
161	bic	sp, sp, #7 /* 8-byte alignment for ABI compliance */
162	ldr	r0,=0x00000000
163	bl	board_init_f
164
165/*------------------------------------------------------------------------------*/
166
167#ifndef CONFIG_SPL_BUILD
168/*
169 * void relocate_code (addr_sp, gd, addr_moni)
170 *
171 * This "function" does not return, instead it continues in RAM
172 * after relocating the monitor code.
173 *
174 */
175ENTRY(relocate_code)
176	mov	r4, r0	/* save addr_sp */
177	mov	r5, r1	/* save addr of gd */
178	mov	r6, r2	/* save addr of destination */
179
180	/* Set up the stack						    */
181stack_setup:
182	mov	sp, r4
183
184	adr	r0, _start
185	cmp	r0, r6
186	moveq	r9, #0		/* no relocation. relocation offset(r9) = 0 */
187	beq	clear_bss		/* skip relocation */
188	mov	r1, r6			/* r1 <- scratch for copy_loop */
189	ldr	r3, _image_copy_end_ofs
190	add	r2, r0, r3		/* r2 <- source end address	    */
191
192copy_loop:
193	ldmia	r0!, {r9-r10}		/* copy from source address [r0]    */
194	stmia	r1!, {r9-r10}		/* copy to   target address [r1]    */
195	cmp	r0, r2			/* until source end address [r2]    */
196	blo	copy_loop
197
198	/*
199	 * fix .rel.dyn relocations
200	 */
201	ldr	r0, _TEXT_BASE		/* r0 <- Text base */
202	sub	r9, r6, r0		/* r9 <- relocation offset */
203	ldr	r10, _dynsym_start_ofs	/* r10 <- sym table ofs */
204	add	r10, r10, r0		/* r10 <- sym table in FLASH */
205	ldr	r2, _rel_dyn_start_ofs	/* r2 <- rel dyn start ofs */
206	add	r2, r2, r0		/* r2 <- rel dyn start in FLASH */
207	ldr	r3, _rel_dyn_end_ofs	/* r3 <- rel dyn end ofs */
208	add	r3, r3, r0		/* r3 <- rel dyn end in FLASH */
209fixloop:
210	ldr	r0, [r2]		/* r0 <- location to fix up, IN FLASH! */
211	add	r0, r0, r9		/* r0 <- location to fix up in RAM */
212	ldr	r1, [r2, #4]
213	and	r7, r1, #0xff
214	cmp	r7, #23			/* relative fixup? */
215	beq	fixrel
216	cmp	r7, #2			/* absolute fixup? */
217	beq	fixabs
218	/* ignore unknown type of fixup */
219	b	fixnext
220fixabs:
221	/* absolute fix: set location to (offset) symbol value */
222	mov	r1, r1, LSR #4		/* r1 <- symbol index in .dynsym */
223	add	r1, r10, r1		/* r1 <- address of symbol in table */
224	ldr	r1, [r1, #4]		/* r1 <- symbol value */
225	add	r1, r1, r9		/* r1 <- relocated sym addr */
226	b	fixnext
227fixrel:
228	/* relative fix: increase location by offset */
229	ldr	r1, [r0]
230	add	r1, r1, r9
231fixnext:
232	str	r1, [r0]
233	add	r2, r2, #8		/* each rel.dyn entry is 8 bytes */
234	cmp	r2, r3
235	blo	fixloop
236	b	clear_bss
237_rel_dyn_start_ofs:
238	.word __rel_dyn_start - _start
239_rel_dyn_end_ofs:
240	.word __rel_dyn_end - _start
241_dynsym_start_ofs:
242	.word __dynsym_start - _start
243
244clear_bss:
245	ldr	r0, _bss_start_ofs
246	ldr	r1, _bss_end_ofs
247	mov	r4, r6			/* reloc addr */
248	add	r0, r0, r4
249	add	r1, r1, r4
250	mov	r2, #0x00000000		/* clear			    */
251
252clbss_l:cmp	r0, r1			/* clear loop... */
253	bhs	clbss_e			/* if reached end of bss, exit */
254	str	r2, [r0]
255	add	r0, r0, #4
256	b	clbss_l
257clbss_e:
258
259/*
260 * We are done. Do not return, instead branch to second part of board
261 * initialization, now running from RAM.
