/*
 * Copyright (C) 2012 ST Microelectronics
 * Viresh Kumar <viresh.linux@gmail.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 *
 * Auxiliary Synthesizer clock implementation
 */

#define pr_fmt(fmt) "clk-aux-synth: " fmt

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

/*
 * DOC: Auxiliary Synthesizer clock
 *
 * Aux synth gives rate for different values of eq, x and y
 *
 * Fout from synthesizer can be given from two equations:
 * Fout1 = (Fin * X/Y)/2		EQ1
 * Fout2 = Fin * X/Y			EQ2
 */

#define to_clk_aux(_hw) container_of(_hw, struct clk_aux, hw)

static struct aux_clk_masks default_aux_masks = {
	.eq_sel_mask = AUX_EQ_SEL_MASK,
	.eq_sel_shift = AUX_EQ_SEL_SHIFT,
	.eq1_mask = AUX_EQ1_SEL,
	.eq2_mask = AUX_EQ2_SEL,
	.xscale_sel_mask = AUX_XSCALE_MASK,
	.xscale_sel_shift = AUX_XSCALE_SHIFT,
	.yscale_sel_mask = AUX_YSCALE_MASK,
	.yscale_sel_shift = AUX_YSCALE_SHIFT,
	.enable_bit = AUX_SYNT_ENB,
};

static unsigned long aux_calc_rate(struct clk_hw *hw, unsigned long prate,
		int index)
{
	struct clk_aux *aux = to_clk_aux(hw);
	struct aux_rate_tbl *rtbl = aux->rtbl;
	u8 eq = rtbl[index].eq ? 1 : 2;

	return (((prate / 10000) * rtbl[index].xscale) /
			(rtbl[index].yscale * eq)) * 10000;
}

static long clk_aux_round_rate(struct clk_hw *hw, unsigned long drate,
		unsigned long *prate)
{
	struct clk_aux *aux = to_clk_aux(hw);
	int unused;

	return clk_round_rate_index(hw, drate, *prate, aux_calc_rate,
			aux->rtbl_cnt, &unused);
}

static unsigned long clk_aux_recalc_rate(struct clk_hw *hw,
		unsigned long parent_rate)
{
	struct clk_aux *aux = to_clk_aux(hw);
	unsigned int num = 1, den = 1, val, eqn;
	unsigned long flags = 0;

	if (aux->lock)
		spin_lock_irqsave(aux->lock, flags);

	val = readl_relaxed(aux->reg);

	if (aux->lock)
		spin_unlock_irqrestore(aux->lock, flags);

	eqn = (val >> aux->masks->eq_sel_shift) & aux->masks->eq_sel_mask;
	if (eqn == aux->masks->eq1_mask)
		den = 2;

	/* calculate numerator */
	num = (val >> aux->masks->xscale_sel_shift) &
		aux->masks->xscale_sel_mask;

	/* calculate denominator */
	den *= (val >> aux->masks->yscale_sel_shift) &
		aux->masks->yscale_sel_mask;

	if (!den)
		return 0;

	return (((parent_rate / 10000) * num) / den) * 10000;
}

/* Configures new clock rate of aux */
static int clk_aux_set_rate(struct clk_hw *hw, unsigned long drate,
				unsigned long prate)
{
	struct clk_aux *aux = to_clk_aux(hw);
	struct aux_rate_tbl *rtbl = aux->rtbl;
	unsigned long val, flags = 0;
	int i;

	clk_round_rate_index(hw, drate, prate, aux_calc_rate, aux->rtbl_cnt,
			&i);

	if (aux->lock)
		spin_lock_irqsave(aux->lock, flags);

	val = readl_relaxed(aux->reg) &
		~(aux->masks->eq_sel_mask << aux->masks->eq_sel_shift);
	val |= (rtbl[i].eq & aux->masks->eq_sel_mask) <<
		aux->masks->eq_sel_shift;
	val &= ~(aux->masks->xscale_sel_mask << aux->masks->xscale_sel_shift);
	val |= (rtbl[i].xscale & aux->masks->xscale_sel_mask) <<
		aux->masks->xscale_sel_shift;
	val &= ~(aux->masks->yscale_sel_mask << aux->masks->yscale_sel_shift);
	val |= (rtbl[i].yscale & aux->masks->yscale_sel_mask) <<
		aux->masks->yscale_sel_shift;
	writel_relaxed(val, aux->reg);

	if (aux->lock)
		spin_unlock_irqrestore(aux->lock, flags);

	return 0;
}

static struct clk_ops clk_aux_ops = {
	.recalc_rate = clk_aux_recalc_rate,
	.round_rate = clk_aux_round_rate,
	.set_rate = clk_aux_set_rate,
};

struct clk *clk_register_aux(const char *aux_name, const char *gate_name,
		const char *parent_name, unsigned long flags, void __iomem *reg,
		struct aux_clk_masks *masks, struct aux_rate_tbl *rtbl,
		u8 rtbl_cnt, spinlock_t *lock, struct clk **gate_clk)
{
	struct clk_aux *aux;
	struct clk_init_data init;
	struct clk *clk;

	if (!aux_name || !parent_name || !reg || !rtbl || !rtbl_cnt) {
		pr_err("Invalid arguments passed");
		return ERR_PTR(-EINVAL);
	}

	aux = kzalloc(sizeof(*aux), GFP_KERNEL);
	if (!aux) {
		pr_err("could not allocate aux clk\n");
		return ERR_PTR(-ENOMEM);
	}

	/* struct clk_aux assignments */
	if (!masks)
		aux->masks = &default_aux_masks;
	else
		aux->masks = masks;

	aux->reg = reg;
	aux->rtbl = rtbl;
	aux->rtbl_cnt = rtbl_cnt;
	aux->lock = lock;
	aux->hw.init = &init;

	init.name = aux_name;
	init.ops = &clk_aux_ops;
	init.flags = flags;
	init.parent_names = &parent_name;
	init.num_parents = 1;

	clk = clk_register(NULL, &aux->hw);
	if (IS_ERR_OR_NULL(clk))
		goto free_aux;

	if (gate_name) {
		struct clk *tgate_clk;

		tgate_clk = clk_register_gate(NULL, gate_name, aux_name,
				CLK_SET_RATE_PARENT, reg,
				aux->masks->enable_bit, 0, lock);
		if (IS_ERR_OR_NULL(tgate_clk))
			goto free_aux;

		if (gate_clk)
			*gate_clk = tgate_clk;
	}

	return clk;

free_aux:
	kfree(aux);
	pr_err("clk register failed\n");

	return NULL;
}