rt-thread/components/drivers/clk/clk.c

/*
 * Copyright (c) 2006-2022, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 * 2022-11-26     GuEe-GUI     first version
 */

#include <rtthread.h>
#include <rtservice.h>
#include <rtdevice.h>

#define DBG_TAG "rtdm.clk"
#define DBG_LVL DBG_INFO
#include <rtdbg.h>

static struct rt_spinlock _clk_lock = { 0 };
static rt_list_t _clk_nodes = RT_LIST_OBJECT_INIT(_clk_nodes);
static rt_list_t _clk_notifier_nodes = RT_LIST_OBJECT_INIT(_clk_notifier_nodes);

static void clk_release(struct rt_ref *r)
{
    struct rt_clk_node *clk_np = rt_container_of(r, struct rt_clk_node, ref);

    LOG_E("%s is release", clk_np->name);
    (void)clk_np;

    RT_ASSERT(0);
}

rt_inline struct rt_clk_node *clk_get(struct rt_clk_node *clk_np)
{
    rt_ref_get(&clk_np->ref);

    return clk_np;
}

rt_inline void clk_put(struct rt_clk_node *clk_np)
{
    rt_ref_put(&clk_np->ref, &clk_release);
}

static struct rt_clk *clk_alloc(struct rt_clk_node *clk_np, const char *dev_id,
        const char *con_id, void *fw_node)
{
    struct rt_clk *clk = rt_calloc(1, sizeof(*clk));

    if (clk)
    {
        clk->clk_np = clk_np;
        clk->dev_id = dev_id;
        clk->con_id = con_id;

        clk->fw_node = fw_node;
    }

    return clk;
}

static void clk_free(struct rt_clk *clk)
{
    struct rt_clk_node *clk_np = clk->clk_np;

    if (clk_np && clk_np->ops->finit)
    {
        clk_np->ops->finit(clk);
    }

    rt_free(clk);
}

static struct rt_clk *clk_create(struct rt_clk_node *clk_np, const char *dev_id,
        const char *con_id, void *fw_data, void *fw_node)
{
    struct rt_clk *clk = clk_alloc(clk_np, dev_id, con_id, fw_node);

    if (clk)
    {
        clk_get(clk_np);

        if (clk_np->ops->init && clk_np->ops->init(clk, fw_data))
        {
            LOG_E("Dev[%s] Con[%s] init fail", dev_id, con_id);

            clk_free(clk);
            clk = RT_NULL;
        }
    }

    return clk;
}

static rt_err_t clk_notify(struct rt_clk_node *clk_np, rt_ubase_t msg, rt_ubase_t old_rate, rt_ubase_t new_rate)
{
    rt_err_t err = RT_EOK;
    struct rt_clk_notifier *notifier;

    rt_list_for_each_entry(notifier, &_clk_notifier_nodes, list)
    {
        if (notifier->clk->clk_np == clk_np)
        {
            err = notifier->callback(notifier, msg, old_rate, new_rate);

            /* Only check hareware's error */
            if (err == -RT_EIO)
            {
                break;
            }
        }
    }

    return err;
}

static void clk_set_parent(struct rt_clk_node *clk_np, struct rt_clk_node *parent_np)
{
    rt_hw_spin_lock(&_clk_lock.lock);

    clk_np->parent = parent_np;

    rt_list_insert_after(&parent_np->children_nodes, &clk_np->list);

    rt_hw_spin_unlock(&_clk_lock.lock);
}

static const struct rt_clk_ops unused_clk_ops =
{
};

rt_err_t rt_clk_register(struct rt_clk_node *clk_np, struct rt_clk_node *parent_np)
{
    rt_err_t err = RT_EOK;
    struct rt_clk *clk = RT_NULL;

    if (clk_np)
    {
        clk = clk_alloc(clk_np, RT_NULL, RT_NULL, RT_NULL);
    }
    else
    {
        err = -RT_EINVAL;
    }

    if (!err && clk_np)
    {
        clk_np->clk = clk;

        if (!clk_np->ops)
        {
            clk_np->ops = &unused_clk_ops;
        }

        rt_ref_init(&clk_np->ref);
        rt_list_init(&clk_np->list);
        rt_list_init(&clk_np->children_nodes);
        clk_np->multi_clk = 0;

        if (parent_np)
        {
            clk_set_parent(clk_np, parent_np);
        }
        else
        {
            clk_np->parent = RT_NULL;

