u-boot/arch/powerpc/cpu/mpc8xx/speed.c
Christophe Leroy 7a0a550c7f powerpc, 8xx: Simplify brgclk calculation and remove get_brgclk()
divider is calculated based on SCCR_DFBRG, with:
SCCR_DFBRG 00 => divider 1  = 1 << 0
SCCR_DFBRG 01 => divider 4  = 1 << 2
SCCR_DFBRG 10 => divider 16 = 1 << 4
SCCR_DFBRG 11 => divider 64 = 1 << 6

This can be easily converted to a single shift operation:
divider = 1 << (SCCR_DFBRG * 2)

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
2017-07-22 22:22:47 -04:00

44 lines
1 KiB
C

/*
* (C) Copyright 2000-2004
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <mpc8xx.h>
#include <asm/processor.h>
#include <asm/io.h>
DECLARE_GLOBAL_DATA_PTR;
/*
* get_clocks() fills in gd->cpu_clock depending on CONFIG_8xx_GCLK_FREQ
*/
int get_clocks(void)
{
uint immr = get_immr(0); /* Return full IMMR contents */
immap_t __iomem *immap = (immap_t __iomem *)(immr & 0xFFFF0000);
uint sccr = in_be32(&immap->im_clkrst.car_sccr);
uint divider = 1 << (((sccr & SCCR_DFBRG11) >> 11) * 2);
/*
* If for some reason measuring the gclk frequency won't
* work, we return the hardwired value.
* (For example, the cogent CMA286-60 CPU module has no
* separate oscillator for PITRTCLK)
*/
gd->cpu_clk = CONFIG_8xx_GCLK_FREQ;
if ((sccr & SCCR_EBDF11) == 0) {
/* No Bus Divider active */
gd->bus_clk = gd->cpu_clk;
} else {
/* The MPC8xx has only one BDF: half clock speed */
gd->bus_clk = gd->cpu_clk / 2;
}
gd->arch.brg_clk = gd->cpu_clk / divider;
return 0;
}