arch/powerpc/boot/mpc8xx.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * MPC8xx support functions
   4  *
   5  * Author: Scott Wood <scottwood@freescale.com>
   6  *
   7  * Copyright (c) 2007 Freescale Semiconductor, Inc.
   8  */
   9
  10 #include "ops.h"
  11 #include "types.h"
  12 #include "fsl-soc.h"
  13 #include "mpc8xx.h"
  14 #include "stdio.h"
  15 #include "io.h"
  16
  17 #define MPC8XX_PLPRCR (0x284/4) /* PLL and Reset Control Register */
  18
  19 /* Return system clock from crystal frequency */
  20 u32 mpc885_get_clock(u32 crystal)
  21 {
  22         u32 *immr;
  23         u32 plprcr;
  24         int mfi, mfn, mfd, pdf;
  25         u32 ret;
  26
  27         immr = fsl_get_immr();
  28         if (!immr) {
  29                 printf("mpc885_get_clock: Couldn't get IMMR base.\r\n");
  30                 return 0;
  31         }
  32
  33         plprcr = in_be32(&immr[MPC8XX_PLPRCR]);
  34
  35         mfi = (plprcr >> 16) & 15;
  36         if (mfi < 5) {
  37                 printf("Warning: PLPRCR[MFI] value of %d out-of-bounds\r\n",
  38                        mfi);
  39                 mfi = 5;
  40         }
  41
  42         pdf = (plprcr >> 1) & 0xf;
  43         mfd = (plprcr >> 22) & 0x1f;
  44         mfn = (plprcr >> 27) & 0x1f;
  45
  46         ret = crystal * mfi;
  47
  48         if (mfn != 0)
  49                 ret += crystal * mfn / (mfd + 1);
  50
  51         return ret / (pdf + 1);
  52 }
  53
  54 /* Set common device tree fields based on the given clock frequencies. */
  55 void mpc8xx_set_clocks(u32 sysclk)
  56 {
  57         void *node;
  58
  59         dt_fixup_cpu_clocks(sysclk, sysclk / 16, sysclk);
  60
  61         node = finddevice("/soc/cpm");
  62         if (node)
  63                 setprop(node, "clock-frequency", &sysclk, 4);
  64
  65         node = finddevice("/soc/cpm/brg");
  66         if (node)
  67                 setprop(node, "clock-frequency", &sysclk, 4);
  68 }
  69
  70 int mpc885_fixup_clocks(u32 crystal)
  71 {
  72         u32 sysclk = mpc885_get_clock(crystal);
  73         if (!sysclk)
  74                 return 0;
  75
  76         mpc8xx_set_clocks(sysclk);
  77         return 1;
  78 }