src/kernel/linux/v4.19/drivers/clk/tegra/clk-utils.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2018, NVIDIA CORPORATION.  All rights reserved.
 */

#include <asm/div64.h>

#include "clk.h"

#define div_mask(w) ((1 << (w)) - 1)

int div_frac_get(unsigned long rate, unsigned parent_rate, u8 width,
		 u8 frac_width, u8 flags)
{
	u64 divider_ux1 = parent_rate;
	int mul;

	if (!rate)
		return 0;

	mul = 1 << frac_width;

	if (!(flags & TEGRA_DIVIDER_INT))
		divider_ux1 *= mul;

	if (flags & TEGRA_DIVIDER_ROUND_UP)
		divider_ux1 += rate - 1;

	do_div(divider_ux1, rate);

	if (flags & TEGRA_DIVIDER_INT)
		divider_ux1 *= mul;

	if (divider_ux1 < mul)
		return 0;

	divider_ux1 -= mul;

	if (divider_ux1 > div_mask(width))
		return div_mask(width);

	return divider_ux1;
}