drivers/clk/clk-fractional-divider.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2014 Intel Corporation
  *
  * Adjustable fractional divider clock implementation.
  * Uses rational best approximation algorithm.
  *
  * Output is calculated as
  *
  *	rate = (m / n) * parent_rate				(1)
  *
  * This is useful when we have a prescaler block which asks for
  * m (numerator) and n (denominator) values to be provided to satisfy
  * the (1) as much as possible.
  *
  * Since m and n have the limitation by a range, e.g.
  *
  *	n >= 1, n < N_width, where N_width = 2^nwidth		(2)
  *
  * for some cases the output may be saturated. Hence, from (1) and (2),
  * assuming the worst case when m = 1, the inequality
  *
  *	floor(log2(parent_rate / rate)) <= nwidth		(3)
  *
  * may be derived. Thus, in cases when
  *
  *	(parent_rate / rate) >> N_width				(4)
  *
  * we might scale up the rate by 2^scale (see the description of
  * CLK_FRAC_DIVIDER_POWER_OF_TWO_PS for additional information), where
  *
  *	scale = floor(log2(parent_rate / rate)) - nwidth	(5)
  *
  * and assume that the IP, that needs m and n, has also its own
  * prescaler, which is capable to divide by 2^scale. In this way
  * we get the denominator to satisfy the desired range (2) and
  * at the same time a much better result of m and n than simple
  * saturated values.
  */

 #include <linux/debugfs.h>
 #include <linux/device.h>
 #include <linux/io.h>
 #include <linux/math.h>
 #include <linux/module.h>
 #include <linux/rational.h>
 #include <linux/slab.h>

 #include <linux/clk-provider.h>

 #include "clk-fractional-divider.h"

 static inline u32 clk_fd_readl(struct clk_fractional_divider *fd)
 {
 	if (fd->flags & CLK_FRAC_DIVIDER_BIG_ENDIAN)
 		return ioread32be(fd->reg);

 	return readl(fd->reg);
 }

 static inline void clk_fd_writel(struct clk_fractional_divider *fd, u32 val)
 {
 	if (fd->flags & CLK_FRAC_DIVIDER_BIG_ENDIAN)
 		iowrite32be(val, fd->reg);
 	else
 		writel(val, fd->reg);
 }

 static void clk_fd_get_div(struct clk_hw *hw, struct u32_fract *fract)
 {
 	struct clk_fractional_divider *fd = to_clk_fd(hw);
 	unsigned long flags = 0;
 	unsigned long m, n;
 	u32 mmask, nmask;
 	u32 val;

 	if (fd->lock)
 		spin_lock_irqsave(fd->lock, flags);
 	else
 		__acquire(fd->lock);

 	val = clk_fd_readl(fd);

 	if (fd->lock)
 		spin_unlock_irqrestore(fd->lock, flags);
 	else
 		__release(fd->lock);

 	mmask = GENMASK(fd->mwidth - 1, 0) << fd->mshift;
 	nmask = GENMASK(fd->nwidth - 1, 0) << fd->nshift;

 	m = (val & mmask) >> fd->mshift;
 	n = (val & nmask) >> fd->nshift;

 	if (fd->flags & CLK_FRAC_DIVIDER_ZERO_BASED) {
 		m++;
 		n++;
 	}

 	fract->numerator = m;
 	fract->denominator = n;
 }

 static unsigned long clk_fd_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
 {
 	struct u32_fract fract;
 	u64 ret;

 	clk_fd_get_div(hw, &fract);

 	if (!fract.numerator || !fract.denominator)
 		return parent_rate;

 	ret = (u64)parent_rate * fract.numerator;
 	do_div(ret, fract.denominator);

 	return ret;
 }

 void clk_fractional_divider_general_approximation(struct clk_hw *hw,
 						  unsigned long rate,
 						  unsigned long *parent_rate,
 						  unsigned long *m, unsigned long *n)
 {
 	struct clk_fractional_divider *fd = to_clk_fd(hw);
 	unsigned long max_m, max_n;

