[linux.git] / drivers / clk / clk-divider.c

/*
 * Copyright (C) 2011 Sascha Hauer, Pengutronix <[email protected]>
 * Copyright (C) 2011 Richard Zhao, Linaro <[email protected]>
 * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <[email protected]>
 *
 * 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>

/*
 * 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 = 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)
#define is_power_of_two(i)	!(i & ~i)

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_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, u8 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 = readl(divider->reg) >> divider->shift;
	val &= div_mask(divider);

	div = _get_div(divider, val);
	if (!div) {
		WARN(1, "%s: Invalid divisor for clock %s\n", __func__,
						__clk_get_name(hw->clk));
		return parent_rate;
	}

	return 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_two(div);
	if (divider->table)
		return _is_valid_table_div(divider->table, div);
	return true;
}

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;

	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_UP(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++) {
		if (!_is_valid_div(divider, i))
			continue;
		parent_rate = __clk_round_rate(__clk_get_parent(hw->clk),
				MULT_ROUND_UP(rate, i));
		now = parent_rate / i;
		if (now <= 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 *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 = parent_rate / rate;
	value = _get_val(divider, div);

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

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

	val = readl(divider->reg);
	val &= ~(div_mask(divider) << divider->shift);
	val |= value << divider->shift;
	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;

	/* 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);
}

/**
 * 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);
}
Commit	Line	Data
9d9f78ed MT	1	/*
	2	* Copyright (C) 2011 Sascha Hauer, Pengutronix <[email protected]>
	3	* Copyright (C) 2011 Richard Zhao, Linaro <[email protected]>
	4	* Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <[email protected]>
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation.
	9	*
	10	* Adjustable divider clock implementation
	11	*/
	12
	13	#include <linux/clk-provider.h>
	14	#include <linux/module.h>
	15	#include <linux/slab.h>
	16	#include <linux/io.h>
	17	#include <linux/err.h>
	18	#include <linux/string.h>
	19
	20	/*
	21	* DOC: basic adjustable divider clock that cannot gate
	22	*
	23	* Traits of this clock:
	24	* prepare - clk_prepare only ensures that parents are prepared
	25	* enable - clk_enable only ensures that parents are enabled
	26	* rate - rate is adjustable. clk->rate = parent->rate / divisor
	27	* parent - fixed parent. No clk_set_parent support
	28	*/
	29
	30	#define to_clk_divider(_hw) container_of(_hw, struct clk_divider, hw)
	31
	32	#define div_mask(d) ((1 << (d->width)) - 1)
6d9252bd RN	33	#define is_power_of_two(i) !(i & ~i)
6d9252bd RN	34
357c3f0a RN	35	static unsigned int _get_table_maxdiv(const struct clk_div_table *table)
	36	{
	37	unsigned int maxdiv = 0;
	38	const struct clk_div_table *clkt;
	39
	40	for (clkt = table; clkt->div; clkt++)
	41	if (clkt->div > maxdiv)
	42	maxdiv = clkt->div;
	43	return maxdiv;
	44	}
	45
6d9252bd RN	46	static unsigned int _get_maxdiv(struct clk_divider *divider)
	47	{
	48	if (divider->flags & CLK_DIVIDER_ONE_BASED)
	49	return div_mask(divider);
	50	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
	51	return 1 << div_mask(divider);
357c3f0a RN	52	if (divider->table)
357c3f0a RN	53	return _get_table_maxdiv(divider->table);
6d9252bd RN	54	return div_mask(divider) + 1;
	55	}
	56
357c3f0a RN	57	static unsigned int _get_table_div(const struct clk_div_table *table,
	58	unsigned int val)
	59	{
	60	const struct clk_div_table *clkt;
	61
	62	for (clkt = table; clkt->div; clkt++)
	63	if (clkt->val == val)
	64	return clkt->div;
	65	return 0;
	66	}
	67
6d9252bd RN	68	static unsigned int _get_div(struct clk_divider *divider, unsigned int val)
	69	{
	70	if (divider->flags & CLK_DIVIDER_ONE_BASED)
