/*
 * Copyright (C) 2015 Jim Quinlan, Broadcom <jim2101024@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Adjustable multiplier clock implementation.  This is essentially
 * the mirror of clk-divider.c.
 */

#include <linux/clk-provider.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/string.h>
#include <linux/log2.h>
#include <linux/of.h>
#include <linux/of_address.h>

/*
 * DOC: basic adjustable multiplier clock that cannot gate
 *
 * Traits of this clock:
 * prepare - clk_prepare only ensures that parents are prepared
 * enable - clk_enable only ensures that parents are enabled
 * rate - rate is adjustable.  clk->rate = (parent->rate * multiplier)
 * parent - fixed parent.  No clk_set_parent support
 */

#define to_clk_multiplier(_hw) container_of(_hw, struct clk_multiplier, hw)

#define mult_mask(width)	((1 << (width)) - 1)

static unsigned int _get_table_minmult(const struct clk_mult_table *table)
{
	unsigned int minmult = UINT_MAX;
	const struct clk_mult_table *clkt;

	for (clkt = table; clkt->mult; clkt++)
		if (clkt->mult < minmult)
			minmult = clkt->mult;
	return minmult;
}

static unsigned int _get_table_maxmult(const struct clk_mult_table *table)
{
	unsigned int maxmult = 0;
	const struct clk_mult_table *clkt;

	for (clkt = table; clkt->mult; clkt++)
		if (clkt->mult > maxmult)
			maxmult = clkt->mult;
	return maxmult;
}

static unsigned int _get_minmult(const struct clk_mult_table *table)
{
	if (table)
		return _get_table_minmult(table);
	return 1;
}

static unsigned int _get_maxmult(const struct clk_mult_table *table, u8 width,
				unsigned long flags)
{
	if (flags & CLK_MULTIPLIER_ONE_BASED)
		return mult_mask(width);
	if (flags & CLK_MULTIPLIER_POWER_OF_TWO)
		return 1 << mult_mask(width);
	if (table)
		return _get_table_maxmult(table);
	return mult_mask(width) + 1;
}

static unsigned int _get_table_mult(const struct clk_mult_table *table,
							unsigned int val)
{
	const struct clk_mult_table *clkt;

	for (clkt = table; clkt->mult; clkt++)
		if (clkt->val == val)
			return clkt->mult;
	return 0;
}

static unsigned int _get_mult(const struct clk_mult_table *table,
			      u8 width, unsigned int val, unsigned long flags)
{
	if (flags & CLK_MULTIPLIER_ONE_BASED)
		return val;
	if (flags & CLK_MULTIPLIER_POWER_OF_TWO)
		return 1 << val;
	if (flags & CLK_MULTIPLIER_MAX_MULT_AT_ZERO)
		return val ? val : mult_mask(width) + 1;
	if (table)
		return _get_table_mult(table, val);
	return val + 1;
}

static unsigned int _get_table_val(const struct clk_mult_table *table,
				   unsigned int mult)
{
	const struct clk_mult_table *clkt;

	for (clkt = table; clkt->mult; clkt++)
		if (clkt->mult == mult)
			return clkt->val;
	return 0;
}

static unsigned int _get_val(const struct clk_mult_table *table,
			     u8 width, unsigned int mult, unsigned long flags)
{
	if (flags & CLK_MULTIPLIER_ONE_BASED)
		return mult;
	if (flags & CLK_MULTIPLIER_POWER_OF_TWO)
		return __ffs(mult);
	if (flags & CLK_MULTIPLIER_MAX_MULT_AT_ZERO)
		return (mult == mult_mask(width) + 1)
			? 0 : mult;
	if (table)
		return  _get_table_val(table, mult);
	return mult - 1;
}

unsigned long multiplier_recalc_rate(struct clk_hw *hw,
				     unsigned long parent_rate,
				     unsigned int val,
				     const struct clk_mult_table *table,
				     unsigned long flags)
{
	struct clk_multiplier *multiplier = to_clk_multiplier(hw);
	unsigned int mult;

	mult = _get_mult(table, multiplier->width, val, flags);
	if (!mult) {
		WARN(!(flags & CLK_MULTIPLIER_ALLOW_ZERO),
			"%s: Zero multiplier and CLK_MULTIPLIER_ALLOW_ZERO not set\n",
			__clk_get_name(hw->clk));
		return parent_rate;
	}

	return parent_rate * mult;
}
EXPORT_SYMBOL_GPL(multiplier_recalc_rate);

