// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2016 Maxime Ripard
 * Maxime Ripard <maxime.ripard@free-electrons.com>
 */

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

#include "ccu_gate.h"
#include "ccu_nkmp.h"

struct _ccu_nkmp {
	unsigned long	n, min_n, max_n;
	unsigned long	k, min_k, max_k;
	unsigned long	m, min_m, max_m;
	unsigned long	p, min_p, max_p;
};

static unsigned long ccu_nkmp_calc_rate(unsigned long parent,
					unsigned long n, unsigned long k,
					unsigned long m, unsigned long p)
{
	u64 rate = parent;

	rate *= n * k;
	do_div(rate, m * p);

	return rate;
}

static void ccu_nkmp_find_best(unsigned long parent, unsigned long rate,
			       struct _ccu_nkmp *nkmp)
{
	unsigned long best_rate = 0;
	unsigned long best_n = 0, best_k = 0, best_m = 0, best_p = 0;
	unsigned long _n, _k, _m, _p;

	for (_k = nkmp->min_k; _k <= nkmp->max_k; _k++) {
		for (_n = nkmp->min_n; _n <= nkmp->max_n; _n++) {
			for (_m = nkmp->min_m; _m <= nkmp->max_m; _m++) {
				for (_p = nkmp->min_p; _p <= nkmp->max_p; _p <<= 1) {
					unsigned long tmp_rate;

					tmp_rate = ccu_nkmp_calc_rate(parent,
								      _n, _k,
								      _m, _p);

					if (tmp_rate > rate)
						continue;

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

	nkmp->n = best_n;
	nkmp->k = best_k;
	nkmp->m = best_m;
	nkmp->p = best_p;
}

static void ccu_nkmp_disable(struct clk_hw *hw)
{
	struct ccu_nkmp *nkmp = hw_to_ccu_nkmp(hw);

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

static int ccu_nkmp_enable(struct clk_hw *hw)
{
	struct ccu_nkmp *nkmp = hw_to_ccu_nkmp(hw);

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

static int ccu_nkmp_is_enabled(struct clk_hw *hw)
{
	struct ccu_nkmp *nkmp = hw_to_ccu_nkmp(hw);

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

static unsigned long ccu_nkmp_recalc_rate(struct clk_hw *hw,
					unsigned long parent_rate)
{
	struct ccu_nkmp *nkmp = hw_to_ccu_nkmp(hw);
	unsigned long n, m, k, p, rate;
	u32 reg;

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

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

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

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

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

	rate = ccu_nkmp_calc_rate(parent_rate, n, k, m, 1 << p);
	if (nkmp->common.features & CCU_FEATURE_FIXED_POSTDIV)
		rate /= nkmp->fixed_post_div;

	return rate;
}

static long ccu_nkmp_round_rate(struct clk_hw *hw, unsigned long rate,
			      unsigned long *parent_rate)
{
	struct ccu_nkmp *nkmp = hw_to_ccu_nkmp(hw);
	struct _ccu_nkmp _nkmp;

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

	if (nkmp->max_rate && rate > nkmp->max_rate) {
		rate = nkmp->max_rate;
		if (nkmp->common.features & CCU_FEATURE_FIXED_POSTDIV)
			rate /= nkmp->fixed_post_div;
		return rate;
	}

	_nkmp.min_n = nkmp->n.min ?: 1;
	_nkmp.max_n = nkmp->n.max ?: 1 << nkmp->n.width;
	_nkmp.min_k = nkmp->k.min ?: 1;
	_nkmp.max_k = nkmp->k.max ?: 1 << nkmp->k.width;
	_nkmp.min_m = 1;
	_nkmp.max_m = nkmp->m.max ?: 1 << nkmp->m.width;
	_nkmp.min_p = 1;
	_nkmp.max_p = nkmp->p.max ?: 1 << ((1 << nkmp->p.width) - 1);

	ccu_nkmp_find_best(*parent_rate, rate, &_nkmp);

	rate = ccu_nkmp_calc_rate(*parent_rate, _nkmp.n, _nkmp.k,
				  _nkmp.m, _nkmp.p);
	if (nkmp->common.features & CCU_FEATURE_FIXED_POSTDIV)
		rate = rate / nkmp->fixed_post_div;

	return rate;
}

static int ccu_nkmp_set_rate(struct clk_hw *hw, unsigned long rate,
			   unsigned long parent_rate)
{
	struct ccu_nkmp *nkmp = hw_to_ccu_nkmp(hw);
	u32 n_mask = 0, k_mask = 0, m_mask = 0, p_mask = 0;
	struct _ccu_nkmp _nkmp;
	unsigned long flags;
	u32 reg;

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

	_nkmp.min_n = nkmp->n.min ?: 1;
	_nkmp.max_n = nkmp->n.max ?: 1 << nkmp->n.width;
	_nkmp.min_k = nkmp->k.min ?: 1;
	_nkmp.max_k = nkmp->k.max ?: 1 << nkmp->k.width;
	_nkmp.min_m = 1;
	_nkmp.max_m = nkmp->m.max ?: 1 << nkmp->m.width;
	_nkmp.min_p = 1;
	_nkmp.max_p = nkmp->p.max ?: 1 << ((1 << nkmp->p.width) - 1);

	ccu_nkmp_find_best(parent_rate, rate, &_nkmp);

	/*
	 * If width is 0, GENMASK() macro may not generate expected mask (0)
	 * as it falls under undefined behaviour by C standard due to shifts
	 * which are equal or greater than width of left operand. This can
	 * be easily avoided by explicitly checking if width is 0.
	 */
	if (nkmp->n.width)
		n_mask = GENMASK(nkmp->n.width + nkmp->n.shift - 1,
				 nkmp->n.shift);
	if (nkmp->k.width)
		k_mask = GENMASK(nkmp->k.width + nkmp->k.shift - 1,
				 nkmp->k.shift);
	if (nkmp->m.width)
		m_mask = GENMASK(nkmp->m.width + nkmp->m.shift - 1,
				 nkmp->m.shift);
	if (nkmp->p.width)
		p_mask = GENMASK(nkmp->p.width + nkmp->p.shift - 1,
				 nkmp->p.shift);

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

	reg = readl(nkmp->common.base + nkmp->common.reg);
	reg &= ~(n_mask | k_mask | m_mask | p_mask);

	reg |= ((_nkmp.n - nkmp->n.offset) << nkmp->n.shift) & n_mask;
	reg |= ((_nkmp.k - nkmp->k.offset) << nkmp->k.shift) & k_mask;
	reg |= ((_nkmp.m - nkmp->m.offset) << nkmp->m.shift) & m_mask;
	reg |= (ilog2(_nkmp.p) << nkmp->p.shift) & p_mask;

	writel(reg, nkmp->common.base + nkmp->common.reg);

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

	ccu_helper_wait_for_lock(&nkmp->common, nkmp->lock);

	return 0;
}

const struct clk_ops ccu_nkmp_ops = {
	.disable	= ccu_nkmp_disable,
	.enable		= ccu_nkmp_enable,
	.is_enabled	= ccu_nkmp_is_enabled,

	.recalc_rate	= ccu_nkmp_recalc_rate,
	.round_rate	= ccu_nkmp_round_rate,
	.set_rate	= ccu_nkmp_set_rate,
};