            rt_hw_spin_lock(&_clk_lock.lock);

            rt_list_insert_after(&_clk_nodes, &clk_np->list);

            rt_hw_spin_unlock(&_clk_lock.lock);
        }
    }
    else
    {
        err = -RT_ENOMEM;
    }

    return err;
}

rt_err_t rt_clk_unregister(struct rt_clk_node *clk_np)
{
    rt_err_t err = RT_EOK;

    if (clk_np)
    {
        err = -RT_EBUSY;

        rt_hw_spin_lock(&_clk_lock.lock);

        if (rt_list_isempty(&clk_np->children_nodes))
        {
            if (rt_ref_read(&clk_np->ref) <= 1)
            {
                rt_list_remove(&clk_np->list);
                clk_free(clk_np->clk);

                err = RT_EOK;
            }
        }

        rt_hw_spin_unlock(&_clk_lock.lock);
    }
    else
    {
        err = -RT_EINVAL;
    }

    return err;
}

rt_err_t rt_clk_notifier_register(struct rt_clk *clk, struct rt_clk_notifier *notifier)
{
    if (!clk || !clk->clk_np || !notifier)
    {
        return -RT_EINVAL;
    }

    rt_hw_spin_lock(&_clk_lock.lock);

    ++clk->clk_np->notifier_count;
    rt_list_init(&notifier->list);
    rt_list_insert_after(&_clk_notifier_nodes, &notifier->list);

    rt_hw_spin_unlock(&_clk_lock.lock);

    return RT_EOK;
}

rt_err_t rt_clk_notifier_unregister(struct rt_clk *clk, struct rt_clk_notifier *notifier)
{
    struct rt_clk_notifier *notifier_find;

    if (!clk || !notifier)
    {
        return -RT_EINVAL;
    }

    rt_hw_spin_lock(&_clk_lock.lock);

    rt_list_for_each_entry(notifier_find, &_clk_notifier_nodes, list)
    {
        if (notifier_find->clk->clk_np == notifier->clk->clk_np)
        {
            --clk->clk_np->notifier_count;
            rt_list_remove(&notifier->list);

            break;
        }
    }

    rt_hw_spin_unlock(&_clk_lock.lock);

    return RT_EOK;
}

static rt_err_t clk_prepare(struct rt_clk *clk, struct rt_clk_node *clk_np)
{
    rt_err_t err = RT_EOK;

    if (clk_np->parent)
    {
        clk_prepare(clk_np->clk, clk_np->parent);
    }

    if (clk_np->ops->prepare)
    {
        err = clk_np->ops->prepare(clk);
    }

    return err;
}

rt_err_t rt_clk_prepare(struct rt_clk *clk)
{
    rt_err_t err = RT_EOK;

    RT_DEBUG_NOT_IN_INTERRUPT;

    if (clk && clk->clk_np)
    {
        rt_hw_spin_lock(&_clk_lock.lock);

        err = clk_prepare(clk, clk->clk_np);

        rt_hw_spin_unlock(&_clk_lock.lock);
    }
    else
    {
        err = -RT_EINVAL;
    }

    return err;
}

static void clk_unprepare(struct rt_clk *clk, struct rt_clk_node *clk_np)
{
    if (clk_np->parent)
    {
        clk_unprepare(clk_np->clk, clk_np->parent);
    }

    if (clk_np->ops->unprepare)
    {
        clk_np->ops->unprepare(clk);
    }
}

rt_err_t rt_clk_unprepare(struct rt_clk *clk)
{
    rt_err_t err = RT_EOK;

    RT_DEBUG_NOT_IN_INTERRUPT;

    if (clk && clk->clk_np)
    {
        rt_hw_spin_lock(&_clk_lock.lock);

        clk_unprepare(clk, clk->clk_np);

        rt_hw_spin_unlock(&_clk_lock.lock);
    }
    else
    {
        err = -RT_EINVAL;
    }

    return err;
}

static rt_err_t clk_enable(struct rt_clk *clk, struct rt_clk_node *clk_np)
{
    rt_err_t err = RT_EOK;

    if (clk_np->parent)
    {
        clk_enable(clk_np->clk, clk_np->parent);
    }

    if (clk_np->ops->enable)
    {
        err = clk_np->ops->enable(clk);
    }

    return err;
}

rt_err_t rt_clk_enable(struct rt_clk *clk)
{
    rt_err_t err = RT_EOK;

