// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2012-2018, The Linux Foundation. All rights reserved.
 * Copyright (C) 2018-2021 Linaro Ltd.
 */

#include <linux/clk.h>
#include <linux/device.h>
#include <linux/interconnect.h>
#include <linux/pm.h>
#include <linux/pm_runtime.h>
#include <linux/bitops.h>

#include "ipa.h"
#include "ipa_power.h"
#include "ipa_endpoint.h"
#include "ipa_modem.h"
#include "ipa_data.h"

/**
 * DOC: IPA Power Management
 *
 * The IPA hardware is enabled when the IPA core clock and all the
 * interconnects (buses) it depends on are enabled.  Runtime power
 * management is used to determine whether the core clock and
 * interconnects are enabled, and if not in use to be suspended
 * automatically.
 *
 * The core clock currently runs at a fixed clock rate when enabled,
 * an all interconnects use a fixed average and peak bandwidth.
 */

#define IPA_AUTOSUSPEND_DELAY   500     /* milliseconds */

/**
 * struct ipa_interconnect - IPA interconnect information
 * @path:               Interconnect path
 * @average_bandwidth:  Average interconnect bandwidth (KB/second)
 * @peak_bandwidth:     Peak interconnect bandwidth (KB/second)
 */
struct ipa_interconnect {
        struct icc_path *path;
        u32 average_bandwidth;
        u32 peak_bandwidth;
};

/**
 * enum ipa_power_flag - IPA power flags
 * @IPA_POWER_FLAG_RESUMED:     Whether resume from suspend has been signaled
 * @IPA_POWER_FLAG_SYSTEM:      Hardware is system (not runtime) suspended
 * @IPA_POWER_FLAG_STOPPED:     Modem TX is disabled by ipa_start_xmit()
 * @IPA_POWER_FLAG_STARTED:     Modem TX was enabled by ipa_runtime_resume()
 * @IPA_POWER_FLAG_COUNT:       Number of defined power flags
 */
enum ipa_power_flag {
        IPA_POWER_FLAG_RESUMED,
        IPA_POWER_FLAG_SYSTEM,
        IPA_POWER_FLAG_STOPPED,
        IPA_POWER_FLAG_STARTED,
        IPA_POWER_FLAG_COUNT,           /* Last; not a flag */
};

/**
 * struct ipa_power - IPA power management information
 * @dev:                IPA device pointer
 * @core:               IPA core clock
 * @spinlock:           Protects modem TX queue enable/disable
 * @flags:              Boolean state flags
 * @interconnect_count: Number of elements in interconnect[]
 * @interconnect:       Interconnect array
 */
struct ipa_power {
        struct device *dev;
        struct clk *core;
        spinlock_t spinlock;    /* used with STOPPED/STARTED power flags */
        DECLARE_BITMAP(flags, IPA_POWER_FLAG_COUNT);
        u32 interconnect_count;
        struct ipa_interconnect *interconnect;
};

static int ipa_interconnect_init_one(struct device *dev,
                                     struct ipa_interconnect *interconnect,
                                     const struct ipa_interconnect_data *data)
{
        struct icc_path *path;

        path = of_icc_get(dev, data->name);
        if (IS_ERR(path)) {
                int ret = PTR_ERR(path);

                dev_err_probe(dev, ret, "error getting %s interconnect\n",
                              data->name);

                return ret;
        }

        interconnect->path = path;
        interconnect->average_bandwidth = data->average_bandwidth;
        interconnect->peak_bandwidth = data->peak_bandwidth;

        return 0;
}

static void ipa_interconnect_exit_one(struct ipa_interconnect *interconnect)
{
        icc_put(interconnect->path);
        memset(interconnect, 0, sizeof(*interconnect));
}

