[PATCH] sh: Simplistic clock framework

This adds a relatively simplistic clock framework for sh.  The initial goal
behind this is to clean up the arch/sh/kernel/time.c mess and to get the CPU
subtype-specific frequency setting and calculation code moved somewhere more
sensible.

This only deals with the core clocks at the moment, though it's trivial for
other drivers to define their own clocks as desired.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 179 insertions, 0 deletions

diff --git a/arch/sh/kernel/cpu/sh4/clock-sh4-202.c b/arch/sh/kernel/cpu/sh4/clock-sh4-202.c
new file mode 100644
index 00000000000..bfdf5fe8d94
--- /dev/null
+++ b/arch/sh/kernel/cpu/sh4/clock-sh4-202.c
@@ -0,0 +1,179 @@
+/*
+ * arch/sh/kernel/cpu/sh4/clock-sh4-202.c
+ *
+ * Additional SH4-202 support for the clock framework
+ *
+ *  Copyright (C) 2005  Paul Mundt
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <asm/clock.h>
+#include <asm/freq.h>
+#include <asm/io.h>
+
+#define CPG2_FRQCR3	0xfe0a0018
+
+static int frqcr3_divisors[] = { 1, 2, 3, 4, 6, 8, 16 };
+static int frqcr3_values[]   = { 0, 1, 2, 3, 4, 5, 6  };
+
+static void emi_clk_recalc(struct clk *clk)
+{
+	int idx = ctrl_inl(CPG2_FRQCR3) & 0x0007;
+	clk->rate = clk->parent->rate / frqcr3_divisors[idx];
+}
+
+static inline int frqcr3_lookup(struct clk *clk, unsigned long rate)
+{
+	int divisor = clk->parent->rate / rate;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(frqcr3_divisors); i++)
+		if (frqcr3_divisors[i] == divisor)
+			return frqcr3_values[i];
+
+	/* Safe fallback */
+	return 5;
+}
+
+static struct clk_ops sh4202_emi_clk_ops = {
+	.recalc		= emi_clk_recalc,
+};
+
+static struct clk sh4202_emi_clk = {
+	.name		= "emi_clk",
+	.flags		= CLK_ALWAYS_ENABLED,
+	.ops		= &sh4202_emi_clk_ops,
+};
+
+static void femi_clk_recalc(struct clk *clk)
+{
+	int idx = (ctrl_inl(CPG2_FRQCR3) >> 3) & 0x0007;
+	clk->rate = clk->parent->rate / frqcr3_divisors[idx];
+}
+
+static struct clk_ops sh4202_femi_clk_ops = {
+	.recalc		= femi_clk_recalc,
+};
+
+static struct clk sh4202_femi_clk = {
+	.name		= "femi_clk",
+	.flags		= CLK_ALWAYS_ENABLED,
+	.ops		= &sh4202_femi_clk_ops,
+};
+
+static void shoc_clk_init(struct clk *clk)
+{
+	int i;
+
+	/*
+	 * For some reason, the shoc_clk seems to be set to some really
+	 * insane value at boot (values outside of the allowable frequency
+	 * range for instance). We deal with this by scaling it back down
+	 * to something sensible just in case.
+	 *
+	 * Start scaling from the high end down until we find something
+	 * that passes rate verification..
+	 */
+	for (i = 0; i < ARRAY_SIZE(frqcr3_divisors); i++) {
+		int divisor = frqcr3_divisors[i];
+
+		if (clk->ops->set_rate(clk, clk->parent->rate / divisor) == 0)
+			break;
+	}
+
+	WARN_ON(i == ARRAY_SIZE(frqcr3_divisors));	/* Undefined clock */
+}
+
+static void shoc_clk_recalc(struct clk *clk)
+{
+	int idx = (ctrl_inl(CPG2_FRQCR3) >> 6) & 0x0007;
+	clk->rate = clk->parent->rate / frqcr3_divisors[idx];
+}
+
+static int shoc_clk_verify_rate(struct clk *clk, unsigned long rate)
+{
+	struct clk *bclk = clk_get("bus_clk");
+	unsigned long bclk_rate = clk_get_rate(bclk);
+
+	clk_put(bclk);
+
+	if (rate > bclk_rate)
+		return 1;
+	if (rate > 66000000)
+		return 1;
+
+	return 0;
+}
+
+static int shoc_clk_set_rate(struct clk *clk, unsigned long rate)
+{
+	unsigned long frqcr3;
+	unsigned int tmp;
+
+	/* Make sure we have something sensible to switch to */
+	if (shoc_clk_verify_rate(clk, rate) != 0)
+		return -EINVAL;
+
+	tmp = frqcr3_lookup(clk, rate);
+
+	frqcr3 = ctrl_inl(CPG2_FRQCR3);
+	frqcr3 &= ~(0x0007 << 6);
+	frqcr3 |= tmp << 6;
+	ctrl_outl(frqcr3, CPG2_FRQCR3);
+
+	clk->rate = clk->parent->rate / frqcr3_divisors[tmp];
+
+	return 0;
+}
+
+static struct clk_ops sh4202_shoc_clk_ops = {
+	.init		= shoc_clk_init,
+	.recalc		= shoc_clk_recalc,
+	.set_rate	= shoc_clk_set_rate,
+};
+
+static struct clk sh4202_shoc_clk = {
+	.name		= "shoc_clk",
+	.flags		= CLK_ALWAYS_ENABLED,
+	.ops		= &sh4202_shoc_clk_ops,
+};
+
+static struct clk *sh4202_onchip_clocks[] = {
+	&sh4202_emi_clk,
+	&sh4202_femi_clk,
+	&sh4202_shoc_clk,
+};
+
+static int __init sh4202_clk_init(void)
+{
+	struct clk *clk = clk_get("master_clk");
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(sh4202_onchip_clocks); i++) {
+		struct clk *clkp = sh4202_onchip_clocks[i];
+
+		clkp->parent = clk;
+		clk_register(clkp);
+		clk_enable(clkp);
+	}
+
+	/*
+	 * Now that we have the rest of the clocks registered, we need to
+	 * force the parent clock to propagate so that these clocks will
+	 * automatically figure out their rate. We cheat by handing the
+	 * parent clock its current rate and forcing child propagation.
+	 */
+	clk_set_rate(clk, clk_get_rate(clk));
+
+	clk_put(clk);
+
+	return 0;
+}
+
+arch_initcall(sh4202_clk_init);
+