arch/arm/mach-omap2/clkt_dpll.c - kernel/msm - Gitiles

 /*
  * OMAP2/3/4 DPLL clock functions
  *
  * Copyright (C) 2005-2008 Texas Instruments, Inc.
  * Copyright (C) 2004-2010 Nokia Corporation
  *
  * Contacts:
  * Richard Woodruff <r-woodruff2@ti.com>
  * Paul Walmsley
  *
  * 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.
  */
 #undef DEBUG

 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/clk.h>
 #include <linux/io.h>

 #include <asm/div64.h>

 #include <plat/clock.h>

 #include "clock.h"
 #include "cm-regbits-24xx.h"
 #include "cm-regbits-34xx.h"

 /* DPLL rate rounding: minimum DPLL multiplier, divider values */
 #define DPLL_MIN_MULTIPLIER		2
 #define DPLL_MIN_DIVIDER		1

 /* Possible error results from _dpll_test_mult */
 #define DPLL_MULT_UNDERFLOW		-1

 /*
  * Scale factor to mitigate roundoff errors in DPLL rate rounding.
  * The higher the scale factor, the greater the risk of arithmetic overflow,
  * but the closer the rounded rate to the target rate.  DPLL_SCALE_FACTOR
  * must be a power of DPLL_SCALE_BASE.
  */
 #define DPLL_SCALE_FACTOR		64
 #define DPLL_SCALE_BASE			2
 #define DPLL_ROUNDING_VAL		((DPLL_SCALE_BASE / 2) * \
 					 (DPLL_SCALE_FACTOR / DPLL_SCALE_BASE))

 /* DPLL valid Fint frequency band limits - from 34xx TRM Section 4.7.6.2 */
 #define DPLL_FINT_BAND1_MIN		750000
 #define DPLL_FINT_BAND1_MAX		2100000
 #define DPLL_FINT_BAND2_MIN		7500000
 #define DPLL_FINT_BAND2_MAX		21000000

 /* _dpll_test_fint() return codes */
 #define DPLL_FINT_UNDERFLOW		-1
 #define DPLL_FINT_INVALID		-2

 /* Private functions */

 /*
  * _dpll_test_fint - test whether an Fint value is valid for the DPLL
  * @clk: DPLL struct clk to test
  * @n: divider value (N) to test
  *
  * Tests whether a particular divider @n will result in a valid DPLL
  * internal clock frequency Fint. See the 34xx TRM 4.7.6.2 "DPLL Jitter
  * Correction".  Returns 0 if OK, -1 if the enclosing loop can terminate
  * (assuming that it is counting N upwards), or -2 if the enclosing loop
  * should skip to the next iteration (again assuming N is increasing).
  */
 static int _dpll_test_fint(struct clk *clk, u8 n)
 {
 	struct dpll_data *dd;
 	long fint;
 	int ret = 0;

 	dd = clk->dpll_data;

 	/* DPLL divider must result in a valid jitter correction val */
 	fint = clk->parent->rate / n;
 	if (fint < DPLL_FINT_BAND1_MIN) {

 		pr_debug("rejecting n=%d due to Fint failure, "
 			 "lowering max_divider\n", n);
 		dd->max_divider = n;
 		ret = DPLL_FINT_UNDERFLOW;

 	} else if (fint > DPLL_FINT_BAND1_MAX &&
 		   fint < DPLL_FINT_BAND2_MIN) {

 		pr_debug("rejecting n=%d due to Fint failure\n", n);
 		ret = DPLL_FINT_INVALID;

 	} else if (fint > DPLL_FINT_BAND2_MAX) {

 		pr_debug("rejecting n=%d due to Fint failure, "
 			 "boosting min_divider\n", n);
 		dd->min_divider = n;
 		ret = DPLL_FINT_INVALID;