 	/*
 	 * Get rate closer to *parent_rate to guarantee there is no overflow
 	 * for m and n. In the result it will be the nearest rate left shifted
 	 * by (scale - fd->nwidth) bits.
 	 *
 	 * For the detailed explanation see the top comment in this file.
 	 */
 	if (fd->flags & CLK_FRAC_DIVIDER_POWER_OF_TWO_PS) {
 		unsigned long scale = fls_long(*parent_rate / rate - 1);

 		if (scale > fd->nwidth)
 			rate <<= scale - fd->nwidth;
 	}

 	if (fd->flags & CLK_FRAC_DIVIDER_ZERO_BASED) {
 		max_m = BIT(fd->mwidth);
 		max_n = BIT(fd->nwidth);
 	} else {
 		max_m = GENMASK(fd->mwidth - 1, 0);
 		max_n = GENMASK(fd->nwidth - 1, 0);
 	}

 	rational_best_approximation(rate, *parent_rate, max_m, max_n, m, n);
 }
 EXPORT_SYMBOL_GPL(clk_fractional_divider_general_approximation);

 static long clk_fd_round_rate(struct clk_hw *hw, unsigned long rate,
 			      unsigned long *parent_rate)
 {
 	struct clk_fractional_divider *fd = to_clk_fd(hw);
 	unsigned long m, n;
 	u64 ret;

 	if (!rate || (!clk_hw_can_set_rate_parent(hw) && rate >= *parent_rate))
 		return *parent_rate;

 	if (fd->approximation)
 		fd->approximation(hw, rate, parent_rate, &m, &n);
 	else
 		clk_fractional_divider_general_approximation(hw, rate, parent_rate, &m, &n);

 	ret = (u64)*parent_rate * m;
 	do_div(ret, n);

 	return ret;
 }

 static int clk_fd_set_rate(struct clk_hw *hw, unsigned long rate,
 			   unsigned long parent_rate)
 {
 	struct clk_fractional_divider *fd = to_clk_fd(hw);
 	unsigned long flags = 0;
 	unsigned long m, n, max_m, max_n;
 	u32 mmask, nmask;
 	u32 val;

 	if (fd->flags & CLK_FRAC_DIVIDER_ZERO_BASED) {
 		max_m = BIT(fd->mwidth);
 		max_n = BIT(fd->nwidth);
 	} else {
 		max_m = GENMASK(fd->mwidth - 1, 0);
 		max_n = GENMASK(fd->nwidth - 1, 0);
 	}
 	rational_best_approximation(rate, parent_rate, max_m, max_n, &m, &n);

 	if (fd->flags & CLK_FRAC_DIVIDER_ZERO_BASED) {
 		m--;
 		n--;
 	}

 	mmask = GENMASK(fd->mwidth - 1, 0) << fd->mshift;
 	nmask = GENMASK(fd->nwidth - 1, 0) << fd->nshift;

 	if (fd->lock)
 		spin_lock_irqsave(fd->lock, flags);
 	else
 		__acquire(fd->lock);

 	val = clk_fd_readl(fd);
 	val &= ~(mmask | nmask);
 	val |= (m << fd->mshift) | (n << fd->nshift);
 	clk_fd_writel(fd, val);

 	if (fd->lock)
 		spin_unlock_irqrestore(fd->lock, flags);
 	else
 		__release(fd->lock);

 	return 0;
 }

 #ifdef CONFIG_DEBUG_FS
 static int clk_fd_numerator_get(void *hw, u64 *val)
 {
 	struct u32_fract fract;

 	clk_fd_get_div(hw, &fract);

 	*val = fract.numerator;

 	return 0;
 }
 DEFINE_DEBUGFS_ATTRIBUTE(clk_fd_numerator_fops, clk_fd_numerator_get, NULL, "%llu\n");

 static int clk_fd_denominator_get(void *hw, u64 *val)
 {
 	struct u32_fract fract;

 	clk_fd_get_div(hw, &fract);

 	*val = fract.denominator;

 	return 0;
 }
 DEFINE_DEBUGFS_ATTRIBUTE(clk_fd_denominator_fops, clk_fd_denominator_get, NULL, "%llu\n");

 static void clk_fd_debug_init(struct clk_hw *hw, struct dentry *dentry)
 {
 	debugfs_create_file("numerator", 0444, dentry, hw, &clk_fd_numerator_fops);
 	debugfs_create_file("denominator", 0444, dentry, hw, &clk_fd_denominator_fops);
 }
 #endif