static unsigned long clk_multiplier_recalc_rate(struct clk_hw *hw,
		unsigned long parent_rate)
{
	struct clk_multiplier *multiplier = to_clk_multiplier(hw);
	unsigned int val;

	val = clk_readl(multiplier->reg) >> multiplier->shift;
	val &= mult_mask(multiplier->width);

	return multiplier_recalc_rate(hw, parent_rate, val, multiplier->table,
				   multiplier->flags);
}

static bool _is_valid_table_mult(const struct clk_mult_table *table,
							 unsigned int mult)
{
	const struct clk_mult_table *clkt;

	for (clkt = table; clkt->mult; clkt++)
		if (clkt->mult == mult)
			return true;
	return false;
}

static bool _is_valid_mult(const struct clk_mult_table *table,
			   unsigned int mult, unsigned long flags)
{
	if (flags & CLK_MULTIPLIER_POWER_OF_TWO)
		return is_power_of_2(mult);
	if (table)
		return _is_valid_table_mult(table, mult);
	return true;
}

static int clk_multiplier_bestmult(struct clk_hw *hw, unsigned long rate,
			       unsigned long *best_parent_rate,
			       const struct clk_mult_table *table, u8 width,
			       unsigned long flags)
{
	int i, bestmult = 0;
	unsigned long parent_rate, best = 0, now, maxmult, minmult;
	unsigned long parent_rate_saved = *best_parent_rate;

	if (!rate)
		rate = 1;

	minmult = _get_minmult(table);
	maxmult = _get_maxmult(table, width, flags);

	if (!(__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT)) {
		parent_rate = *best_parent_rate;
		bestmult = rate / parent_rate;
		bestmult = bestmult == 0 ? minmult : bestmult;
		bestmult = bestmult > maxmult ? maxmult : bestmult;
		return bestmult;
	}

	/*
	 * The maximum multiplier we can use without overflowing
	 * unsigned long in rate * i below
	 */
	maxmult = min(ULONG_MAX / parent_rate_saved, maxmult);

	for (i = 1; i <= maxmult; i++) {
		if (!_is_valid_mult(table, i, flags))
			continue;
		if (rate == parent_rate_saved * i) {
			/*
			 * It's the most ideal case if the requested rate can be
			 * multiplied from parent clock without needing to
			 * change the parent rate, so return the multiplier
			 * immediately.
			 */
			*best_parent_rate = parent_rate_saved;
			return i;
		}
		parent_rate = __clk_round_rate(__clk_get_parent(hw->clk),
					       rate / i);
		now = parent_rate * i;
		if (now <= rate && now > best) {
			bestmult = i;
			best = now;
			*best_parent_rate = parent_rate;
		}
	}

	if (!bestmult) {
		bestmult = _get_minmult(table);
		*best_parent_rate
			= __clk_round_rate(__clk_get_parent(hw->clk), 1);
	}

	return bestmult;
}

long multiplier_round_rate(struct clk_hw *hw, unsigned long rate,
			   unsigned long *prate,
			   const struct clk_mult_table *table,
			   u8 width, unsigned long flags)
{
	int mult;

	mult = clk_multiplier_bestmult(hw, rate, prate, table, width, flags);

	return *prate * mult;
}
EXPORT_SYMBOL_GPL(multiplier_round_rate);

static long clk_multiplier_round_rate(struct clk_hw *hw, unsigned long rate,
				unsigned long *prate)
{
	struct clk_multiplier *multiplier = to_clk_multiplier(hw);
	int bestmult;

	/* if read only, just return current value */
	if (multiplier->flags & CLK_MULTIPLIER_READ_ONLY) {
		bestmult = readl(multiplier->reg) >> multiplier->shift;
		bestmult &= mult_mask(multiplier->width);
		bestmult = _get_mult(multiplier->table, multiplier->width,
				     bestmult, multiplier->flags);
		if ((__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT))
			*prate = __clk_round_rate(__clk_get_parent(hw->clk),
						  rate);
		return *prate * bestmult;
	}

	return multiplier_round_rate(hw, rate, prate, multiplier->table,
				  multiplier->width, multiplier->flags);
}

int multiplier_get_val(unsigned long rate, unsigned long parent_rate,
		    const struct clk_mult_table *table, u8 width,
		    unsigned long flags)
{
	unsigned int mult, value;

	mult = rate / parent_rate;
	value = _get_val(table, width, mult, flags);
	return min_t(unsigned int, value, mult_mask(width));
}
EXPORT_SYMBOL_GPL(multiplier_get_val);

static int clk_multiplier_set_rate(struct clk_hw *hw, unsigned long rate,
				unsigned long parent_rate)
{
	struct clk_multiplier *multiplier = to_clk_multiplier(hw);
	unsigned int value;
	unsigned long flags = 0;
	u32 val;

	value = multiplier_get_val(rate, parent_rate, multiplier->table,
				multiplier->width, multiplier->flags);

