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authorGuo Ren <ren_guo@c-sky.com>2018-12-19 19:56:14 +0800
committerGuo Ren <ren_guo@c-sky.com>2018-12-31 23:03:53 +0800
commit859e5f45cbb33fe5d591a8e429667f0b7d4f4be8 (patch)
treec3cd065d0ac34d9bc09af2a53d3cf64695329c89 /arch
parent1d95fe4d3de42e915bc22d5fd6cd4de103c5e517 (diff)
downloadlinux-859e5f45cbb33fe5d591a8e429667f0b7d4f4be8.tar.gz
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/csky/Kconfig9
-rw-r--r--arch/csky/include/asm/smp.h4
-rw-r--r--arch/csky/kernel/smp.c71
3 files changed, 69 insertions, 15 deletions
diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index cb64f8dacd08..8bdbe9219662 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -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"
diff --git a/arch/csky/include/asm/smp.h b/arch/csky/include/asm/smp.h
index 4a929c4d6437..668b79ce29ea 100644
--- a/arch/csky/include/asm/smp.h
+++ b/arch/csky/include/asm/smp.h
@@ -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 */
diff --git a/arch/csky/kernel/smp.c b/arch/csky/kernel/smp.c
index 74d627300c55..ddc4dd79f282 100644
--- a/arch/csky/kernel/smp.c
+++ b/arch/csky/kernel/smp.c
@@ -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