// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)
 *
 * Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>
 * and Jonas Aaberg <jonas.aberg@stericsson.com>.
 */

#include <linux/init.h>
#include <linux/cpuidle.h>
#include <linux/spinlock.h>
#include <linux/atomic.h>
#include <linux/smp.h>
#include <linux/mfd/dbx500-prcmu.h>
#include <linux/platform_data/arm-ux500-pm.h>
#include <linux/platform_device.h>

#include <asm/cpuidle.h>

static atomic_t master = ATOMIC_INIT(0);
static DEFINE_SPINLOCK(master_lock);

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;
}

static struct cpuidle_driver ux500_idle_driver = {
        .name = "ux500_idle",
        .owner = THIS_MODULE,
        .states = {
                ARM_CPUIDLE_WFI_STATE,
                {
                        .enter            = ux500_enter_idle,
                        .exit_latency     = 70,
                        .target_residency = 260,
                        .flags            = CPUIDLE_FLAG_TIMER_STOP,
                        .name             = "ApIdle",
                        .desc             = "ARM Retention",
                },
        },
        .safe_state_index = 0,
        .state_count = 2,
};

static int dbx500_cpuidle_probe(struct platform_device *pdev)
{
        /* Configure wake up reasons */
        prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
                             PRCMU_WAKEUP(ABB));

        return cpuidle_register(&ux500_idle_driver, NULL);
}

static struct platform_driver dbx500_cpuidle_plat_driver = {
        .driver = {
                .name = "db8500-cpuidle",
        },
        .probe = dbx500_cpuidle_probe,
};
builtin_platform_driver(dbx500_cpuidle_plat_driver);