 const struct clk_ops clk_fractional_divider_ops = {
 	.recalc_rate = clk_fd_recalc_rate,
 	.round_rate = clk_fd_round_rate,
 	.set_rate = clk_fd_set_rate,
 #ifdef CONFIG_DEBUG_FS
 	.debug_init = clk_fd_debug_init,
 #endif
 };
 EXPORT_SYMBOL_GPL(clk_fractional_divider_ops);

 struct clk_hw *clk_hw_register_fractional_divider(struct device *dev,
 		const char *name, const char *parent_name, unsigned long flags,
 		void __iomem *reg, u8 mshift, u8 mwidth, u8 nshift, u8 nwidth,
 		u8 clk_divider_flags, spinlock_t *lock)
 {
 	struct clk_fractional_divider *fd;
 	struct clk_init_data init;
 	struct clk_hw *hw;
 	int ret;

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

 	init.name = name;
 	init.ops = &clk_fractional_divider_ops;
 	init.flags = flags;
 	init.parent_names = parent_name ? &parent_name : NULL;
 	init.num_parents = parent_name ? 1 : 0;

 	fd->reg = reg;
 	fd->mshift = mshift;
 	fd->mwidth = mwidth;
 	fd->nshift = nshift;
 	fd->nwidth = nwidth;
 	fd->flags = clk_divider_flags;
 	fd->lock = lock;
 	fd->hw.init = &init;

 	hw = &fd->hw;
 	ret = clk_hw_register(dev, hw);
 	if (ret) {
 		kfree(fd);
 		hw = ERR_PTR(ret);
 	}

 	return hw;
 }
 EXPORT_SYMBOL_GPL(clk_hw_register_fractional_divider);

 struct clk *clk_register_fractional_divider(struct device *dev,
 		const char *name, const char *parent_name, unsigned long flags,
 		void __iomem *reg, u8 mshift, u8 mwidth, u8 nshift, u8 nwidth,
 		u8 clk_divider_flags, spinlock_t *lock)
 {
 	struct clk_hw *hw;

 	hw = clk_hw_register_fractional_divider(dev, name, parent_name, flags,
 			reg, mshift, mwidth, nshift, nwidth, clk_divider_flags,
 			lock);
 	if (IS_ERR(hw))
 		return ERR_CAST(hw);
 	return hw->clk;
 }
 EXPORT_SYMBOL_GPL(clk_register_fractional_divider);

 void clk_hw_unregister_fractional_divider(struct clk_hw *hw)
 {
 	struct clk_fractional_divider *fd;

 	fd = to_clk_fd(hw);

 	clk_hw_unregister(hw);
 	kfree(fd);
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright (C) 2014 Intel Corporation
	*
	* Adjustable fractional divider clock implementation.
	* Uses rational best approximation algorithm.
	*
	* Output is calculated as
	*
	* rate = (m / n) * parent_rate (1)
	*
	* This is useful when we have a prescaler block which asks for
	* m (numerator) and n (denominator) values to be provided to satisfy
	* the (1) as much as possible.
	*
	* Since m and n have the limitation by a range, e.g.
	*
	* n >= 1, n < N_width, where N_width = 2^nwidth (2)
	*
	* for some cases the output may be saturated. Hence, from (1) and (2),
	* assuming the worst case when m = 1, the inequality
	*
	* floor(log2(parent_rate / rate)) <= nwidth (3)
	*
	* may be derived. Thus, in cases when
	*
	* (parent_rate / rate) >> N_width (4)
	*
	* we might scale up the rate by 2^scale (see the description of
	* CLK_FRAC_DIVIDER_POWER_OF_TWO_PS for additional information), where
	*
	* scale = floor(log2(parent_rate / rate)) - nwidth (5)
	*
	* and assume that the IP, that needs m and n, has also its own
	* prescaler, which is capable to divide by 2^scale. In this way
	* we get the denominator to satisfy the desired range (2) and
	* at the same time a much better result of m and n than simple
	* saturated values.
	*/

	#include <linux/debugfs.h>
	#include <linux/device.h>
	#include <linux/io.h>
	#include <linux/math.h>
	#include <linux/module.h>
	#include <linux/rational.h>
	#include <linux/slab.h>

