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 */
20u32 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(fmt: "mpc885_get_clock: Couldn't get IMMR base.\r\n");
30 return 0;
31 }
32
33 plprcr = in_be32(addr: &immr[MPC8XX_PLPRCR]);
34
35 mfi = (plprcr >> 16) & 15;
36 if (mfi < 5) {
37 printf(fmt: "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. */
55void mpc8xx_set_clocks(u32 sysclk)
56{
57 void *node;
58
59 dt_fixup_cpu_clocks(cpufreq: sysclk, tbfreq: sysclk / 16, busfreq: sysclk);
60
61 node = finddevice(name: "/soc/cpm");
62 if (node)
63 setprop(devp: node, name: "clock-frequency", buf: &sysclk, buflen: 4);
64
65 node = finddevice(name: "/soc/cpm/brg");
66 if (node)
67 setprop(devp: node, name: "clock-frequency", buf: &sysclk, buflen: 4);
68}
69
70int 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}
79

source code of linux/arch/powerpc/boot/mpc8xx.c