/*
 * 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 = 1; _p <= max_p; _p <<= 1) {
		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_find_best_with_parent_adj(struct clk_hw *hw,
						      unsigned long *parent,
						      unsigned long rate,
						      unsigned int max_m,
						      unsigned int max_p)
{
	unsigned long parent_rate_saved;
	unsigned long parent_rate, now;
	unsigned long best_rate = 0;
	unsigned int _m, _p, div;
	unsigned long maxdiv;

	parent_rate_saved = *parent;

	/*
	 * The maximum divider we can use without overflowing
	 * unsigned long in rate * m * p below
	 */
	maxdiv = max_m * max_p;
	maxdiv = min(ULONG_MAX / rate, maxdiv);

	for (_p = 1; _p <= max_p; _p <<= 1) {
		for (_m = 1; _m <= max_m; _m++) {
			div = _m * _p;

			if (div > maxdiv)
				break;

			if (rate * div == parent_rate_saved) {
				/*
				 * It's the most ideal case if the requested
				 * rate can be divided from parent clock without
				 * needing to change parent rate, so return the
				 * divider immediately.
				 */
				*parent = parent_rate_saved;
				return rate;
			}

			parent_rate = clk_hw_round_rate(hw, rate * div);
			now = parent_rate / div;

			if (now <= rate && now > best_rate) {
				best_rate = now;
				*parent = parent_rate;

				if (now == rate)
					return rate;
			}
		}
	}

	return best_rate;
}

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

	if (cmp->common.features & CCU_FEATURE_FIXED_POSTDIV)
		rate *= cmp->fixed_post_div;

	max_m = cmp->m.max ?: 1 << cmp->m.width;
	max_p = cmp->p.max ?: 1 << ((1 << cmp->p.width) - 1);

	if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
		ccu_mp_find_best(*parent_rate, rate, max_m, max_p, &m, &p);
		rate = *parent_rate / p / m;
	} else {
		rate = ccu_mp_find_best_with_parent_adj(hw, parent_rate, rate,
							max_m, max_p);
	}

	if (cmp->common.features & CCU_FEATURE_FIXED_POSTDIV)
		rate /= cmp->fixed_post_div;

	return rate;
}

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 long rate;
	unsigned int m, p;
	u32 reg;

	/* Adjust parent_rate according to pre-dividers */
	parent_rate = ccu_mux_helper_apply_prediv(&cmp->common, &cmp->mux, -1,
						  parent_rate);

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

	m = reg >> cmp->m.shift;
	m &= (1 << cmp->m.width) - 1;
	m += cmp->m.offset;
	if (!m)
		m++;

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

	rate = (parent_rate >> p) / m;
	if (cmp->common.features & CCU_FEATURE_FIXED_POSTDIV)
		rate /= cmp->fixed_post_div;

	return rate;
}

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 max_m, max_p;
	unsigned int m, p;
	u32 reg;

	/* Adjust parent_rate according to pre-dividers */
	parent_rate = ccu_mux_helper_apply_prediv(&cmp->common, &cmp->mux, -1,
						  parent_rate);

	max_m = cmp->m.max ?: 1 << cmp->m.width;
	max_p = cmp->p.max ?: 1 << ((1 << cmp->p.width) - 1);

	/* Adjust target rate according to post-dividers */
	if (cmp->common.features & CCU_FEATURE_FIXED_POSTDIV)
		rate = rate * cmp->fixed_post_div;

	ccu_mp_find_best(parent_rate, rate, max_m, max_p, &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);
	reg |= (m - cmp->m.offset) << cmp->m.shift;
	reg |= ilog2(p) << cmp->p.shift;

	writel(reg, 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,
};

/*
 * Support for MMC timing mode switching
 *
 * The MMC clocks on some SoCs support switching between old and
 * new timing modes. A platform specific API is provided to query
 * and set the timing mode on supported SoCs.
 *
 * In addition, a special class of ccu_mp_ops is provided, which
 * takes in to account the timing mode switch. When the new timing
 * mode is active, the clock output rate is halved. This new class
 * is a wrapper around the generic ccu_mp_ops. When clock rates
 * are passed through to ccu_mp_ops callbacks, they are doubled
 * if the new timing mode bit is set, to account for the post
 * divider. Conversely, when clock rates are passed back, they
 * are halved if the mode bit is set.
 */

static unsigned long ccu_mp_mmc_recalc_rate(struct clk_hw *hw,
					    unsigned long parent_rate)
{
	unsigned long rate = ccu_mp_recalc_rate(hw, parent_rate);
	struct ccu_common *cm = hw_to_ccu_common(hw);
	u32 val = readl(cm->base + cm->reg);

	if (val & CCU_MMC_NEW_TIMING_MODE)
		return rate / 2;
	return rate;
}

static int ccu_mp_mmc_determine_rate(struct clk_hw *hw,
				     struct clk_rate_request *req)
{
	struct ccu_common *cm = hw_to_ccu_common(hw);
	u32 val = readl(cm->base + cm->reg);
	int ret;

	/* adjust the requested clock rate */
	if (val & CCU_MMC_NEW_TIMING_MODE) {
		req->rate *= 2;
		req->min_rate *= 2;
		req->max_rate *= 2;
	}

	ret = ccu_mp_determine_rate(hw, req);

	/* re-adjust the requested clock rate back */
	if (val & CCU_MMC_NEW_TIMING_MODE) {
		req->rate /= 2;
		req->min_rate /= 2;
		req->max_rate /= 2;
	}

	return ret;
}

static int ccu_mp_mmc_set_rate(struct clk_hw *hw, unsigned long rate,
			       unsigned long parent_rate)
{
	struct ccu_common *cm = hw_to_ccu_common(hw);
	u32 val = readl(cm->base + cm->reg);

	if (val & CCU_MMC_NEW_TIMING_MODE)
		rate *= 2;

	return ccu_mp_set_rate(hw, rate, parent_rate);
}

const struct clk_ops ccu_mp_mmc_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_mmc_determine_rate,
	.recalc_rate	= ccu_mp_mmc_recalc_rate,
	.set_rate	= ccu_mp_mmc_set_rate,
};