drivers/clk/clk-divider.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
  * Copyright (C) 2011 Richard Zhao, Linaro <richard.zhao@linaro.org>
  * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
  *
  * 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 divider clock implementation
  */

 #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>

 /*
  * DOC: basic adjustable divider 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 = DIV_ROUND_UP(parent->rate / divisor)
  * parent - fixed parent.  No clk_set_parent support
  */

 #define to_clk_divider(_hw) container_of(_hw, struct clk_divider, hw)

 #define div_mask(d)	((1 << ((d)->width)) - 1)

 static unsigned int _get_table_maxdiv(const struct clk_div_table *table)
 {
 	unsigned int maxdiv = 0;
 	const struct clk_div_table *clkt;

 	for (clkt = table; clkt->div; clkt++)
 		if (clkt->div > maxdiv)
 			maxdiv = clkt->div;
 	return maxdiv;
 }

 static unsigned int _get_table_mindiv(const struct clk_div_table *table)
 {
 	unsigned int mindiv = UINT_MAX;
 	const struct clk_div_table *clkt;

 	for (clkt = table; clkt->div; clkt++)
 		if (clkt->div < mindiv)
 			mindiv = clkt->div;
 	return mindiv;
 }

 static unsigned int _get_maxdiv(struct clk_divider *divider)
 {
 	if (divider->flags & CLK_DIVIDER_ONE_BASED)
 		return div_mask(divider);
 	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
 		return 1 << div_mask(divider);
 	if (divider->table)
 		return _get_table_maxdiv(divider->table);
 	return div_mask(divider) + 1;
 }

 static unsigned int _get_table_div(const struct clk_div_table *table,
 							unsigned int val)
 {
 	const struct clk_div_table *clkt;

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

 static unsigned int _get_div(struct clk_divider *divider, unsigned int val)
 {
 	if (divider->flags & CLK_DIVIDER_ONE_BASED)
 		return val;
 	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
 		return 1 << val;
 	if (divider->table)
 		return _get_table_div(divider->table, val);
 	return val + 1;
 }

 static unsigned int _get_table_val(const struct clk_div_table *table,
 							unsigned int div)
 {
 	const struct clk_div_table *clkt;

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

 static unsigned int _get_val(struct clk_divider *divider, unsigned int div)
 {
 	if (divider->flags & CLK_DIVIDER_ONE_BASED)
 		return div;
 	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
 		return __ffs(div);
 	if (divider->table)
 		return  _get_table_val(divider->table, div);
 	return div - 1;
 }

 static unsigned long clk_divider_recalc_rate(struct clk_hw *hw,
 		unsigned long parent_rate)
 {
 	struct clk_divider *divider = to_clk_divider(hw);
 	unsigned int div, val;

 	val = clk_readl(divider->reg) >> divider->shift;
 	val &= div_mask(divider);

 	div = _get_div(divider, val);
 	if (!div) {
 		WARN(!(divider->flags & CLK_DIVIDER_ALLOW_ZERO),
 			"%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
 			__clk_get_name(hw->clk));
 		return parent_rate;
 	}

 	return DIV_ROUND_UP(parent_rate, div);
 }

 /*
  * The reverse of DIV_ROUND_UP: The maximum number which
  * divided by m is r
  */
 #define MULT_ROUND_UP(r, m) ((r) * (m) + (m) - 1)

 static bool _is_valid_table_div(const struct clk_div_table *table,
 							 unsigned int div)
 {
 	const struct clk_div_table *clkt;

