/*
 * wakeirq.c - Device wakeirq helper functions
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>
#include <linux/pm_wakeirq.h>

#include "power.h"

/**
 * dev_pm_attach_wake_irq - Attach device interrupt as a wake IRQ
 * @dev: Device entry
 * @irq: Device wake-up capable interrupt
 * @wirq: Wake irq specific data
 *
 * Internal function to attach either a device IO interrupt or a
 * dedicated wake-up interrupt as a wake IRQ.
 */
static int dev_pm_attach_wake_irq(struct device *dev, int irq,
                                  struct wake_irq *wirq)
{
        unsigned long flags;

        if (!dev || !wirq)
                return -EINVAL;

        spin_lock_irqsave(&dev->power.lock, flags);
        if (dev_WARN_ONCE(dev, dev->power.wakeirq,
                          "wake irq already initialized\n")) {
                spin_unlock_irqrestore(&dev->power.lock, flags);
                return -EEXIST;
        }

        dev->power.wakeirq = wirq;
        device_wakeup_attach_irq(dev, wirq);

        spin_unlock_irqrestore(&dev->power.lock, flags);
        return 0;
}

/**
 * dev_pm_set_wake_irq - Attach device IO interrupt as wake IRQ
 * @dev: Device entry
 * @irq: Device IO interrupt
 *
 * Attach a device IO interrupt as a wake IRQ. The wake IRQ gets
 * automatically configured for wake-up from suspend  based
 * on the device specific sysfs wakeup entry. Typically called
 * during driver probe after calling device_init_wakeup().
 */
int dev_pm_set_wake_irq(struct device *dev, int irq)
{
        struct wake_irq *wirq;
        int err;

        if (irq < 0)
                return -EINVAL;

        wirq = kzalloc(sizeof(*wirq), GFP_KERNEL);
        if (!wirq)
                return -ENOMEM;

        wirq->dev = dev;
        wirq->irq = irq;

        err = dev_pm_attach_wake_irq(dev, irq, wirq);
        if (err)
                kfree(wirq);

        return err;
}
EXPORT_SYMBOL_GPL(dev_pm_set_wake_irq);

/**
 * dev_pm_clear_wake_irq - Detach a device IO interrupt wake IRQ
 * @dev: Device entry
 *
 * Detach a device wake IRQ and free resources.
 *
 * Note that it's OK for drivers to call this without calling
 * dev_pm_set_wake_irq() as all the driver instances may not have
 * a wake IRQ configured. This avoid adding wake IRQ specific
 * checks into the drivers.
 */
void dev_pm_clear_wake_irq(struct device *dev)
{
        struct wake_irq *wirq = dev->power.wakeirq;
        unsigned long flags;

        if (!wirq)
                return;

        spin_lock_irqsave(&dev->power.lock, flags);
        device_wakeup_detach_irq(dev);
        dev->power.wakeirq = NULL;
        spin_unlock_irqrestore(&dev->power.lock, flags);

        if (wirq->status & WAKE_IRQ_DEDICATED_ALLOCATED) {
                free_irq(wirq->irq, wirq);
                wirq->status &= ~WAKE_IRQ_DEDICATED_MASK;
        }
        kfree(wirq->name);
        kfree(wirq);
}
EXPORT_SYMBOL_GPL(dev_pm_clear_wake_irq);

/**
 * handle_threaded_wake_irq - Handler for dedicated wake-up interrupts
 * @irq: Device specific dedicated wake-up interrupt
 * @_wirq: Wake IRQ data
 *
 * Some devices have a separate wake-up interrupt in addition to the
 * device IO interrupt. The wake-up interrupt signals that a device
 * should be woken up from it's idle state. This handler uses device
 * specific pm_runtime functions to wake the device, and then it's
 * up to the device to do whatever it needs to. Note that as the
 * device may need to restore context and start up regulators, we
 * use a threaded IRQ.
 *
 * Also note that we are not resending the lost device interrupts.
 * We assume that the wake-up interrupt just needs to wake-up the
 * device, and then device's pm_runtime_resume() can deal with the
 * situation.
 */
static irqreturn_t handle_threaded_wake_irq(int irq, void *_wirq)
{
        struct wake_irq *wirq = _wirq;
        int res;

        /* Maybe abort suspend? */
        if (irqd_is_wakeup_set(irq_get_irq_data(irq))) {
                pm_wakeup_event(wirq->dev, 0);

                return IRQ_HANDLED;
        }

        /* We don't want RPM_ASYNC or RPM_NOWAIT here */
        res = pm_runtime_resume(wirq->dev);
        if (res < 0)
                dev_warn(wirq->dev,
                         "wake IRQ with no resume: %i\n", res);

        return IRQ_HANDLED;
}

/**
 * dev_pm_set_dedicated_wake_irq - Request a dedicated wake-up interrupt
 * @dev: Device entry
 * @irq: Device wake-up interrupt
 *
 * Unless your hardware has separate wake-up interrupts in addition
 * to the device IO interrupts, you don't need this.
 *
 * Sets up a threaded interrupt handler for a device that has
 * a dedicated wake-up interrupt in addition to the device IO
 * interrupt.
 *
 * The interrupt starts disabled, and needs to be managed for
 * the device by the bus code or the device driver using
 * dev_pm_enable_wake_irq() and dev_pm_disable_wake_irq()
 * functions.
 */
int dev_pm_set_dedicated_wake_irq(struct device *dev, int irq)
{
        struct wake_irq *wirq;
        int err;

        if (irq < 0)
                return -EINVAL;

        wirq = kzalloc(sizeof(*wirq), GFP_KERNEL);
        if (!wirq)
                return -ENOMEM;

        wirq->name = kasprintf(GFP_KERNEL, "%s:wakeup", dev_name(dev));
        if (!wirq->name) {
                err = -ENOMEM;
                goto err_free;
        }

        wirq->dev = dev;
        wirq->irq = irq;
        irq_set_status_flags(irq, IRQ_NOAUTOEN);