    if (clk && clk->clk_np)
    {
        rt_hw_spin_lock(&_clk_lock.lock);

        err = clk_enable(clk, clk->clk_np);

        rt_hw_spin_unlock(&_clk_lock.lock);
    }
    else
    {
        err = -RT_EINVAL;
    }

    return err;
}

static void clk_disable(struct rt_clk *clk, struct rt_clk_node *clk_np)
{
    if (clk_np->parent)
    {
        clk_disable(clk_np->clk, clk_np->parent);
    }

    if (clk_np->ops->disable)
    {
        clk_np->ops->disable(clk);
    }
}

void rt_clk_disable(struct rt_clk *clk)
{
    if (clk && clk->clk_np)
    {
        rt_hw_spin_lock(&_clk_lock.lock);

        clk_disable(clk, clk->clk_np);

        rt_hw_spin_unlock(&_clk_lock.lock);
    }
}

rt_err_t rt_clk_prepare_enable(struct rt_clk *clk)
{
    rt_err_t err;

    RT_DEBUG_NOT_IN_INTERRUPT;

    if (clk)
    {
        err = rt_clk_prepare(clk);

        if (!err)
        {
            err = rt_clk_enable(clk);

            if (err)
            {
                rt_clk_unprepare(clk);
            }
        }
    }
    else
    {
        err = -RT_EINVAL;
    }

    return err;
}

void rt_clk_disable_unprepare(struct rt_clk *clk)
{
    RT_DEBUG_NOT_IN_INTERRUPT;

    if (clk)
    {
        rt_clk_disable(clk);
        rt_clk_unprepare(clk);
    }
}

rt_err_t rt_clk_array_prepare(struct rt_clk_array *clk_arr)
{
    rt_err_t err = RT_EOK;

    if (clk_arr)
    {
        for (int i = 0; i < clk_arr->count; ++i)
        {
            if ((err = rt_clk_prepare(clk_arr->clks[i])))
            {
                LOG_E("CLK Array[%d] %s failed error = %s", i,
                        "prepare", rt_strerror(err));

                while (i --> 0)
                {
                    rt_clk_unprepare(clk_arr->clks[i]);
                }

                break;
            }
        }
    }
    else
    {
        err = -RT_EINVAL;
    }

    return err;
}

rt_err_t rt_clk_array_unprepare(struct rt_clk_array *clk_arr)
{
    rt_err_t err = RT_EOK;

    if (clk_arr)
    {
        for (int i = 0; i < clk_arr->count; ++i)
        {
            if ((err = rt_clk_unprepare(clk_arr->clks[i])))
            {
                LOG_E("CLK Array[%d] %s failed error = %s", i,
                        "unprepare", rt_strerror(err));

                break;
            }
        }
    }
    else
    {
        err = -RT_EINVAL;
    }

    return err;
}

rt_err_t rt_clk_array_enable(struct rt_clk_array *clk_arr)
{
    rt_err_t err = RT_EOK;

    if (clk_arr)
    {
        for (int i = 0; i < clk_arr->count; ++i)
        {
            if ((err = rt_clk_enable(clk_arr->clks[i])))
            {
                LOG_E("CLK Array[%d] %s failed error = %s", i,
                        "enable", rt_strerror(err));

                while (i --> 0)
                {
                    rt_clk_disable(clk_arr->clks[i]);
                }

                break;
            }
        }
    }
    else
    {
        err = -RT_EINVAL;
    }

    return err;
}

void rt_clk_array_disable(struct rt_clk_array *clk_arr)
{
    if (clk_arr)
    {
        for (int i = 0; i < clk_arr->count; ++i)
        {
            rt_clk_disable(clk_arr->clks[i]);
        }
    }
}

rt_err_t rt_clk_array_prepare_enable(struct rt_clk_array *clk_arr)
{
    rt_err_t err = RT_EOK;

    if (clk_arr)
    {
        for (int i = 0; i < clk_arr->count; ++i)
        {
            if ((err = rt_clk_prepare_enable(clk_arr->clks[i])))
            {
                LOG_E("CLK Array[%d] %s failed error = %s", i,
                        "prepare_enable", rt_strerror(err));

                while (i --> 0)
                {
                    rt_clk_disable_unprepare(clk_arr->clks[i]);
                }