/* Initialize interconnects required for IPA operation */
static int ipa_interconnect_init(struct ipa_power *power, struct device *dev,
                                 const struct ipa_interconnect_data *data)
{
        struct ipa_interconnect *interconnect;
        u32 count;
        int ret;

        count = power->interconnect_count;
        interconnect = kcalloc(count, sizeof(*interconnect), GFP_KERNEL);
        if (!interconnect)
                return -ENOMEM;
        power->interconnect = interconnect;

        while (count--) {
                ret = ipa_interconnect_init_one(dev, interconnect, data++);
                if (ret)
                        goto out_unwind;
                interconnect++;
        }

        return 0;

out_unwind:
        while (interconnect-- > power->interconnect)
                ipa_interconnect_exit_one(interconnect);
        kfree(power->interconnect);
        power->interconnect = NULL;

        return ret;
}

/* Inverse of ipa_interconnect_init() */
static void ipa_interconnect_exit(struct ipa_power *power)
{
        struct ipa_interconnect *interconnect;

        interconnect = power->interconnect + power->interconnect_count;
        while (interconnect-- > power->interconnect)
                ipa_interconnect_exit_one(interconnect);
        kfree(power->interconnect);
        power->interconnect = NULL;
}

/* Currently we only use one bandwidth level, so just "enable" interconnects */
static int ipa_interconnect_enable(struct ipa *ipa)
{
        struct ipa_interconnect *interconnect;
        struct ipa_power *power = ipa->power;
        int ret;
        u32 i;

        interconnect = power->interconnect;
        for (i = 0; i < power->interconnect_count; i++) {
                ret = icc_set_bw(interconnect->path,
                                 interconnect->average_bandwidth,
                                 interconnect->peak_bandwidth);
                if (ret) {
                        dev_err(&ipa->pdev->dev,
                                "error %d enabling %s interconnect\n",
                                ret, icc_get_name(interconnect->path));
                        goto out_unwind;
                }
                interconnect++;
        }

        return 0;

out_unwind:
        while (interconnect-- > power->interconnect)
                (void)icc_set_bw(interconnect->path, 0, 0);

        return ret;
}

/* To disable an interconnect, we just its bandwidth to 0 */
static int ipa_interconnect_disable(struct ipa *ipa)
{
        struct ipa_interconnect *interconnect;
        struct ipa_power *power = ipa->power;
        struct device *dev = &ipa->pdev->dev;
        int result = 0;
        u32 count;
        int ret;

        count = power->interconnect_count;
        interconnect = power->interconnect + count;
        while (count--) {
                interconnect--;
                ret = icc_set_bw(interconnect->path, 0, 0);
                if (ret) {
                        dev_err(dev, "error %d disabling %s interconnect\n",
                                ret, icc_get_name(interconnect->path));
                        /* Try to disable all; record only the first error */
                        if (!result)
                                result = ret;
                }
        }

        return result;
}

/* Enable IPA power, enabling interconnects and the core clock */
static int ipa_power_enable(struct ipa *ipa)
{
        int ret;

        ret = ipa_interconnect_enable(ipa);
        if (ret)
                return ret;

        ret = clk_prepare_enable(ipa->power->core);
        if (ret) {
                dev_err(&ipa->pdev->dev, "error %d enabling core clock\n", ret);
                (void)ipa_interconnect_disable(ipa);
        }

        return ret;
}

/* Inverse of ipa_power_enable() */
static int ipa_power_disable(struct ipa *ipa)
{
        clk_disable_unprepare(ipa->power->core);

        return ipa_interconnect_disable(ipa);
}

static int ipa_runtime_suspend(struct device *dev)
{
        struct ipa *ipa = dev_get_drvdata(dev);

        /* Endpoints aren't usable until setup is complete */
        if (ipa->setup_complete) {
                __clear_bit(IPA_POWER_FLAG_RESUMED, ipa->power->flags);
                ipa_endpoint_suspend(ipa);
                gsi_suspend(&ipa->gsi);
        }

        return ipa_power_disable(ipa);
}

static int ipa_runtime_resume(struct device *dev)
{
        struct ipa *ipa = dev_get_drvdata(dev);
        int ret;

        ret = ipa_power_enable(ipa);
        if (WARN_ON(ret < 0))
                return ret;

