// SPDX-License-Identifier: GPL-2.0

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

#include <linux/refcount.h>
#include <linux/mutex.h>
#include <linux/clk.h>
#include <linux/device.h>
#include <linux/interconnect.h>

#include "ipa.h"
#include "ipa_clock.h"
#include "ipa_modem.h"
#include "ipa_data.h"

/**
 * DOC: IPA Clocking
 *
 * The "IPA Clock" manages both the IPA core clock and the interconnects
 * (buses) the IPA depends on as a single logical entity.  A reference count
 * is incremented by "get" operations and decremented by "put" operations.
 * Transitions of that count from 0 to 1 result in the clock and interconnects
 * being enabled, and transitions of the count from 1 to 0 cause them to be
 * disabled.  We currently operate the core clock at a fixed clock rate, and
 * all buses at a fixed average and peak bandwidth.  As more advanced IPA
 * features are enabled, we can make better use of clock and bus scaling.
 *
 * An IPA clock reference must be held for any access to IPA hardware.
 */

/**
 * 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;
};

/**
 * struct ipa_clock - IPA clocking information
 * @count:              Clocking reference count
 * @mutex:              Protects clock enable/disable
 * @core:               IPA core clock
 * @interconnect_count: Number of elements in interconnect[]
 * @interconnect:       Interconnect array
 */
struct ipa_clock {
        refcount_t count;
        struct mutex mutex; /* protects clock enable/disable */
        struct clk *core;
        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_clock *clock, struct device *dev,
                                 const struct ipa_interconnect_data *data)
{
        struct ipa_interconnect *interconnect;
        u32 count;
        int ret;

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

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

        return 0;

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

        return ret;
}

/* Inverse of ipa_interconnect_init() */
static void ipa_interconnect_exit(struct ipa_clock *clock)
{
        struct ipa_interconnect *interconnect;

        interconnect = clock->interconnect + clock->interconnect_count;
        while (interconnect-- > clock->interconnect)
                ipa_interconnect_exit_one(interconnect);
        kfree(clock->interconnect);
        clock->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_clock *clock = ipa->clock;
        int ret;
        u32 i;

        interconnect = clock->interconnect;
        for (i = 0; i < clock->interconnect_count; i++) {
                ret = icc_set_bw(interconnect->path,
                                 interconnect->average_bandwidth,
                                 interconnect->peak_bandwidth);
                if (ret)
                        goto out_unwind;
                interconnect++;
        }

        return 0;

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

        return ret;
}

/* To disable an interconnect, we just its bandwidth to 0 */
static void ipa_interconnect_disable(struct ipa *ipa)
{
        struct ipa_interconnect *interconnect;
        struct ipa_clock *clock = ipa->clock;
        int result = 0;
        u32 count;
        int ret;

        count = clock->interconnect_count;
        interconnect = clock->interconnect + count;
        while (count--) {
                interconnect--;
                ret = icc_set_bw(interconnect->path, 0, 0);
                if (ret && !result)
                        result = ret;
        }

        if (result)
                dev_err(&ipa->pdev->dev,
                        "error %d disabling IPA interconnects\n", ret);
}

/* Turn on IPA clocks, including interconnects */
static int ipa_clock_enable(struct ipa *ipa)
{
        int ret;

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

        ret = clk_prepare_enable(ipa->clock->core);
        if (ret)
                ipa_interconnect_disable(ipa);

        return ret;
}

/* Inverse of ipa_clock_enable() */
static void ipa_clock_disable(struct ipa *ipa)
{
        clk_disable_unprepare(ipa->clock->core);
        ipa_interconnect_disable(ipa);
}

/* Get an IPA clock reference, but only if the reference count is
 * already non-zero.  Returns true if the additional reference was
 * added successfully, or false otherwise.
 */
bool ipa_clock_get_additional(struct ipa *ipa)
{
        return refcount_inc_not_zero(&ipa->clock->count);
}

/* Get an IPA clock reference.  If the reference count is non-zero, it is
 * incremented and return is immediate.  Otherwise it is checked again
 * under protection of the mutex, and if appropriate the IPA clock
 * is enabled.
 *
 * Incrementing the reference count is intentionally deferred until
 * after the clock is running and endpoints are resumed.
 */
void ipa_clock_get(struct ipa *ipa)
{
        struct ipa_clock *clock = ipa->clock;
        int ret;

        /* If the clock is running, just bump the reference count */
        if (ipa_clock_get_additional(ipa))
                return;

        /* Otherwise get the mutex and check again */
        mutex_lock(&clock->mutex);

        /* A reference might have been added before we got the mutex. */
        if (ipa_clock_get_additional(ipa))
                goto out_mutex_unlock;

        ret = ipa_clock_enable(ipa);
        if (ret) {
                dev_err(&ipa->pdev->dev, "error %d enabling IPA clock\n", ret);
                goto out_mutex_unlock;
        }

        refcount_set(&clock->count, 1);

out_mutex_unlock:
        mutex_unlock(&clock->mutex);
}

/* Attempt to remove an IPA clock reference.  If this represents the
 * last reference, disable the IPA clock under protection of the mutex.
 */
void ipa_clock_put(struct ipa *ipa)
{
        struct ipa_clock *clock = ipa->clock;

        /* If this is not the last reference there's nothing more to do */
        if (!refcount_dec_and_mutex_lock(&clock->count, &clock->mutex))
                return;

        ipa_clock_disable(ipa);

        mutex_unlock(&clock->mutex);
}

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

/* Initialize IPA clocking */
struct ipa_clock *
ipa_clock_init(struct device *dev, const struct ipa_clock_data *data)
{
        struct ipa_clock *clock;
        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;
        }

        clock = kzalloc(sizeof(*clock), GFP_KERNEL);
        if (!clock) {
                ret = -ENOMEM;
                goto err_clk_put;
        }
        clock->core = clk;
        clock->interconnect_count = data->interconnect_count;

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

        mutex_init(&clock->mutex);
        refcount_set(&clock->count, 0);

        return clock;

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

        return ERR_PTR(ret);
}

/* Inverse of ipa_clock_init() */
void ipa_clock_exit(struct ipa_clock *clock)
{
        struct clk *clk = clock->core;

        WARN_ON(refcount_read(&clock->count) != 0);
        mutex_destroy(&clock->mutex);
        ipa_interconnect_exit(clock);
        kfree(clock);
        clk_put(clk);
}