u-boot/arch/arm/cpu/armv7/start.S

/*
 * armboot - Startup Code for OMAP3530/ARM Cortex CPU-core
 *
 * Copyright (c) 2004	Texas Instruments <r-woodruff2@ti.com>
 *
 * 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) 2006-2008 Syed Mohammed Khasim <x0khasim@ti.com>
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

#include <asm-offsets.h>
#include <config.h>
#include <version.h>
#include <asm/system.h>
#include <linux/linkage.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:
	bl	save_boot_params
	/*
	 * disable interrupts (FIQ and IRQ), also set the cpu to SVC32 mode,
	 * except if in HYP mode already
	 */
	mrs	r0, cpsr
	and	r1, r0, #0x1f		@ mask mode bits
	teq	r1, #0x1a		@ test for HYP mode
	bicne	r0, r0, #0x1f		@ clear all mode bits
	orrne	r0, r0, #0x13		@ set SVC mode
	orr	r0, r0, #0xc0		@ disable FIQ and IRQ
	msr	cpsr,r0

/*
 * Setup vector:
 * (OMAP4 spl TEXT_BASE is not 32 byte aligned.
 * Continue to use ROM code vector only in OMAP4 spl)
 */
#if !(defined(CONFIG_OMAP44XX) && defined(CONFIG_SPL_BUILD))
	/* Set V=0 in CP15 SCTLR register - for VBAR to point to vector */
	mrc	p15, 0, r0, c1, c0, 0	@ Read CP15 SCTLR Register
	bic	r0, #CR_V		@ V = 0
	mcr	p15, 0, r0, c1, c0, 0	@ Write CP15 SCTLR Register

	/* Set vector address in CP15 VBAR register */
	ldr	r0, =_start
	mcr	p15, 0, r0, c12, c0, 0	@Set VBAR
#endif

	/* the mask ROM code should have PLL and others stable */
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
	bl	cpu_init_cp15
	bl	cpu_init_crit
#endif

	bl	_main

/*------------------------------------------------------------------------------*/

ENTRY(c_runtime_cpu_setup)
/*
 * If I-cache is enabled invalidate it
 */
#ifndef CONFIG_SYS_ICACHE_OFF
	mcr	p15, 0, r0, c7, c5, 0	@ invalidate icache
	mcr     p15, 0, r0, c7, c10, 4	@ DSB
	mcr     p15, 0, r0, c7, c5, 4	@ ISB
#endif

	bx	lr

ENDPROC(c_runtime_cpu_setup)

/*************************************************************************
 *
 * void save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3)
 *	__attribute__((weak));
 *
 * Stack pointer is not yet initialized at this moment
 * Don't save anything to stack even if compiled with -O0
 *
 *************************************************************************/
ENTRY(save_boot_params)
	bx	lr			@ back to my caller
ENDPROC(save_boot_params)
	.weak	save_boot_params

/*************************************************************************
 *
 * cpu_init_cp15
 *
 * Setup CP15 registers (cache, MMU, TLBs). The I-cache is turned on unless
 * CONFIG_SYS_ICACHE_OFF is defined.
 *
 *************************************************************************/
ENTRY(cpu_init_cp15)
	/*
	 * Invalidate L1 I/D
	 */
	mov	r0, #0			@ set up for MCR
	mcr	p15, 0, r0, c8, c7, 0	@ invalidate TLBs
	mcr	p15, 0, r0, c7, c5, 0	@ invalidate icache
	mcr	p15, 0, r0, c7, c5, 6	@ invalidate BP array
	mcr     p15, 0, r0, c7, c10, 4	@ DSB
	mcr     p15, 0, r0, c7, c5, 4	@ ISB

	/*
	 * disable MMU stuff and caches
	 */
	mrc	p15, 0, r0, c1, c0, 0
	bic	r0, r0, #0x00002000	@ clear bits 13 (--V-)
	bic	r0, r0, #0x00000007	@ clear bits 2:0 (-CAM)
	orr	r0, r0, #0x00000002	@ set bit 1 (--A-) Align
	orr	r0, r0, #0x00000800	@ set bit 11 (Z---) BTB
#ifdef CONFIG_SYS_ICACHE_OFF
	bic	r0, r0, #0x00001000	@ clear bit 12 (I) I-cache
#else
	orr	r0, r0, #0x00001000	@ set bit 12 (I) I-cache
#endif
	mcr	p15, 0, r0, c1, c0, 0

#ifdef CONFIG_ARM_ERRATA_716044
	mrc	p15, 0, r0, c1, c0, 0	@ read system control register
	orr	r0, r0, #1 << 11	@ set bit #11
	mcr	p15, 0, r0, c1, c0, 0	@ write system control register
#endif

#if (defined(CONFIG_ARM_ERRATA_742230) || defined(CONFIG_ARM_ERRATA_794072))
	mrc	p15, 0, r0, c15, c0, 1	@ read diagnostic register
	orr	r0, r0, #1 << 4		@ set bit #4
	mcr	p15, 0, r0, c15, c0, 1	@ write diagnostic register
#endif

#ifdef CONFIG_ARM_ERRATA_743622
	mrc	p15, 0, r0, c15, c0, 1	@ read diagnostic register
	orr	r0, r0, #1 << 6		@ set bit #6
	mcr	p15, 0, r0, c15, c0, 1	@ write diagnostic register
#endif

#ifdef CONFIG_ARM_ERRATA_751472
	mrc	p15, 0, r0, c15, c0, 1	@ read diagnostic register
	orr	r0, r0, #1 << 11	@ set bit #11
	mcr	p15, 0, r0, c15, c0, 1	@ write diagnostic register
#endif
#ifdef CONFIG_ARM_ERRATA_761320
	mrc	p15, 0, r0, c15, c0, 1	@ read diagnostic register
	orr	r0, r0, #1 << 21	@ set bit #21
	mcr	p15, 0, r0, c15, c0, 1	@ write diagnostic register
#endif

	mov	pc, lr			@ back to my caller
ENDPROC(cpu_init_cp15)

#ifndef CONFIG_SKIP_LOWLEVEL_INIT
/*************************************************************************
 *
 * CPU_init_critical registers
 *
 * setup important registers
 * setup memory timing
 *
 *************************************************************************/
ENTRY(cpu_init_crit)
	/*
	 * Jump to board specific initialization...
	 * The Mask ROM will have already initialized
	 * basic memory. Go here to bump up clock rate and handle
	 * wake up conditions.
	 */
	b	lowlevel_init		@ go setup pll,mux,memory
ENDPROC(cpu_init_crit)
#endif