        /* Endpoints aren't usable until setup is complete */
        if (ipa->setup_complete) {
                gsi_resume(&ipa->gsi);
                ipa_endpoint_resume(ipa);
        }

        return 0;
}

static int ipa_suspend(struct device *dev)
{
        struct ipa *ipa = dev_get_drvdata(dev);

        __set_bit(IPA_POWER_FLAG_SYSTEM, ipa->power->flags);

        return pm_runtime_force_suspend(dev);
}

static int ipa_resume(struct device *dev)
{
        struct ipa *ipa = dev_get_drvdata(dev);
        int ret;

        ret = pm_runtime_force_resume(dev);

        __clear_bit(IPA_POWER_FLAG_SYSTEM, ipa->power->flags);

        return ret;
}

/* Return the current IPA core clock rate */
u32 ipa_core_clock_rate(struct ipa *ipa)
{
        return ipa->power ? (u32)clk_get_rate(ipa->power->core) : 0;
}

/**
 * ipa_suspend_handler() - Handle the suspend IPA interrupt
 * @ipa:        IPA pointer
 * @irq_id:     IPA interrupt type (unused)
 *
 * If an RX endpoint is suspended, and the IPA has a packet destined for
 * that endpoint, the IPA generates a SUSPEND interrupt to inform the AP
 * that it should resume the endpoint.  If we get one of these interrupts
 * we just wake up the system.
 */
static void ipa_suspend_handler(struct ipa *ipa, enum ipa_irq_id irq_id)
{
        /* To handle an IPA interrupt we will have resumed the hardware
         * just to handle the interrupt, so we're done.  If we are in a
         * system suspend, trigger a system resume.
         */
        if (!__test_and_set_bit(IPA_POWER_FLAG_RESUMED, ipa->power->flags))
                if (test_bit(IPA_POWER_FLAG_SYSTEM, ipa->power->flags))
                        pm_wakeup_dev_event(&ipa->pdev->dev, 0, true);

        /* Acknowledge/clear the suspend interrupt on all endpoints */
        ipa_interrupt_suspend_clear_all(ipa->interrupt);
}

/* The next few functions coordinate stopping and starting the modem
 * network device transmit queue.
 *
 * Transmit can be running concurrent with power resume, and there's a
 * chance the resume completes before the transmit path stops the queue,
 * leaving the queue in a stopped state.  The next two functions are used
 * to avoid this: ipa_power_modem_queue_stop() is used by ipa_start_xmit()
 * to conditionally stop the TX queue; and ipa_power_modem_queue_start()
 * is used by ipa_runtime_resume() to conditionally restart it.
 *
 * Two flags and a spinlock are used.  If the queue is stopped, the STOPPED
 * power flag is set.  And if the queue is started, the STARTED flag is set.
 * The queue is only started on resume if the STOPPED flag is set.  And the
 * queue is only started in ipa_start_xmit() if the STARTED flag is *not*
 * set.  As a result, the queue remains operational if the two activites
 * happen concurrently regardless of the order they complete.  The spinlock
 * ensures the flag and TX queue operations are done atomically.
 *
 * The first function stops the modem netdev transmit queue, but only if
 * the STARTED flag is *not* set.  That flag is cleared if it was set.
 * If the queue is stopped, the STOPPED flag is set.  This is called only
 * from the power ->runtime_resume operation.
 */
void ipa_power_modem_queue_stop(struct ipa *ipa)
{
        struct ipa_power *power = ipa->power;
        unsigned long flags;

        spin_lock_irqsave(&power->spinlock, flags);

