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457 lines
13 KiB
457 lines
13 KiB
/*
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* arch/arm/common/mcpm_entry.c -- entry point for multi-cluster PM
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*
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* Created by: Nicolas Pitre, March 2012
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* Copyright: (C) 2012-2013 Linaro Limited
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/irqflags.h>
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#include <linux/cpu_pm.h>
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#include <asm/mcpm.h>
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#include <asm/cacheflush.h>
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#include <asm/idmap.h>
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#include <asm/cputype.h>
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#include <asm/suspend.h>
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/*
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* The public API for this code is documented in arch/arm/include/asm/mcpm.h.
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* For a comprehensive description of the main algorithm used here, please
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* see Documentation/arm/cluster-pm-race-avoidance.txt.
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*/
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struct sync_struct mcpm_sync;
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/*
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* __mcpm_cpu_going_down: Indicates that the cpu is being torn down.
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* This must be called at the point of committing to teardown of a CPU.
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* The CPU cache (SCTRL.C bit) is expected to still be active.
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*/
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static void __mcpm_cpu_going_down(unsigned int cpu, unsigned int cluster)
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{
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mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_GOING_DOWN;
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sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu);
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}
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/*
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* __mcpm_cpu_down: Indicates that cpu teardown is complete and that the
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* cluster can be torn down without disrupting this CPU.
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* To avoid deadlocks, this must be called before a CPU is powered down.
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* The CPU cache (SCTRL.C bit) is expected to be off.
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* However L2 cache might or might not be active.
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*/
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static void __mcpm_cpu_down(unsigned int cpu, unsigned int cluster)
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{
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dmb();
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mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_DOWN;
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sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu);
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sev();
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}
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/*
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* __mcpm_outbound_leave_critical: Leave the cluster teardown critical section.
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* @state: the final state of the cluster:
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* CLUSTER_UP: no destructive teardown was done and the cluster has been
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* restored to the previous state (CPU cache still active); or
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* CLUSTER_DOWN: the cluster has been torn-down, ready for power-off
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* (CPU cache disabled, L2 cache either enabled or disabled).
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*/
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static void __mcpm_outbound_leave_critical(unsigned int cluster, int state)
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{
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dmb();
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mcpm_sync.clusters[cluster].cluster = state;
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sync_cache_w(&mcpm_sync.clusters[cluster].cluster);
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sev();
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}
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/*
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* __mcpm_outbound_enter_critical: Enter the cluster teardown critical section.
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* This function should be called by the last man, after local CPU teardown
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* is complete. CPU cache expected to be active.
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*
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* Returns:
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* false: the critical section was not entered because an inbound CPU was
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* observed, or the cluster is already being set up;
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* true: the critical section was entered: it is now safe to tear down the
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* cluster.
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*/
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static bool __mcpm_outbound_enter_critical(unsigned int cpu, unsigned int cluster)
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{
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unsigned int i;
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struct mcpm_sync_struct *c = &mcpm_sync.clusters[cluster];
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/* Warn inbound CPUs that the cluster is being torn down: */
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c->cluster = CLUSTER_GOING_DOWN;
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sync_cache_w(&c->cluster);
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/* Back out if the inbound cluster is already in the critical region: */
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sync_cache_r(&c->inbound);
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if (c->inbound == INBOUND_COMING_UP)
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goto abort;
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/*
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* Wait for all CPUs to get out of the GOING_DOWN state, so that local
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* teardown is complete on each CPU before tearing down the cluster.
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*
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* If any CPU has been woken up again from the DOWN state, then we
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* shouldn't be taking the cluster down at all: abort in that case.
