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>

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);