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xtensa: implement CPU hotplug 

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
This commit is contained in:
Max Filippov 2013-10-17 02:42:28 +04:00 committed by Chris Zankel
parent f615136c06
commit 49b424feda
8 changed files with 248 additions and 4 deletions
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9
arch/xtensa/Kconfig
View File

@ -140,6 +140,15 @@ config NR_CPUS
range 2 32
default "4"
config HOTPLUG_CPU
bool "Enable CPU hotplug support"
depends on SMP
help
Say Y here to allow turning CPUs off and on. CPUs can be
controlled through /sys/devices/system/cpu.
Say N if you want to disable CPU hotplug.
config MATH_EMULATION
bool "Math emulation"
help

1
arch/xtensa/include/asm/irq.h
View File

@ -45,6 +45,7 @@ static __inline__ int irq_canonicalize(int irq)
struct irqaction;
struct irq_domain;
void migrate_irqs(void);
int xtensa_irq_domain_xlate(const u32 *intspec, unsigned int intsize,
unsigned long int_irq, unsigned long ext_irq,
unsigned long *out_hwirq, unsigned int *out_type);

9
arch/xtensa/include/asm/smp.h
View File

@ -29,6 +29,15 @@ void ipi_init(void);
struct seq_file;
void show_ipi_list(struct seq_file *p, int prec);
#ifdef CONFIG_HOTPLUG_CPU
void __cpu_die(unsigned int cpu);
int __cpu_disable(void);
void cpu_die(void);
void cpu_restart(void);
#endif /* CONFIG_HOTPLUG_CPU */
#endif /* CONFIG_SMP */
#endif /* _XTENSA_SMP_H */

51
arch/xtensa/kernel/head.S
View File

@ -103,7 +103,7 @@ _SetupMMU:
ENDPROC(_start)
__INIT
__REF
.literal_position
ENTRY(_startup)
@ -302,6 +302,55 @@ should_never_return:
ENDPROC(_startup)
#ifdef CONFIG_HOTPLUG_CPU
ENTRY(cpu_restart)
#if XCHAL_DCACHE_IS_WRITEBACK
___flush_invalidate_dcache_all a2 a3
#else
___invalidate_dcache_all a2 a3
#endif
memw
movi a2, CCON # MX External Register to Configure Cache
movi a3, 0
wer a3, a2
extw
rsr a0, prid
neg a2, a0
movi a3, cpu_start_id
s32i a2, a3, 0
#if XCHAL_DCACHE_IS_WRITEBACK
dhwbi a3, 0
#endif
1:
l32i a2, a3, 0
dhi a3, 0
bne a2, a0, 1b
/*
* Initialize WB, WS, and clear PS.EXCM (to allow loop instructions).
* Set Interrupt Level just below XCHAL_DEBUGLEVEL to allow
* xt-gdb to single step via DEBUG exceptions received directly
* by ocd.
*/
movi a1, 1
movi a0, 0
wsr a1, windowstart
wsr a0, windowbase
rsync
movi a1, LOCKLEVEL
wsr a1, ps
rsync
j _startup
ENDPROC(cpu_restart)
#endif /* CONFIG_HOTPLUG_CPU */
/*
* DATA section
*/

49
arch/xtensa/kernel/irq.c
View File

@ -153,3 +153,52 @@ void __init init_IRQ(void)
#endif
variant_init_irq();
}
#ifdef CONFIG_HOTPLUG_CPU
static void route_irq(struct irq_data *data, unsigned int irq, unsigned int cpu)
{
struct irq_desc *desc = irq_to_desc(irq);
struct irq_chip *chip = irq_data_get_irq_chip(data);
unsigned long flags;
raw_spin_lock_irqsave(&desc->lock, flags);
if (chip->irq_set_affinity)
chip->irq_set_affinity(data, cpumask_of(cpu), false);
raw_spin_unlock_irqrestore(&desc->lock, flags);
}
/*
* The CPU has been marked offline. Migrate IRQs off this CPU. If
* the affinity settings do not allow other CPUs, force them onto any
* available CPU.
*/
void migrate_irqs(void)
{
unsigned int i, cpu = smp_processor_id();
struct irq_desc *desc;
for_each_irq_desc(i, desc) {
struct irq_data *data = irq_desc_get_irq_data(desc);
unsigned int newcpu;
if (irqd_is_per_cpu(data))
continue;
if (!cpumask_test_cpu(cpu, data->affinity))
continue;
newcpu = cpumask_any_and(data->affinity, cpu_online_mask);
if (newcpu >= nr_cpu_ids) {
pr_info_ratelimited("IRQ%u no longer affine to CPU%u\n",
i, cpu);
cpumask_setall(data->affinity);
newcpu = cpumask_any_and(data->affinity,
cpu_online_mask);
}
route_irq(data, i, newcpu);
}
}
#endif /* CONFIG_HOTPLUG_CPU */

1
arch/xtensa/kernel/setup.c
View File

@ -527,6 +527,7 @@ static int __init topology_init(void)
for_each_possible_cpu(i) {
struct cpu *cpu = &per_cpu(cpu_data, i);
cpu->hotpluggable = !!i;
register_cpu(cpu, i);
}

