2017-12-26 03:54:31 +08:00
|
|
|
/* SPDX-License-Identifier: GPL-2.0 */
|
2010-07-26 20:08:52 +08:00
|
|
|
/*
|
|
|
|
|
* Cloned from linux/arch/arm/mach-realview/headsmp.S
|
|
|
|
|
*
|
|
|
|
|
* Copyright (c) 2003 ARM Limited
|
|
|
|
|
* All Rights Reserved
|
|
|
|
|
*/
|
|
|
|
|
#include <linux/linkage.h>
|
|
|
|
|
#include <linux/init.h>
|
|
|
|
|
|
2016-06-21 18:20:24 +08:00
|
|
|
#include <asm/assembler.h>
|
|
|
|
|
|
2010-07-26 20:08:52 +08:00
|
|
|
/*
|
2011-02-14 15:33:10 +08:00
|
|
|
* exynos4 specific entry point for secondary CPUs. This provides
|
2010-07-26 20:08:52 +08:00
|
|
|
* a "holding pen" into which all secondary cores are held until we're
|
|
|
|
|
* ready for them to initialise.
|
|
|
|
|
*/
|
2011-02-14 15:33:10 +08:00
|
|
|
ENTRY(exynos4_secondary_startup)
|
2016-06-21 18:20:24 +08:00
|
|
|
ARM_BE8(setend be)
|
2010-07-26 20:08:52 +08:00
|
|
|
mrc p15, 0, r0, c0, c0, 5
|
|
|
|
|
and r0, r0, #15
|
|
|
|
|
adr r4, 1f
|
|
|
|
|
ldmia r4, {r5, r6}
|
|
|
|
|
sub r4, r4, r5
|
|
|
|
|
add r6, r6, r4
|
|
|
|
|
pen: ldr r7, [r6]
|
|
|
|
|
cmp r7, r0
|
|
|
|
|
bne pen
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* we've been released from the holding pen: secondary_stack
|
|
|
|
|
* should now contain the SVC stack for this core
|
|
|
|
|
*/
|
|
|
|
|
b secondary_startup
|
2012-01-10 05:39:19 +08:00
|
|
|
ENDPROC(exynos4_secondary_startup)
|
2010-07-26 20:08:52 +08:00
|
|
|
|
2012-01-10 05:39:19 +08:00
|
|
|
.align 2
|
2010-07-26 20:08:52 +08:00
|
|
|
1: .long .
|
ARM: smp: remove arch-provided "pen_release"
Consolidating the "pen_release" stuff amongst the various SoC
implementations gives credence to having a CPU holding pen for
secondary CPUs. However, this is far from the truth.
Many SoC implementations cargo-cult copied various bits of the pen
release implementation from the initial Realview/Versatile Express
implementation without understanding what it was or why it existed.
The reason it existed is because these are _development_ platforms,
and some board firmware is unable to individually control the
startup of secondary CPUs. Moreover, they do not have a way to
power down or reset secondary CPUs for hot-unplug. Hence, the
pen_release implementation was designed for ARM Ltd's development
platforms to provide a working implementation, even though it is
very far from what is required.
It was decided a while back to reduce the duplication by consolidating
the "pen_release" variable, but this only made the situation worse -
we have ended up with several implementations that read this variable
but do not write it - again, showing the cargo-cult mentality at work,
lack of proper review of new code, and in some cases a lack of testing.
While it would be preferable to remove pen_release entirely from the
kernel, this is not possible without help from the SoC maintainers,
which seems to be lacking. However, I want to remove pen_release from
arch code to remove the credence that having it gives.
This patch removes pen_release from the arch code entirely, adding
private per-SoC definitions for it instead, and explicitly stating
that write_pen_release() is cargo-cult copied and should not be
copied any further. Rename write_pen_release() in a similar fashion
as well.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-12-13 22:02:48 +08:00
|
|
|
.long exynos_pen_release
|