linux/arch/arm/mach-zynq/platsmp.c
Russell King 02b4e2756e ARM: v7 setup function should invalidate L1 cache
All ARMv5 and older CPUs invalidate their caches in the early assembly
setup function, prior to enabling the MMU.  This is because the L1
cache should not contain any data relevant to the execution of the
kernel at this point; all data should have been flushed out to memory.

This requirement should also be true for ARMv6 and ARMv7 CPUs - indeed,
these typically do not search their caches when caching is disabled (as
it needs to be when the MMU is disabled) so this change should be safe.

ARMv7 allows there to be CPUs which search their caches while caching is
disabled, and it's permitted that the cache is uninitialised at boot;
for these, the architecture reference manual requires that an
implementation specific code sequence is used immediately after reset
to ensure that the cache is placed into a sane state.  Such
functionality is definitely outside the remit of the Linux kernel, and
must be done by the SoC's firmware before _any_ CPU gets to the Linux
kernel.

Changing the data cache clean+invalidate to a mere invalidate allows us
to get rid of a lot of platform specific hacks around this issue for
their secondary CPU bringup paths - some of which were buggy.

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Dinh Nguyen <dinguyen@opensource.altera.com>
Acked-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Tested-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Tested-by: Thierry Reding <treding@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Michal Simek <michal.simek@xilinx.com>
Tested-by: Wei Xu <xuwei5@hisilicon.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2015-06-01 11:30:26 +01:00

170 lines
4.2 KiB
C

/*
* This file contains Xilinx specific SMP code, used to start up
* the second processor.
*
* Copyright (C) 2011-2013 Xilinx
*
* based on linux/arch/arm/mach-realview/platsmp.c
*
* Copyright (C) 2002 ARM Ltd.
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/export.h>
#include <linux/jiffies.h>
#include <linux/init.h>
#include <linux/io.h>
#include <asm/cacheflush.h>
#include <asm/smp_scu.h>
#include <linux/irqchip/arm-gic.h>
#include "common.h"
/*
* Store number of cores in the system
* Because of scu_get_core_count() must be in __init section and can't
* be called from zynq_cpun_start() because it is not in __init section.
*/
static int ncores;
int zynq_cpun_start(u32 address, int cpu)
{
u32 trampoline_code_size = &zynq_secondary_trampoline_end -
&zynq_secondary_trampoline;
/* MS: Expectation that SLCR are directly map and accessible */
/* Not possible to jump to non aligned address */
if (!(address & 3) && (!address || (address >= trampoline_code_size))) {
/* Store pointer to ioremap area which points to address 0x0 */
static u8 __iomem *zero;
u32 trampoline_size = &zynq_secondary_trampoline_jump -
&zynq_secondary_trampoline;
zynq_slcr_cpu_stop(cpu);
if (address) {
if (__pa(PAGE_OFFSET)) {
zero = ioremap(0, trampoline_code_size);
if (!zero) {
pr_warn("BOOTUP jump vectors not accessible\n");
return -1;
}
} else {
zero = (__force u8 __iomem *)PAGE_OFFSET;
}
/*
* This is elegant way how to jump to any address
* 0x0: Load address at 0x8 to r0
* 0x4: Jump by mov instruction
* 0x8: Jumping address
*/
memcpy((__force void *)zero, &zynq_secondary_trampoline,
trampoline_size);
writel(address, zero + trampoline_size);
flush_cache_all();
outer_flush_range(0, trampoline_code_size);
smp_wmb();
if (__pa(PAGE_OFFSET))
iounmap(zero);
}
zynq_slcr_cpu_start(cpu);
return 0;
}
pr_warn("Can't start CPU%d: Wrong starting address %x\n", cpu, address);
return -1;
}
EXPORT_SYMBOL(zynq_cpun_start);
static int zynq_boot_secondary(unsigned int cpu, struct task_struct *idle)
{
return zynq_cpun_start(virt_to_phys(secondary_startup), cpu);
}
/*
* Initialise the CPU possible map early - this describes the CPUs
* which may be present or become present in the system.
*/
static void __init zynq_smp_init_cpus(void)
{
int i;
ncores = scu_get_core_count(zynq_scu_base);
for (i = 0; i < ncores && i < CONFIG_NR_CPUS; i++)
set_cpu_possible(i, true);
}
static void __init zynq_smp_prepare_cpus(unsigned int max_cpus)
{
scu_enable(zynq_scu_base);
}
/**
* zynq_secondary_init - Initialize secondary CPU cores
* @cpu: CPU that is initialized
*
* This function is in the hotplug path. Don't move it into the
* init section!!
*/
static void zynq_secondary_init(unsigned int cpu)
{
zynq_core_pm_init();
}
#ifdef CONFIG_HOTPLUG_CPU
static int zynq_cpu_kill(unsigned cpu)
{
unsigned long timeout = jiffies + msecs_to_jiffies(50);
while (zynq_slcr_cpu_state_read(cpu))
if (time_after(jiffies, timeout))
return 0;
zynq_slcr_cpu_stop(cpu);
return 1;
}
/**
* zynq_cpu_die - Let a CPU core die
* @cpu: Dying CPU
*
* Platform-specific code to shutdown a CPU.
* Called with IRQs disabled on the dying CPU.
*/
static void zynq_cpu_die(unsigned int cpu)
{
zynq_slcr_cpu_state_write(cpu, true);
/*
* there is no power-control hardware on this platform, so all
* we can do is put the core into WFI; this is safe as the calling
* code will have already disabled interrupts
*/
for (;;)
cpu_do_idle();
}
#endif
struct smp_operations zynq_smp_ops __initdata = {
.smp_init_cpus = zynq_smp_init_cpus,
.smp_prepare_cpus = zynq_smp_prepare_cpus,
.smp_boot_secondary = zynq_boot_secondary,
.smp_secondary_init = zynq_secondary_init,
#ifdef CONFIG_HOTPLUG_CPU
.cpu_die = zynq_cpu_die,
.cpu_kill = zynq_cpu_kill,
#endif
};