xref: /openbmc/u-boot/arch/arm/cpu/arm920t/start.S (revision 64a93860) 
1/*
2 *  armboot - Startup Code for ARM920 CPU-core
3 *
4 *  Copyright (c) 2001	Marius Gröger <mag@sysgo.de>
5 *  Copyright (c) 2002	Alex Züpke <azu@sysgo.de>
6 *  Copyright (c) 2002	Gary Jennejohn <garyj@denx.de>
7 *
8 * See file CREDITS for list of people who contributed to this
9 * project.
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License as
13 * published by the Free Software Foundation; either version 2 of
14 * the License, or (at your option) any later version.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19 * GNU General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
24 * MA 02111-1307 USA
25 */
26
27#include <asm-offsets.h>
28#include <common.h>
29#include <config.h>
30
31/*
32 *************************************************************************
33 *
34 * Jump vector table as in table 3.1 in [1]
35 *
36 *************************************************************************
37 */
38
39
40.globl _start
41_start:	b	start_code
42	ldr	pc, _undefined_instruction
43	ldr	pc, _software_interrupt
44	ldr	pc, _prefetch_abort
45	ldr	pc, _data_abort
46	ldr	pc, _not_used
47	ldr	pc, _irq
48	ldr	pc, _fiq
49
50_undefined_instruction:	.word undefined_instruction
51_software_interrupt:	.word software_interrupt
52_prefetch_abort:	.word prefetch_abort
53_data_abort:		.word data_abort
54_not_used:		.word not_used
55_irq:			.word irq
56_fiq:			.word fiq
57
58	.balignl 16,0xdeadbeef
59
60
61/*
62 *************************************************************************
63 *
64 * Startup Code (called from the ARM reset exception vector)
65 *
66 * do important init only if we don't start from memory!
67 * relocate armboot to ram
68 * setup stack
69 * jump to second stage
70 *
71 *************************************************************************
72 */
73
74.globl _TEXT_BASE
75_TEXT_BASE:
76	.word	CONFIG_SYS_TEXT_BASE
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 start code
115 */
116
117start_code:
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#if	defined(CONFIG_AT91RM9200DK) || defined(CONFIG_AT91RM9200EK)
127	/*
128	 * relocate exception table
129	 */
130	ldr	r0, =_start
131	ldr	r1, =0x0
132	mov	r2, #16
133copyex:
134	subs	r2, r2, #1
135	ldr	r3, [r0], #4
136	str	r3, [r1], #4
137	bne	copyex
138#endif
139
140#ifdef CONFIG_S3C24X0
141	/* turn off the watchdog */
142
143# if defined(CONFIG_S3C2400)
144#  define pWTCON	0x15300000
145#  define INTMSK	0x14400008	/* Interrupt-Controller base addresses */
146#  define CLKDIVN	0x14800014	/* clock divisor register */
147#else
148#  define pWTCON	0x53000000
149#  define INTMSK	0x4A000008	/* Interrupt-Controller base addresses */
150#  define INTSUBMSK	0x4A00001C
151#  define CLKDIVN	0x4C000014	/* clock divisor register */
152# endif
153
154	ldr	r0, =pWTCON
155	mov	r1, #0x0
156	str	r1, [r0]
157
158	/*
159	 * mask all IRQs by setting all bits in the INTMR - default
160	 */
161	mov	r1, #0xffffffff
162	ldr	r0, =INTMSK
163	str	r1, [r0]
164# if defined(CONFIG_S3C2410)
165	ldr	r1, =0x3ff
166	ldr	r0, =INTSUBMSK
167	str	r1, [r0]
168# endif
169
170	/* FCLK:HCLK:PCLK = 1:2:4 */
171	/* default FCLK is 120 MHz ! */
172	ldr	r0, =CLKDIVN
173	mov	r1, #3
174	str	r1, [r0]
175#endif	/* CONFIG_S3C24X0 */
176
177	/*
178	 * we do sys-critical inits only at reboot,
179	 * not when booting from ram!
180	 */
181#ifndef CONFIG_SKIP_LOWLEVEL_INIT
182	bl	cpu_init_crit
183#endif
184
185	bl	_main
186
187/*------------------------------------------------------------------------------*/
188
189/*
190 * void relocate_code (addr_sp, gd, addr_moni)
191 *
192 * This "function" does not return, instead it continues in RAM
193 * after relocating the monitor code.
