clk-gpt-synth.c

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/*
 * Copyright (C) 2012 ST Microelectronics
 * Viresh Kumar <[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.
 *
 * General Purpose Timer Synthesizer clock implementation
 */

#define pr_fmt(fmt) "clk-gpt-synth: " fmt

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

#define GPT_MSCALE_MASK     0xFFF
#define GPT_NSCALE_SHIFT    12
#define GPT_NSCALE_MASK     0xF

/*
 * DOC: General Purpose Timer Synthesizer clock
 *
 * Calculates gpt synth clk rate for different values of mscale and nscale
 *
 * Fout= Fin/((2 ^ (N+1)) * (M+1))
 */

#define to_clk_gpt(_hw) container_of(_hw, struct clk_gpt, hw)

static unsigned long gpt_calc_rate(struct clk_hw *hw, unsigned long prate,
        int index)
{
    struct clk_gpt *gpt = to_clk_gpt(hw);
    struct gpt_rate_tbl *rtbl = gpt->rtbl;

    prate /= ((1 << (rtbl[index].nscale + 1)) * (rtbl[index].mscale + 1));

    return prate;
}

static long clk_gpt_round_rate(struct clk_hw *hw, unsigned long drate,
        unsigned long *prate)
{
    struct clk_gpt *gpt = to_clk_gpt(hw);
    int unused;

    return clk_round_rate_index(hw, drate, *prate, gpt_calc_rate,
            gpt->rtbl_cnt, &unused);
}

static unsigned long clk_gpt_recalc_rate(struct clk_hw *hw,
        unsigned long parent_rate)
{
    struct clk_gpt *gpt = to_clk_gpt(hw);
    unsigned long flags = 0;
    unsigned int div = 1, val;

    if (gpt->lock)
        spin_lock_irqsave(gpt->lock, flags);

    val = readl_relaxed(gpt->reg);

    if (gpt->lock)
        spin_unlock_irqrestore(gpt->lock, flags);

    div += val & GPT_MSCALE_MASK;
    div *= 1 << (((val >> GPT_NSCALE_SHIFT) & GPT_NSCALE_MASK) + 1);

    if (!div)
        return 0;

    return parent_rate / div;
}

/* Configures new clock rate of gpt */
static int clk_gpt_set_rate(struct clk_hw *hw, unsigned long drate,
                unsigned long prate)
{
    struct clk_gpt *gpt = to_clk_gpt(hw);
    struct gpt_rate_tbl *rtbl = gpt->rtbl;
    unsigned long flags = 0, val;
    int i;

    clk_round_rate_index(hw, drate, prate, gpt_calc_rate, gpt->rtbl_cnt,
            &i);

    if (gpt->lock)
        spin_lock_irqsave(gpt->lock, flags);

    val = readl(gpt->reg) & ~GPT_MSCALE_MASK;
    val &= ~(GPT_NSCALE_MASK << GPT_NSCALE_SHIFT);

    val |= rtbl[i].mscale & GPT_MSCALE_MASK;
    val |= (rtbl[i].nscale & GPT_NSCALE_MASK) << GPT_NSCALE_SHIFT;

    writel_relaxed(val, gpt->reg);

    if (gpt->lock)
        spin_unlock_irqrestore(gpt->lock, flags);

    return 0;
}

static struct clk_ops clk_gpt_ops = {
    .recalc_rate = clk_gpt_recalc_rate,
    .round_rate = clk_gpt_round_rate,
    .set_rate = clk_gpt_set_rate,
};

struct clk *clk_register_gpt(const char *name, const char *parent_name, unsigned
        long flags, void __iomem *reg, struct gpt_rate_tbl *rtbl, u8
        rtbl_cnt, spinlock_t *lock)
{
    struct clk_init_data init;
    struct clk_gpt *gpt;
    struct clk *clk;

    if (!name || !parent_name || !reg || !rtbl || !rtbl_cnt) {
        pr_err("Invalid arguments passed");
        return ERR_PTR(-EINVAL);
    }

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

    /* struct clk_gpt assignments */
    gpt->reg = reg;
    gpt->rtbl = rtbl;
    gpt->rtbl_cnt = rtbl_cnt;
    gpt->lock = lock;
    gpt->hw.init = &init;

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

    clk = clk_register(NULL, &gpt->hw);
    if (!IS_ERR_OR_NULL(clk))
        return clk;

    pr_err("clk register failed\n");
    kfree(gpt);

    return NULL;
}