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

 static bool _is_valid_div(struct clk_divider *divider, unsigned int div)
 {
 	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
 		return is_power_of_2(div);
 	if (divider->table)
 		return _is_valid_table_div(divider->table, div);
 	return true;
 }

 static int _round_up_table(const struct clk_div_table *table, int div)
 {
 	const struct clk_div_table *clkt;
 	int up = _get_table_maxdiv(table);

 	for (clkt = table; clkt->div; clkt++) {
 		if (clkt->div == div)
 			return clkt->div;
 		else if (clkt->div < div)
 			continue;

 		if ((clkt->div - div) < (up - div))
 			up = clkt->div;
 	}

 	return up;
 }

 static int _round_down_table(const struct clk_div_table *table, int div)
 {
 	const struct clk_div_table *clkt;
 	int down = _get_table_mindiv(table);

 	for (clkt = table; clkt->div; clkt++) {
 		if (clkt->div == div)
 			return clkt->div;
 		else if (clkt->div > div)
 			continue;

 		if ((div - clkt->div) < (div - down))
 			down = clkt->div;
 	}

 	return down;
 }

 static int _div_round_up(struct clk_divider *divider,
 		unsigned long parent_rate, unsigned long rate)
 {
 	int div = DIV_ROUND_UP(parent_rate, rate);

 	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
 		div = __roundup_pow_of_two(div);
 	if (divider->table)
 		div = _round_up_table(divider->table, div);

 	return div;
 }

 static int _div_round_closest(struct clk_divider *divider,
 		unsigned long parent_rate, unsigned long rate)
 {
 	int up, down, div;

 	up = down = div = DIV_ROUND_CLOSEST(parent_rate, rate);

 	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO) {
 		up = __roundup_pow_of_two(div);
 		down = __rounddown_pow_of_two(div);
 	} else if (divider->table) {
 		up = _round_up_table(divider->table, div);
 		down = _round_down_table(divider->table, div);
 	}

 	return (up - div) <= (div - down) ? up : down;
 }

 static int _div_round(struct clk_divider *divider, unsigned long parent_rate,
 		unsigned long rate)
 {
 	if (divider->flags & CLK_DIVIDER_ROUND_CLOSEST)
 		return _div_round_closest(divider, parent_rate, rate);

 	return _div_round_up(divider, parent_rate, rate);
 }

 static bool _is_best_div(struct clk_divider *divider,
 		int rate, int now, int best)
 {
 	if (divider->flags & CLK_DIVIDER_ROUND_CLOSEST)
 		return abs(rate - now) < abs(rate - best);

 	return now <= rate && now > best;
 }

 static int _next_div(struct clk_divider *divider, int div)
 {
 	div++;

 	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
 		return __roundup_pow_of_two(div);
 	if (divider->table)
 		return _round_up_table(divider->table, div);

 	return div;
 }

 static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
 		unsigned long *best_parent_rate)
 {
 	struct clk_divider *divider = to_clk_divider(hw);
 	int i, bestdiv = 0;
 	unsigned long parent_rate, best = 0, now, maxdiv;
 	unsigned long parent_rate_saved = *best_parent_rate;

 	if (!rate)
 		rate = 1;

 	maxdiv = _get_maxdiv(divider);

 	if (!(__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT)) {
 		parent_rate = *best_parent_rate;
 		bestdiv = _div_round(divider, parent_rate, rate);
 		bestdiv = bestdiv == 0 ? 1 : bestdiv;
 		bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
 		return bestdiv;
 	}

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

 	for (i = 1; i <= maxdiv; i = _next_div(divider, i)) {
 		if (!_is_valid_div(divider, i))
 			continue;
 		if (rate * i == parent_rate_saved) {
 			/*
 			 * It's the most ideal case if the requested rate can be
 			 * divided from parent clock without needing to change
 			 * parent rate, so return the divider immediately.
 			 */
 			*best_parent_rate = parent_rate_saved;
 			return i;
 		}
 		parent_rate = __clk_round_rate(__clk_get_parent(hw->clk),
 				MULT_ROUND_UP(rate, i));
 		now = DIV_ROUND_UP(parent_rate, i);
 		if (_is_best_div(divider, rate, now, best)) {
 			bestdiv = i;
 			best = now;
 			*best_parent_rate = parent_rate;
 		}
 	}

