/*
 *  Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.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 <linux/clkdev.h>
#include <linux/clk/at91_pmc.h>
#include <linux/of.h>
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>

#include "pmc.h"

#define PROG_ID_MAX		7

#define PROG_STATUS_MASK(id)	(1 << ((id) + 8))
#define PROG_PRES_MASK		0x7
#define PROG_PRES(layout, pckr)	((pckr >> layout->pres_shift) & PROG_PRES_MASK)
#define PROG_MAX_RM9200_CSS	3

struct clk_programmable {
	struct clk_hw hw;
	struct regmap *regmap;
	u8 id;
	const struct clk_programmable_layout *layout;
};

#define to_clk_programmable(hw) container_of(hw, struct clk_programmable, hw)

static unsigned long clk_programmable_recalc_rate(struct clk_hw *hw,
						  unsigned long parent_rate)
{
	struct clk_programmable *prog = to_clk_programmable(hw);
	unsigned int pckr;

	regmap_read(prog->regmap, AT91_PMC_PCKR(prog->id), &pckr);

	return parent_rate >> PROG_PRES(prog->layout, pckr);
}

static int clk_programmable_determine_rate(struct clk_hw *hw,
					   struct clk_rate_request *req)
{
	struct clk_hw *parent;
	long best_rate = -EINVAL;
	unsigned long parent_rate;
	unsigned long tmp_rate;
	int shift;
	int i;

	for (i = 0; i < clk_hw_get_num_parents(hw); i++) {
		parent = clk_hw_get_parent_by_index(hw, i);
		if (!parent)
			continue;

		parent_rate = clk_hw_get_rate(parent);
		for (shift = 0; shift < PROG_PRES_MASK; shift++) {
			tmp_rate = parent_rate >> shift;
			if (tmp_rate <= req->rate)
				break;
		}

		if (tmp_rate > req->rate)
			continue;

		if (best_rate < 0 ||
		    (req->rate - tmp_rate) < (req->rate - best_rate)) {
			best_rate = tmp_rate;
			req->best_parent_rate = parent_rate;
			req->best_parent_hw = parent;
		}

		if (!best_rate)
			break;
	}

	if (best_rate < 0)
		return best_rate;

	req->rate = best_rate;
	return 0;
}

static int clk_programmable_set_parent(struct clk_hw *hw, u8 index)
{
	struct clk_programmable *prog = to_clk_programmable(hw);
	const struct clk_programmable_layout *layout = prog->layout;
	unsigned int mask = layout->css_mask;
	unsigned int pckr = index;

	if (layout->have_slck_mck)
		mask |= AT91_PMC_CSSMCK_MCK;

	if (index > layout->css_mask) {
		if (index > PROG_MAX_RM9200_CSS && !layout->have_slck_mck)
			return -EINVAL;

		pckr |= AT91_PMC_CSSMCK_MCK;
	}

	regmap_update_bits(prog->regmap, AT91_PMC_PCKR(prog->id), mask, pckr);

	return 0;
}

static u8 clk_programmable_get_parent(struct clk_hw *hw)
{
	struct clk_programmable *prog = to_clk_programmable(hw);
	const struct clk_programmable_layout *layout = prog->layout;
	unsigned int pckr;
	u8 ret;

	regmap_read(prog->regmap, AT91_PMC_PCKR(prog->id), &pckr);

	ret = pckr & layout->css_mask;

	if (layout->have_slck_mck && (pckr & AT91_PMC_CSSMCK_MCK) && !ret)
		ret = PROG_MAX_RM9200_CSS + 1;

	return ret;
}

static int clk_programmable_set_rate(struct clk_hw *hw, unsigned long rate,
				     unsigned long parent_rate)
{
	struct clk_programmable *prog = to_clk_programmable(hw);
	const struct clk_programmable_layout *layout = prog->layout;
	unsigned long div = parent_rate / rate;
	int shift = 0;

	if (!div)
		return -EINVAL;

	shift = fls(div) - 1;

	if (div != (1 << shift))
		return -EINVAL;

	if (shift >= PROG_PRES_MASK)
		return -EINVAL;

	regmap_update_bits(prog->regmap, AT91_PMC_PCKR(prog->id),
			   PROG_PRES_MASK << layout->pres_shift,
			   shift << layout->pres_shift);

	return 0;
}

static const struct clk_ops programmable_ops = {
	.recalc_rate = clk_programmable_recalc_rate,
	.determine_rate = clk_programmable_determine_rate,
	.get_parent = clk_programmable_get_parent,
	.set_parent = clk_programmable_set_parent,
	.set_rate = clk_programmable_set_rate,
};

struct clk_hw * __init
at91_clk_register_programmable(struct regmap *regmap,
			       const char *name, const char **parent_names,
			       u8 num_parents, u8 id,
			       const struct clk_programmable_layout *layout)
{
	struct clk_programmable *prog;
	struct clk_hw *hw;
	struct clk_init_data init;
	int ret;

	if (id > PROG_ID_MAX)
		return ERR_PTR(-EINVAL);

	prog = kzalloc(sizeof(*prog), GFP_KERNEL);
	if (!prog)
		return ERR_PTR(-ENOMEM);

	init.name = name;
	init.ops = &programmable_ops;
	init.parent_names = parent_names;
	init.num_parents = num_parents;
	init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE;

	prog->id = id;
	prog->layout = layout;
	prog->hw.init = &init;
	prog->regmap = regmap;

	hw = &prog->hw;
	ret = clk_hw_register(NULL, &prog->hw);
	if (ret) {
		kfree(prog);
		hw = ERR_PTR(ret);
	} else {
		pmc_register_pck(id);
	}

	return hw;
}

const struct clk_programmable_layout at91rm9200_programmable_layout = {
	.pres_shift = 2,
	.css_mask = 0x3,
	.have_slck_mck = 0,
};

const struct clk_programmable_layout at91sam9g45_programmable_layout = {
	.pres_shift = 2,
	.css_mask = 0x3,
	.have_slck_mck = 1,
};

const struct clk_programmable_layout at91sam9x5_programmable_layout = {
	.pres_shift = 4,
	.css_mask = 0x7,
	.have_slck_mck = 0,
};