linux_dsm_epyc7002/arch/arm/mach-spear/generic.h
Russell King 6213f70e7c 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>
2019-02-01 22:05:23 +00:00

59 lines
1.7 KiB
C

/*
* spear machine family generic header file
*
* Copyright (C) 2009-2012 ST Microelectronics
* Rajeev Kumar <rajeev-dlh.kumar@st.com>
* Viresh Kumar <vireshk@kernel.org>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#ifndef __MACH_GENERIC_H
#define __MACH_GENERIC_H
#include <linux/dmaengine.h>
#include <linux/amba/pl08x.h>
#include <linux/init.h>
#include <linux/reboot.h>
#include <asm/mach/time.h>
extern volatile int spear_pen_release;
extern void spear13xx_timer_init(void);
extern void spear3xx_timer_init(void);
extern struct pl022_ssp_controller pl022_plat_data;
extern struct pl08x_platform_data pl080_plat_data;
void __init spear_setup_of_timer(void);
void __init spear3xx_clk_init(void __iomem *misc_base,
void __iomem *soc_config_base);
void __init spear3xx_map_io(void);
void __init spear3xx_dt_init_irq(void);
void __init spear6xx_clk_init(void __iomem *misc_base);
void __init spear13xx_map_io(void);
void __init spear13xx_l2x0_init(void);
void spear_restart(enum reboot_mode, const char *);
void spear13xx_secondary_startup(void);
void spear13xx_cpu_die(unsigned int cpu);
extern const struct smp_operations spear13xx_smp_ops;
#ifdef CONFIG_MACH_SPEAR1310
void __init spear1310_clk_init(void __iomem *misc_base, void __iomem *ras_base);
#else
static inline void spear1310_clk_init(void __iomem *misc_base, void __iomem *ras_base) {}
#endif
#ifdef CONFIG_MACH_SPEAR1340
void __init spear1340_clk_init(void __iomem *misc_base);
#else
static inline void spear1340_clk_init(void __iomem *misc_base) {}
#endif
#endif /* __MACH_GENERIC_H */