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

	if (multiplier->flags & CLK_MULTIPLIER_HIWORD_MASK) {
		val = mult_mask(multiplier->width) << (multiplier->shift + 16);
	} else {
		val = clk_readl(multiplier->reg);
		val &= ~(mult_mask(multiplier->width) << multiplier->shift);
	}
	val |= value << multiplier->shift;
	clk_writel(val, multiplier->reg);

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

	return 0;
}

const struct clk_ops clk_multiplier_ops = {
	.recalc_rate = clk_multiplier_recalc_rate,
	.round_rate = clk_multiplier_round_rate,
	.set_rate = clk_multiplier_set_rate,
};
EXPORT_SYMBOL_GPL(clk_multiplier_ops);

const struct clk_ops clk_multiplier_ro_ops = {
	.recalc_rate = clk_multiplier_recalc_rate,
};
EXPORT_SYMBOL_GPL(clk_multiplier_ro_ops);

static struct clk *_register_multiplier(struct device *dev, const char *name,
		const char *parent_name, unsigned long flags,
		void __iomem *reg, u8 shift, u8 width,
		u8 clk_multiplier_flags, const struct clk_mult_table *table,
		spinlock_t *lock)
{
	struct clk_multiplier *mult;
	struct clk *clk;
	struct clk_init_data init;

	if (clk_multiplier_flags & CLK_MULTIPLIER_HIWORD_MASK) {
		if (width + shift > 16) {
			pr_warn("multiplier value exceeds LOWORD field\n");
			return ERR_PTR(-EINVAL);
		}
	}

	/* allocate the multiplier */
	mult = kzalloc(sizeof(struct clk_multiplier), GFP_KERNEL);
	if (!mult)
		return ERR_PTR(-ENOMEM);

	init.name = name;
	if (clk_multiplier_flags & CLK_MULTIPLIER_READ_ONLY)
		init.ops = &clk_multiplier_ro_ops;
	else
		init.ops = &clk_multiplier_ops;
	init.flags = flags | CLK_IS_BASIC;
	init.parent_names = (parent_name ? &parent_name : NULL);
	init.num_parents = (parent_name ? 1 : 0);

	/* struct clk_multiplier assignments */
	mult->reg = reg;
	mult->shift = shift;
	mult->width = width;
	mult->flags = clk_multiplier_flags;
	mult->lock = lock;
	mult->hw.init = &init;
	mult->table = table;

	/* register the clock */
	clk = clk_register(dev, &mult->hw);

	if (IS_ERR(clk))
		kfree(mult);

	return clk;
}

/**
 * clk_register_multiplier - register a multiplier clock with the clock framework
 * @dev: device registering this clock
 * @name: name of this clock
 * @parent_name: name of clock's parent
 * @flags: framework-specific flags
 * @reg: register address to adjust multiplier
 * @shift: number of bits to shift the bitfield
 * @width: width of the bitfield
 * @clk_multiplier_flags: multiplier-specific flags for this clock
 * @lock: shared register lock for this clock
 */
struct clk *clk_register_multiplier(struct device *dev, const char *name,
		const char *parent_name, unsigned long flags,
		void __iomem *reg, u8 shift, u8 width,
		u8 clk_multiplier_flags, spinlock_t *lock)
{
	return _register_multiplier(dev, name, parent_name, flags, reg, shift,
			width, clk_multiplier_flags, NULL, lock);
}
EXPORT_SYMBOL_GPL(clk_register_multiplier);

