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csky: CPU-hotplug supported for SMP 

This is a simple implement of CPU-hotplug for power saving. CPU use
wait instruction to enter power saving mode and waiting for IPI wakeup
signal.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
hifive-unleashed-5.1
Guo Ren 2018-12-19 19:56:14 +08:00
parent 1d95fe4d3d
commit 859e5f45cb
3 changed files with 69 additions and 15 deletions
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9
arch/csky/Kconfig
View File

@ -198,6 +198,15 @@ config RAM_BASE
hex "DRAM start addr (the same with memory-section in dts)"
default 0x0
config HOTPLUG_CPU
bool "Support for hot-pluggable CPUs"
select GENERIC_IRQ_MIGRATION
depends on SMP
help
Say Y here to allow turning CPUs off and on. CPUs can be
controlled through /sys/devices/system/cpu/cpu1/hotplug/target.
Say N if you want to disable CPU hotplug.
endmenu
source "kernel/Kconfig.hz"

4
arch/csky/include/asm/smp.h
View File

@ -21,6 +21,10 @@ void __init set_send_ipi(void (*func)(const struct cpumask *mask), int irq);
#define raw_smp_processor_id() (current_thread_info()->cpu)
int __cpu_disable(void);
void __cpu_die(unsigned int cpu);
#endif /* CONFIG_SMP */
#endif /* __ASM_CSKY_SMP_H */

71
arch/csky/kernel/smp.c
View File

@ -16,6 +16,7 @@
#include <linux/of.h>
#include <linux/sched/task_stack.h>
#include <linux/sched/mm.h>
#include <linux/sched/hotplug.h>
#include <asm/irq.h>
#include <asm/traps.h>
#include <asm/sections.h>
@ -112,12 +113,8 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
{
}
static void __init enable_smp_ipi(void)
{
enable_percpu_irq(ipi_irq, 0);
}
static int ipi_dummy_dev;
void __init setup_smp_ipi(void)
{
int rc;
@ -130,7 +127,7 @@ void __init setup_smp_ipi(void)
if (rc)
panic("%s IRQ request failed\n", __func__);
enable_smp_ipi();
enable_percpu_irq(ipi_irq, 0);
}
void __init setup_smp(void)
@ -161,12 +158,10 @@ volatile unsigned int secondary_stack;
int __cpu_up(unsigned int cpu, struct task_struct *tidle)
{
unsigned int tmp;
secondary_stack = (unsigned int)tidle->stack + THREAD_SIZE;
unsigned long mask = 1 << cpu;
secondary_stack = (unsigned int)tidle->stack + THREAD_SIZE - 8;
secondary_hint = mfcr("cr31");
secondary_ccr = mfcr("cr18");
/*
@ -176,10 +171,13 @@ int __cpu_up(unsigned int cpu, struct task_struct *tidle)
*/
mtcr("cr17", 0x22);
/* Enable cpu in SMP reset ctrl reg */
tmp = mfcr("cr<29, 0>");
tmp |= 1 << cpu;
mtcr("cr<29, 0>", tmp);
if (mask & mfcr("cr<29, 0>")) {
send_arch_ipi(cpumask_of(cpu));
} else {
/* Enable cpu in SMP reset ctrl reg */
mask |= mfcr("cr<29, 0>");
mtcr("cr<29, 0>", mask);
}
/* Wait for the cpu online */
while (!cpu_online(cpu));
@ -219,7 +217,7 @@ void csky_start_secondary(void)
init_fpu();
#endif
enable_smp_ipi();
enable_percpu_irq(ipi_irq, 0);
mmget(mm);
mmgrab(mm);
@ -235,3 +233,46 @@ void csky_start_secondary(void)
preempt_disable();
cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
}
#ifdef CONFIG_HOTPLUG_CPU
int __cpu_disable(void)
{
unsigned int cpu = smp_processor_id();
set_cpu_online(cpu, false);
irq_migrate_all_off_this_cpu();
clear_tasks_mm_cpumask(cpu);
return 0;
}
void __cpu_die(unsigned int cpu)
{
if (!cpu_wait_death(cpu, 5)) {
pr_crit("CPU%u: shutdown failed\n", cpu);
return;
}
pr_notice("CPU%u: shutdown\n", cpu);
}
void arch_cpu_idle_dead(void)
{
idle_task_exit();
cpu_report_death();
while (!secondary_stack)
arch_cpu_idle();
local_irq_disable();
asm volatile(
"mov sp, %0\n"
"mov r8, %0\n"
"jmpi csky_start_secondary"
:
: "r" (secondary_stack));
}
#endif