                break;
            }
        }
    }
    else
    {
        err = -RT_EINVAL;
    }

    return err;
}

void rt_clk_array_disable_unprepare(struct rt_clk_array *clk_arr)
{
    if (clk_arr)
    {
        for (int i = 0; i < clk_arr->count; ++i)
        {
            rt_clk_disable_unprepare(clk_arr->clks[i]);
        }
    }
}

rt_err_t rt_clk_set_rate_range(struct rt_clk *clk, rt_ubase_t min, rt_ubase_t max)
{
    rt_err_t err = RT_EOK;

    if (clk && clk->clk_np)
    {
        struct rt_clk_node *clk_np = clk->clk_np;

        rt_hw_spin_lock(&_clk_lock.lock);

        if (clk_np->ops->set_rate)
        {
            rt_ubase_t rate = clk_np->rate;
            rt_ubase_t old_min = clk_np->min_rate;
            rt_ubase_t old_max = clk_np->max_rate;

            clk_np->min_rate = min;
            clk_np->max_rate = max;

            rate = rt_clamp(rate, min, max);
            err = clk_np->ops->set_rate(clk, rate,
                rt_clk_get_rate(clk_np->parent ? clk_np->parent->clk : RT_NULL));

            if (err)
            {
                clk_np->min_rate = old_min;
                clk_np->max_rate = old_max;
            }
        }
        else
        {
            err = -RT_ENOSYS;
        }

        rt_hw_spin_unlock(&_clk_lock.lock);
    }
    else
    {
        err = -RT_EINVAL;
    }

    return err;
}

rt_err_t rt_clk_set_min_rate(struct rt_clk *clk, rt_ubase_t rate)
{
    rt_err_t err = RT_EOK;

    if (clk && clk->clk_np)
    {
        struct rt_clk_node *clk_np = clk->clk_np;

        err = rt_clk_set_rate_range(clk, rate, clk_np->max_rate);
    }
    else
    {
        err = -RT_EINVAL;
    }

    return err;
}

rt_err_t rt_clk_set_max_rate(struct rt_clk *clk, rt_ubase_t rate)
{
    rt_err_t err = RT_EOK;

    if (clk && clk->clk_np)
    {
        struct rt_clk_node *clk_np = clk->clk_np;

        err = rt_clk_set_rate_range(clk, clk_np->min_rate, rate);
    }
    else
    {
        err = -RT_EINVAL;
    }

    return err;
}

rt_err_t rt_clk_set_rate(struct rt_clk *clk, rt_ubase_t rate)
{
    rt_err_t err = RT_EOK;

    if (clk && clk->clk_np)
    {
        struct rt_clk_node *clk_np = clk->clk_np;

        rt_hw_spin_lock(&_clk_lock.lock);

        if (clk_np->min_rate && rate < clk_np->min_rate)
        {
            err = -RT_EINVAL;
        }

        if (clk_np->max_rate && rate > clk_np->max_rate)
        {
            err = -RT_EINVAL;
        }

        if (!err)
        {
            if (clk_np->ops->set_rate)
            {
                rt_ubase_t old_rate = clk_np->rate;

                err = clk_np->ops->set_rate(clk, rate,
                    rt_clk_get_rate(clk_np->parent ? clk_np->parent->clk : RT_NULL));

                if (clk_np->rate != old_rate)
                {
                    clk_notify(clk_np, RT_CLK_MSG_PRE_RATE_CHANGE, old_rate, clk_np->rate);
                }
            }
            else
            {
                err = -RT_ENOSYS;
            }
        }

        rt_hw_spin_unlock(&_clk_lock.lock);
    }
    else
    {
        err = -RT_EINVAL;
    }

    return err;
}

rt_ubase_t rt_clk_get_rate(struct rt_clk *clk)
{
    rt_ubase_t rate = -1UL;

    if (clk)
    {
        if (clk->rate)
        {
            rate = clk->rate;
        }
        else if (clk->clk_np)
        {
            rate = clk->clk_np->rate;
        }
    }

    return rate;
}

rt_err_t rt_clk_set_phase(struct rt_clk *clk, int degrees)
{
    rt_err_t err = RT_EOK;

    if (clk && clk->clk_np && clk->clk_np->ops->set_phase)
    {
        rt_hw_spin_lock(&_clk_lock.lock);