 	if (!bestdiv) {
 		bestdiv = _get_maxdiv(divider);
 		*best_parent_rate = __clk_round_rate(__clk_get_parent(hw->clk), 1);
 	}

 	return bestdiv;
 }

 static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
 				unsigned long *prate)
 {
 	int div;
 	div = clk_divider_bestdiv(hw, rate, prate);

 	return DIV_ROUND_UP(*prate, div);
 }

 static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
 				unsigned long parent_rate)
 {
 	struct clk_divider *divider = to_clk_divider(hw);
 	unsigned int div, value;
 	unsigned long flags = 0;
 	u32 val;

 	div = DIV_ROUND_UP(parent_rate, rate);

 	if (!_is_valid_div(divider, div))
 		return -EINVAL;

 	value = _get_val(divider, div);

 	if (value > div_mask(divider))
 		value = div_mask(divider);

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

 	if (divider->flags & CLK_DIVIDER_HIWORD_MASK) {
 		val = div_mask(divider) << (divider->shift + 16);
 	} else {
 		val = clk_readl(divider->reg);
 		val &= ~(div_mask(divider) << divider->shift);
 	}
 	val |= value << divider->shift;
 	clk_writel(val, divider->reg);

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

 	return 0;
 }

 const struct clk_ops clk_divider_ops = {
 	.recalc_rate = clk_divider_recalc_rate,
 	.round_rate = clk_divider_round_rate,
 	.set_rate = clk_divider_set_rate,
 };
 EXPORT_SYMBOL_GPL(clk_divider_ops);

 static struct clk *_register_divider(struct device *dev, const char *name,
 		const char *parent_name, unsigned long flags,
 		void __iomem *reg, u8 shift, u8 width,
 		u8 clk_divider_flags, const struct clk_div_table *table,
 		spinlock_t *lock)
 {
 	struct clk_divider *div;
 	struct clk *clk;
 	struct clk_init_data init;

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

 	/* allocate the divider */
 	div = kzalloc(sizeof(struct clk_divider), GFP_KERNEL);
 	if (!div) {
 		pr_err("%s: could not allocate divider clk\n", __func__);
 		return ERR_PTR(-ENOMEM);
 	}

 	init.name = name;
 	init.ops = &clk_divider_ops;
 	init.flags = flags | CLK_IS_BASIC;
 	init.parent_names = (parent_name ? &parent_name: NULL);
 	init.num_parents = (parent_name ? 1 : 0);

 	/* struct clk_divider assignments */
 	div->reg = reg;
 	div->shift = shift;
 	div->width = width;
 	div->flags = clk_divider_flags;
 	div->lock = lock;
 	div->hw.init = &init;
 	div->table = table;

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

 	if (IS_ERR(clk))
 		kfree(div);

 	return clk;
 }

 /**
  * clk_register_divider - register a divider 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 divider
  * @shift: number of bits to shift the bitfield
  * @width: width of the bitfield
  * @clk_divider_flags: divider-specific flags for this clock
  * @lock: shared register lock for this clock
  */
 struct clk *clk_register_divider(struct device *dev, const char *name,
 		const char *parent_name, unsigned long flags,
 		void __iomem *reg, u8 shift, u8 width,
 		u8 clk_divider_flags, spinlock_t *lock)
 {
 	return _register_divider(dev, name, parent_name, flags, reg, shift,
 			width, clk_divider_flags, NULL, lock);
 }
 EXPORT_SYMBOL_GPL(clk_register_divider);

 /**
  * clk_register_divider_table - register a table based divider 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 divider
  * @shift: number of bits to shift the bitfield
  * @width: width of the bitfield
  * @clk_divider_flags: divider-specific flags for this clock
  * @table: array of divider/value pairs ending with a div set to 0
  * @lock: shared register lock for this clock
  */
 struct clk *clk_register_divider_table(struct device *dev, const char *name,
 		const char *parent_name, unsigned long flags,
 		void __iomem *reg, u8 shift, u8 width,
 		u8 clk_divider_flags, const struct clk_div_table *table,
 		spinlock_t *lock)
 {
 	return _register_divider(dev, name, parent_name, flags, reg, shift,
 			width, clk_divider_flags, table, lock);
 }
 EXPORT_SYMBOL_GPL(clk_register_divider_table);
	/*
	* Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
	* Copyright (C) 2011 Richard Zhao, Linaro <richard.zhao@linaro.org>
	* Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
	*
	* 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 divider clock implementation
	*/

