drivers/clk/clk-fixed-factor.c

/*
 * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
 *
 * 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);
	unsigned long long int rate;

	rate = (unsigned long long int)parent_rate * fix->mult;
	do_div(rate, fix->div);
	return (unsigned long)rate;
}

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;
}