 	}

 	return ret;
 }

 static unsigned long _dpll_compute_new_rate(unsigned long parent_rate,
 					    unsigned int m, unsigned int n)
 {
 	unsigned long long num;

 	num = (unsigned long long)parent_rate * m;
 	do_div(num, n);
 	return num;
 }

 /*
  * _dpll_test_mult - test a DPLL multiplier value
  * @m: pointer to the DPLL m (multiplier) value under test
  * @n: current DPLL n (divider) value under test
  * @new_rate: pointer to storage for the resulting rounded rate
  * @target_rate: the desired DPLL rate
  * @parent_rate: the DPLL's parent clock rate
  *
  * This code tests a DPLL multiplier value, ensuring that the
  * resulting rate will not be higher than the target_rate, and that
  * the multiplier value itself is valid for the DPLL.  Initially, the
  * integer pointed to by the m argument should be prescaled by
  * multiplying by DPLL_SCALE_FACTOR.  The code will replace this with
  * a non-scaled m upon return.  This non-scaled m will result in a
  * new_rate as close as possible to target_rate (but not greater than
  * target_rate) given the current (parent_rate, n, prescaled m)
  * triple. Returns DPLL_MULT_UNDERFLOW in the event that the
  * non-scaled m attempted to underflow, which can allow the calling
  * function to bail out early; or 0 upon success.
  */
 static int _dpll_test_mult(int *m, int n, unsigned long *new_rate,
 			   unsigned long target_rate,
 			   unsigned long parent_rate)
 {
 	int r = 0, carry = 0;

 	/* Unscale m and round if necessary */
 	if (*m % DPLL_SCALE_FACTOR >= DPLL_ROUNDING_VAL)
 		carry = 1;
 	*m = (*m / DPLL_SCALE_FACTOR) + carry;

 	/*
 	 * The new rate must be <= the target rate to avoid programming
 	 * a rate that is impossible for the hardware to handle
 	 */
 	*new_rate = _dpll_compute_new_rate(parent_rate, *m, n);
 	if (*new_rate > target_rate) {
 		(*m)--;
 		*new_rate = 0;
 	}

 	/* Guard against m underflow */
 	if (*m < DPLL_MIN_MULTIPLIER) {
 		*m = DPLL_MIN_MULTIPLIER;
 		*new_rate = 0;
 		r = DPLL_MULT_UNDERFLOW;
 	}

 	if (*new_rate == 0)
 		*new_rate = _dpll_compute_new_rate(parent_rate, *m, n);

 	return r;
 }

 /* Public functions */

 void omap2_init_dpll_parent(struct clk *clk)
 {
 	u32 v;
 	struct dpll_data *dd;

 	dd = clk->dpll_data;
 	if (!dd)
 		return;

 	v = __raw_readl(dd->control_reg);
 	v &= dd->enable_mask;
 	v >>= __ffs(dd->enable_mask);

 	/* Reparent the struct clk in case the dpll is in bypass */
 	if (cpu_is_omap24xx()) {
 		if (v == OMAP2XXX_EN_DPLL_LPBYPASS ||
 		    v == OMAP2XXX_EN_DPLL_FRBYPASS)
 			clk_reparent(clk, dd->clk_bypass);
 	} else if (cpu_is_omap34xx()) {
 		if (v == OMAP3XXX_EN_DPLL_LPBYPASS ||
 		    v == OMAP3XXX_EN_DPLL_FRBYPASS)
 			clk_reparent(clk, dd->clk_bypass);
 	} else if (cpu_is_omap44xx()) {
 		if (v == OMAP4XXX_EN_DPLL_LPBYPASS ||
 		    v == OMAP4XXX_EN_DPLL_FRBYPASS ||
 		    v == OMAP4XXX_EN_DPLL_MNBYPASS)
 			clk_reparent(clk, dd->clk_bypass);
 	}
 	return;
 }

 /**
  * omap2_get_dpll_rate - returns the current DPLL CLKOUT rate
  * @clk: struct clk * of a DPLL
  *
  * DPLLs can be locked or bypassed - basically, enabled or disabled.
  * When locked, the DPLL output depends on the M and N values.  When
  * bypassed, on OMAP2xxx, the output rate is either the 32KiHz clock
  * or sys_clk.  Bypass rates on OMAP3 depend on the DPLL: DPLLs 1 and
  * 2 are bypassed with dpll1_fclk and dpll2_fclk respectively
  * (generated by DPLL3), while DPLL 3, 4, and 5 bypass rates are sys_clk.
  * Returns the current DPLL CLKOUT rate (*not* CLKOUTX2) if the DPLL is
  * locked, or the appropriate bypass rate if the DPLL is bypassed, or 0
  * if the clock @clk is not a DPLL.
  */
 u32 omap2_get_dpll_rate(struct clk *clk)
 {
 	long long dpll_clk;
 	u32 dpll_mult, dpll_div, v;
 	struct dpll_data *dd;

 	dd = clk->dpll_data;
 	if (!dd)
 		return 0;