        if (!__test_and_clear_bit(IPA_POWER_FLAG_STARTED, power->flags)) {
                netif_stop_queue(ipa->modem_netdev);
                __set_bit(IPA_POWER_FLAG_STOPPED, power->flags);
        }

        spin_unlock_irqrestore(&power->spinlock, flags);
}

/* This function starts the modem netdev transmit queue, but only if the
 * STOPPED flag is set.  That flag is cleared if it was set.  If the queue
 * was restarted, the STARTED flag is set; this allows ipa_start_xmit()
 * to skip stopping the queue in the event of a race.
 */
void ipa_power_modem_queue_wake(struct ipa *ipa)
{
        struct ipa_power *power = ipa->power;
        unsigned long flags;

        spin_lock_irqsave(&power->spinlock, flags);

        if (__test_and_clear_bit(IPA_POWER_FLAG_STOPPED, power->flags)) {
                __set_bit(IPA_POWER_FLAG_STARTED, power->flags);
                netif_wake_queue(ipa->modem_netdev);
        }

        spin_unlock_irqrestore(&power->spinlock, flags);
}

/* This function clears the STARTED flag once the TX queue is operating */
void ipa_power_modem_queue_active(struct ipa *ipa)
{
        clear_bit(IPA_POWER_FLAG_STARTED, ipa->power->flags);
}

int ipa_power_setup(struct ipa *ipa)
{
        int ret;

        ipa_interrupt_add(ipa->interrupt, IPA_IRQ_TX_SUSPEND,
                          ipa_suspend_handler);

        ret = device_init_wakeup(&ipa->pdev->dev, true);
        if (ret)
                ipa_interrupt_remove(ipa->interrupt, IPA_IRQ_TX_SUSPEND);

        return ret;
}

void ipa_power_teardown(struct ipa *ipa)
{
        (void)device_init_wakeup(&ipa->pdev->dev, false);
        ipa_interrupt_remove(ipa->interrupt, IPA_IRQ_TX_SUSPEND);
}

/* Initialize IPA power management */
struct ipa_power *
ipa_power_init(struct device *dev, const struct ipa_power_data *data)
{
        struct ipa_power *power;
        struct clk *clk;
        int ret;

        clk = clk_get(dev, "core");
        if (IS_ERR(clk)) {
                dev_err_probe(dev, PTR_ERR(clk), "error getting core clock\n");

                return ERR_CAST(clk);
        }

        ret = clk_set_rate(clk, data->core_clock_rate);
        if (ret) {
                dev_err(dev, "error %d setting core clock rate to %u\n",
                        ret, data->core_clock_rate);
                goto err_clk_put;
        }

        power = kzalloc(sizeof(*power), GFP_KERNEL);
        if (!power) {
                ret = -ENOMEM;
                goto err_clk_put;
        }
        power->dev = dev;
        power->core = clk;
        spin_lock_init(&power->spinlock);
        power->interconnect_count = data->interconnect_count;

        ret = ipa_interconnect_init(power, dev, data->interconnect_data);
        if (ret)
                goto err_kfree;

        pm_runtime_set_autosuspend_delay(dev, IPA_AUTOSUSPEND_DELAY);
        pm_runtime_use_autosuspend(dev);
        pm_runtime_enable(dev);

        return power;

err_kfree:
        kfree(power);
err_clk_put:
        clk_put(clk);

        return ERR_PTR(ret);
}

/* Inverse of ipa_power_init() */
void ipa_power_exit(struct ipa_power *power)
{
        struct device *dev = power->dev;
        struct clk *clk = power->core;

        pm_runtime_disable(dev);
        pm_runtime_dont_use_autosuspend(dev);
        ipa_interconnect_exit(power);
        kfree(power);
        clk_put(clk);
}

const struct dev_pm_ops ipa_pm_ops = {
        .suspend                = ipa_suspend,
        .resume                 = ipa_resume,
        .runtime_suspend        = ipa_runtime_suspend,
        .runtime_resume         = ipa_runtime_resume,
};