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authorMike Frysinger <vapier.adi@gmail.com>2008-07-26 18:52:56 +0800
committerBryan Wu <cooloney@kernel.org>2008-07-26 18:52:56 +0800
commit3a2521fa75359450f5ec7e6b76847f933b7ee680 (patch)
treee423ec0bd00a670593e557a30a45fe26350f6e50 /arch
parent377d43e7d07fc9a64eb162c6f70e6d1961604629 (diff)
downloadblackbird-op-linux-3a2521fa75359450f5ec7e6b76847f933b7ee680.tar.gz
blackbird-op-linux-3a2521fa75359450f5ec7e6b76847f933b7ee680.zip
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/blackfin/kernel/setup.c44
1 files changed, 34 insertions, 10 deletions
diff --git a/arch/blackfin/kernel/setup.c b/arch/blackfin/kernel/setup.c
index 102a9db98559..5a455b6bb542 100644
--- a/arch/blackfin/kernel/setup.c
+++ b/arch/blackfin/kernel/setup.c
@@ -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);
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