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*/
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sync_cache_r(&c->cpus);
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for (i = 0; i < MAX_CPUS_PER_CLUSTER; i++) {
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int cpustate;
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if (i == cpu)
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continue;
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while (1) {
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cpustate = c->cpus[i].cpu;
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if (cpustate != CPU_GOING_DOWN)
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break;
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wfe();
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sync_cache_r(&c->cpus[i].cpu);
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}
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switch (cpustate) {
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case CPU_DOWN:
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continue;
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default:
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goto abort;
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}
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}
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return true;
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abort:
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__mcpm_outbound_leave_critical(cluster, CLUSTER_UP);
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return false;
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}
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static int __mcpm_cluster_state(unsigned int cluster)
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{
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sync_cache_r(&mcpm_sync.clusters[cluster].cluster);
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return mcpm_sync.clusters[cluster].cluster;
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}
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extern unsigned long mcpm_entry_vectors[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER];
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void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr)
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{
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unsigned long val = ptr ? __pa_symbol(ptr) : 0;
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mcpm_entry_vectors[cluster][cpu] = val;
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sync_cache_w(&mcpm_entry_vectors[cluster][cpu]);
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}
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extern unsigned long mcpm_entry_early_pokes[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER][2];
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void mcpm_set_early_poke(unsigned cpu, unsigned cluster,
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unsigned long poke_phys_addr, unsigned long poke_val)
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{
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unsigned long *poke = &mcpm_entry_early_pokes[cluster][cpu][0];
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poke[0] = poke_phys_addr;
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poke[1] = poke_val;
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__sync_cache_range_w(poke, 2 * sizeof(*poke));
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}
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static const struct mcpm_platform_ops *platform_ops;
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int __init mcpm_platform_register(const struct mcpm_platform_ops *ops)
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{
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if (platform_ops)
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return -EBUSY;
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platform_ops = ops;
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return 0;
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}
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bool mcpm_is_available(void)
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{
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return (platform_ops) ? true : false;
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}
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/*
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* We can't use regular spinlocks. In the switcher case, it is possible
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* for an outbound CPU to call power_down() after its inbound counterpart
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* is already live using the same logical CPU number which trips lockdep
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* debugging.
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*/
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static arch_spinlock_t mcpm_lock = __ARCH_SPIN_LOCK_UNLOCKED;
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static int mcpm_cpu_use_count[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER];
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static inline bool mcpm_cluster_unused(unsigned int cluster)
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{
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int i, cnt;
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for (i = 0, cnt = 0; i < MAX_CPUS_PER_CLUSTER; i++)
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cnt |= mcpm_cpu_use_count[cluster][i];
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return !cnt;
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}
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int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster)
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{
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bool cpu_is_down, cluster_is_down;
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int ret = 0;
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pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
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if (!platform_ops)
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return -EUNATCH; /* try not to shadow power_up errors */
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might_sleep();
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/*
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* Since this is called with IRQs enabled, and no arch_spin_lock_irq
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* variant exists, we need to disable IRQs manually here.
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*/
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local_irq_disable();
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arch_spin_lock(&mcpm_lock);
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cpu_is_down = !mcpm_cpu_use_count[cluster][cpu];
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cluster_is_down = mcpm_cluster_unused(cluster);
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mcpm_cpu_use_count[cluster][cpu]++;
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/*
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* The only possible values are:
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* 0 = CPU down
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* 1 = CPU (still) up
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* 2 = CPU requested to be up before it had a chance
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* to actually make itself down.
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* Any other value is a bug.
