clk-frac.c

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/*
 * mmp factor clock operation source file
 *
 * Copyright (C) 2012 Marvell
 * Chao Xie <[email protected]>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/clk-provider.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/err.h>

#include "clk.h"
/*
 * It is M/N clock
 *
 * Fout from synthesizer can be given from two equations:
 * numerator/denominator = Fin / (Fout * factor)
 */

#define to_clk_factor(hw) container_of(hw, struct clk_factor, hw)
struct clk_factor {
    struct clk_hw       hw;
    void __iomem        *base;
    struct clk_factor_masks *masks;
    struct clk_factor_tbl   *ftbl;
    unsigned int        ftbl_cnt;
};

static long clk_factor_round_rate(struct clk_hw *hw, unsigned long drate,
        unsigned long *prate)
{
    struct clk_factor *factor = to_clk_factor(hw);
    unsigned long rate = 0, prev_rate;
    int i;

    for (i = 0; i < factor->ftbl_cnt; i++) {
        prev_rate = rate;
        rate = (((*prate / 10000) * factor->ftbl[i].num) /
            (factor->ftbl[i].den * factor->masks->factor)) * 10000;
        if (rate > drate)
            break;
    }
    if (i == 0)
        return rate;
    else
        return prev_rate;
}

static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
        unsigned long parent_rate)
{
    struct clk_factor *factor = to_clk_factor(hw);
    struct clk_factor_masks *masks = factor->masks;
    unsigned int val, num, den;

    val = readl_relaxed(factor->base);

    /* calculate numerator */
    num = (val >> masks->num_shift) & masks->num_mask;

    /* calculate denominator */
    den = (val >> masks->den_shift) & masks->num_mask;

    if (!den)
        return 0;

    return (((parent_rate / 10000)  * den) /
            (num * factor->masks->factor)) * 10000;
}

/* Configures new clock rate*/
static int clk_factor_set_rate(struct clk_hw *hw, unsigned long drate,
                unsigned long prate)
{
    struct clk_factor *factor = to_clk_factor(hw);
    struct clk_factor_masks *masks = factor->masks;
    int i;
    unsigned long val;
    unsigned long prev_rate, rate = 0;

    for (i = 0; i < factor->ftbl_cnt; i++) {
        prev_rate = rate;
        rate = (((prate / 10000) * factor->ftbl[i].num) /
            (factor->ftbl[i].den * factor->masks->factor)) * 10000;
        if (rate > drate)
            break;
    }
    if (i > 0)
        i--;

    val = readl_relaxed(factor->base);

    val &= ~(masks->num_mask << masks->num_shift);
    val |= (factor->ftbl[i].num & masks->num_mask) << masks->num_shift;

    val &= ~(masks->den_mask << masks->den_shift);
    val |= (factor->ftbl[i].den & masks->den_mask) << masks->den_shift;

    writel_relaxed(val, factor->base);

    return 0;
}

static struct clk_ops clk_factor_ops = {
    .recalc_rate = clk_factor_recalc_rate,
    .round_rate = clk_factor_round_rate,
    .set_rate = clk_factor_set_rate,
};

struct clk *mmp_clk_register_factor(const char *name, const char *parent_name,
        unsigned long flags, void __iomem *base,
        struct clk_factor_masks *masks, struct clk_factor_tbl *ftbl,
        unsigned int ftbl_cnt)
{
    struct clk_factor *factor;
    struct clk_init_data init;
    struct clk *clk;

    if (!masks) {
        pr_err("%s: must pass a clk_factor_mask\n", __func__);
        return ERR_PTR(-EINVAL);
    }

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

    /* struct clk_aux assignments */
    factor->base = base;
    factor->masks = masks;
    factor->ftbl = ftbl;
    factor->ftbl_cnt = ftbl_cnt;
    factor->hw.init = &init;

    init.name = name;
    init.ops = &clk_factor_ops;
    init.flags = flags;
    init.parent_names = &parent_name;
    init.num_parents = 1;

    clk = clk_register(NULL, &factor->hw);
    if (IS_ERR_OR_NULL(clk))
        kfree(factor);

    return clk;
}