/*
   * 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_round_rate(struct ccu_mux_internal *mux,
  				       unsigned long parent_rate,
  				       unsigned long rate,
  				       void *data)
  {
  	struct ccu_mp *cmp = data;

  	unsigned int max_m, max_p;

  	unsigned int m, p;

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

  	ccu_mp_find_best(parent_rate, rate, max_m, max_p, &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 max_m, max_p;

  	unsigned int m, p;
  	u32 reg;

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

  	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);

  	writel(reg | (ilog2(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,
  };