 	/* Return bypass rate if DPLL is bypassed */
 	v = __raw_readl(dd->control_reg);
 	v &= dd->enable_mask;
 	v >>= __ffs(dd->enable_mask);

 	if (cpu_is_omap24xx()) {
 		if (v == OMAP2XXX_EN_DPLL_LPBYPASS ||
 		    v == OMAP2XXX_EN_DPLL_FRBYPASS)
 			return dd->clk_bypass->rate;
 	} else if (cpu_is_omap34xx()) {
 		if (v == OMAP3XXX_EN_DPLL_LPBYPASS ||
 		    v == OMAP3XXX_EN_DPLL_FRBYPASS)
 			return dd->clk_bypass->rate;
 	} else if (cpu_is_omap44xx()) {
 		if (v == OMAP4XXX_EN_DPLL_LPBYPASS ||
 		    v == OMAP4XXX_EN_DPLL_FRBYPASS ||
 		    v == OMAP4XXX_EN_DPLL_MNBYPASS)
 			return dd->clk_bypass->rate;
 	}

 	v = __raw_readl(dd->mult_div1_reg);
 	dpll_mult = v & dd->mult_mask;
 	dpll_mult >>= __ffs(dd->mult_mask);
 	dpll_div = v & dd->div1_mask;
 	dpll_div >>= __ffs(dd->div1_mask);

 	dpll_clk = (long long)dd->clk_ref->rate * dpll_mult;
 	do_div(dpll_clk, dpll_div + 1);

 	return dpll_clk;
 }

 /* DPLL rate rounding code */

 /**
  * omap2_dpll_round_rate - round a target rate for an OMAP DPLL
  * @clk: struct clk * for a DPLL
  * @target_rate: desired DPLL clock rate
  *
  * Given a DPLL and a desired target rate, round the target rate to a
  * possible, programmable rate for this DPLL.  Attempts to select the
  * minimum possible n.  Stores the computed (m, n) in the DPLL's
  * dpll_data structure so set_rate() will not need to call this
  * (expensive) function again.  Returns ~0 if the target rate cannot
  * be rounded, or the rounded rate upon success.
  */
 long omap2_dpll_round_rate(struct clk *clk, unsigned long target_rate)
 {
 	int m, n, r, scaled_max_m;
 	unsigned long scaled_rt_rp;
 	unsigned long new_rate = 0;
 	struct dpll_data *dd;

 	if (!clk || !clk->dpll_data)
 		return ~0;

 	dd = clk->dpll_data;

 	pr_debug("clock: %s: starting DPLL round_rate, target rate %ld\n",
 		 clk->name, target_rate);

 	scaled_rt_rp = target_rate / (dd->clk_ref->rate / DPLL_SCALE_FACTOR);
 	scaled_max_m = dd->max_multiplier * DPLL_SCALE_FACTOR;

 	dd->last_rounded_rate = 0;

 	for (n = dd->min_divider; n <= dd->max_divider; n++) {

 		/* Is the (input clk, divider) pair valid for the DPLL? */
 		r = _dpll_test_fint(clk, n);
 		if (r == DPLL_FINT_UNDERFLOW)
 			break;
 		else if (r == DPLL_FINT_INVALID)
 			continue;

 		/* Compute the scaled DPLL multiplier, based on the divider */
 		m = scaled_rt_rp * n;

 		/*
 		 * Since we're counting n up, a m overflow means we
 		 * can bail out completely (since as n increases in
 		 * the next iteration, there's no way that m can
 		 * increase beyond the current m)
 		 */
 		if (m > scaled_max_m)
 			break;

 		r = _dpll_test_mult(&m, n, &new_rate, target_rate,
 				    dd->clk_ref->rate);

