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Blackfin arch: cache the values of vco/sclk/cclk as the overhead of doing so (~24 bytes) is worth avoiding the software mult/div routines 

Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
This commit is contained in:
Mike Frysinger 2008-07-26 18:52:56 +08:00 committed by Bryan Wu
parent 377d43e7d0
commit 3a2521fa75
1 changed files with 34 additions and 10 deletions
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44
arch/blackfin/kernel/setup.c
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@ -850,38 +850,55 @@ static int __init topology_init(void)
subsys_initcall(topology_init);
/* Get the voltage input multiplier */
static u_long cached_vco_pll_ctl, cached_vco;
static u_long get_vco(void)
{
u_long msel;
u_long vco;
msel = (bfin_read_PLL_CTL() >> 9) & 0x3F;
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;
vco = CONFIG_CLKIN_HZ;
vco >>= (1 & bfin_read_PLL_CTL()); /* DF bit */
vco = msel * vco;
return vco;
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 */
return get_vco() / ssel;
return get_vco() >> csel;
cached_cclk = get_vco() / ssel;
else
cached_cclk = get_vco() >> csel;
return cached_cclk;
}
EXPORT_SYMBOL(get_cclk);
/* Get the System clock */
static u_long cached_sclk_pll_div, cached_sclk;
u_long get_sclk(void)
{
u_long ssel;
@ -889,13 +906,20 @@ u_long get_sclk(void)
if (bfin_read_PLL_STAT() & 0x1)
return CONFIG_CLKIN_HZ;
ssel = (bfin_read_PLL_DIV() & 0xf);
ssel = bfin_read_PLL_DIV();
if (ssel == cached_sclk_pll_div)
return cached_sclk;
else
cached_sclk_pll_div = ssel;
ssel &= 0xf;
if (0 == ssel) {
printk(KERN_WARNING "Invalid System Clock\n");
ssel = 1;
}
return get_vco() / ssel;
cached_sclk = get_vco() / ssel;
return cached_sclk;
}
EXPORT_SYMBOL(get_sclk);