clk-fixed-rate.c

Go to the documentation of this file.

/*
 * Copyright (C) 2010-2011 Canonical Ltd <[email protected]>
 * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <[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.
 *
 * Fixed rate clock implementation
 */

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

/*
 * DOC: basic fixed-rate clock that cannot gate
 *
 * Traits of this clock:
 * prepare - clk_(un)prepare only ensures parents are prepared
 * enable - clk_enable only ensures parents are enabled
 * rate - rate is always a fixed value.  No clk_set_rate support
 * parent - fixed parent.  No clk_set_parent support
 */

#define to_clk_fixed_rate(_hw) container_of(_hw, struct clk_fixed_rate, hw)

static unsigned long clk_fixed_rate_recalc_rate(struct clk_hw *hw,
        unsigned long parent_rate)
{
    return to_clk_fixed_rate(hw)->fixed_rate;
}

const struct clk_ops clk_fixed_rate_ops = {
    .recalc_rate = clk_fixed_rate_recalc_rate,
};
EXPORT_SYMBOL_GPL(clk_fixed_rate_ops);

struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
        const char *parent_name, unsigned long flags,
        unsigned long fixed_rate)
{
    struct clk_fixed_rate *fixed;
    struct clk *clk;
    struct clk_init_data init;

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

    init.name = name;
    init.ops = &clk_fixed_rate_ops;
    init.flags = flags | CLK_IS_BASIC;
    init.parent_names = (parent_name ? &parent_name: NULL);
    init.num_parents = (parent_name ? 1 : 0);

    /* struct clk_fixed_rate assignments */
    fixed->fixed_rate = fixed_rate;
    fixed->hw.init = &init;

    /* register the clock */
    clk = clk_register(dev, &fixed->hw);

    if (IS_ERR(clk))
        kfree(fixed);

    return clk;
}

#ifdef CONFIG_OF

void __init of_fixed_clk_setup(struct device_node *node)
{
    struct clk *clk;
    const char *clk_name = node->name;
    u32 rate;

    if (of_property_read_u32(node, "clock-frequency", &rate))
        return;

    of_property_read_string(node, "clock-output-names", &clk_name);

    clk = clk_register_fixed_rate(NULL, clk_name, NULL, CLK_IS_ROOT, rate);
    if (clk)
        of_clk_add_provider(node, of_clk_src_simple_get, clk);
}
EXPORT_SYMBOL_GPL(of_fixed_clk_setup);
#endif