/*
   * 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_nk.h"

  struct _ccu_nk {

  	unsigned long	n, min_n, max_n;
  	unsigned long	k, min_k, max_k;

  };

  static void ccu_nk_find_best(unsigned long parent, unsigned long rate,

  			     struct _ccu_nk *nk)

  {
  	unsigned long best_rate = 0;
  	unsigned int best_k = 0, best_n = 0;
  	unsigned int _k, _n;

  	for (_k = nk->min_k; _k <= nk->max_k; _k++) {
  		for (_n = nk->min_n; _n <= nk->max_n; _n++) {

  			unsigned long tmp_rate = parent * _n * _k;
  
  			if (tmp_rate > rate)
  				continue;
  
  			if ((rate - tmp_rate) < (rate - best_rate)) {
  				best_rate = tmp_rate;
  				best_k = _k;
  				best_n = _n;
  			}
  		}
  	}

  	nk->k = best_k;
  	nk->n = best_n;

  }
  
  static void ccu_nk_disable(struct clk_hw *hw)
  {
  	struct ccu_nk *nk = hw_to_ccu_nk(hw);
  
  	return ccu_gate_helper_disable(&nk->common, nk->enable);
  }
  
  static int ccu_nk_enable(struct clk_hw *hw)
  {
  	struct ccu_nk *nk = hw_to_ccu_nk(hw);
  
  	return ccu_gate_helper_enable(&nk->common, nk->enable);
  }
  
  static int ccu_nk_is_enabled(struct clk_hw *hw)
  {
  	struct ccu_nk *nk = hw_to_ccu_nk(hw);
  
  	return ccu_gate_helper_is_enabled(&nk->common, nk->enable);
  }
  
  static unsigned long ccu_nk_recalc_rate(struct clk_hw *hw,
  					unsigned long parent_rate)
  {
  	struct ccu_nk *nk = hw_to_ccu_nk(hw);
  	unsigned long rate, n, k;
  	u32 reg;
  
  	reg = readl(nk->common.base + nk->common.reg);
  
  	n = reg >> nk->n.shift;
  	n &= (1 << nk->n.width) - 1;

  	n += nk->n.offset;
  	if (!n)
  		n++;

  
  	k = reg >> nk->k.shift;
  	k &= (1 << nk->k.width) - 1;

  	k += nk->k.offset;
  	if (!k)
  		k++;

  	rate = parent_rate * n * k;

  	if (nk->common.features & CCU_FEATURE_FIXED_POSTDIV)
  		rate /= nk->fixed_post_div;
  
  	return rate;
  }
  
  static long ccu_nk_round_rate(struct clk_hw *hw, unsigned long rate,
  			      unsigned long *parent_rate)
  {
  	struct ccu_nk *nk = hw_to_ccu_nk(hw);

  	struct _ccu_nk _nk;

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

  	_nk.min_n = nk->n.min ?: 1;

  	_nk.max_n = nk->n.max ?: 1 << nk->n.width;

  	_nk.min_k = nk->k.min ?: 1;

  	_nk.max_k = nk->k.max ?: 1 << nk->k.width;

  
  	ccu_nk_find_best(*parent_rate, rate, &_nk);
  	rate = *parent_rate * _nk.n * _nk.k;

  	if (nk->common.features & CCU_FEATURE_FIXED_POSTDIV)
  		rate = rate / nk->fixed_post_div;
  
  	return rate;
  }
  
  static int ccu_nk_set_rate(struct clk_hw *hw, unsigned long rate,
  			   unsigned long parent_rate)
  {
  	struct ccu_nk *nk = hw_to_ccu_nk(hw);
  	unsigned long flags;

  	struct _ccu_nk _nk;

  	u32 reg;
  
  	if (nk->common.features & CCU_FEATURE_FIXED_POSTDIV)
  		rate = rate * nk->fixed_post_div;

  	_nk.min_n = nk->n.min ?: 1;

  	_nk.max_n = nk->n.max ?: 1 << nk->n.width;

  	_nk.min_k = nk->k.min ?: 1;

  	_nk.max_k = nk->k.max ?: 1 << nk->k.width;

  
  	ccu_nk_find_best(parent_rate, rate, &_nk);

  
  	spin_lock_irqsave(nk->common.lock, flags);
  
  	reg = readl(nk->common.base + nk->common.reg);
  	reg &= ~GENMASK(nk->n.width + nk->n.shift - 1, nk->n.shift);
  	reg &= ~GENMASK(nk->k.width + nk->k.shift - 1, nk->k.shift);

  	reg |= (_nk.k - nk->k.offset) << nk->k.shift;
  	reg |= (_nk.n - nk->n.offset) << nk->n.shift;
  	writel(reg, nk->common.base + nk->common.reg);

  
  	spin_unlock_irqrestore(nk->common.lock, flags);
  
  	ccu_helper_wait_for_lock(&nk->common, nk->lock);
  
  	return 0;
  }
  
  const struct clk_ops ccu_nk_ops = {
  	.disable	= ccu_nk_disable,
  	.enable		= ccu_nk_enable,
  	.is_enabled	= ccu_nk_is_enabled,
  
  	.recalc_rate	= ccu_nk_recalc_rate,
  	.round_rate	= ccu_nk_round_rate,
  	.set_rate	= ccu_nk_set_rate,
  };