xref: /openbmc/linux/arch/arc/kernel/head.S (revision 59ed9413533897823bcdb4c79fd2904718e25b0a)
1c121c506SVineet Gupta/*
2c121c506SVineet Gupta * ARC CPU startup Code
3c121c506SVineet Gupta *
4c121c506SVineet Gupta * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
5c121c506SVineet Gupta *
6c121c506SVineet Gupta * This program is free software; you can redistribute it and/or modify
7c121c506SVineet Gupta * it under the terms of the GNU General Public License version 2 as
8c121c506SVineet Gupta * published by the Free Software Foundation.
9c121c506SVineet Gupta *
10c121c506SVineet Gupta * Vineetg: Dec 2007
11c121c506SVineet Gupta *  -Check if we are running on Simulator or on real hardware
12c121c506SVineet Gupta *      to skip certain things during boot on simulator
13c121c506SVineet Gupta */
14c121c506SVineet Gupta
15c121c506SVineet Gupta#include <asm/asm-offsets.h>
16c121c506SVineet Gupta#include <asm/entry.h>
17c121c506SVineet Gupta#include <linux/linkage.h>
18c121c506SVineet Gupta#include <asm/arcregs.h>
19c121c506SVineet Gupta
20c121c506SVineet Gupta	.cpu A7
21c121c506SVineet Gupta
22c121c506SVineet Gupta	.section .init.text, "ax",@progbits
23c121c506SVineet Gupta	.type stext, @function
24c121c506SVineet Gupta	.globl stext
25c121c506SVineet Guptastext:
26c121c506SVineet Gupta	;-------------------------------------------------------------------
27c121c506SVineet Gupta	; Don't clobber r0-r4 yet. It might have bootloader provided info
28c121c506SVineet Gupta	;-------------------------------------------------------------------
29c121c506SVineet Gupta
3005b016ecSVineet Gupta	sr	@_int_vec_base_lds, [AUX_INTR_VEC_BASE]
3105b016ecSVineet Gupta
3241195d23SVineet Gupta#ifdef CONFIG_SMP
3341195d23SVineet Gupta	; Only Boot (Master) proceeds. Others wait in platform dependent way
3441195d23SVineet Gupta	;	IDENTITY Reg [ 3  2  1  0 ]
3541195d23SVineet Gupta	;	(cpu-id)             ^^^	=> Zero for UP ARC700
3641195d23SVineet Gupta	;					=> #Core-ID if SMP (Master 0)
37c3567f8aSNoam Camus	; Note that non-boot CPUs might not land here if halt-on-reset and
38c3567f8aSNoam Camus	; instead breath life from @first_lines_of_secondary, but we still
39c3567f8aSNoam Camus	; need to make sure only boot cpu takes this path.
4041195d23SVineet Gupta	GET_CPU_ID  r5
4141195d23SVineet Gupta	cmp	r5, 0
4241195d23SVineet Gupta	jnz	arc_platform_smp_wait_to_boot
4341195d23SVineet Gupta#endif
44c121c506SVineet Gupta	; Clear BSS before updating any globals
45c121c506SVineet Gupta	; XXX: use ZOL here
46c121c506SVineet Gupta	mov	r5, __bss_start
47c121c506SVineet Gupta	mov	r6, __bss_stop
48c121c506SVineet Gupta1:
49c121c506SVineet Gupta	st.ab   0, [r5,4]
50c121c506SVineet Gupta	brlt    r5, r6, 1b
51c121c506SVineet Gupta
52*59ed9413SVineet Gupta	; Uboot - kernel ABI
53*59ed9413SVineet Gupta	;    r0 = [0] No uboot interaction, [1] cmdline in r2, [2] DTB in r2
54*59ed9413SVineet Gupta	;    r1 = magic number (board identity, unused as of now
55*59ed9413SVineet Gupta	;    r2 = pointer to uboot provided cmdline or external DTB in mem
56*59ed9413SVineet Gupta	; These are handled later in setup_arch()
57*59ed9413SVineet Gupta	st	r0, [@uboot_tag]
58*59ed9413SVineet Gupta	st	r2, [@uboot_arg]
59c121c506SVineet Gupta
60c121c506SVineet Gupta	; Identify if running on ISS vs Silicon
61c121c506SVineet Gupta	; 	IDENTITY Reg [ 3  2  1  0 ]
62c121c506SVineet Gupta	;	(chip-id)      ^^^^^		==> 0xffff for ISS
63c121c506SVineet Gupta	lr	r0, [identity]
64c121c506SVineet Gupta	lsr	r3, r0, 16
65c121c506SVineet Gupta	cmp	r3, 0xffff
66c121c506SVineet Gupta	mov.z	r4, 0
67c121c506SVineet Gupta	mov.nz	r4, 1
68c121c506SVineet Gupta	st	r4, [@running_on_hw]
69c121c506SVineet Gupta
70c121c506SVineet Gupta	; setup "current" tsk and optionally cache it in dedicated r25
71c121c506SVineet Gupta	mov	r9, @init_task
72c121c506SVineet Gupta	SET_CURR_TASK_ON_CPU  r9, r0	; r9 = tsk, r0 = scratch
73c121c506SVineet Gupta
74c121c506SVineet Gupta	; setup stack (fp, sp)
75c121c506SVineet Gupta	mov	fp, 0
76c121c506SVineet Gupta
77c121c506SVineet Gupta	; tsk->thread_info is really a PAGE, whose bottom hoists stack
78c121c506SVineet Gupta	GET_TSK_STACK_BASE r9, sp	; r9 = tsk, sp = stack base(output)
79c121c506SVineet Gupta
80c121c506SVineet Gupta	j	start_kernel	; "C" entry point
8141195d23SVineet Gupta
8241195d23SVineet Gupta#ifdef CONFIG_SMP
8341195d23SVineet Gupta;----------------------------------------------------------------
8441195d23SVineet Gupta;     First lines of code run by secondary before jumping to 'C'
8541195d23SVineet Gupta;----------------------------------------------------------------
868f5d221bSChen Gang	.section .text, "ax",@progbits
8741195d23SVineet Gupta	.type first_lines_of_secondary, @function
8841195d23SVineet Gupta	.globl first_lines_of_secondary
8941195d23SVineet Gupta
9041195d23SVineet Guptafirst_lines_of_secondary:
9141195d23SVineet Gupta
92c3567f8aSNoam Camus	sr	@_int_vec_base_lds, [AUX_INTR_VEC_BASE]
93c3567f8aSNoam Camus
9441195d23SVineet Gupta	; setup per-cpu idle task as "current" on this CPU
9541195d23SVineet Gupta	ld	r0, [@secondary_idle_tsk]
9641195d23SVineet Gupta	SET_CURR_TASK_ON_CPU  r0, r1
9741195d23SVineet Gupta
9841195d23SVineet Gupta	; setup stack (fp, sp)
9941195d23SVineet Gupta	mov	fp, 0
10041195d23SVineet Gupta
10141195d23SVineet Gupta	; set it's stack base to tsk->thread_info bottom
10241195d23SVineet Gupta	GET_TSK_STACK_BASE r0, sp
10341195d23SVineet Gupta
10441195d23SVineet Gupta	j	start_kernel_secondary
10541195d23SVineet Gupta
10641195d23SVineet Gupta#endif
107