/**
 * clk_register_multiplier_table - register a table based multiplier clock with
 * the clock framework
 * @dev: device registering this clock
 * @name: name of this clock
 * @parent_name: name of clock's parent
 * @flags: framework-specific flags
 * @reg: register address to adjust multiplier
 * @shift: number of bits to shift the bitfield
 * @width: width of the bitfield
 * @clk_multiplier_flags: multiplier-specific flags for this clock
 * @table: array of multiplier/value pairs ending with a mult set to 0
 * @lock: shared register lock for this clock
 */
struct clk *clk_register_multiplier_table(struct device *dev, const char *name,
		const char *parent_name, unsigned long flags,
		void __iomem *reg, u8 shift, u8 width,
		u8 clk_multiplier_flags, const struct clk_mult_table *table,
		spinlock_t *lock)
{
	return _register_multiplier(dev, name, parent_name, flags, reg, shift,
			width, clk_multiplier_flags, table, lock);
}
EXPORT_SYMBOL_GPL(clk_register_multiplier_table);

void clk_unregister_multiplier(struct clk *clk)
{
	struct clk_multiplier *mult;
	struct clk_hw *hw;

	hw = __clk_get_hw(clk);
	if (!hw)
		return;

	mult = to_clk_multiplier(hw);

	clk_unregister(clk);
	kfree(mult);
}
EXPORT_SYMBOL_GPL(clk_unregister_multiplier);

#ifdef CONFIG_OF
static struct clk_mult_table *of_clk_get_mult_table(struct device_node *node)
{
	int i;
	unsigned int table_size;
	struct clk_mult_table *table;
	const __be32 *tablespec;
	u32 val;

	tablespec = of_get_property(node, "table", (int *) &table_size);

	if (!tablespec)
		return NULL;

	table_size /= sizeof(struct clk_mult_table);

	if (!table_size) {
		pr_err("%s: %s table has zero length\n", __func__,
		       node->name);
		return ERR_PTR(-EINVAL);
	}

	table = kzalloc(sizeof(struct clk_mult_table) * (table_size + 1),
			GFP_KERNEL);
	if (!table) {
		pr_err("%s: unable to allocate memory for %s table\n", __func__,
		       node->name);
		return NULL;
	}

	for (i = 0; i < table_size; i++) {
		of_property_read_u32_index(node, "table", i * 2, &val);
		table[i].mult = val;
		of_property_read_u32_index(node, "table", i * 2 + 1, &val);
		table[i].val = val;
	}

	return table;
}

/**
 * of_multiplier_clk_setup() - Setup function for simple mult rate clock
 */
void of_multiplier_clk_setup(struct device_node *node)
{
	struct clk *clk;
	const char *clk_name = node->name;
	void __iomem *reg;
	const char *parent_name;
	u8 clk_multiplier_flags = 0;
	u32 mask = 0;
	u32 shift = 0;
	u32 width;
	struct clk_mult_table *table;

	of_property_read_string(node, "clock-output-names", &clk_name);

	parent_name = of_clk_get_parent_name(node, 0);

	reg = of_iomap(node, 0);
	if (!reg) {
		pr_err("%s: no memory mapped for property reg\n", __func__);
		return;
	}

	if (of_property_read_u32(node, "bit-mask", &mask)) {
		pr_err("%s: missing bit-mask property for %s\n", __func__,
		       node->name);
		return;
	}
	width = fls(mask);
	if ((1 << width) - 1 != mask) {
		pr_err("%s: bad bit-mask for %s\n", __func__, node->name);
		return;
	}

	if (of_property_read_u32(node, "bit-shift", &shift)) {
		shift = __ffs(mask);
		pr_debug("%s: bit-shift property defaults to 0x%x for %s\n",
				__func__, shift, node->name);
	}

	if (of_property_read_bool(node, "index-starts-at-one"))
		clk_multiplier_flags |= CLK_MULTIPLIER_ONE_BASED;

	if (of_property_read_bool(node, "index-power-of-two"))
		clk_multiplier_flags |= CLK_MULTIPLIER_POWER_OF_TWO;

	if (of_property_read_bool(node, "index-allow-zero"))
		clk_multiplier_flags |= CLK_MULTIPLIER_ALLOW_ZERO;

	if (of_property_read_bool(node, "index-max-mult-at-zero"))
		clk_multiplier_flags |= CLK_MULTIPLIER_MAX_MULT_AT_ZERO;

	table = of_clk_get_mult_table(node);
	if (IS_ERR(table))
		return;

	clk = _register_multiplier(NULL, clk_name, parent_name, 0, reg, shift,
			width, clk_multiplier_flags, table, NULL);

	if (!IS_ERR(clk))
		of_clk_add_provider(node, of_clk_src_simple_get, clk);
}
EXPORT_SYMBOL_GPL(of_multiplier_clk_setup);
CLK_OF_DECLARE(multiplier_clk, "multiplier-clock", of_multiplier_clk_setup);
#endif