/*
 * Copyright (C) 2016 Maxime Ripard
 * Maxime Ripard <maxime.ripard@free-electrons.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 */

#include <linux/clk-provider.h>

#include "ccu_gate.h"
#include "ccu_mp.h"

static void ccu_mp_find_best(unsigned long parent, unsigned long rate,
			     unsigned int max_m, unsigned int max_p,
			     unsigned int *m, unsigned int *p)
{
	unsigned long best_rate = 0;
	unsigned int best_m = 0, best_p = 0;
	unsigned int _m, _p;

	for (_p = 0; _p <= max_p; _p++) {
		for (_m = 1; _m <= max_m; _m++) {
			unsigned long tmp_rate = (parent >> _p) / _m;

			if (tmp_rate > rate)
				continue;

			if ((rate - tmp_rate) < (rate - best_rate)) {
				best_rate = tmp_rate;
				best_m = _m;
				best_p = _p;
			}
		}
	}

	*m = best_m;
	*p = best_p;
}

static unsigned long ccu_mp_round_rate(struct ccu_mux_internal *mux,
				       unsigned long parent_rate,
				       unsigned long rate,
				       void *data)
{
	struct ccu_mp *cmp = data;
	unsigned int m, p;

	ccu_mp_find_best(parent_rate, rate,
			 1 << cmp->m.width, (1 << cmp->p.width) - 1,
			 &m, &p);

	return (parent_rate >> p) / m;
}

static void ccu_mp_disable(struct clk_hw *hw)
{
	struct ccu_mp *cmp = hw_to_ccu_mp(hw);

	return ccu_gate_helper_disable(&cmp->common, cmp->enable);
}

static int ccu_mp_enable(struct clk_hw *hw)
{
	struct ccu_mp *cmp = hw_to_ccu_mp(hw);

	return ccu_gate_helper_enable(&cmp->common, cmp->enable);
}

static int ccu_mp_is_enabled(struct clk_hw *hw)
{
	struct ccu_mp *cmp = hw_to_ccu_mp(hw);

	return ccu_gate_helper_is_enabled(&cmp->common, cmp->enable);
}

static unsigned long ccu_mp_recalc_rate(struct clk_hw *hw,
					unsigned long parent_rate)
{
	struct ccu_mp *cmp = hw_to_ccu_mp(hw);
	unsigned int m, p;
	u32 reg;

	reg = readl(cmp->common.base + cmp->common.reg);

	m = reg >> cmp->m.shift;
	m &= (1 << cmp->m.width) - 1;

	p = reg >> cmp->p.shift;
	p &= (1 << cmp->p.width) - 1;

	return (parent_rate >> p) / (m + 1);
}

static int ccu_mp_determine_rate(struct clk_hw *hw,
				 struct clk_rate_request *req)
{
	struct ccu_mp *cmp = hw_to_ccu_mp(hw);

	return ccu_mux_helper_determine_rate(&cmp->common, &cmp->mux,
					     req, ccu_mp_round_rate, cmp);
}

static int ccu_mp_set_rate(struct clk_hw *hw, unsigned long rate,
			   unsigned long parent_rate)
{
	struct ccu_mp *cmp = hw_to_ccu_mp(hw);
	unsigned long flags;
	unsigned int m, p;
	u32 reg;

	ccu_mp_find_best(parent_rate, rate,
			 1 << cmp->m.width, (1 << cmp->p.width) - 1,
			 &m, &p);


	spin_lock_irqsave(cmp->common.lock, flags);

	reg = readl(cmp->common.base + cmp->common.reg);
	reg &= ~GENMASK(cmp->m.width + cmp->m.shift - 1, cmp->m.shift);
	reg &= ~GENMASK(cmp->p.width + cmp->p.shift - 1, cmp->p.shift);

	writel(reg | (p << cmp->p.shift) | ((m - 1) << cmp->m.shift),
	       cmp->common.base + cmp->common.reg);

	spin_unlock_irqrestore(cmp->common.lock, flags);

	return 0;
}

static u8 ccu_mp_get_parent(struct clk_hw *hw)
{
	struct ccu_mp *cmp = hw_to_ccu_mp(hw);

	return ccu_mux_helper_get_parent(&cmp->common, &cmp->mux);
}

static int ccu_mp_set_parent(struct clk_hw *hw, u8 index)
{
	struct ccu_mp *cmp = hw_to_ccu_mp(hw);

	return ccu_mux_helper_set_parent(&cmp->common, &cmp->mux, index);
}

const struct clk_ops ccu_mp_ops = {
	.disable	= ccu_mp_disable,
	.enable		= ccu_mp_enable,
	.is_enabled	= ccu_mp_is_enabled,

	.get_parent	= ccu_mp_get_parent,
	.set_parent	= ccu_mp_set_parent,

	.determine_rate	= ccu_mp_determine_rate,
	.recalc_rate	= ccu_mp_recalc_rate,
	.set_rate	= ccu_mp_set_rate,
};