u-boot/lib_blackfin/clocks.c
Mike Frysinger 40599239e7 Blackfin: cache core/system clock values
Calculating the clocks requires a bit of calls to gcc math functions, so
cache the values after the first run since they'll most likely never
change once U-Boot is up and running.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
2009-02-02 12:24:42 -05:00

77 lines
1.5 KiB
C

/*
* clocks.c - figure out sclk/cclk/vco and such
*
* Copyright (c) 2005-2008 Analog Devices Inc.
*
* Licensed under the GPL-2 or later.
*/
#include <common.h>
#include <asm/blackfin.h>
/* Get the voltage input multiplier */
static u_long cached_vco_pll_ctl, cached_vco;
u_long get_vco(void)
{
u_long msel;
u_long pll_ctl = bfin_read_PLL_CTL();
if (pll_ctl == cached_vco_pll_ctl)
return cached_vco;
else
cached_vco_pll_ctl = pll_ctl;
msel = (pll_ctl >> 9) & 0x3F;
if (0 == msel)
msel = 64;
cached_vco = CONFIG_CLKIN_HZ;
cached_vco >>= (1 & pll_ctl); /* DF bit */
cached_vco *= msel;
return cached_vco;
}
/* Get the Core clock */
static u_long cached_cclk_pll_div, cached_cclk;
u_long get_cclk(void)
{
u_long csel, ssel;
if (bfin_read_PLL_STAT() & 0x1)
return CONFIG_CLKIN_HZ;
ssel = bfin_read_PLL_DIV();
if (ssel == cached_cclk_pll_div)
return cached_cclk;
else
cached_cclk_pll_div = ssel;
csel = ((ssel >> 4) & 0x03);
ssel &= 0xf;
if (ssel && ssel < (1 << csel)) /* SCLK > CCLK */
cached_cclk = get_vco() / ssel;
else
cached_cclk = get_vco() >> csel;
return cached_cclk;
}
/* Get the System clock */
static u_long cached_sclk_pll_div, cached_sclk;
u_long get_sclk(void)
{
u_long ssel;
if (bfin_read_PLL_STAT() & 0x1)
return CONFIG_CLKIN_HZ;
ssel = bfin_read_PLL_DIV();
if (ssel == cached_sclk_pll_div)
return cached_sclk;
else
cached_sclk_pll_div = ssel;
ssel &= 0xf;
cached_sclk = get_vco() / ssel;
return cached_sclk;
}