	#include <linux/clk-provider.h>

	#include "clk-fractional-divider.h"

	static inline u32 clk_fd_readl(struct clk_fractional_divider *fd)
	{
	if (fd->flags & CLK_FRAC_DIVIDER_BIG_ENDIAN)
	return ioread32be(fd->reg);

	return readl(fd->reg);
	}

	static inline void clk_fd_writel(struct clk_fractional_divider *fd, u32 val)
	{
	if (fd->flags & CLK_FRAC_DIVIDER_BIG_ENDIAN)
	iowrite32be(val, fd->reg);
	else
	writel(val, fd->reg);
	}

	static void clk_fd_get_div(struct clk_hw hw, struct u32_fract fract)
	{
	struct clk_fractional_divider *fd = to_clk_fd(hw);
	unsigned long flags = 0;
	unsigned long m, n;
	u32 mmask, nmask;
	u32 val;

	if (fd->lock)
	spin_lock_irqsave(fd->lock, flags);
	else
	__acquire(fd->lock);

	val = clk_fd_readl(fd);

	if (fd->lock)
	spin_unlock_irqrestore(fd->lock, flags);
	else
	__release(fd->lock);

	mmask = GENMASK(fd->mwidth - 1, 0) << fd->mshift;
	nmask = GENMASK(fd->nwidth - 1, 0) << fd->nshift;

	m = (val & mmask) >> fd->mshift;
	n = (val & nmask) >> fd->nshift;

	if (fd->flags & CLK_FRAC_DIVIDER_ZERO_BASED) {
	m++;
	n++;
	}

	fract->numerator = m;
	fract->denominator = n;
	}

	static unsigned long clk_fd_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
	{
	struct u32_fract fract;
	u64 ret;

	clk_fd_get_div(hw, &fract);

	if (!fract.numerator \|\| !fract.denominator)
	return parent_rate;

	ret = (u64)parent_rate * fract.numerator;
	do_div(ret, fract.denominator);

	return ret;
	}

	void clk_fractional_divider_general_approximation(struct clk_hw *hw,
	unsigned long rate,
	unsigned long *parent_rate,
	unsigned long m, unsigned long n)
	{
	struct clk_fractional_divider *fd = to_clk_fd(hw);
	unsigned long max_m, max_n;

	/*
	* Get rate closer to *parent_rate to guarantee there is no overflow
	* for m and n. In the result it will be the nearest rate left shifted
	* by (scale - fd->nwidth) bits.
	*
	* For the detailed explanation see the top comment in this file.
	*/
	if (fd->flags & CLK_FRAC_DIVIDER_POWER_OF_TWO_PS) {
	unsigned long scale = fls_long(*parent_rate / rate - 1);

	if (scale > fd->nwidth)
	rate <<= scale - fd->nwidth;
	}

	if (fd->flags & CLK_FRAC_DIVIDER_ZERO_BASED) {
	max_m = BIT(fd->mwidth);
	max_n = BIT(fd->nwidth);
	} else {
	max_m = GENMASK(fd->mwidth - 1, 0);
	max_n = GENMASK(fd->nwidth - 1, 0);
	}

	rational_best_approximation(rate, *parent_rate, max_m, max_n, m, n);
	}
	EXPORT_SYMBOL_GPL(clk_fractional_divider_general_approximation);

	static long clk_fd_round_rate(struct clk_hw *hw, unsigned long rate,
	unsigned long *parent_rate)
	{
	struct clk_fractional_divider *fd = to_clk_fd(hw);
	unsigned long m, n;
	u64 ret;

	if (!rate \|\| (!clk_hw_can_set_rate_parent(hw) && rate >= *parent_rate))
	return *parent_rate;

	if (fd->approximation)
	fd->approximation(hw, rate, parent_rate, &m, &n);
	else
	clk_fractional_divider_general_approximation(hw, rate, parent_rate, &m, &n);

	ret = (u64)parent_rate m;
	do_div(ret, n);

	return ret;
	}

	static int clk_fd_set_rate(struct clk_hw *hw, unsigned long rate,
	unsigned long parent_rate)
	{
	struct clk_fractional_divider *fd = to_clk_fd(hw);
	unsigned long flags = 0;
	unsigned long m, n, max_m, max_n;
	u32 mmask, nmask;
	u32 val;

	if (fd->flags & CLK_FRAC_DIVIDER_ZERO_BASED) {
	max_m = BIT(fd->mwidth);
	max_n = BIT(fd->nwidth);
	} else {
	max_m = GENMASK(fd->mwidth - 1, 0);
	max_n = GENMASK(fd->nwidth - 1, 0);
	}
	rational_best_approximation(rate, parent_rate, max_m, max_n, &m, &n);

