arm: tcc8k: Fix bus clock calculation

There are two dividers used to derive bus clock from system clock:
system clock is divided by SCKDIV+1, then by BCKDIV+1. SCKDIV divider
has been ignored up to now, which is no problem as long as it is 0.

Take SCKDIV into account for bus clock calculation.

Signed-off-by: Oskar Schirmer <oskar@linutronix.de>
Cc: bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 10 insertions, 3 deletions

diff --git a/arch/arm/mach-tcc8k/clock.c b/arch/arm/mach-tcc8k/clock.c
index 8d8c99f8955..e7cdae5c77a 100644
--- a/arch/arm/mach-tcc8k/clock.c
+++ b/arch/arm/mach-tcc8k/clock.c
@@ -308,10 +308,17 @@ static unsigned long get_rate_sys(struct clk *clk)
 
 static unsigned long get_rate_bus(struct clk *clk)
 {
-        unsigned int div;
+        unsigned int reg, sdiv, bdiv, rate;
 
-        div = (__raw_readl(CKC_BASE + CLKCTRL_OFFS) >> 4) & 0xff;
-        return get_rate_sys(clk) / (div + 1);
+        reg = __raw_readl(CKC_BASE + CLKCTRL_OFFS);
+        rate = get_rate_sys(clk);
+        sdiv = (reg >> 20) & 3;
+        if (sdiv)
+                rate /= sdiv + 1;
+        bdiv = (reg >> 4) & 0xff;
+        if (bdiv)
+                rate /= bdiv + 1;
+        return rate;
 }
 
 static unsigned long get_rate_cpu(struct clk *clk)