diff options
Diffstat (limited to 'arch/arm/common/mcpm_entry.c')
| -rw-r--r-- | arch/arm/common/mcpm_entry.c | 281 |
1 files changed, 126 insertions, 155 deletions
diff --git a/arch/arm/common/mcpm_entry.c b/arch/arm/common/mcpm_entry.c index 5f8a52ac7..a923524d1 100644 --- a/arch/arm/common/mcpm_entry.c +++ b/arch/arm/common/mcpm_entry.c @@ -20,6 +20,126 @@ #include <asm/cputype.h> #include <asm/suspend.h> +/* + * The public API for this code is documented in arch/arm/include/asm/mcpm.h. + * For a comprehensive description of the main algorithm used here, please + * see Documentation/arm/cluster-pm-race-avoidance.txt. + */ + +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. + */ +static 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. + */ +static 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); + 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). + */ +static 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); + 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. + */ +static 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; +} + +static 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_entry_vectors[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER]; void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr) @@ -78,16 +198,11 @@ int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster) bool cpu_is_down, cluster_is_down; int ret = 0; + pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster); if (!platform_ops) return -EUNATCH; /* try not to shadow power_up errors */ might_sleep(); - /* backward compatibility callback */ - if (platform_ops->power_up) - return platform_ops->power_up(cpu, cluster); - - pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster); - /* * Since this is called with IRQs enabled, and no arch_spin_lock_irq * variant exists, we need to disable IRQs manually here. @@ -128,29 +243,17 @@ void mcpm_cpu_power_down(void) bool cpu_going_down, last_man; phys_reset_t phys_reset; + mpidr = read_cpuid_mpidr(); + cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); + cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); + pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster); if (WARN_ON_ONCE(!platform_ops)) 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(); - /* backward compatibility callback */ - if (platform_ops->power_down) { - platform_ops->power_down(); - goto not_dead; - } - - mpidr = read_cpuid_mpidr(); - cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); - cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); - pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster); - __mcpm_cpu_going_down(cpu, cluster); - arch_spin_lock(&mcpm_lock); BUG_ON(__mcpm_cluster_state(cluster) != CLUSTER_UP); @@ -187,7 +290,6 @@ void mcpm_cpu_power_down(void) if (cpu_going_down) wfi(); -not_dead: /* * It is possible for a power_up request to happen concurrently * with a power_down request for the same CPU. In this case the @@ -219,22 +321,11 @@ int mcpm_wait_for_cpu_powerdown(unsigned int cpu, unsigned int cluster) return ret; } -void mcpm_cpu_suspend(u64 expected_residency) +void mcpm_cpu_suspend(void) { if (WARN_ON_ONCE(!platform_ops)) return; - /* backward compatibility callback */ - if (platform_ops->suspend) { - phys_reset_t phys_reset; - BUG_ON(!irqs_disabled()); - 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(); - } - /* Some platforms might have to enable special resume modes, etc. */ if (platform_ops->cpu_suspend_prepare) { unsigned int mpidr = read_cpuid_mpidr(); @@ -256,12 +347,6 @@ int mcpm_cpu_powered_up(void) if (!platform_ops) return -EUNATCH; - /* backward compatibility callback */ - if (platform_ops->powered_up) { - platform_ops->powered_up(); - return 0; - } - mpidr = read_cpuid_mpidr(); cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); @@ -334,120 +419,6 @@ int __init mcpm_loopback(void (*cache_disable)(void)) #endif -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); - 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); - 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( |