	if (fd->flags & CLK_FRAC_DIVIDER_ZERO_BASED) {
	m--;
	n--;
	}

	mmask = GENMASK(fd->mwidth - 1, 0) << fd->mshift;
	nmask = GENMASK(fd->nwidth - 1, 0) << fd->nshift;

	if (fd->lock)
	spin_lock_irqsave(fd->lock, flags);
	else
	__acquire(fd->lock);

	val = clk_fd_readl(fd);
	val &= ~(mmask \| nmask);
	val \|= (m << fd->mshift) \| (n << fd->nshift);
	clk_fd_writel(fd, val);

	if (fd->lock)
	spin_unlock_irqrestore(fd->lock, flags);
	else
	__release(fd->lock);

	return 0;
	}

	#ifdef CONFIG_DEBUG_FS
	static int clk_fd_numerator_get(void hw, u64 val)
	{
	struct u32_fract fract;

	clk_fd_get_div(hw, &fract);

	*val = fract.numerator;

	return 0;
	}
	DEFINE_DEBUGFS_ATTRIBUTE(clk_fd_numerator_fops, clk_fd_numerator_get, NULL, "%llu\n");

	static int clk_fd_denominator_get(void hw, u64 val)
	{
	struct u32_fract fract;

	clk_fd_get_div(hw, &fract);

	*val = fract.denominator;

	return 0;
	}
	DEFINE_DEBUGFS_ATTRIBUTE(clk_fd_denominator_fops, clk_fd_denominator_get, NULL, "%llu\n");

	static void clk_fd_debug_init(struct clk_hw hw, struct dentry dentry)
	{
	debugfs_create_file("numerator", 0444, dentry, hw, &clk_fd_numerator_fops);
	debugfs_create_file("denominator", 0444, dentry, hw, &clk_fd_denominator_fops);
	}
	#endif

	const struct clk_ops clk_fractional_divider_ops = {
	.recalc_rate = clk_fd_recalc_rate,
	.round_rate = clk_fd_round_rate,
	.set_rate = clk_fd_set_rate,
	#ifdef CONFIG_DEBUG_FS
	.debug_init = clk_fd_debug_init,
	#endif
	};
	EXPORT_SYMBOL_GPL(clk_fractional_divider_ops);

	struct clk_hw clk_hw_register_fractional_divider(struct device dev,
	const char name, const char parent_name, unsigned long flags,
	void __iomem *reg, u8 mshift, u8 mwidth, u8 nshift, u8 nwidth,
	u8 clk_divider_flags, spinlock_t *lock)
	{
	struct clk_fractional_divider *fd;
	struct clk_init_data init;
	struct clk_hw *hw;
	int ret;

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

	init.name = name;
	init.ops = &clk_fractional_divider_ops;
	init.flags = flags;
	init.parent_names = parent_name ? &parent_name : NULL;
	init.num_parents = parent_name ? 1 : 0;

	fd->reg = reg;
	fd->mshift = mshift;
	fd->mwidth = mwidth;
	fd->nshift = nshift;
	fd->nwidth = nwidth;
	fd->flags = clk_divider_flags;
	fd->lock = lock;
	fd->hw.init = &init;

	hw = &fd->hw;
	ret = clk_hw_register(dev, hw);
	if (ret) {
	kfree(fd);
	hw = ERR_PTR(ret);
	}

	return hw;
	}
	EXPORT_SYMBOL_GPL(clk_hw_register_fractional_divider);

	struct clk clk_register_fractional_divider(struct device dev,
	const char name, const char parent_name, unsigned long flags,
	void __iomem *reg, u8 mshift, u8 mwidth, u8 nshift, u8 nwidth,
	u8 clk_divider_flags, spinlock_t *lock)
	{
	struct clk_hw *hw;

	hw = clk_hw_register_fractional_divider(dev, name, parent_name, flags,
	reg, mshift, mwidth, nshift, nwidth, clk_divider_flags,
	lock);
	if (IS_ERR(hw))
	return ERR_CAST(hw);
	return hw->clk;
	}
	EXPORT_SYMBOL_GPL(clk_register_fractional_divider);

	void clk_hw_unregister_fractional_divider(struct clk_hw *hw)
	{
	struct clk_fractional_divider *fd;

	fd = to_clk_fd(hw);

	clk_hw_unregister(hw);
	kfree(fd);
	}