in cpuidle-ux500.c [23:89]
static inline int ux500_enter_idle(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index)
{
int this_cpu = smp_processor_id();
bool recouple = false;
if (atomic_inc_return(&master) == num_online_cpus()) {
/* With this lock, we prevent the other cpu to exit and enter
* this function again and become the master */
if (!spin_trylock(&master_lock))
goto wfi;
/* decouple the gic from the A9 cores */
if (prcmu_gic_decouple()) {
spin_unlock(&master_lock);
goto out;
}
/* If an error occur, we will have to recouple the gic
* manually */
recouple = true;
/* At this state, as the gic is decoupled, if the other
* cpu is in WFI, we have the guarantee it won't be wake
* up, so we can safely go to retention */
if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
goto out;
/* The prcmu will be in charge of watching the interrupts
* and wake up the cpus */
if (prcmu_copy_gic_settings())
goto out;
/* Check in the meantime an interrupt did
* not occur on the gic ... */
if (prcmu_gic_pending_irq())
goto out;
/* ... and the prcmu */
if (prcmu_pending_irq())
goto out;
/* Go to the retention state, the prcmu will wait for the
* cpu to go WFI and this is what happens after exiting this
* 'master' critical section */
if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
goto out;
/* When we switch to retention, the prcmu is in charge
* of recoupling the gic automatically */
recouple = false;
spin_unlock(&master_lock);
}
wfi:
cpu_do_idle();
out:
atomic_dec(&master);
if (recouple) {
prcmu_gic_recouple();
spin_unlock(&master_lock);
}
return index;
}