u-boot/arch/arm/cpu/arm926ejs/start.S
Simon Glass b5bd09820c arm: Allow skipping of low-level init with I-cache on
At present CONFIG_SKIP_LOWLEVEL_INIT prevents U-Boot from calling
lowlevel_init(). This means that the instruction cache is not enabled and
the board runs very slowly.

What is really needed in many cases is to skip the call to lowlevel_init()
but still perform CP15 init. Add an option to handle this.

Reviewed-by: Heiko Schocher <hs@denx.de>
Tested-on: smartweb, corvus, taurus, axm
Tested-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Joe Hershberger <joe.hershberger@ni.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Andreas Bießmann <andreas@biessmann.org>
2016-06-12 23:49:38 +02:00

113 lines
2.7 KiB
ArmAsm

/*
* armboot - Startup Code for ARM926EJS CPU-core
*
* Copyright (c) 2003 Texas Instruments
*
* ----- Adapted for OMAP1610 OMAP730 from ARM925t code ------
*
* Copyright (c) 2001 Marius Gröger <mag@sysgo.de>
* Copyright (c) 2002 Alex Züpke <azu@sysgo.de>
* Copyright (c) 2002 Gary Jennejohn <garyj@denx.de>
* Copyright (c) 2003 Richard Woodruff <r-woodruff2@ti.com>
* Copyright (c) 2003 Kshitij <kshitij@ti.com>
* Copyright (c) 2010 Albert Aribaud <albert.u.boot@aribaud.net>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <asm-offsets.h>
#include <config.h>
#include <common.h>
/*
*************************************************************************
*
* Startup Code (reset vector)
*
* do important init only if we don't start from memory!
* setup Memory and board specific bits prior to relocation.
* relocate armboot to ram
* setup stack
*
*************************************************************************
*/
.globl reset
reset:
/*
* set the cpu to SVC32 mode
*/
mrs r0,cpsr
bic r0,r0,#0x1f
orr r0,r0,#0xd3
msr cpsr,r0
/*
* we do sys-critical inits only at reboot,
* not when booting from ram!
*/
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
bl cpu_init_crit
#endif
bl _main
/*------------------------------------------------------------------------------*/
.globl c_runtime_cpu_setup
c_runtime_cpu_setup:
bx lr
/*
*************************************************************************
*
* CPU_init_critical registers
*
* setup important registers
* setup memory timing
*
*************************************************************************
*/
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
cpu_init_crit:
/*
* flush D cache before disabling it
*/
mov r0, #0
flush_dcache:
mrc p15, 0, r15, c7, c10, 3
bne flush_dcache
mcr p15, 0, r0, c8, c7, 0 /* invalidate TLB */
mcr p15, 0, r0, c7, c5, 0 /* invalidate I Cache */
/*
* disable MMU and D cache
* enable I cache if CONFIG_SYS_ICACHE_OFF is not defined
*/
mrc p15, 0, r0, c1, c0, 0
bic r0, r0, #0x00000300 /* clear bits 9:8 (---- --RS) */
bic r0, r0, #0x00000087 /* clear bits 7, 2:0 (B--- -CAM) */
#ifdef CONFIG_SYS_EXCEPTION_VECTORS_HIGH
orr r0, r0, #0x00002000 /* set bit 13 (--V- ----) */
#else
bic r0, r0, #0x00002000 /* clear bit 13 (--V- ----) */
#endif
orr r0, r0, #0x00000002 /* set bit 1 (A) Align */
#ifndef CONFIG_SYS_ICACHE_OFF
orr r0, r0, #0x00001000 /* set bit 12 (I) I-Cache */
#endif
mcr p15, 0, r0, c1, c0, 0
#ifndef CONFIG_SKIP_LOWLEVEL_INIT_ONLY
/*
* Go setup Memory and board specific bits prior to relocation.
*/
mov ip, lr /* perserve link reg across call */
bl lowlevel_init /* go setup pll,mux,memory */
mov lr, ip /* restore link */
#endif
mov pc, lr /* back to my caller */
#endif /* CONFIG_SKIP_LOWLEVEL_INIT */