blob: 990250965f2cfb4e4e3a984678fcf62eedbcdb8d [file] [log] [blame]
/*
* arch/arm/common/mcpm_entry.c -- entry point for multi-cluster PM
*
* Created by: Nicolas Pitre, March 2012
* Copyright: (C) 2012-2013 Linaro Limited
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/irqflags.h>
#include <asm/mcpm.h>
#include <asm/cacheflush.h>
#include <asm/idmap.h>
#include <asm/cputype.h>
extern unsigned long mcpm_entry_vectors[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER];
void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr)
{
unsigned long val = ptr ? virt_to_phys(ptr) : 0;
mcpm_entry_vectors[cluster][cpu] = val;
sync_cache_w(&mcpm_entry_vectors[cluster][cpu]);
}
static const struct mcpm_platform_ops *platform_ops;
int __init mcpm_platform_register(const struct mcpm_platform_ops *ops)
{
if (platform_ops)
return -EBUSY;
platform_ops = ops;
return 0;
}
int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster)
{
if (!platform_ops)
return -EUNATCH; /* try not to shadow power_up errors */
might_sleep();
return platform_ops->power_up(cpu, cluster);
}
typedef void (*phys_reset_t)(unsigned long);
void mcpm_cpu_power_down(void)
{
phys_reset_t phys_reset;
if (WARN_ON_ONCE(!platform_ops || !platform_ops->power_down))
return;
BUG_ON(!irqs_disabled());
/*
* Do this before calling into the power_down method,
* as it might not always be safe to do afterwards.
*/
setup_mm_for_reboot();
platform_ops->power_down();
/*
* It is possible for a power_up request to happen concurrently
* with a power_down request for the same CPU. In this case the
* power_down method might not be able to actually enter a
* powered down state with the WFI instruction if the power_up
* method has removed the required reset condition. The
* power_down method is then allowed to return. We must perform
* a re-entry in the kernel as if the power_up method just had
* deasserted reset on the CPU.
*
* To simplify race issues, the platform specific implementation
* must accommodate for the possibility of unordered calls to
* power_down and power_up with a usage count. Therefore, if a
* call to power_up is issued for a CPU that is not down, then
* the next call to power_down must not attempt a full shutdown
* but only do the minimum (normally disabling L1 cache and CPU
* coherency) and return just as if a concurrent power_up request
* had happened as described above.
*/
phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset);
phys_reset(virt_to_phys(mcpm_entry_point));
/* should never get here */
BUG();
}
void mcpm_cpu_suspend(u64 expected_residency)
{
phys_reset_t phys_reset;
if (WARN_ON_ONCE(!platform_ops || !platform_ops->suspend))
return;
BUG_ON(!irqs_disabled());
/* Very similar to mcpm_cpu_power_down() */
setup_mm_for_reboot();
platform_ops->suspend(expected_residency);
phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset);
phys_reset(virt_to_phys(mcpm_entry_point));
BUG();
}
int mcpm_cpu_powered_up(void)
{
if (!platform_ops)
return -EUNATCH;
if (platform_ops->powered_up)
platform_ops->powered_up();
return 0;
}
struct sync_struct mcpm_sync;
/*
* __mcpm_cpu_going_down: Indicates that the cpu is being torn down.
* This must be called at the point of committing to teardown of a CPU.
* The CPU cache (SCTRL.C bit) is expected to still be active.
*/
void __mcpm_cpu_going_down(unsigned int cpu, unsigned int cluster)
{
mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_GOING_DOWN;
sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu);
}
/*
* __mcpm_cpu_down: Indicates that cpu teardown is complete and that the
* cluster can be torn down without disrupting this CPU.
* To avoid deadlocks, this must be called before a CPU is powered down.
* The CPU cache (SCTRL.C bit) is expected to be off.
* However L2 cache might or might not be active.
*/
void __mcpm_cpu_down(unsigned int cpu, unsigned int cluster)
{
dmb();
mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_DOWN;
sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu);
dsb_sev();
}
/*
* __mcpm_outbound_leave_critical: Leave the cluster teardown critical section.