128
arch/xtensa/kernel/smp.c
View File

@ -40,6 +40,11 @@
# endif
#endif
static void system_invalidate_dcache_range(unsigned long start,
unsigned long size);
static void system_flush_invalidate_dcache_range(unsigned long start,
unsigned long size);
/* IPI (Inter Process Interrupt) */
#define IPI_IRQ 0
@ -106,7 +111,7 @@ void __init smp_cpus_done(unsigned int max_cpus)
static int boot_secondary_processors = 1; /* Set with xt-gdb via .xt-gdb */
static DECLARE_COMPLETION(cpu_running);
void __init secondary_start_kernel(void)
void secondary_start_kernel(void)
{
struct mm_struct *mm = &init_mm;
unsigned int cpu = smp_processor_id();
@ -174,6 +179,9 @@ static void mx_cpu_stop(void *p)
__func__, cpu, run_stall_mask, get_er(MPSCORE));
}
#ifdef CONFIG_HOTPLUG_CPU
unsigned long cpu_start_id __cacheline_aligned;
#endif
unsigned long cpu_start_ccount;
static int boot_secondary(unsigned int cpu, struct task_struct *ts)
@ -182,6 +190,11 @@ static int boot_secondary(unsigned int cpu, struct task_struct *ts)
unsigned long ccount;
int i;
#ifdef CONFIG_HOTPLUG_CPU
cpu_start_id = cpu;
system_flush_invalidate_dcache_range(
(unsigned long)&cpu_start_id, sizeof(cpu_start_id));
#endif
smp_call_function_single(0, mx_cpu_start, (void *)cpu, 1);
for (i = 0; i < 2; ++i) {
@ -234,6 +247,85 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
return ret;
}
#ifdef CONFIG_HOTPLUG_CPU
/*
* __cpu_disable runs on the processor to be shutdown.
*/
int __cpu_disable(void)
{
unsigned int cpu = smp_processor_id();
/*
* Take this CPU offline. Once we clear this, we can't return,
* and we must not schedule until we're ready to give up the cpu.
*/
set_cpu_online(cpu, false);
/*
* OK - migrate IRQs away from this CPU
*/
migrate_irqs();
/*
* Flush user cache and TLB mappings, and then remove this CPU
* from the vm mask set of all processes.
*/
local_flush_cache_all();
local_flush_tlb_all();
invalidate_page_directory();
clear_tasks_mm_cpumask(cpu);
return 0;
}
static void platform_cpu_kill(unsigned int cpu)
{
smp_call_function_single(0, mx_cpu_stop, (void *)cpu, true);
}
/*
* called on the thread which is asking for a CPU to be shutdown -
* waits until shutdown has completed, or it is timed out.
*/
void __cpu_die(unsigned int cpu)
{
unsigned long timeout = jiffies + msecs_to_jiffies(1000);
while (time_before(jiffies, timeout)) {
system_invalidate_dcache_range((unsigned long)&cpu_start_id,
sizeof(cpu_start_id));
if (cpu_start_id == -cpu) {
platform_cpu_kill(cpu);
return;
}
}
pr_err("CPU%u: unable to kill\n", cpu);
}
void arch_cpu_idle_dead(void)
{
cpu_die();
}
/*
* Called from the idle thread for the CPU which has been shutdown.
*
* Note that we disable IRQs here, but do not re-enable them
* before returning to the caller. This is also the behaviour
* of the other hotplug-cpu capable cores, so presumably coming
* out of idle fixes this.
*/
void __ref cpu_die(void)
{
idle_task_exit();
local_irq_disable();
__asm__ __volatile__(
" movi a2, cpu_restart\n"
" jx a2\n");
}
#endif /* CONFIG_HOTPLUG_CPU */
enum ipi_msg_type {
IPI_RESCHEDULE = 0,
IPI_CALL_FUNC,
@ -463,3 +555,37 @@ void flush_icache_range(unsigned long start, unsigned long end)
};
on_each_cpu(ipi_flush_icache_range, &fd, 1);
}
/* ------------------------------------------------------------------------- */
static void ipi_invalidate_dcache_range(void *arg)
{
struct flush_data *fd = arg;
__invalidate_dcache_range(fd->addr1, fd->addr2);
}
static void system_invalidate_dcache_range(unsigned long start,
unsigned long size)
{
struct flush_data fd = {
.addr1 = start,
.addr2 = size,
};
on_each_cpu(ipi_invalidate_dcache_range, &fd, 1);
}
static void ipi_flush_invalidate_dcache_range(void *arg)
{
struct flush_data *fd = arg;
__flush_invalidate_dcache_range(fd->addr1, fd->addr2);
}
static void system_flush_invalidate_dcache_range(unsigned long start,
unsigned long size)
{
struct flush_data fd = {
.addr1 = start,
.addr2 = size,
};
on_each_cpu(ipi_flush_invalidate_dcache_range, &fd, 1);
}

4
arch/xtensa/kernel/traps.c
View File

@ -332,7 +332,7 @@ void * __init trap_set_handler(int cause, void *handler)
}
static void __init trap_init_excsave(void)
static void trap_init_excsave(void)
{
unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table);
__asm__ __volatile__("wsr %0, excsave1\n" : : "a" (excsave1));
@ -384,7 +384,7 @@ void __init trap_init(void)
}
#ifdef CONFIG_SMP
void __init secondary_trap_init(void)
void secondary_trap_init(void)
{
trap_init_excsave();
}