 		/* m can't be set low enough for this n - try with a larger n */
 		if (r == DPLL_MULT_UNDERFLOW)
 			continue;

 		pr_debug("clock: %s: m = %d: n = %d: new_rate = %ld\n",
 			 clk->name, m, n, new_rate);

 		if (target_rate == new_rate) {
 			dd->last_rounded_m = m;
 			dd->last_rounded_n = n;
 			dd->last_rounded_rate = target_rate;
 			break;
 		}
 	}

 	if (target_rate != new_rate) {
 		pr_debug("clock: %s: cannot round to rate %ld\n", clk->name,
 			 target_rate);
 		return ~0;
 	}

 	return target_rate;
 }
	/*
	* OMAP2/3/4 DPLL clock functions
	*
	* Copyright (C) 2005-2008 Texas Instruments, Inc.
	* Copyright (C) 2004-2010 Nokia Corporation
	*
	* Contacts:
	* Richard Woodruff <r-woodruff2@ti.com>
	* Paul Walmsley
	*
	* 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.
	*/
	#undef DEBUG

	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/clk.h>
	#include <linux/io.h>

	#include <asm/div64.h>

	#include <plat/clock.h>

	#include "clock.h"
	#include "cm-regbits-24xx.h"
	#include "cm-regbits-34xx.h"

	/* DPLL rate rounding: minimum DPLL multiplier, divider values */
	#define DPLL_MIN_MULTIPLIER 2
	#define DPLL_MIN_DIVIDER 1

	/* Possible error results from _dpll_test_mult */
	#define DPLL_MULT_UNDERFLOW -1

	/*
	* Scale factor to mitigate roundoff errors in DPLL rate rounding.
	* The higher the scale factor, the greater the risk of arithmetic overflow,
	* but the closer the rounded rate to the target rate. DPLL_SCALE_FACTOR
	* must be a power of DPLL_SCALE_BASE.
	*/
	#define DPLL_SCALE_FACTOR 64
	#define DPLL_SCALE_BASE 2
	#define DPLL_ROUNDING_VAL ((DPLL_SCALE_BASE / 2) * \
	(DPLL_SCALE_FACTOR / DPLL_SCALE_BASE))

	/* DPLL valid Fint frequency band limits - from 34xx TRM Section 4.7.6.2 */
	#define DPLL_FINT_BAND1_MIN 750000
	#define DPLL_FINT_BAND1_MAX 2100000
	#define DPLL_FINT_BAND2_MIN 7500000
	#define DPLL_FINT_BAND2_MAX 21000000

	/* _dpll_test_fint() return codes */
	#define DPLL_FINT_UNDERFLOW -1
	#define DPLL_FINT_INVALID -2

	/* Private functions */

	/*
	* _dpll_test_fint - test whether an Fint value is valid for the DPLL
	* @clk: DPLL struct clk to test
	* @n: divider value (N) to test
	*
	* Tests whether a particular divider @n will result in a valid DPLL
	* internal clock frequency Fint. See the 34xx TRM 4.7.6.2 "DPLL Jitter
	* Correction". Returns 0 if OK, -1 if the enclosing loop can terminate
	* (assuming that it is counting N upwards), or -2 if the enclosing loop
	* should skip to the next iteration (again assuming N is increasing).
	*/
	static int _dpll_test_fint(struct clk *clk, u8 n)
	{
	struct dpll_data *dd;
	long fint;
	int ret = 0;

	dd = clk->dpll_data;

	/* DPLL divider must result in a valid jitter correction val */
	fint = clk->parent->rate / n;
	if (fint < DPLL_FINT_BAND1_MIN) {

	pr_debug("rejecting n=%d due to Fint failure, "
	"lowering max_divider\n", n);
	dd->max_divider = n;
	ret = DPLL_FINT_UNDERFLOW;

	} else if (fint > DPLL_FINT_BAND1_MAX &&
	fint < DPLL_FINT_BAND2_MIN) {

	pr_debug("rejecting n=%d due to Fint failure\n", n);
	ret = DPLL_FINT_INVALID;

	} else if (fint > DPLL_FINT_BAND2_MAX) {

	pr_debug("rejecting n=%d due to Fint failure, "
	"boosting min_divider\n", n);
	dd->min_divider = n;
	ret = DPLL_FINT_INVALID;