	71	return val;
	72	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
	73	return 1 << val;
357c3f0a RN	74	if (divider->table)
357c3f0a RN	75	return _get_table_div(divider->table, val);
6d9252bd RN	76	return val + 1;
	77	}
	78
357c3f0a RN	79	static unsigned int _get_table_val(const struct clk_div_table *table,
	80	unsigned int div)
	81	{
	82	const struct clk_div_table *clkt;
	83
	84	for (clkt = table; clkt->div; clkt++)
	85	if (clkt->div == div)
	86	return clkt->val;
	87	return 0;
	88	}
	89
6d9252bd RN	90	static unsigned int _get_val(struct clk_divider *divider, u8 div)
	91	{
	92	if (divider->flags & CLK_DIVIDER_ONE_BASED)
	93	return div;
	94	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
	95	return __ffs(div);
357c3f0a RN	96	if (divider->table)
357c3f0a RN	97	return _get_table_val(divider->table, div);
6d9252bd RN	98	return div - 1;
6d9252bd RN	99	}
9d9f78ed MT	100
	101	static unsigned long clk_divider_recalc_rate(struct clk_hw *hw,
	102	unsigned long parent_rate)
	103	{
	104	struct clk_divider *divider = to_clk_divider(hw);
6d9252bd	105	unsigned int div, val;
9d9f78ed	106
6d9252bd RN	107	val = readl(divider->reg) >> divider->shift;
6d9252bd RN	108	val &= div_mask(divider);
9d9f78ed	109
6d9252bd RN	110	div = _get_div(divider, val);
	111	if (!div) {
	112	WARN(1, "%s: Invalid divisor for clock %s\n", __func__,
	113	__clk_get_name(hw->clk));
	114	return parent_rate;
	115	}
9d9f78ed MT	116
	117	return parent_rate / div;
	118	}
9d9f78ed MT	119
	120	/*
	121	* The reverse of DIV_ROUND_UP: The maximum number which
	122	* divided by m is r
	123	*/
	124	#define MULT_ROUND_UP(r, m) ((r) * (m) + (m) - 1)
	125
357c3f0a RN	126	static bool _is_valid_table_div(const struct clk_div_table *table,
	127	unsigned int div)
	128	{
	129	const struct clk_div_table *clkt;
	130
	131	for (clkt = table; clkt->div; clkt++)
	132	if (clkt->div == div)
	133	return true;
	134	return false;
	135	}
	136
	137	static bool _is_valid_div(struct clk_divider *divider, unsigned int div)
	138	{
	139	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
	140	return is_power_of_two(div);
	141	if (divider->table)
	142	return _is_valid_table_div(divider->table, div);
	143	return true;
	144	}
	145
9d9f78ed MT	146	static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
	147	unsigned long *best_parent_rate)
	148	{
	149	struct clk_divider *divider = to_clk_divider(hw);
	150	int i, bestdiv = 0;
	151	unsigned long parent_rate, best = 0, now, maxdiv;
	152
	153	if (!rate)
	154	rate = 1;
	155
6d9252bd	156	maxdiv = _get_maxdiv(divider);
9d9f78ed	157
81536e07 SG	158	if (!(__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT)) {
81536e07 SG	159	parent_rate = *best_parent_rate;
9d9f78ed MT	160	bestdiv = DIV_ROUND_UP(parent_rate, rate);
	161	bestdiv = bestdiv == 0 ? 1 : bestdiv;
	162	bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
	163	return bestdiv;
	164	}
	165
	166	/*
	167	* The maximum divider we can use without overflowing
	168	* unsigned long in rate * i below
	169	*/
	170	maxdiv = min(ULONG_MAX / rate, maxdiv);
	171
	172	for (i = 1; i <= maxdiv; i++) {
357c3f0a	173	if (!_is_valid_div(divider, i))
6d9252bd	174	continue;
9d9f78ed MT	175	parent_rate = __clk_round_rate(__clk_get_parent(hw->clk),
	176	MULT_ROUND_UP(rate, i));
	177	now = parent_rate / i;
	178	if (now <= rate && now > best) {
	179	bestdiv = i;
	180	best = now;
	181	*best_parent_rate = parent_rate;
	182	}
	183	}
	184
	185	if (!bestdiv) {
6d9252bd	186	bestdiv = _get_maxdiv(divider);
9d9f78ed MT	187	*best_parent_rate = __clk_round_rate(__clk_get_parent(hw->clk), 1);
	188	}
	189
	190	return bestdiv;
	191	}
	192
	193	static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
	194	unsigned long *prate)
	195	{
	196	int div;
	197	div = clk_divider_bestdiv(hw, rate, prate);
	198
81536e07	199	return *prate / div;
9d9f78ed	200	}
9d9f78ed	201
1c0035d7 SG	202	static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
1c0035d7 SG	203	unsigned long parent_rate)
9d9f78ed MT	204	{
9d9f78ed MT	205	struct clk_divider *divider = to_clk_divider(hw);
6d9252bd	206	unsigned int div, value;
9d9f78ed MT	207	unsigned long flags = 0;
	208	u32 val;
