LXR linux/drivers/clk/tegra/clk-utils.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (c) 2018, NVIDIA CORPORATION.  All rights reserved.
   4 */
   5
   6#include <asm/div64.h>
   7
   8#include "clk.h"
   9
  10#define div_mask(w) ((1 << (w)) - 1)
  11
  12int div_frac_get(unsigned long rate, unsigned parent_rate, u8 width,
  13                 u8 frac_width, u8 flags)
  14{
  15        u64 divider_ux1 = parent_rate;
  16        int mul;
  17
  18        if (!rate)
  19                return 0;
  20
  21        mul = 1 << frac_width;
  22
  23        if (!(flags & TEGRA_DIVIDER_INT))
  24                divider_ux1 *= mul;
  25
  26        if (flags & TEGRA_DIVIDER_ROUND_UP)
  27                divider_ux1 += rate - 1;
  28
  29        do_div(divider_ux1, rate);
  30
  31        if (flags & TEGRA_DIVIDER_INT)
  32                divider_ux1 *= mul;
  33
  34        if (divider_ux1 < mul)
  35                return 0;
  36
  37        divider_ux1 -= mul;
  38
  39        if (divider_ux1 > div_mask(width))
  40                return div_mask(width);
  41
  42        return divider_ux1;
  43}
  44