	}

	return ret;
	}

	static unsigned long _dpll_compute_new_rate(unsigned long parent_rate,
	unsigned int m, unsigned int n)
	{
	unsigned long long num;

	num = (unsigned long long)parent_rate * m;
	do_div(num, n);
	return num;
	}

	/*
	* _dpll_test_mult - test a DPLL multiplier value
	* @m: pointer to the DPLL m (multiplier) value under test
	* @n: current DPLL n (divider) value under test
	* @new_rate: pointer to storage for the resulting rounded rate
	* @target_rate: the desired DPLL rate
	* @parent_rate: the DPLL's parent clock rate
	*
	* This code tests a DPLL multiplier value, ensuring that the
	* resulting rate will not be higher than the target_rate, and that
	* the multiplier value itself is valid for the DPLL. Initially, the
	* integer pointed to by the m argument should be prescaled by
	* multiplying by DPLL_SCALE_FACTOR. The code will replace this with
	* a non-scaled m upon return. This non-scaled m will result in a
	* new_rate as close as possible to target_rate (but not greater than
	* target_rate) given the current (parent_rate, n, prescaled m)
	* triple. Returns DPLL_MULT_UNDERFLOW in the event that the
	* non-scaled m attempted to underflow, which can allow the calling
	* function to bail out early; or 0 upon success.
	*/
	static int _dpll_test_mult(int m, int n, unsigned long new_rate,
	unsigned long target_rate,
	unsigned long parent_rate)
	{
	int r = 0, carry = 0;

	/* Unscale m and round if necessary */
	if (*m % DPLL_SCALE_FACTOR >= DPLL_ROUNDING_VAL)
	carry = 1;
	m = (m / DPLL_SCALE_FACTOR) + carry;

	/*
	* The new rate must be <= the target rate to avoid programming
	* a rate that is impossible for the hardware to handle
	*/
	new_rate = _dpll_compute_new_rate(parent_rate, m, n);
	if (*new_rate > target_rate) {
	(*m)--;
	*new_rate = 0;
	}

	/* Guard against m underflow */
	if (*m < DPLL_MIN_MULTIPLIER) {
	*m = DPLL_MIN_MULTIPLIER;
	*new_rate = 0;
	r = DPLL_MULT_UNDERFLOW;
	}

	if (*new_rate == 0)
	new_rate = _dpll_compute_new_rate(parent_rate, m, n);

	return r;
	}

	/* Public functions */

	void omap2_init_dpll_parent(struct clk *clk)
	{
	u32 v;
	struct dpll_data *dd;

	dd = clk->dpll_data;
	if (!dd)
	return;

	v = __raw_readl(dd->control_reg);
	v &= dd->enable_mask;
	v >>= __ffs(dd->enable_mask);

	/* Reparent the struct clk in case the dpll is in bypass */
	if (cpu_is_omap24xx()) {
	if (v == OMAP2XXX_EN_DPLL_LPBYPASS \|\|
	v == OMAP2XXX_EN_DPLL_FRBYPASS)
	clk_reparent(clk, dd->clk_bypass);
	} else if (cpu_is_omap34xx()) {
	if (v == OMAP3XXX_EN_DPLL_LPBYPASS \|\|
	v == OMAP3XXX_EN_DPLL_FRBYPASS)
	clk_reparent(clk, dd->clk_bypass);
	} else if (cpu_is_omap44xx()) {
	if (v == OMAP4XXX_EN_DPLL_LPBYPASS \|\|
	v == OMAP4XXX_EN_DPLL_FRBYPASS \|\|
	v == OMAP4XXX_EN_DPLL_MNBYPASS)
	clk_reparent(clk, dd->clk_bypass);
	}
	return;
	}

	/**
	* omap2_get_dpll_rate - returns the current DPLL CLKOUT rate
	* @clk: struct clk * of a DPLL
	*
	* DPLLs can be locked or bypassed - basically, enabled or disabled.
	* When locked, the DPLL output depends on the M and N values. When
	* bypassed, on OMAP2xxx, the output rate is either the 32KiHz clock
	* or sys_clk. Bypass rates on OMAP3 depend on the DPLL: DPLLs 1 and
	* 2 are bypassed with dpll1_fclk and dpll2_fclk respectively
	* (generated by DPLL3), while DPLL 3, 4, and 5 bypass rates are sys_clk.
	* Returns the current DPLL CLKOUT rate (not CLKOUTX2) if the DPLL is
	* locked, or the appropriate bypass rate if the DPLL is bypassed, or 0
	* if the clock @clk is not a DPLL.
	*/
	u32 omap2_get_dpll_rate(struct clk *clk)
	{
	long long dpll_clk;
	u32 dpll_mult, dpll_div, v;
	struct dpll_data *dd;

	dd = clk->dpll_data;
	if (!dd)
	return 0;