	209
1c0035d7	210	div = parent_rate / rate;
6d9252bd	211	value = _get_val(divider, div);
9d9f78ed	212
6d9252bd RN	213	if (value > div_mask(divider))
6d9252bd RN	214	value = div_mask(divider);
9d9f78ed MT	215
	216	if (divider->lock)
	217	spin_lock_irqsave(divider->lock, flags);
	218
	219	val = readl(divider->reg);
	220	val &= ~(div_mask(divider) << divider->shift);
6d9252bd	221	val \|= value << divider->shift;
9d9f78ed MT	222	writel(val, divider->reg);
	223
	224	if (divider->lock)
	225	spin_unlock_irqrestore(divider->lock, flags);
	226
	227	return 0;
	228	}
9d9f78ed	229
822c250e	230	const struct clk_ops clk_divider_ops = {
9d9f78ed MT	231	.recalc_rate = clk_divider_recalc_rate,
	232	.round_rate = clk_divider_round_rate,
	233	.set_rate = clk_divider_set_rate,
	234	};
	235	EXPORT_SYMBOL_GPL(clk_divider_ops);
	236
357c3f0a	237	static struct clk _register_divider(struct device dev, const char *name,
9d9f78ed MT	238	const char *parent_name, unsigned long flags,
9d9f78ed MT	239	void __iomem *reg, u8 shift, u8 width,
357c3f0a RN	240	u8 clk_divider_flags, const struct clk_div_table *table,
357c3f0a RN	241	spinlock_t *lock)
9d9f78ed MT	242	{
	243	struct clk_divider *div;
	244	struct clk *clk;
0197b3ea	245	struct clk_init_data init;
9d9f78ed	246
27d54591	247	/* allocate the divider */
9d9f78ed	248	div = kzalloc(sizeof(struct clk_divider), GFP_KERNEL);
9d9f78ed MT	249	if (!div) {
9d9f78ed MT	250	pr_err("%s: could not allocate divider clk\n", __func__);
27d54591	251	return ERR_PTR(-ENOMEM);
9d9f78ed MT	252	}
9d9f78ed MT	253
0197b3ea SK	254	init.name = name;
0197b3ea SK	255	init.ops = &clk_divider_ops;
f7d8caad	256	init.flags = flags \| CLK_IS_BASIC;
0197b3ea SK	257	init.parent_names = (parent_name ? &parent_name: NULL);
	258	init.num_parents = (parent_name ? 1 : 0);
	259
9d9f78ed MT	260	/* struct clk_divider assignments */
	261	div->reg = reg;
	262	div->shift = shift;
	263	div->width = width;
	264	div->flags = clk_divider_flags;
	265	div->lock = lock;
0197b3ea	266	div->hw.init = &init;
357c3f0a	267	div->table = table;
9d9f78ed	268
27d54591	269	/* register the clock */
0197b3ea	270	clk = clk_register(dev, &div->hw);
9d9f78ed	271
27d54591 MT	272	if (IS_ERR(clk))
27d54591 MT	273	kfree(div);
9d9f78ed	274
27d54591	275	return clk;
9d9f78ed	276	}
357c3f0a RN	277
	278	/**
	279	* clk_register_divider - register a divider clock with the clock framework
	280	* @dev: device registering this clock
	281	* @name: name of this clock
	282	* @parent_name: name of clock's parent
	283	* @flags: framework-specific flags
	284	* @reg: register address to adjust divider
	285	* @shift: number of bits to shift the bitfield
	286	* @width: width of the bitfield
	287	* @clk_divider_flags: divider-specific flags for this clock
	288	* @lock: shared register lock for this clock
	289	*/
	290	struct clk clk_register_divider(struct device dev, const char *name,
	291	const char *parent_name, unsigned long flags,
	292	void __iomem *reg, u8 shift, u8 width,
	293	u8 clk_divider_flags, spinlock_t *lock)
	294	{
	295	return _register_divider(dev, name, parent_name, flags, reg, shift,
	296	width, clk_divider_flags, NULL, lock);
	297	}
	298
	299	/**
	300	* clk_register_divider_table - register a table based divider clock with
	301	* the clock framework
	302	* @dev: device registering this clock
	303	* @name: name of this clock
	304	* @parent_name: name of clock's parent
	305	* @flags: framework-specific flags
	306	* @reg: register address to adjust divider
	307	* @shift: number of bits to shift the bitfield
	308	* @width: width of the bitfield
	309	* @clk_divider_flags: divider-specific flags for this clock
	310	* @table: array of divider/value pairs ending with a div set to 0
	311	* @lock: shared register lock for this clock
	312	*/
	313	struct clk clk_register_divider_table(struct device dev, const char *name,
	314	const char *parent_name, unsigned long flags,
	315	void __iomem *reg, u8 shift, u8 width,
	316	u8 clk_divider_flags, const struct clk_div_table *table,
	317	spinlock_t *lock)
	318	{
	319	return _register_divider(dev, name, parent_name, flags, reg, shift,
	320	width, clk_divider_flags, table, lock);
	321	}