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
  12 int 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 }