lib_blackfin/clocks.c

   1 /*
   2  * clocks.c - figure out sclk/cclk/vco and such
   3  *
   4  * Copyright (c) 2005-2008 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2 or later.
   7  */
   8
   9 #include <common.h>
  10 #include <asm/blackfin.h>
  11
  12 /* Get the voltage input multiplier */
  13 static u_long cached_vco_pll_ctl, cached_vco;
  14 u_long get_vco(void)
  15 {
  16         u_long msel;
  17
  18         u_long pll_ctl = bfin_read_PLL_CTL();
  19         if (pll_ctl == cached_vco_pll_ctl)
  20                 return cached_vco;
  21         else
  22                 cached_vco_pll_ctl = pll_ctl;
  23
  24         msel = (pll_ctl >> 9) & 0x3F;
  25         if (0 == msel)
  26                 msel = 64;
  27
  28         cached_vco = CONFIG_CLKIN_HZ;
  29         cached_vco >>= (1 & pll_ctl);   /* DF bit */
  30         cached_vco *= msel;
  31         return cached_vco;
  32 }
  33
  34 /* Get the Core clock */
  35 static u_long cached_cclk_pll_div, cached_cclk;
  36 u_long get_cclk(void)
  37 {
  38         u_long csel, ssel;
  39
  40         if (bfin_read_PLL_STAT() & 0x1)
  41                 return CONFIG_CLKIN_HZ;
  42
  43         ssel = bfin_read_PLL_DIV();
  44         if (ssel == cached_cclk_pll_div)
  45                 return cached_cclk;
  46         else
  47                 cached_cclk_pll_div = ssel;
  48
  49         csel = ((ssel >> 4) & 0x03);
  50         ssel &= 0xf;
  51         if (ssel && ssel < (1 << csel)) /* SCLK > CCLK */
  52                 cached_cclk = get_vco() / ssel;
  53         else
  54                 cached_cclk = get_vco() >> csel;
  55         return cached_cclk;
  56 }
  57
  58 /* Get the System clock */
  59 static u_long cached_sclk_pll_div, cached_sclk;
  60 u_long get_sclk(void)
  61 {
  62         u_long ssel;
  63
  64         if (bfin_read_PLL_STAT() & 0x1)
  65                 return CONFIG_CLKIN_HZ;
  66
  67         ssel = bfin_read_PLL_DIV();
  68         if (ssel == cached_sclk_pll_div)
  69                 return cached_sclk;
  70         else
  71                 cached_sclk_pll_div = ssel;
  72
  73         ssel &= 0xf;
  74
  75         cached_sclk = get_vco() / ssel;
  76         return cached_sclk;
  77 }