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>

1 files changed, 77 insertions, 0 deletions

diff --git a/lib_blackfin/clocks.c b/lib_blackfin/clocks.c
new file mode 100644
index 0000000..0be395b
--- /dev/null
+++ b/lib_blackfin/clocks.c
@@ -0,0 +1,77 @@
+/*
+ * 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;
+}