arch/powerpc/boot/mpc8xx.c

   1 /*
   2  * MPC8xx support functions
   3  *
   4  * Author: Scott Wood <scottwood@freescale.com>
   5  *
   6  * Copyright (c) 2007 Freescale Semiconductor, Inc.
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License version 2 as published
  10  * by the Free Software Foundation.
  11  */
  12
  13 #include "ops.h"
  14 #include "types.h"
  15 #include "fsl-soc.h"
  16 #include "mpc8xx.h"
  17 #include "stdio.h"
  18 #include "io.h"
  19
  20 #define MPC8XX_PLPRCR (0x284/4) /* PLL and Reset Control Register */
  21
  22 /* Return system clock from crystal frequency */
  23 u32 mpc885_get_clock(u32 crystal)
  24 {
  25         u32 *immr;
  26         u32 plprcr;
  27         int mfi, mfn, mfd, pdf, div;
  28         u32 ret;
  29
  30         immr = fsl_get_immr();
  31         if (!immr) {
  32                 printf("mpc885_get_clock: Couldn't get IMMR base.\r\n");
  33                 return 0;
  34         }
  35
  36         plprcr = in_be32(&immr[MPC8XX_PLPRCR]);
  37
  38         mfi = (plprcr >> 16) & 15;
  39         if (mfi < 5) {
  40                 printf("Warning: PLPRCR[MFI] value of %d out-of-bounds\r\n",
  41                        mfi);
  42                 mfi = 5;
  43         }
  44
  45         pdf = (plprcr >> 1) & 0xf;
  46         div = (plprcr >> 20) & 3;
  47         mfd = (plprcr >> 22) & 0x1f;
  48         mfn = (plprcr >> 27) & 0x1f;
  49
  50         ret = crystal * mfi;
  51
  52         if (mfn != 0)
  53                 ret += crystal * mfn / (mfd + 1);
  54
  55         return ret / (pdf + 1);
  56 }
  57
  58 /* Set common device tree fields based on the given clock frequencies. */
  59 void mpc8xx_set_clocks(u32 sysclk)
  60 {
  61         void *node;
  62
  63         dt_fixup_cpu_clocks(sysclk, sysclk / 16, sysclk);
  64
  65         node = finddevice("/soc/cpm");
  66         if (node)
  67                 setprop(node, "clock-frequency", &sysclk, 4);
  68
  69         node = finddevice("/soc/cpm/brg");
  70         if (node)
  71                 setprop(node, "clock-frequency", &sysclk, 4);
  72 }
  73
  74 int mpc885_fixup_clocks(u32 crystal)
  75 {
  76         u32 sysclk = mpc885_get_clock(crystal);
  77         if (!sysclk)
  78                 return 0;
  79
  80         mpc8xx_set_clocks(sysclk);
  81         return 1;
  82 }