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*/
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BUG_ON(mcpm_cpu_use_count[cluster][cpu] != 1 &&
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mcpm_cpu_use_count[cluster][cpu] != 2);
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if (cluster_is_down)
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ret = platform_ops->cluster_powerup(cluster);
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if (cpu_is_down && !ret)
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ret = platform_ops->cpu_powerup(cpu, cluster);
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arch_spin_unlock(&mcpm_lock);
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local_irq_enable();
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return ret;
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}
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typedef typeof(cpu_reset) phys_reset_t;
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void mcpm_cpu_power_down(void)
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{
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unsigned int mpidr, cpu, cluster;
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bool cpu_going_down, last_man;
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phys_reset_t phys_reset;
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mpidr = read_cpuid_mpidr();
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cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
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cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
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pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
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if (WARN_ON_ONCE(!platform_ops))
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return;
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BUG_ON(!irqs_disabled());
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setup_mm_for_reboot();
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__mcpm_cpu_going_down(cpu, cluster);
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arch_spin_lock(&mcpm_lock);
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BUG_ON(__mcpm_cluster_state(cluster) != CLUSTER_UP);
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mcpm_cpu_use_count[cluster][cpu]--;
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BUG_ON(mcpm_cpu_use_count[cluster][cpu] != 0 &&
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mcpm_cpu_use_count[cluster][cpu] != 1);
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cpu_going_down = !mcpm_cpu_use_count[cluster][cpu];
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last_man = mcpm_cluster_unused(cluster);
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if (last_man && __mcpm_outbound_enter_critical(cpu, cluster)) {
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platform_ops->cpu_powerdown_prepare(cpu, cluster);
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platform_ops->cluster_powerdown_prepare(cluster);
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arch_spin_unlock(&mcpm_lock);
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platform_ops->cluster_cache_disable();
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__mcpm_outbound_leave_critical(cluster, CLUSTER_DOWN);
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} else {
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if (cpu_going_down)
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platform_ops->cpu_powerdown_prepare(cpu, cluster);
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arch_spin_unlock(&mcpm_lock);
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/*
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* If cpu_going_down is false here, that means a power_up
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* request raced ahead of us. Even if we do not want to
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* shut this CPU down, the caller still expects execution
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* to return through the system resume entry path, like
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* when the WFI is aborted due to a new IRQ or the like..
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* So let's continue with cache cleaning in all cases.
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*/
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platform_ops->cpu_cache_disable();
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}
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__mcpm_cpu_down(cpu, cluster);
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/* Now we are prepared for power-down, do it: */
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if (cpu_going_down)
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wfi();
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/*
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* It is possible for a power_up request to happen concurrently
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* with a power_down request for the same CPU. In this case the
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* CPU might not be able to actually enter a powered down state
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* with the WFI instruction if the power_up request has removed
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* the required reset condition. We must perform a re-entry in
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* the kernel as if the power_up method just had deasserted reset
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* on the CPU.
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*/
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phys_reset = (phys_reset_t)(unsigned long)__pa_symbol(cpu_reset);
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phys_reset(__pa_symbol(mcpm_entry_point), false);
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/* should never get here */
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BUG();
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}
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int mcpm_wait_for_cpu_powerdown(unsigned int cpu, unsigned int cluster)
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{
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int ret;
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if (WARN_ON_ONCE(!platform_ops || !platform_ops->wait_for_powerdown))
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return -EUNATCH;
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ret = platform_ops->wait_for_powerdown(cpu, cluster);
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if (ret)
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pr_warn("%s: cpu %u, cluster %u failed to power down (%d)\n",
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__func__, cpu, cluster, ret);
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return ret;
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}
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void mcpm_cpu_suspend(void)
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{
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if (WARN_ON_ONCE(!platform_ops))
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return;
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/* Some platforms might have to enable special resume modes, etc. */
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if (platform_ops->cpu_suspend_prepare) {
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unsigned int mpidr = read_cpuid_mpidr();
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unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
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unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
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arch_spin_lock(&mcpm_lock);
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platform_ops->cpu_suspend_prepare(cpu, cluster);
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arch_spin_unlock(&mcpm_lock);
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}