194 *
195 */
196	.globl	relocate_code
197relocate_code:
198	mov	r4, r0	/* save addr_sp */
199	mov	r5, r1	/* save addr of gd */
200	mov	r6, r2	/* save addr of destination */
201
202	adr	r0, _start
203	cmp	r0, r6
204	moveq	r9, #0		/* no relocation. relocation offset(r9) = 0 */
205	beq	relocate_done		/* skip relocation */
206	mov	r1, r6			/* r1 <- scratch for copy_loop */
207	ldr	r3, _bss_start_ofs
208	add	r2, r0, r3		/* r2 <- source end address	    */
209
210copy_loop:
211	ldmia	r0!, {r9-r10}		/* copy from source address [r0]    */
212	stmia	r1!, {r9-r10}		/* copy to   target address [r1]    */
213	cmp	r0, r2			/* until source end address [r2]    */
214	blo	copy_loop
215
216#ifndef CONFIG_SPL_BUILD
217	/*
218	 * fix .rel.dyn relocations
219	 */
220	ldr	r0, _TEXT_BASE		/* r0 <- Text base */
221	sub	r9, r6, r0		/* r9 <- relocation offset */
222	ldr	r10, _dynsym_start_ofs	/* r10 <- sym table ofs */
223	add	r10, r10, r0		/* r10 <- sym table in FLASH */
224	ldr	r2, _rel_dyn_start_ofs	/* r2 <- rel dyn start ofs */
225	add	r2, r2, r0		/* r2 <- rel dyn start in FLASH */
226	ldr	r3, _rel_dyn_end_ofs	/* r3 <- rel dyn end ofs */
227	add	r3, r3, r0		/* r3 <- rel dyn end in FLASH */
228fixloop:
229	ldr	r0, [r2]		/* r0 <- location to fix up, IN FLASH! */
230	add	r0, r0, r9		/* r0 <- location to fix up in RAM */
231	ldr	r1, [r2, #4]
232	and	r7, r1, #0xff
233	cmp	r7, #23			/* relative fixup? */
234	beq	fixrel
235	cmp	r7, #2			/* absolute fixup? */
236	beq	fixabs
237	/* ignore unknown type of fixup */
238	b	fixnext
239fixabs:
240	/* absolute fix: set location to (offset) symbol value */
241	mov	r1, r1, LSR #4		/* r1 <- symbol index in .dynsym */
242	add	r1, r10, r1		/* r1 <- address of symbol in table */
243	ldr	r1, [r1, #4]		/* r1 <- symbol value */
244	add	r1, r1, r9		/* r1 <- relocated sym addr */
245	b	fixnext
246fixrel:
247	/* relative fix: increase location by offset */
248	ldr	r1, [r0]
249	add	r1, r1, r9
250fixnext:
251	str	r1, [r0]
252	add	r2, r2, #8		/* each rel.dyn entry is 8 bytes */
253	cmp	r2, r3
254	blo	fixloop
255#endif
256
257relocate_done:
258
259	mov	pc, lr
260
261_rel_dyn_start_ofs:
262	.word __rel_dyn_start - _start
263_rel_dyn_end_ofs:
264	.word __rel_dyn_end - _start
265_dynsym_start_ofs:
266	.word __dynsym_start - _start
267
268	.globl	c_runtime_cpu_setup
269c_runtime_cpu_setup:
270
271	mov	pc, lr
272
273/*
274 *************************************************************************
275 *
276 * CPU_init_critical registers
277 *
278 * setup important registers
279 * setup memory timing
280 *
281 *************************************************************************
282 */
283
284
285#ifndef CONFIG_SKIP_LOWLEVEL_INIT
286cpu_init_crit:
287	/*
288	 * flush v4 I/D caches
289	 */
290	mov	r0, #0
291	mcr	p15, 0, r0, c7, c7, 0	/* flush v3/v4 cache */
292	mcr	p15, 0, r0, c8, c7, 0	/* flush v4 TLB */
293
294	/*
295	 * disable MMU stuff and caches
296	 */
297	mrc	p15, 0, r0, c1, c0, 0
298	bic	r0, r0, #0x00002300	@ clear bits 13, 9:8 (--V- --RS)
299	bic	r0, r0, #0x00000087	@ clear bits 7, 2:0 (B--- -CAM)
300	orr	r0, r0, #0x00000002	@ set bit 2 (A) Align
301	orr	r0, r0, #0x00001000	@ set bit 12 (I) I-Cache
302	mcr	p15, 0, r0, c1, c0, 0
303
304	/*
305	 * before relocating, we have to setup RAM timing
306	 * because memory timing is board-dependend, you will
307	 * find a lowlevel_init.S in your board directory.
308	 */
309	mov	ip, lr
310
311	bl	lowlevel_init
312
313	mov	lr, ip
314	mov	pc, lr
315#endif /* CONFIG_SKIP_LOWLEVEL_INIT */
316
317/*
318 *************************************************************************
319 *
320 * Interrupt handling
321 *
322 *************************************************************************
323 */
324
325@
326@ IRQ stack frame.
