clk-fixed-factor.c

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/*
 * Copyright (C) 2011 Sascha Hauer, Pengutronix <[email protected]>
 *
 * 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.
 *
 * Standard functionality for the common clock API.
 */
#include <linux/module.h>
#include <linux/clk-provider.h>
#include <linux/slab.h>
#include <linux/err.h>

/*
 * DOC: basic fixed multiplier and divider clock that cannot gate
 *
 * Traits of this clock:
 * prepare - clk_prepare only ensures that parents are prepared
 * enable - clk_enable only ensures that parents are enabled
 * rate - rate is fixed.  clk->rate = parent->rate / div * mult
 * parent - fixed parent.  No clk_set_parent support
 */

#define to_clk_fixed_factor(_hw) container_of(_hw, struct clk_fixed_factor, hw)

static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
        unsigned long parent_rate)
{
    struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);

    return parent_rate * fix->mult / fix->div;
}

static long clk_factor_round_rate(struct clk_hw *hw, unsigned long rate,
                unsigned long *prate)
{
    struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);

    if (__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT) {
        unsigned long best_parent;

        best_parent = (rate / fix->mult) * fix->div;
        *prate = __clk_round_rate(__clk_get_parent(hw->clk),
                best_parent);
    }

    return (*prate / fix->div) * fix->mult;
}

static int clk_factor_set_rate(struct clk_hw *hw, unsigned long rate,
                unsigned long parent_rate)
{
    return 0;
}

struct clk_ops clk_fixed_factor_ops = {
    .round_rate = clk_factor_round_rate,
    .set_rate = clk_factor_set_rate,
    .recalc_rate = clk_factor_recalc_rate,
};
EXPORT_SYMBOL_GPL(clk_fixed_factor_ops);

struct clk *clk_register_fixed_factor(struct device *dev, const char *name,
        const char *parent_name, unsigned long flags,
        unsigned int mult, unsigned int div)
{
    struct clk_fixed_factor *fix;
    struct clk_init_data init;
    struct clk *clk;

    fix = kmalloc(sizeof(*fix), GFP_KERNEL);
    if (!fix) {
        pr_err("%s: could not allocate fixed factor clk\n", __func__);
        return ERR_PTR(-ENOMEM);
    }

    /* struct clk_fixed_factor assignments */
    fix->mult = mult;
    fix->div = div;
    fix->hw.init = &init;

    init.name = name;
    init.ops = &clk_fixed_factor_ops;
    init.flags = flags | CLK_IS_BASIC;
    init.parent_names = &parent_name;
    init.num_parents = 1;

    clk = clk_register(dev, &fix->hw);

    if (IS_ERR(clk))
        kfree(fix);

    return clk;
}