linux/arch/arc/kernel/head.S
Vineet Gupta bf02454a74 ARC: smp-boot: Decouple Non masters waiting API from jump to entry point
For run-on-reset SMP configs, non master cores call a routine which
waits until Master gives it a "go" signal (currently using a shared
mem flag). The same routine then jumps off the well known entry point of
all non Master cores i.e. @first_lines_of_secondary

This patch moves out the last part into one single place in early boot
code.

This is better in terms of absraction (the wait API only waits) and
returns, leaving out the "jump off to" part.

In actual implementation this requires some restructuring of the early
boot code as well as Master now jumps to BSS setup explicitly,
vs. falling thru into it before.

Technically this patch doesn't cause any functional change, it just
moves the ugly #ifdef'ry from assembly code to "C"

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2017-01-24 11:12:28 -08:00

136 lines
3.5 KiB
ArmAsm

/*
* ARC CPU startup Code
*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Vineetg: Dec 2007
* -Check if we are running on Simulator or on real hardware
* to skip certain things during boot on simulator
*/
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/entry.h>
#include <asm/arcregs.h>
#include <asm/cache.h>
.macro CPU_EARLY_SETUP
; Setting up Vectror Table (in case exception happens in early boot
sr @_int_vec_base_lds, [AUX_INTR_VEC_BASE]
; Disable I-cache/D-cache if kernel so configured
lr r5, [ARC_REG_IC_BCR]
breq r5, 0, 1f ; I$ doesn't exist
lr r5, [ARC_REG_IC_CTRL]
#ifdef CONFIG_ARC_HAS_ICACHE
bclr r5, r5, 0 ; 0 - Enable, 1 is Disable
#else
bset r5, r5, 0 ; I$ exists, but is not used
#endif
sr r5, [ARC_REG_IC_CTRL]
1:
lr r5, [ARC_REG_DC_BCR]
breq r5, 0, 1f ; D$ doesn't exist
lr r5, [ARC_REG_DC_CTRL]
bclr r5, r5, 6 ; Invalidate (discard w/o wback)
#ifdef CONFIG_ARC_HAS_DCACHE
bclr r5, r5, 0 ; Enable (+Inv)
#else
bset r5, r5, 0 ; Disable (+Inv)
#endif
sr r5, [ARC_REG_DC_CTRL]
1:
.endm
.section .init.text, "ax",@progbits
;----------------------------------------------------------------
; Default Reset Handler (jumped into from Reset vector)
; - Don't clobber r0,r1,r2 as they might have u-boot provided args
; - Platforms can override this weak version if needed
;----------------------------------------------------------------
WEAK(res_service)
j stext
END(res_service)
;----------------------------------------------------------------
; Kernel Entry point
;----------------------------------------------------------------
ENTRY(stext)
CPU_EARLY_SETUP
#ifdef CONFIG_SMP
GET_CPU_ID r5
cmp r5, 0
mov.nz r0, r5
bz .Lmaster_proceed
; Non-Masters wait for Master to boot enough and bring them up
; when they resume, tail-call to entry point
mov blink, @first_lines_of_secondary
j arc_platform_smp_wait_to_boot
.Lmaster_proceed:
#endif
; Clear BSS before updating any globals
; XXX: use ZOL here
mov r5, __bss_start
sub r6, __bss_stop, r5
lsr.f lp_count, r6, 2
lpnz 1f
st.ab 0, [r5, 4]
1:
#ifdef CONFIG_ARC_UBOOT_SUPPORT
; Uboot - kernel ABI
; r0 = [0] No uboot interaction, [1] cmdline in r2, [2] DTB in r2
; r1 = magic number (board identity, unused as of now
; r2 = pointer to uboot provided cmdline or external DTB in mem
; These are handled later in setup_arch()
st r0, [@uboot_tag]
st r2, [@uboot_arg]
#endif
; setup "current" tsk and optionally cache it in dedicated r25
mov r9, @init_task
SET_CURR_TASK_ON_CPU r9, r0 ; r9 = tsk, r0 = scratch
; setup stack (fp, sp)
mov fp, 0
; tsk->thread_info is really a PAGE, whose bottom hoists stack
GET_TSK_STACK_BASE r9, sp ; r9 = tsk, sp = stack base(output)
j start_kernel ; "C" entry point
END(stext)
#ifdef CONFIG_SMP
;----------------------------------------------------------------
; First lines of code run by secondary before jumping to 'C'
;----------------------------------------------------------------
.section .text, "ax",@progbits
ENTRY(first_lines_of_secondary)
; setup per-cpu idle task as "current" on this CPU
ld r0, [@secondary_idle_tsk]
SET_CURR_TASK_ON_CPU r0, r1
; setup stack (fp, sp)
mov fp, 0
; set it's stack base to tsk->thread_info bottom
GET_TSK_STACK_BASE r0, sp
j start_kernel_secondary
END(first_lines_of_secondary)
#endif