327@
328#define S_FRAME_SIZE	72
329
330#define S_OLD_R0	68
331#define S_PSR		64
332#define S_PC		60
333#define S_LR		56
334#define S_SP		52
335
336#define S_IP		48
337#define S_FP		44
338#define S_R10		40
339#define S_R9		36
340#define S_R8		32
341#define S_R7		28
342#define S_R6		24
343#define S_R5		20
344#define S_R4		16
345#define S_R3		12
346#define S_R2		8
347#define S_R1		4
348#define S_R0		0
349
350#define MODE_SVC	0x13
351#define I_BIT		0x80
352
353/*
354 * use bad_save_user_regs for abort/prefetch/undef/swi ...
355 * use irq_save_user_regs / irq_restore_user_regs for IRQ/FIQ handling
356 */
357
358	.macro	bad_save_user_regs
359	sub	sp, sp, #S_FRAME_SIZE
360	stmia	sp, {r0 - r12}			@ Calling r0-r12
361	ldr	r2, IRQ_STACK_START_IN
362	ldmia	r2, {r2 - r3}			@ get pc, cpsr
363	add	r0, sp, #S_FRAME_SIZE		@ restore sp_SVC
364
365	add	r5, sp, #S_SP
366	mov	r1, lr
367	stmia	r5, {r0 - r3}			@ save sp_SVC, lr_SVC, pc, cpsr
368	mov	r0, sp
369	.endm
370
371	.macro	irq_save_user_regs
372	sub	sp, sp, #S_FRAME_SIZE
373	stmia	sp, {r0 - r12}			@ Calling r0-r12
374	add	r7, sp, #S_PC
375	stmdb	r7, {sp, lr}^			@ Calling SP, LR
376	str	lr, [r7, #0]			@ Save calling PC
377	mrs	r6, spsr
378	str	r6, [r7, #4]			@ Save CPSR
379	str	r0, [r7, #8]			@ Save OLD_R0
380	mov	r0, sp
381	.endm
382
383	.macro	irq_restore_user_regs
384	ldmia	sp, {r0 - lr}^			@ Calling r0 - lr
385	mov	r0, r0
386	ldr	lr, [sp, #S_PC]			@ Get PC
387	add	sp, sp, #S_FRAME_SIZE
388	/* return & move spsr_svc into cpsr */
389	subs	pc, lr, #4
390	.endm
391
392	.macro get_bad_stack
393	ldr	r13, IRQ_STACK_START_IN		@ setup our mode stack
394
395	str	lr, [r13]			@ save caller lr / spsr
396	mrs	lr, spsr
397	str	lr, [r13, #4]
398
399	mov	r13, #MODE_SVC			@ prepare SVC-Mode
400	@ msr	spsr_c, r13
401	msr	spsr, r13
402	mov	lr, pc
403	movs	pc, lr
404	.endm
405
406	.macro get_irq_stack			@ setup IRQ stack
407	ldr	sp, IRQ_STACK_START
408	.endm
409
410	.macro get_fiq_stack			@ setup FIQ stack
411	ldr	sp, FIQ_STACK_START
412	.endm
413
414/*
415 * exception handlers
416 */
417	.align  5
418undefined_instruction:
419	get_bad_stack
420	bad_save_user_regs
421	bl	do_undefined_instruction
422
423	.align	5
424software_interrupt:
425	get_bad_stack
426	bad_save_user_regs
427	bl	do_software_interrupt
428
429	.align	5
430prefetch_abort:
431	get_bad_stack
432	bad_save_user_regs
433	bl	do_prefetch_abort
434
435	.align	5
436data_abort:
437	get_bad_stack
438	bad_save_user_regs
439	bl	do_data_abort
440
441	.align	5
442not_used:
443	get_bad_stack
444	bad_save_user_regs
445	bl	do_not_used
446
447#ifdef CONFIG_USE_IRQ
448
449	.align	5
450irq:
451	get_irq_stack
452	irq_save_user_regs
453	bl	do_irq
454	irq_restore_user_regs
455
456	.align	5
457fiq:
458	get_fiq_stack
459	/* someone ought to write a more effiction fiq_save_user_regs */
460	irq_save_user_regs
461	bl	do_fiq
462	irq_restore_user_regs
463
464#else
465
466	.align	5
467irq:
468	get_bad_stack
469	bad_save_user_regs
470	bl	do_irq
471
472	.align	5
473fiq:
474	get_bad_stack
475	bad_save_user_regs
476	bl	do_fiq
477
478#endif
479