	#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>

	/*
	* DOC: basic adjustable divider 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 = DIV_ROUND_UP(parent->rate / divisor)
	* parent - fixed parent. No clk_set_parent support
	*/

	#define to_clk_divider(_hw) container_of(_hw, struct clk_divider, hw)

	#define div_mask(d) ((1 << ((d)->width)) - 1)

	static unsigned int _get_table_maxdiv(const struct clk_div_table *table)
	{
	unsigned int maxdiv = 0;
	const struct clk_div_table *clkt;

	for (clkt = table; clkt->div; clkt++)
	if (clkt->div > maxdiv)
	maxdiv = clkt->div;
	return maxdiv;
	}

	static unsigned int _get_table_mindiv(const struct clk_div_table *table)
	{
	unsigned int mindiv = UINT_MAX;
	const struct clk_div_table *clkt;

	for (clkt = table; clkt->div; clkt++)
	if (clkt->div < mindiv)
	mindiv = clkt->div;
	return mindiv;
	}

	static unsigned int _get_maxdiv(struct clk_divider *divider)
	{
	if (divider->flags & CLK_DIVIDER_ONE_BASED)
	return div_mask(divider);
	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
	return 1 << div_mask(divider);
	if (divider->table)
	return _get_table_maxdiv(divider->table);
	return div_mask(divider) + 1;
	}

	static unsigned int _get_table_div(const struct clk_div_table *table,
	unsigned int val)
	{
	const struct clk_div_table *clkt;

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

	static unsigned int _get_div(struct clk_divider *divider, unsigned int val)
	{
	if (divider->flags & CLK_DIVIDER_ONE_BASED)
	return val;
	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
	return 1 << val;
	if (divider->table)
	return _get_table_div(divider->table, val);
	return val + 1;
	}

	static unsigned int _get_table_val(const struct clk_div_table *table,
	unsigned int div)
	{
	const struct clk_div_table *clkt;

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

	static unsigned int _get_val(struct clk_divider *divider, unsigned int div)
	{
	if (divider->flags & CLK_DIVIDER_ONE_BASED)
	return div;
	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
	return __ffs(div);
	if (divider->table)
	return _get_table_val(divider->table, div);
	return div - 1;
	}

	static unsigned long clk_divider_recalc_rate(struct clk_hw *hw,
	unsigned long parent_rate)
	{
	struct clk_divider *divider = to_clk_divider(hw);
	unsigned int div, val;

	val = clk_readl(divider->reg) >> divider->shift;
	val &= div_mask(divider);

	div = _get_div(divider, val);
	if (!div) {
	WARN(!(divider->flags & CLK_DIVIDER_ALLOW_ZERO),
	"%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
	__clk_get_name(hw->clk));
	return parent_rate;
	}

	return DIV_ROUND_UP(parent_rate, div);
	}

	/*
	* The reverse of DIV_ROUND_UP: The maximum number which
	* divided by m is r
	*/
	#define MULT_ROUND_UP(r, m) ((r) * (m) + (m) - 1)

	static bool _is_valid_table_div(const struct clk_div_table *table,
	unsigned int div)
	{
	const struct clk_div_table *clkt;