262 */
263jump_2_ram:
264/*
265 * If I-cache is enabled invalidate it
266 */
267#ifndef CONFIG_SYS_ICACHE_OFF
268	mcr	p15, 0, r0, c7, c5, 0	@ invalidate icache
269	mcr     p15, 0, r0, c7, c10, 4	@ DSB
270	mcr     p15, 0, r0, c7, c5, 4	@ ISB
271#endif
272/*
273 * Move vector table
274 */
275#if !defined(CONFIG_TEGRA20)
276	/* Set vector address in CP15 VBAR register */
277	ldr     r0, =_start
278	add     r0, r0, r9
279	mcr     p15, 0, r0, c12, c0, 0  @Set VBAR
280#endif /* !Tegra20 */
281
282	ldr	r0, _board_init_r_ofs
283	adr	r1, _start
284	add	lr, r0, r1
285	add	lr, lr, r9
286	/* setup parameters for board_init_r */
287	mov	r0, r5		/* gd_t */
288	mov	r1, r6		/* dest_addr */
289	/* jump to it ... */
290	mov	pc, lr
291
292_board_init_r_ofs:
293	.word board_init_r - _start
294ENDPROC(relocate_code)
295#endif
296
297/*************************************************************************
298 *
299 * void save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3)
300 *	__attribute__((weak));
301 *
302 * Stack pointer is not yet initialized at this moment
303 * Don't save anything to stack even if compiled with -O0
304 *
305 *************************************************************************/
306ENTRY(save_boot_params)
307	bx	lr			@ back to my caller
308ENDPROC(save_boot_params)
309	.weak	save_boot_params
310
311/*************************************************************************
312 *
313 * cpu_init_cp15
314 *
315 * Setup CP15 registers (cache, MMU, TLBs). The I-cache is turned on unless
316 * CONFIG_SYS_ICACHE_OFF is defined.
317 *
318 *************************************************************************/
319ENTRY(cpu_init_cp15)
320	/*
321	 * Invalidate L1 I/D
322	 */
323	mov	r0, #0			@ set up for MCR
324	mcr	p15, 0, r0, c8, c7, 0	@ invalidate TLBs
325	mcr	p15, 0, r0, c7, c5, 0	@ invalidate icache
326	mcr	p15, 0, r0, c7, c5, 6	@ invalidate BP array
327	mcr     p15, 0, r0, c7, c10, 4	@ DSB
328	mcr     p15, 0, r0, c7, c5, 4	@ ISB
329
330	/*
331	 * disable MMU stuff and caches
332	 */
333	mrc	p15, 0, r0, c1, c0, 0
334	bic	r0, r0, #0x00002000	@ clear bits 13 (--V-)
335	bic	r0, r0, #0x00000007	@ clear bits 2:0 (-CAM)
336	orr	r0, r0, #0x00000002	@ set bit 1 (--A-) Align
337	orr	r0, r0, #0x00000800	@ set bit 11 (Z---) BTB
338#ifdef CONFIG_SYS_ICACHE_OFF
339	bic	r0, r0, #0x00001000	@ clear bit 12 (I) I-cache
340#else
341	orr	r0, r0, #0x00001000	@ set bit 12 (I) I-cache
342#endif
343	mcr	p15, 0, r0, c1, c0, 0
344	mov	pc, lr			@ back to my caller
345ENDPROC(cpu_init_cp15)
346
347#ifndef CONFIG_SKIP_LOWLEVEL_INIT
348/*************************************************************************
349 *
350 * CPU_init_critical registers
351 *
352 * setup important registers
353 * setup memory timing
354 *
355 *************************************************************************/
356ENTRY(cpu_init_crit)
357	/*
358	 * Jump to board specific initialization...
359	 * The Mask ROM will have already initialized
360	 * basic memory. Go here to bump up clock rate and handle
361	 * wake up conditions.
362	 */
363	b	lowlevel_init		@ go setup pll,mux,memory
364ENDPROC(cpu_init_crit)
365#endif
366
367#ifndef CONFIG_SPL_BUILD
368/*
369 *************************************************************************
370 *
371 * Interrupt handling
372 *
373 *************************************************************************
374 */
375@
376@ IRQ stack frame.
377@
378#define S_FRAME_SIZE	72
379
380#define S_OLD_R0	68
381#define S_PSR		64
382#define S_PC		60
383#define S_LR		56
384#define S_SP		52
385
386#define S_IP		48
387#define S_FP		44
388#define S_R10		40
389#define S_R9		36
390#define S_R8		32
391#define S_R7		28
392#define S_R6		24
393#define S_R5		20
394#define S_R4		16
395#define S_R3		12
396#define S_R2		8
397#define S_R1		4
398#define S_R0		0
399
400#define MODE_SVC 0x13
401#define I_BIT	 0x80
402
403/*
404 * use bad_save_user_regs for abort/prefetch/undef/swi ...