	/* Return bypass rate if DPLL is bypassed */
	v = __raw_readl(dd->control_reg);
	v &= dd->enable_mask;
	v >>= __ffs(dd->enable_mask);

	if (cpu_is_omap24xx()) {
	if (v == OMAP2XXX_EN_DPLL_LPBYPASS \|\|
	v == OMAP2XXX_EN_DPLL_FRBYPASS)
	return dd->clk_bypass->rate;
	} else if (cpu_is_omap34xx()) {
	if (v == OMAP3XXX_EN_DPLL_LPBYPASS \|\|
	v == OMAP3XXX_EN_DPLL_FRBYPASS)
	return dd->clk_bypass->rate;
	} else if (cpu_is_omap44xx()) {
	if (v == OMAP4XXX_EN_DPLL_LPBYPASS \|\|
	v == OMAP4XXX_EN_DPLL_FRBYPASS \|\|
	v == OMAP4XXX_EN_DPLL_MNBYPASS)
	return dd->clk_bypass->rate;
	}

	v = __raw_readl(dd->mult_div1_reg);
	dpll_mult = v & dd->mult_mask;
	dpll_mult >>= __ffs(dd->mult_mask);
	dpll_div = v & dd->div1_mask;
	dpll_div >>= __ffs(dd->div1_mask);

	dpll_clk = (long long)dd->clk_ref->rate * dpll_mult;
	do_div(dpll_clk, dpll_div + 1);

	return dpll_clk;
	}

	/* DPLL rate rounding code */

	/**
	* omap2_dpll_round_rate - round a target rate for an OMAP DPLL
	* @clk: struct clk * for a DPLL
	* @target_rate: desired DPLL clock rate
	*
	* Given a DPLL and a desired target rate, round the target rate to a
	* possible, programmable rate for this DPLL. Attempts to select the
	* minimum possible n. Stores the computed (m, n) in the DPLL's
	* dpll_data structure so set_rate() will not need to call this
	* (expensive) function again. Returns ~0 if the target rate cannot
	* be rounded, or the rounded rate upon success.
	*/
	long omap2_dpll_round_rate(struct clk *clk, unsigned long target_rate)
	{
	int m, n, r, scaled_max_m;
	unsigned long scaled_rt_rp;
	unsigned long new_rate = 0;
	struct dpll_data *dd;

	if (!clk \|\| !clk->dpll_data)
	return ~0;

	dd = clk->dpll_data;

	pr_debug("clock: %s: starting DPLL round_rate, target rate %ld\n",
	clk->name, target_rate);

	scaled_rt_rp = target_rate / (dd->clk_ref->rate / DPLL_SCALE_FACTOR);
	scaled_max_m = dd->max_multiplier * DPLL_SCALE_FACTOR;

	dd->last_rounded_rate = 0;

	for (n = dd->min_divider; n <= dd->max_divider; n++) {

	/* Is the (input clk, divider) pair valid for the DPLL? */
	r = _dpll_test_fint(clk, n);
	if (r == DPLL_FINT_UNDERFLOW)
	break;
	else if (r == DPLL_FINT_INVALID)
	continue;

	/* Compute the scaled DPLL multiplier, based on the divider */
	m = scaled_rt_rp * n;

	/*
	* Since we're counting n up, a m overflow means we
	* can bail out completely (since as n increases in
	* the next iteration, there's no way that m can
	* increase beyond the current m)
	*/
	if (m > scaled_max_m)
	break;

	r = _dpll_test_mult(&m, n, &new_rate, target_rate,
	dd->clk_ref->rate);

	/* m can't be set low enough for this n - try with a larger n */
	if (r == DPLL_MULT_UNDERFLOW)
	continue;

	pr_debug("clock: %s: m = %d: n = %d: new_rate = %ld\n",
	clk->name, m, n, new_rate);

	if (target_rate == new_rate) {
	dd->last_rounded_m = m;
	dd->last_rounded_n = n;
	dd->last_rounded_rate = target_rate;
	break;
	}
	}

	if (target_rate != new_rate) {
	pr_debug("clock: %s: cannot round to rate %ld\n", clk->name,
	target_rate);
	return ~0;
	}

	return target_rate;
	}