* @state: the final state of the cluster:
* CLUSTER_UP: no destructive teardown was done and the cluster has been
* restored to the previous state (CPU cache still active); or
* CLUSTER_DOWN: the cluster has been torn-down, ready for power-off
* (CPU cache disabled, L2 cache either enabled or disabled).
*/
void __mcpm_outbound_leave_critical(unsigned int cluster, int state)
{
dmb();
mcpm_sync.clusters[cluster].cluster = state;
sync_cache_w(&mcpm_sync.clusters[cluster].cluster);
dsb_sev();
}
/*
* __mcpm_outbound_enter_critical: Enter the cluster teardown critical section.
* This function should be called by the last man, after local CPU teardown
* is complete. CPU cache expected to be active.
*
* Returns:
* false: the critical section was not entered because an inbound CPU was
* observed, or the cluster is already being set up;
* true: the critical section was entered: it is now safe to tear down the
* cluster.
*/
bool __mcpm_outbound_enter_critical(unsigned int cpu, unsigned int cluster)
{
unsigned int i;
struct mcpm_sync_struct *c = &mcpm_sync.clusters[cluster];
/* Warn inbound CPUs that the cluster is being torn down: */
c->cluster = CLUSTER_GOING_DOWN;
sync_cache_w(&c->cluster);
/* Back out if the inbound cluster is already in the critical region: */
sync_cache_r(&c->inbound);
if (c->inbound == INBOUND_COMING_UP)
goto abort;
/*
* Wait for all CPUs to get out of the GOING_DOWN state, so that local
* teardown is complete on each CPU before tearing down the cluster.
*
* If any CPU has been woken up again from the DOWN state, then we
* shouldn't be taking the cluster down at all: abort in that case.
*/
sync_cache_r(&c->cpus);
for (i = 0; i < MAX_CPUS_PER_CLUSTER; i++) {
int cpustate;
if (i == cpu)
continue;
while (1) {
cpustate = c->cpus[i].cpu;
if (cpustate != CPU_GOING_DOWN)
break;
wfe();
sync_cache_r(&c->cpus[i].cpu);
}
switch (cpustate) {
case CPU_DOWN:
continue;
default:
goto abort;
}
}
return true;
abort:
__mcpm_outbound_leave_critical(cluster, CLUSTER_UP);
return false;
}
int __mcpm_cluster_state(unsigned int cluster)
{
sync_cache_r(&mcpm_sync.clusters[cluster].cluster);
return mcpm_sync.clusters[cluster].cluster;
}
extern unsigned long mcpm_power_up_setup_phys;
int __init mcpm_sync_init(
void (*power_up_setup)(unsigned int affinity_level))
{
unsigned int i, j, mpidr, this_cluster;
BUILD_BUG_ON(MCPM_SYNC_CLUSTER_SIZE * MAX_NR_CLUSTERS != sizeof mcpm_sync);
BUG_ON((unsigned long)&mcpm_sync & (__CACHE_WRITEBACK_GRANULE - 1));
/*
* Set initial CPU and cluster states.
* Only one cluster is assumed to be active at this point.
*/
for (i = 0; i < MAX_NR_CLUSTERS; i++) {
mcpm_sync.clusters[i].cluster = CLUSTER_DOWN;
mcpm_sync.clusters[i].inbound = INBOUND_NOT_COMING_UP;
for (j = 0; j < MAX_CPUS_PER_CLUSTER; j++)
mcpm_sync.clusters[i].cpus[j].cpu = CPU_DOWN;
}
mpidr = read_cpuid_mpidr();
this_cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
for_each_online_cpu(i)
mcpm_sync.clusters[this_cluster].cpus[i].cpu = CPU_UP;
mcpm_sync.clusters[this_cluster].cluster = CLUSTER_UP;
sync_cache_w(&mcpm_sync);
if (power_up_setup) {
mcpm_power_up_setup_phys = virt_to_phys(power_up_setup);
sync_cache_w(&mcpm_power_up_setup_phys);
}
return 0;
}