        err = clk->clk_np->ops->set_phase(clk, degrees);

        rt_hw_spin_unlock(&_clk_lock.lock);
    }
    else
    {
        err = -RT_EINVAL;
    }

    return err;
}

rt_base_t rt_clk_get_phase(struct rt_clk *clk)
{
    rt_base_t res = RT_EOK;

    if (clk && clk->clk_np && clk->clk_np->ops->get_phase)
    {
        rt_hw_spin_lock(&_clk_lock.lock);

        res = clk->clk_np->ops->get_phase(clk);

        rt_hw_spin_unlock(&_clk_lock.lock);
    }
    else
    {
        res = -RT_EINVAL;
    }

    return res;
}

rt_base_t rt_clk_round_rate(struct rt_clk *clk, rt_ubase_t rate)
{
    rt_base_t res = RT_EOK;

    if (clk && clk->clk_np && clk->clk_np->ops->round_rate)
    {
        rt_ubase_t best_parent_rate;
        struct rt_clk_node *clk_np = clk->clk_np;

        rt_hw_spin_lock(&_clk_lock.lock);

        if (clk_np->min_rate && clk_np->max_rate)
        {
            rate = rt_clamp(rate, clk_np->min_rate, clk_np->max_rate);
        }

        res = clk->clk_np->ops->round_rate(clk, rate, &best_parent_rate);
        (void)best_parent_rate;

        rt_hw_spin_unlock(&_clk_lock.lock);
    }
    else
    {
        res = -RT_EINVAL;
    }

    return res;
}

rt_err_t rt_clk_set_parent(struct rt_clk *clk, struct rt_clk *clk_parent)
{
    rt_err_t err = RT_EOK;

    if (clk && clk->clk_np && clk->clk_np->ops->set_parent)
    {
        rt_hw_spin_lock(&_clk_lock.lock);

        err = clk->clk_np->ops->set_parent(clk, clk_parent);

        rt_hw_spin_unlock(&_clk_lock.lock);
    }
    else
    {
        err = -RT_EINVAL;
    }

    return err;
}

struct rt_clk *rt_clk_get_parent(struct rt_clk *clk)
{
    struct rt_clk *parent = RT_NULL;

    if (clk)
    {
        struct rt_clk_node *clk_np = clk->clk_np;

        rt_hw_spin_lock(&_clk_lock.lock);

        parent = clk_np->parent ? clk_np->parent->clk : RT_NULL;

        rt_hw_spin_unlock(&_clk_lock.lock);
    }

    return parent;
}

struct rt_clk_array *rt_clk_get_array(struct rt_device *dev)
{
    struct rt_clk_array *clk_arr = RT_NULL;

#ifdef RT_USING_OFW
    clk_arr = rt_ofw_get_clk_array(dev->ofw_node);
#endif

    return clk_arr;
}

struct rt_clk *rt_clk_get_by_index(struct rt_device *dev, int index)
{
    struct rt_clk *clk = RT_NULL;

#ifdef RT_USING_OFW
    clk = rt_ofw_get_clk(dev->ofw_node, index);
#endif

    return clk;
}

struct rt_clk *rt_clk_get_by_name(struct rt_device *dev, const char *name)
{
    struct rt_clk *clk = RT_NULL;

#ifdef RT_USING_OFW
    clk = rt_ofw_get_clk_by_name(dev->ofw_node, name);
#endif

    return clk;
}

void rt_clk_array_put(struct rt_clk_array *clk_arr)
{
    if (clk_arr)
    {
        for (int i = 0; i < clk_arr->count; ++i)
        {
            if (clk_arr->clks[i])
            {
                rt_clk_put(clk_arr->clks[i]);
            }
            else
            {
                break;
            }
        }

        rt_free(clk_arr);
    }
}

void rt_clk_put(struct rt_clk *clk)
{
    if (clk)
    {
        clk_put(clk->clk_np);
        clk_free(clk);
    }
}