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

	static bool _is_valid_div(struct clk_divider *divider, unsigned int div)
	{
	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
	return is_power_of_2(div);
	if (divider->table)
	return _is_valid_table_div(divider->table, div);
	return true;
	}

	static int _round_up_table(const struct clk_div_table *table, int div)
	{
	const struct clk_div_table *clkt;
	int up = _get_table_maxdiv(table);

	for (clkt = table; clkt->div; clkt++) {
	if (clkt->div == div)
	return clkt->div;
	else if (clkt->div < div)
	continue;

	if ((clkt->div - div) < (up - div))
	up = clkt->div;
	}

	return up;
	}

	static int _round_down_table(const struct clk_div_table *table, int div)
	{
	const struct clk_div_table *clkt;
	int down = _get_table_mindiv(table);

	for (clkt = table; clkt->div; clkt++) {
	if (clkt->div == div)
	return clkt->div;
	else if (clkt->div > div)
	continue;

	if ((div - clkt->div) < (div - down))
	down = clkt->div;
	}

	return down;
	}

	static int _div_round_up(struct clk_divider *divider,
	unsigned long parent_rate, unsigned long rate)
	{
	int div = DIV_ROUND_UP(parent_rate, rate);

	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
	div = __roundup_pow_of_two(div);
	if (divider->table)
	div = _round_up_table(divider->table, div);

	return div;
	}

	static int _div_round_closest(struct clk_divider *divider,
	unsigned long parent_rate, unsigned long rate)
	{
	int up, down, div;

	up = down = div = DIV_ROUND_CLOSEST(parent_rate, rate);

	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO) {
	up = __roundup_pow_of_two(div);
	down = __rounddown_pow_of_two(div);
	} else if (divider->table) {
	up = _round_up_table(divider->table, div);
	down = _round_down_table(divider->table, div);
	}

	return (up - div) <= (div - down) ? up : down;
	}

	static int _div_round(struct clk_divider *divider, unsigned long parent_rate,
	unsigned long rate)
	{
	if (divider->flags & CLK_DIVIDER_ROUND_CLOSEST)
	return _div_round_closest(divider, parent_rate, rate);

	return _div_round_up(divider, parent_rate, rate);
	}

	static bool _is_best_div(struct clk_divider *divider,
	int rate, int now, int best)
	{
	if (divider->flags & CLK_DIVIDER_ROUND_CLOSEST)
	return abs(rate - now) < abs(rate - best);

	return now <= rate && now > best;
	}

	static int _next_div(struct clk_divider *divider, int div)
	{
	div++;

	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
	return __roundup_pow_of_two(div);
	if (divider->table)
	return _round_up_table(divider->table, div);

	return div;
	}

	static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
	unsigned long *best_parent_rate)
	{
	struct clk_divider *divider = to_clk_divider(hw);
	int i, bestdiv = 0;
	unsigned long parent_rate, best = 0, now, maxdiv;
	unsigned long parent_rate_saved = *best_parent_rate;

	if (!rate)
	rate = 1;

	maxdiv = _get_maxdiv(divider);

	if (!(__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT)) {
	parent_rate = *best_parent_rate;
	bestdiv = _div_round(divider, parent_rate, rate);
	bestdiv = bestdiv == 0 ? 1 : bestdiv;
	bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
	return bestdiv;
	}

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

	for (i = 1; i <= maxdiv; i = _next_div(divider, i)) {
	if (!_is_valid_div(divider, i))
	continue;
	if (rate * i == parent_rate_saved) {
	/*
	* It's the most ideal case if the requested rate can be
	* divided from parent clock without needing to change
	* parent rate, so return the divider immediately.
	*/
	*best_parent_rate = parent_rate_saved;
	return i;
	}
	parent_rate = __clk_round_rate(__clk_get_parent(hw->clk),
	MULT_ROUND_UP(rate, i));
	now = DIV_ROUND_UP(parent_rate, i);
	if (_is_best_div(divider, rate, now, best)) {
	bestdiv = i;
	best = now;
	*best_parent_rate = parent_rate;
	}
	}

	if (!bestdiv) {
	bestdiv = _get_maxdiv(divider);
	*best_parent_rate = __clk_round_rate(__clk_get_parent(hw->clk), 1);
	}