405 * use irq_save_user_regs / irq_restore_user_regs for IRQ/FIQ handling
406 */
407
408	.macro	bad_save_user_regs
409	sub	sp, sp, #S_FRAME_SIZE		@ carve out a frame on current
410						@ user stack
411	stmia	sp, {r0 - r12}			@ Save user registers (now in
412						@ svc mode) r0-r12
413	ldr	r2, IRQ_STACK_START_IN		@ set base 2 words into abort
414						@ stack
415	ldmia	r2, {r2 - r3}			@ get values for "aborted" pc
416						@ and cpsr (into parm regs)
417	add	r0, sp, #S_FRAME_SIZE		@ grab pointer to old stack
418
419	add	r5, sp, #S_SP
420	mov	r1, lr
421	stmia	r5, {r0 - r3}			@ save sp_SVC, lr_SVC, pc, cpsr
422	mov	r0, sp				@ save current stack into r0
423						@ (param register)
424	.endm
425
426	.macro	irq_save_user_regs
427	sub	sp, sp, #S_FRAME_SIZE
428	stmia	sp, {r0 - r12}			@ Calling r0-r12
429	add	r8, sp, #S_PC			@ !! R8 NEEDS to be saved !!
430						@ a reserved stack spot would
431						@ be good.
432	stmdb	r8, {sp, lr}^			@ Calling SP, LR
433	str	lr, [r8, #0]			@ Save calling PC
434	mrs	r6, spsr
435	str	r6, [r8, #4]			@ Save CPSR
436	str	r0, [r8, #8]			@ Save OLD_R0
437	mov	r0, sp
438	.endm
439
440	.macro	irq_restore_user_regs
441	ldmia	sp, {r0 - lr}^			@ Calling r0 - lr
442	mov	r0, r0
443	ldr	lr, [sp, #S_PC]			@ Get PC
444	add	sp, sp, #S_FRAME_SIZE
445	subs	pc, lr, #4			@ return & move spsr_svc into
446						@ cpsr
447	.endm
448
449	.macro get_bad_stack
450	ldr	r13, IRQ_STACK_START_IN		@ setup our mode stack (enter
451						@ in banked mode)
452
453	str	lr, [r13]			@ save caller lr in position 0
454						@ of saved stack
455	mrs	lr, spsr			@ get the spsr
456	str	lr, [r13, #4]			@ save spsr in position 1 of
457						@ saved stack
458
459	mov	r13, #MODE_SVC			@ prepare SVC-Mode
460	@ msr	spsr_c, r13
461	msr	spsr, r13			@ switch modes, make sure
462						@ moves will execute
463	mov	lr, pc				@ capture return pc
464	movs	pc, lr				@ jump to next instruction &
465						@ switch modes.
466	.endm
467
468	.macro get_bad_stack_swi
469	sub	r13, r13, #4			@ space on current stack for
470						@ scratch reg.
471	str	r0, [r13]			@ save R0's value.
472	ldr	r0, IRQ_STACK_START_IN		@ get data regions start
473						@ spots for abort stack
474	str	lr, [r0]			@ save caller lr in position 0
475						@ of saved stack
476	mrs	r0, spsr			@ get the spsr
477	str	lr, [r0, #4]			@ save spsr in position 1 of
478						@ saved stack
479	ldr	r0, [r13]			@ restore r0
480	add	r13, r13, #4			@ pop stack entry
481	.endm
482
483	.macro get_irq_stack			@ setup IRQ stack
484	ldr	sp, IRQ_STACK_START
485	.endm
486
487	.macro get_fiq_stack			@ setup FIQ stack
488	ldr	sp, FIQ_STACK_START
489	.endm
490
491/*
492 * exception handlers
493 */
494	.align	5
495undefined_instruction:
496	get_bad_stack
497	bad_save_user_regs
498	bl	do_undefined_instruction
499
500	.align	5
501software_interrupt:
502	get_bad_stack_swi
503	bad_save_user_regs
504	bl	do_software_interrupt
505
506	.align	5
507prefetch_abort:
508	get_bad_stack
509	bad_save_user_regs
510	bl	do_prefetch_abort
511
512	.align	5
513data_abort:
514	get_bad_stack
515	bad_save_user_regs
516	bl	do_data_abort
517
518	.align	5
519not_used:
520	get_bad_stack
521	bad_save_user_regs
522	bl	do_not_used
523
524#ifdef CONFIG_USE_IRQ
525
526	.align	5
527irq:
528	get_irq_stack
529	irq_save_user_regs
530	bl	do_irq
531	irq_restore_user_regs
532
533	.align	5
534fiq:
535	get_fiq_stack
536	/* someone ought to write a more effective fiq_save_user_regs */
537	irq_save_user_regs
538	bl	do_fiq
539	irq_restore_user_regs
540
541#else
542
543	.align	5
544irq:
545	get_bad_stack
546	bad_save_user_regs
547	bl	do_irq
548
549	.align	5
550fiq:
551	get_bad_stack
552	bad_save_user_regs
553	bl	do_fiq
554
555#endif /* CONFIG_USE_IRQ */
556#endif /* CONFIG_SPL_BUILD */
557