        /* Prevent deferred spurious wakeirqs with disable_irq_nosync() */
        irq_set_status_flags(irq, IRQ_DISABLE_UNLAZY);

        /*
         * Consumer device may need to power up and restore state
         * so we use a threaded irq.
         */
        err = request_threaded_irq(irq, NULL, handle_threaded_wake_irq,
                                   IRQF_ONESHOT, wirq->name, wirq);
        if (err)
                goto err_free_name;

        err = dev_pm_attach_wake_irq(dev, irq, wirq);
        if (err)
                goto err_free_irq;

        wirq->status = WAKE_IRQ_DEDICATED_ALLOCATED;

        return err;

err_free_irq:
        free_irq(irq, wirq);
err_free_name:
        kfree(wirq->name);
err_free:
        kfree(wirq);

        return err;
}
EXPORT_SYMBOL_GPL(dev_pm_set_dedicated_wake_irq);

/**
 * dev_pm_enable_wake_irq - Enable device wake-up interrupt
 * @dev: Device
 *
 * Optionally called from the bus code or the device driver for
 * runtime_resume() to override the PM runtime core managed wake-up
 * interrupt handling to enable the wake-up interrupt.
 *
 * Note that for runtime_suspend()) the wake-up interrupts
 * should be unconditionally enabled unlike for suspend()
 * that is conditional.
 */
void dev_pm_enable_wake_irq(struct device *dev)
{
        struct wake_irq *wirq = dev->power.wakeirq;

        if (wirq && (wirq->status & WAKE_IRQ_DEDICATED_ALLOCATED))
                enable_irq(wirq->irq);
}
EXPORT_SYMBOL_GPL(dev_pm_enable_wake_irq);

/**
 * dev_pm_disable_wake_irq - Disable device wake-up interrupt
 * @dev: Device
 *
 * Optionally called from the bus code or the device driver for
 * runtime_suspend() to override the PM runtime core managed wake-up
 * interrupt handling to disable the wake-up interrupt.
 */
void dev_pm_disable_wake_irq(struct device *dev)
{
        struct wake_irq *wirq = dev->power.wakeirq;

        if (wirq && (wirq->status & WAKE_IRQ_DEDICATED_ALLOCATED))
                disable_irq_nosync(wirq->irq);
}
EXPORT_SYMBOL_GPL(dev_pm_disable_wake_irq);

/**
 * dev_pm_enable_wake_irq_check - Checks and enables wake-up interrupt
 * @dev: Device
 * @can_change_status: Can change wake-up interrupt status
 *
 * Enables wakeirq conditionally. We need to enable wake-up interrupt
 * lazily on the first rpm_suspend(). This is needed as the consumer device
 * starts in RPM_SUSPENDED state, and the the first pm_runtime_get() would
 * otherwise try to disable already disabled wakeirq. The wake-up interrupt
 * starts disabled with IRQ_NOAUTOEN set.
 *
 * Should be only called from rpm_suspend() and rpm_resume() path.
 * Caller must hold &dev->power.lock to change wirq->status
 */
void dev_pm_enable_wake_irq_check(struct device *dev,
                                  bool can_change_status)
{
        struct wake_irq *wirq = dev->power.wakeirq;

        if (!wirq || !((wirq->status & WAKE_IRQ_DEDICATED_MASK)))
                return;

        if (likely(wirq->status & WAKE_IRQ_DEDICATED_MANAGED)) {
                goto enable;
        } else if (can_change_status) {
                wirq->status |= WAKE_IRQ_DEDICATED_MANAGED;
                goto enable;
        }

        return;

enable:
        enable_irq(wirq->irq);
}

/**
 * dev_pm_disable_wake_irq_check - Checks and disables wake-up interrupt
 * @dev: Device
 *
 * Disables wake-up interrupt conditionally based on status.
 * Should be only called from rpm_suspend() and rpm_resume() path.
 */
void dev_pm_disable_wake_irq_check(struct device *dev)
{
        struct wake_irq *wirq = dev->power.wakeirq;

        if (!wirq || !((wirq->status & WAKE_IRQ_DEDICATED_MASK)))
                return;

        if (wirq->status & WAKE_IRQ_DEDICATED_MANAGED)
                disable_irq_nosync(wirq->irq);
}

/**
 * dev_pm_arm_wake_irq - Arm device wake-up
 * @wirq: Device wake-up interrupt
 *
 * Sets up the wake-up event conditionally based on the
 * device_may_wake().
 */
void dev_pm_arm_wake_irq(struct wake_irq *wirq)
{
        if (!wirq)
                return;

        if (device_may_wakeup(wirq->dev)) {
                if (wirq->status & WAKE_IRQ_DEDICATED_ALLOCATED &&
                    !pm_runtime_status_suspended(wirq->dev))
                        enable_irq(wirq->irq);

                enable_irq_wake(wirq->irq);
        }
}

/**
 * dev_pm_disarm_wake_irq - Disarm device wake-up
 * @wirq: Device wake-up interrupt
 *
 * Clears up the wake-up event conditionally based on the
 * device_may_wake().
 */
void dev_pm_disarm_wake_irq(struct wake_irq *wirq)
{
        if (!wirq)
                return;

        if (device_may_wakeup(wirq->dev)) {
                disable_irq_wake(wirq->irq);

                if (wirq->status & WAKE_IRQ_DEDICATED_ALLOCATED &&
                    !pm_runtime_status_suspended(wirq->dev))
                        disable_irq_nosync(wirq->irq);
        }
}