	return bestdiv;
	}

	static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
	unsigned long *prate)
	{
	int div;
	div = clk_divider_bestdiv(hw, rate, prate);

	return DIV_ROUND_UP(*prate, div);
	}

	static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
	unsigned long parent_rate)
	{
	struct clk_divider *divider = to_clk_divider(hw);
	unsigned int div, value;
	unsigned long flags = 0;
	u32 val;

	div = DIV_ROUND_UP(parent_rate, rate);

	if (!_is_valid_div(divider, div))
	return -EINVAL;

	value = _get_val(divider, div);

	if (value > div_mask(divider))
	value = div_mask(divider);

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

	if (divider->flags & CLK_DIVIDER_HIWORD_MASK) {
	val = div_mask(divider) << (divider->shift + 16);
	} else {
	val = clk_readl(divider->reg);
	val &= ~(div_mask(divider) << divider->shift);
	}
	val \|= value << divider->shift;
	clk_writel(val, divider->reg);

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

	return 0;
	}

	const struct clk_ops clk_divider_ops = {
	.recalc_rate = clk_divider_recalc_rate,
	.round_rate = clk_divider_round_rate,
	.set_rate = clk_divider_set_rate,
	};
	EXPORT_SYMBOL_GPL(clk_divider_ops);

	static struct clk _register_divider(struct device dev, const char *name,
	const char *parent_name, unsigned long flags,
	void __iomem *reg, u8 shift, u8 width,
	u8 clk_divider_flags, const struct clk_div_table *table,
	spinlock_t *lock)
	{
	struct clk_divider *div;
	struct clk *clk;
	struct clk_init_data init;

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

	/* allocate the divider */
	div = kzalloc(sizeof(struct clk_divider), GFP_KERNEL);
	if (!div) {
	pr_err("%s: could not allocate divider clk\n", __func__);
	return ERR_PTR(-ENOMEM);
	}

	init.name = name;
	init.ops = &clk_divider_ops;
	init.flags = flags \| CLK_IS_BASIC;
	init.parent_names = (parent_name ? &parent_name: NULL);
	init.num_parents = (parent_name ? 1 : 0);

	/* struct clk_divider assignments */
	div->reg = reg;
	div->shift = shift;
	div->width = width;
	div->flags = clk_divider_flags;
	div->lock = lock;
	div->hw.init = &init;
	div->table = table;

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

	if (IS_ERR(clk))
	kfree(div);

	return clk;
	}

	/**
	* clk_register_divider - register a divider 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 divider
	* @shift: number of bits to shift the bitfield
	* @width: width of the bitfield
	* @clk_divider_flags: divider-specific flags for this clock
	* @lock: shared register lock for this clock
	*/
	struct clk clk_register_divider(struct device dev, const char *name,
	const char *parent_name, unsigned long flags,
	void __iomem *reg, u8 shift, u8 width,
	u8 clk_divider_flags, spinlock_t *lock)
	{
	return _register_divider(dev, name, parent_name, flags, reg, shift,
	width, clk_divider_flags, NULL, lock);
	}
	EXPORT_SYMBOL_GPL(clk_register_divider);

	/**
	* clk_register_divider_table - register a table based divider 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 divider
	* @shift: number of bits to shift the bitfield
	* @width: width of the bitfield
	* @clk_divider_flags: divider-specific flags for this clock
	* @table: array of divider/value pairs ending with a div set to 0
	* @lock: shared register lock for this clock
	*/
	struct clk clk_register_divider_table(struct device dev, const char *name,
	const char *parent_name, unsigned long flags,
	void __iomem *reg, u8 shift, u8 width,
	u8 clk_divider_flags, const struct clk_div_table *table,
	spinlock_t *lock)
	{
	return _register_divider(dev, name, parent_name, flags, reg, shift,
	width, clk_divider_flags, table, lock);
	}
	EXPORT_SYMBOL_GPL(clk_register_divider_table);