u-boot/arch/arm/mach-rmobile/lowlevel_init_gen3.S
Andre Przywara 5ff4857d35 armv8: Fix and simplify branch_if_master/branch_if_slave
The branch_if_master macro jumps to a label if the CPU is the "master"
core, which we define as having all affinity levels set to 0. To check
for this condition, we need to mask off some bits from the MPIDR
register, then compare the remaining register value against zero.

The implementation of this was slighly broken (it preserved the upper
RES0 bits), overly complicated and hard to understand, especially since
it lacked comments. The same was true for the very similar
branch_if_slave macro.

Use a much shorter assembly sequence for those checks, use the same
masking for both macros (just negate the final branch), and put some
comments on them, to make it clear what the code does.
This allows to drop the second temporary register for branch_if_master,
so we adjust all call sites as well.

Also use the opportunity to remove a misleading comment: the macro
works fine on SoCs with multiple clusters. Judging by the commit
message, the original problem with the Juno SoC stems from the fact that
the master CPU *can* be configured to be from cluster 1, so the
assumption that the master CPU has all affinity values set to 0 does not
hold there. But this is already mentioned above in a comment, so remove
the extra comment.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
2022-03-02 13:59:29 -05:00

104 lines
2.0 KiB
ArmAsm

/* SPDX-License-Identifier: GPL-2.0+ */
/*
* arch/arm/cpu/armv8/rcar_gen3/lowlevel_init.S
* This file is lowlevel initialize routine.
*
* (C) Copyright 2015 Renesas Electronics Corporation
*
* This file is based on the arch/arm/cpu/armv8/start.S
*
* (C) Copyright 2013
* David Feng <fenghua@phytium.com.cn>
*/
#include <asm-offsets.h>
#include <config.h>
#include <linux/linkage.h>
#include <asm/macro.h>
.align 8
.globl rcar_atf_boot_args
rcar_atf_boot_args:
.dword 0
.dword 0
.dword 0
.dword 0
ENTRY(save_boot_params)
adr x8, rcar_atf_boot_args
stp x0, x1, [x8], #16
stp x2, x3, [x8], #16
b save_boot_params_ret
ENDPROC(save_boot_params)
.pushsection .text.s_init, "ax"
WEAK(s_init)
ret
ENDPROC(s_init)
.popsection
ENTRY(lowlevel_init)
mov x29, lr /* Save LR */
#ifndef CONFIG_ARMV8_MULTIENTRY
/*
* For single-entry systems the lowlevel init is very simple.
*/
ldr x0, =GICD_BASE
bl gic_init_secure
#else /* CONFIG_ARMV8_MULTIENTRY is set */
#if defined(CONFIG_GICV2) || defined(CONFIG_GICV3)
branch_if_slave x0, 1f
ldr x0, =GICD_BASE
bl gic_init_secure
1:
#if defined(CONFIG_GICV3)
ldr x0, =GICR_BASE
bl gic_init_secure_percpu
#elif defined(CONFIG_GICV2)
ldr x0, =GICD_BASE
ldr x1, =GICC_BASE
bl gic_init_secure_percpu
#endif
#endif
branch_if_master x0, 2f
/*
* Slave should wait for master clearing spin table.
* This sync prevent salves observing incorrect
* value of spin table and jumping to wrong place.
*/
#if defined(CONFIG_GICV2) || defined(CONFIG_GICV3)
#ifdef CONFIG_GICV2
ldr x0, =GICC_BASE
#endif
bl gic_wait_for_interrupt
#endif
/*
* All slaves will enter EL2 and optionally EL1.
*/
adr x4, lowlevel_in_el2
ldr x5, =ES_TO_AARCH64
bl armv8_switch_to_el2
lowlevel_in_el2:
#ifdef CONFIG_ARMV8_SWITCH_TO_EL1
adr x4, lowlevel_in_el1
ldr x5, =ES_TO_AARCH64
bl armv8_switch_to_el1
lowlevel_in_el1:
#endif
#endif /* CONFIG_ARMV8_MULTIENTRY */
bl s_init
2:
mov lr, x29 /* Restore LR */
ret
ENDPROC(lowlevel_init)