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lib: rational: copy the rational fraction lib routines from Linux

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Copy the best rational approximation calculation routines from Linux.
Typical usecase for these routines is to calculate the M/N divider
values for PLLs to reach a specific clock rate.

This is based on linux kernel commit:
"lib/math/rational.c: fix possible incorrect result from rational
fractions helper"
(sha1: 323dd2c3ed0641f49e89b4e420f9eef5d3d5a881)

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Tero Kristo <kristo@kernel.org>
This commit is contained in:
Tero Kristo 2021-06-11 11:45:02 +03:00 • committed by Lokesh Vutla
parent 08ea87a6de
commit 7d0f3fbb93
4 changed files with 128 additions and 0 deletions
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20
include/linux/rational.h Normal file
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/* SPDX-License-Identifier: GPL-2.0 */
/*
* rational fractions
*
* Copyright (C) 2009 emlix GmbH, Oskar Schirmer <oskar@scara.com>
*
* helper functions when coping with rational numbers,
* e.g. when calculating optimum numerator/denominator pairs for
* pll configuration taking into account restricted register size
*/
#ifndef _LINUX_RATIONAL_H
#define _LINUX_RATIONAL_H
void rational_best_approximation(
unsigned long given_numerator, unsigned long given_denominator,
unsigned long max_numerator, unsigned long max_denominator,
unsigned long *best_numerator, unsigned long *best_denominator);
#endif /* _LINUX_RATIONAL_H */