sound/soc/codecs/adau-utils.c

   1 /*
   2  * Shared helper functions for devices from the ADAU family
   3  *
   4  * Copyright 2011-2016 Analog Devices Inc.
   5  * Author: Lars-Peter Clausen <lars@metafoo.de>
   6  *
   7  * Licensed under the GPL-2 or later.
   8  */
   9
  10 #include <linux/gcd.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13
  14 #include "adau-utils.h"
  15
  16 int adau_calc_pll_cfg(unsigned int freq_in, unsigned int freq_out,
  17         uint8_t regs[5])
  18 {
  19         unsigned int r, n, m, i, j;
  20         unsigned int div;
  21
  22         if (!freq_out) {
  23                 r = 0;
  24                 n = 0;
  25                 m = 0;
  26                 div = 0;
  27         } else {
  28                 if (freq_out % freq_in != 0) {
  29                         div = DIV_ROUND_UP(freq_in, 13500000);
  30                         freq_in /= div;
  31                         r = freq_out / freq_in;
  32                         i = freq_out % freq_in;
  33                         j = gcd(i, freq_in);
  34                         n = i / j;
  35                         m = freq_in / j;
  36                         div--;
  37                 } else {
  38                         r = freq_out / freq_in;
  39                         n = 0;
  40                         m = 0;
  41                         div = 0;
  42                 }
  43                 if (n > 0xffff || m > 0xffff || div > 3 || r > 8 || r < 2)
  44                         return -EINVAL;
  45         }
  46
  47         regs[0] = m >> 8;
  48         regs[1] = m & 0xff;
  49         regs[2] = n >> 8;
  50         regs[3] = n & 0xff;
  51         regs[4] = (r << 3) | (div << 1);
  52         if (m != 0)
  53                 regs[4] |= 1; /* Fractional mode */
  54
  55         return 0;
  56 }
  57 EXPORT_SYMBOL_GPL(adau_calc_pll_cfg);
  58
  59 MODULE_DESCRIPTION("ASoC ADAU audio CODECs shared helper functions");
  60 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
  61 MODULE_LICENSE("GPL v2");