// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)
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*
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* Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>
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* and Jonas Aaberg <jonas.aberg@stericsson.com>.
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*/
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#include <linux/init.h>
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#include <linux/cpuidle.h>
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#include <linux/spinlock.h>
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#include <linux/atomic.h>
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#include <linux/smp.h>
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#include <linux/mfd/dbx500-prcmu.h>
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#include <linux/platform_data/arm-ux500-pm.h>
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#include <linux/platform_device.h>
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#include <asm/cpuidle.h>
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static atomic_t master = ATOMIC_INIT(0);
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static DEFINE_SPINLOCK(master_lock);
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static inline int ux500_enter_idle(struct cpuidle_device *dev,
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struct cpuidle_driver *drv, int index)
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{
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int this_cpu = smp_processor_id();
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bool recouple = false;
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if (atomic_inc_return(&master) == num_online_cpus()) {
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/* With this lock, we prevent the other cpu to exit and enter
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* this function again and become the master */
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if (!spin_trylock(&master_lock))
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goto wfi;
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/* decouple the gic from the A9 cores */
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if (prcmu_gic_decouple()) {
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spin_unlock(&master_lock);
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goto out;
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}
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/* If an error occur, we will have to recouple the gic
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* manually */
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recouple = true;
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/* At this state, as the gic is decoupled, if the other
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* cpu is in WFI, we have the guarantee it won't be wake
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* up, so we can safely go to retention */
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if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
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goto out;
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/* The prcmu will be in charge of watching the interrupts
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* and wake up the cpus */
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if (prcmu_copy_gic_settings())
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goto out;
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/* Check in the meantime an interrupt did
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* not occur on the gic ... */
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if (prcmu_gic_pending_irq())
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goto out;
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/* ... and the prcmu */
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if (prcmu_pending_irq())
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goto out;
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/* Go to the retention state, the prcmu will wait for the
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* cpu to go WFI and this is what happens after exiting this
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* 'master' critical section */
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if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
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goto out;
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/* When we switch to retention, the prcmu is in charge
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* of recoupling the gic automatically */
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recouple = false;
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spin_unlock(&master_lock);
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}
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wfi:
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cpu_do_idle();
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out:
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atomic_dec(&master);
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if (recouple) {
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prcmu_gic_recouple();
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spin_unlock(&master_lock);
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}
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return index;
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}
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static struct cpuidle_driver ux500_idle_driver = {
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.name = "ux500_idle",
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.owner = THIS_MODULE,
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.states = {
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ARM_CPUIDLE_WFI_STATE,
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{
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.enter = ux500_enter_idle,
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.exit_latency = 70,
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.target_residency = 260,
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.flags = CPUIDLE_FLAG_TIMER_STOP,
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.name = "ApIdle",
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.desc = "ARM Retention",
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},
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},
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.safe_state_index = 0,
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.state_count = 2,
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};
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static int dbx500_cpuidle_probe(struct platform_device *pdev)
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{
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/* Configure wake up reasons */
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prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
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PRCMU_WAKEUP(ABB));
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return cpuidle_register(&ux500_idle_driver, NULL);
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}
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static struct platform_driver dbx500_cpuidle_plat_driver = {
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.driver = {
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.name = "cpuidle-dbx500",
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},
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.probe = dbx500_cpuidle_probe,
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};
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builtin_platform_driver(dbx500_cpuidle_plat_driver);
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