#ifdef RT_USING_OFW
static struct rt_clk *ofw_get_clk_no_lock(struct rt_ofw_node *np, int index, const char *name)
{
    struct rt_clk *clk = RT_NULL;
    struct rt_ofw_cell_args clk_args;

    if (!rt_ofw_parse_phandle_cells(np, "clocks", "#clock-cells", index, &clk_args))
    {
        int count;
        struct rt_ofw_node *clk_ofw_np = clk_args.data;
        struct rt_clk_node *clk_np = rt_ofw_data(clk_ofw_np);

        count = rt_ofw_count_of_clk(clk_ofw_np);

        rt_ofw_node_put(clk_ofw_np);

        if (clk_np)
        {
            if (count > 1)
            {
                /* args[0] must be the index of CLK */
                clk_np = &clk_np[clk_args.args[0]];
            }

            clk = clk_create(clk_np, np->full_name, name, &clk_args, np);
        }
    }

    return clk;
}

static struct rt_clk *ofw_get_clk(struct rt_ofw_node *np, int index, const char *name)
{
    struct rt_clk *clk;

    rt_hw_spin_lock(&_clk_lock.lock);

    clk = ofw_get_clk_no_lock(np, index, name);

    rt_hw_spin_unlock(&_clk_lock.lock);

    return clk;
}

struct rt_clk_array *rt_ofw_get_clk_array(struct rt_ofw_node *np)
{
    int count;
    struct rt_clk_array *clk_arr = RT_NULL;

    if ((count = rt_ofw_count_phandle_cells(np, "clocks", "#clock-cells")) > 0)
    {
        clk_arr = rt_calloc(1, sizeof(*clk_arr) + sizeof(clk_arr->clks[0]) * count);

        if (clk_arr)
        {
            int i;
            rt_bool_t has_name = rt_ofw_prop_read_bool(np, "clock-names");

            clk_arr->count = count;

            rt_hw_spin_lock(&_clk_lock.lock);

            for (i = 0; i < count; ++i)
            {
                const char *name = RT_NULL;

                if (has_name)
                {
                    rt_ofw_prop_read_string_index(np, "clock-names", i, &name);
                }

                clk_arr->clks[i] = ofw_get_clk_no_lock(np, i, name);

                if (!clk_arr->clks[i])
                {
                    --i;
                    break;
                }
            }

            rt_hw_spin_unlock(&_clk_lock.lock);

            if (i > 0 && i < count)
            {
                rt_clk_array_put(clk_arr);
                clk_arr = RT_NULL;
            }
        }
    }

    return clk_arr;
}

struct rt_clk *rt_ofw_get_clk(struct rt_ofw_node *np, int index)
{
    struct rt_clk *clk = RT_NULL;

    if (np && index >= 0)
    {
        clk = ofw_get_clk(np, index, RT_NULL);
    }

    return clk;
}

struct rt_clk *rt_ofw_get_clk_by_name(struct rt_ofw_node *np, const char *name)
{
    struct rt_clk *clk = RT_NULL;

    if (np && name)
    {
        int index = rt_ofw_prop_index_of_string(np, "clock-names", name);

        if (index >= 0)
        {
            clk = ofw_get_clk(np, index, name);
        }
    }

    return clk;
}

rt_ssize_t rt_ofw_count_of_clk(struct rt_ofw_node *clk_ofw_np)
{
    if (clk_ofw_np)
    {
        struct rt_clk_node *clk_np = rt_ofw_data(clk_ofw_np);

        if (clk_np && clk_np->multi_clk)
        {
            return clk_np->multi_clk;
        }
        else
        {
            const fdt32_t *cell;
            rt_uint32_t count = 0;
            struct rt_ofw_prop *prop;

            prop = rt_ofw_get_prop(clk_ofw_np, "clock-indices", RT_NULL);

            if (prop)
            {
                rt_uint32_t max_idx = 0, idx;

                for (cell = rt_ofw_prop_next_u32(prop, RT_NULL, &idx);
                    cell;
                    cell = rt_ofw_prop_next_u32(prop, cell, &idx))
                {
                    if (idx > max_idx)
                    {
                        max_idx = idx;
                    }
                }

                count = max_idx + 1;
            }
            else
            {
                rt_ssize_t len;

                if ((prop = rt_ofw_get_prop(clk_ofw_np, "clock-output-names", &len)))
                {
                    char *value = prop->value;

                    for (int i = 0; i < len; ++i, ++value)
                    {
                        if (*value == '\0')
                        {
                            ++count;
                        }
                    }
                }
                else
                {
                    count = 1;
                }
            }

            if (clk_np)
            {
                clk_np->multi_clk = count;
            }

            return count;
        }
    }

    return -RT_EINVAL;
}
#endif /* RT_USING_OFW */