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mcpm_cpu_power_down();
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}
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int mcpm_cpu_powered_up(void)
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{
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unsigned int mpidr, cpu, cluster;
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bool cpu_was_down, first_man;
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unsigned long flags;
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if (!platform_ops)
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return -EUNATCH;
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mpidr = read_cpuid_mpidr();
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cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
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cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
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local_irq_save(flags);
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arch_spin_lock(&mcpm_lock);
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cpu_was_down = !mcpm_cpu_use_count[cluster][cpu];
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first_man = mcpm_cluster_unused(cluster);
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if (first_man && platform_ops->cluster_is_up)
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platform_ops->cluster_is_up(cluster);
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if (cpu_was_down)
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mcpm_cpu_use_count[cluster][cpu] = 1;
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if (platform_ops->cpu_is_up)
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platform_ops->cpu_is_up(cpu, cluster);
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arch_spin_unlock(&mcpm_lock);
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local_irq_restore(flags);
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return 0;
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}
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#ifdef CONFIG_ARM_CPU_SUSPEND
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static int __init nocache_trampoline(unsigned long _arg)
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{
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void (*cache_disable)(void) = (void *)_arg;
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unsigned int mpidr = read_cpuid_mpidr();
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unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
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unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
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phys_reset_t phys_reset;
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mcpm_set_entry_vector(cpu, cluster, cpu_resume_no_hyp);
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setup_mm_for_reboot();
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__mcpm_cpu_going_down(cpu, cluster);
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BUG_ON(!__mcpm_outbound_enter_critical(cpu, cluster));
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cache_disable();
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__mcpm_outbound_leave_critical(cluster, CLUSTER_DOWN);
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__mcpm_cpu_down(cpu, cluster);
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phys_reset = (phys_reset_t)(unsigned long)__pa_symbol(cpu_reset);
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phys_reset(__pa_symbol(mcpm_entry_point), false);
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BUG();
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}
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int __init mcpm_loopback(void (*cache_disable)(void))
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{
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int ret;
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/*
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* We're going to soft-restart the current CPU through the
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* low-level MCPM code by leveraging the suspend/resume
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* infrastructure. Let's play it safe by using cpu_pm_enter()
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* in case the CPU init code path resets the VFP or similar.
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*/
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local_irq_disable();
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local_fiq_disable();
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ret = cpu_pm_enter();
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if (!ret) {
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ret = cpu_suspend((unsigned long)cache_disable, nocache_trampoline);
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cpu_pm_exit();
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}
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local_fiq_enable();
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local_irq_enable();
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if (ret)
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pr_err("%s returned %d\n", __func__, ret);
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return ret;
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}
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#endif
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extern unsigned long mcpm_power_up_setup_phys;
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int __init mcpm_sync_init(
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void (*power_up_setup)(unsigned int affinity_level))
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{
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unsigned int i, j, mpidr, this_cluster;
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BUILD_BUG_ON(MCPM_SYNC_CLUSTER_SIZE * MAX_NR_CLUSTERS != sizeof mcpm_sync);
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BUG_ON((unsigned long)&mcpm_sync & (__CACHE_WRITEBACK_GRANULE - 1));
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/*
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* Set initial CPU and cluster states.
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* Only one cluster is assumed to be active at this point.
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*/
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for (i = 0; i < MAX_NR_CLUSTERS; i++) {
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mcpm_sync.clusters[i].cluster = CLUSTER_DOWN;
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mcpm_sync.clusters[i].inbound = INBOUND_NOT_COMING_UP;
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for (j = 0; j < MAX_CPUS_PER_CLUSTER; j++)
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mcpm_sync.clusters[i].cpus[j].cpu = CPU_DOWN;
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}
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mpidr = read_cpuid_mpidr();
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this_cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
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for_each_online_cpu(i) {
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mcpm_cpu_use_count[this_cluster][i] = 1;
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mcpm_sync.clusters[this_cluster].cpus[i].cpu = CPU_UP;
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}
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mcpm_sync.clusters[this_cluster].cluster = CLUSTER_UP;
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sync_cache_w(&mcpm_sync);
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if (power_up_setup) {
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mcpm_power_up_setup_phys = __pa_symbol(power_up_setup);
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sync_cache_w(&mcpm_power_up_setup_phys);
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}
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return 0;
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}
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