cpuidle: coupled: add parallel barrier function
Adds cpuidle_coupled_parallel_barrier, which can be used by coupled cpuidle state enter functions to handle resynchronization after determining if any cpu needs to abort. The normal use case will be: static bool abort_flag; static atomic_t abort_barrier; int arch_cpuidle_enter(struct cpuidle_device *dev, ...) { if (arch_turn_off_irq_controller()) { /* returns an error if an irq is pending and would be lost if idle continued and turned off power */ abort_flag = true; } cpuidle_coupled_parallel_barrier(dev, &abort_barrier); if (abort_flag) { /* One of the cpus didn't turn off it's irq controller */ arch_turn_on_irq_controller(); return -EINTR; } /* continue with idle */ ... } This will cause all cpus to abort idle together if one of them needs to abort. Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Kevin Hilman <khilman@ti.com> Tested-by: Kevin Hilman <khilman@ti.com> Signed-off-by: Colin Cross <ccross@android.com> Signed-off-by: Len Brown <len.brown@intel.com>
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@ -129,6 +129,43 @@ static DEFINE_PER_CPU(struct call_single_data, cpuidle_coupled_poke_cb);
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*/
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*/
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static cpumask_t cpuidle_coupled_poked_mask;
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static cpumask_t cpuidle_coupled_poked_mask;
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/**
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* cpuidle_coupled_parallel_barrier - synchronize all online coupled cpus
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* @dev: cpuidle_device of the calling cpu
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* @a: atomic variable to hold the barrier
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*
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* No caller to this function will return from this function until all online
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* cpus in the same coupled group have called this function. Once any caller
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* has returned from this function, the barrier is immediately available for
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* reuse.
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*
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* The atomic variable a must be initialized to 0 before any cpu calls
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* this function, will be reset to 0 before any cpu returns from this function.
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*
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* Must only be called from within a coupled idle state handler
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* (state.enter when state.flags has CPUIDLE_FLAG_COUPLED set).
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*
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* Provides full smp barrier semantics before and after calling.
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*/
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void cpuidle_coupled_parallel_barrier(struct cpuidle_device *dev, atomic_t *a)
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{
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int n = dev->coupled->online_count;
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smp_mb__before_atomic_inc();
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atomic_inc(a);
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while (atomic_read(a) < n)
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cpu_relax();
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if (atomic_inc_return(a) == n * 2) {
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atomic_set(a, 0);
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return;
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}
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while (atomic_read(a) > n)
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cpu_relax();
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}
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/**
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/**
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* cpuidle_state_is_coupled - check if a state is part of a coupled set
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* cpuidle_state_is_coupled - check if a state is part of a coupled set
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* @dev: struct cpuidle_device for the current cpu
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* @dev: struct cpuidle_device for the current cpu
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@ -183,6 +183,10 @@ static inline int cpuidle_play_dead(void) {return -ENODEV; }
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#endif
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#endif
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#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
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void cpuidle_coupled_parallel_barrier(struct cpuidle_device *dev, atomic_t *a);
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#endif
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/******************************
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/******************************
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* CPUIDLE GOVERNOR INTERFACE *
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* CPUIDLE GOVERNOR INTERFACE *
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******************************/
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******************************/
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