clk-pfd.c

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/*
 * Copyright 2012 Freescale Semiconductor, Inc.
 * Copyright 2012 Linaro Ltd.
 *
 * The code contained herein is licensed under the GNU General Public
 * License. You may obtain a copy of the GNU General Public License
 * Version 2 or later at the following locations:
 *
 * http://www.opensource.org/licenses/gpl-license.html
 * http://www.gnu.org/copyleft/gpl.html
 */

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

struct clk_pfd {
    struct clk_hw   hw;
    void __iomem    *reg;
    u8      idx;
};

#define to_clk_pfd(_hw) container_of(_hw, struct clk_pfd, hw)

#define SET 0x4
#define CLR 0x8
#define OTG 0xc

static int clk_pfd_enable(struct clk_hw *hw)
{
    struct clk_pfd *pfd = to_clk_pfd(hw);

    writel_relaxed(1 << ((pfd->idx + 1) * 8 - 1), pfd->reg + CLR);

    return 0;
}

static void clk_pfd_disable(struct clk_hw *hw)
{
    struct clk_pfd *pfd = to_clk_pfd(hw);

    writel_relaxed(1 << ((pfd->idx + 1) * 8 - 1), pfd->reg + SET);
}

static unsigned long clk_pfd_recalc_rate(struct clk_hw *hw,
                     unsigned long parent_rate)
{
    struct clk_pfd *pfd = to_clk_pfd(hw);
    u64 tmp = parent_rate;
    u8 frac = (readl_relaxed(pfd->reg) >> (pfd->idx * 8)) & 0x3f;

    tmp *= 18;
    do_div(tmp, frac);

    return tmp;
}

static long clk_pfd_round_rate(struct clk_hw *hw, unsigned long rate,
                   unsigned long *prate)
{
    u64 tmp = *prate;
    u8 frac;

    tmp = tmp * 18 + rate / 2;
    do_div(tmp, rate);
    frac = tmp;
    if (frac < 12)
        frac = 12;
    else if (frac > 35)
        frac = 35;
    tmp = *prate;
    tmp *= 18;
    do_div(tmp, frac);

    return tmp;
}

static int clk_pfd_set_rate(struct clk_hw *hw, unsigned long rate,
        unsigned long parent_rate)
{
    struct clk_pfd *pfd = to_clk_pfd(hw);
    u64 tmp = parent_rate;
    u8 frac;

    tmp = tmp * 18 + rate / 2;
    do_div(tmp, rate);
    frac = tmp;
    if (frac < 12)
        frac = 12;
    else if (frac > 35)
        frac = 35;

    writel_relaxed(0x3f << (pfd->idx * 8), pfd->reg + CLR);
    writel_relaxed(frac << (pfd->idx * 8), pfd->reg + SET);

    return 0;
}

static const struct clk_ops clk_pfd_ops = {
    .enable     = clk_pfd_enable,
    .disable    = clk_pfd_disable,
    .recalc_rate    = clk_pfd_recalc_rate,
    .round_rate = clk_pfd_round_rate,
    .set_rate   = clk_pfd_set_rate,
};

struct clk *imx_clk_pfd(const char *name, const char *parent_name,
            void __iomem *reg, u8 idx)
{
    struct clk_pfd *pfd;
    struct clk *clk;
    struct clk_init_data init;

    pfd = kzalloc(sizeof(*pfd), GFP_KERNEL);
    if (!pfd)
        return ERR_PTR(-ENOMEM);

    pfd->reg = reg;
    pfd->idx = idx;

    init.name = name;
    init.ops = &clk_pfd_ops;
    init.flags = 0;
    init.parent_names = &parent_name;
    init.num_parents = 1;

    pfd->hw.init = &init;

    clk = clk_register(NULL, &pfd->hw);
    if (IS_ERR(clk))
        kfree(pfd);

    return clk;
}