On 09/26/2011 01:40 PM, Jamie Iles wrote:

Hi Rob,

On Mon, Sep 26, 2011 at 01:33:08PM -0500, Rob Herring wrote:

quoted

Mike,

On 09/22/2011 05:26 PM, Mike Turquette wrote:

quoted

From: Jeremy Kerr <redacted>

Signed-off-by: Jeremy Kerr <redacted>
Signed-off-by: Mark Brown <redacted>
Signed-off-by: Jamie Iles <redacted>
Signed-off-by: Mike Turquette <redacted>
---
Changes since v1:
Add copyright header
Fold in Jamie's patch for set-to-disable clks
Use BIT macro instead of shift

 drivers/clk/Kconfig    |    4 ++
 drivers/clk/Makefile   |    1 +
 drivers/clk/clk-gate.c |   78 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/clk.h    |   13 ++++++++
 4 files changed, 96 insertions(+), 0 deletions(-)
 create mode 100644 drivers/clk/clk-gate.c

diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index d8313d7..a78967c 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig

@@ -12,3 +12,7 @@ config GENERIC_CLK
 config GENERIC_CLK_FIXED
 	bool
 	depends on GENERIC_CLK
+
+config GENERIC_CLK_GATE
+	bool
+	depends on GENERIC_CLK

diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 9a3325a..d186446 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile

@@ -2,3 +2,4 @@
 obj-$(CONFIG_CLKDEV_LOOKUP)	+= clkdev.o
 obj-$(CONFIG_GENERIC_CLK)	+= clk.o
 obj-$(CONFIG_GENERIC_CLK_FIXED)	+= clk-fixed.o
+obj-$(CONFIG_GENERIC_CLK_GATE)	+= clk-gate.o

diff --git a/drivers/clk/clk-gate.c b/drivers/clk/clk-gate.c
new file mode 100644
index 0000000..a1d8e79
--- /dev/null
+++ b/drivers/clk/clk-gate.c

@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Simple clk gate implementation
+ */
+
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <asm/io.h>

use linux/io.h

quoted

+
+#define to_clk_gate(clk) container_of(clk, struct clk_gate, hw)
+
+static unsigned long clk_gate_get_rate(struct clk_hw *clk)
+{
+	return clk_get_rate(clk_get_parent(clk->clk));
+}
+
+static void clk_gate_set_bit(struct clk_hw *clk)
+{
+	struct clk_gate *gate = to_clk_gate(clk);
+	u32 reg;
+
+	reg = __raw_readl(gate->reg);
+	reg |= BIT(gate->bit_idx);
+	__raw_writel(reg, gate->reg);

Don't these read-mod-writes need a spinlock around it?

It's possible to have an enable bits and dividers in the same register.
If you did a set_rate and while doing an enable/disable, there would be
a problem. Also, it may be 2 different clocks in the same register, so
the spinlock needs to be shared and not per clock.

Well the prepare lock will be held here and I believe that would be 
sufficient.

No, the enable spinlock is protecting enable/disable. But set_rate is
protected by the prepare mutex. So you clearly don't need locking if you
have a register of only 1 bit enables. If you have a register accessed
by both enable/disable and prepare/unprepare/set_rate, then you need
some protection.

quoted

quoted

+}
+
+static void clk_gate_clear_bit(struct clk_hw *clk)
+{
+	struct clk_gate *gate = to_clk_gate(clk);
+	u32 reg;
+
+	reg = __raw_readl(gate->reg);
+	reg &= ~BIT(gate->bit_idx);
+	__raw_writel(reg, gate->reg);
+}
+
+static int clk_gate_enable_set(struct clk_hw *clk)
+{
+	clk_gate_set_bit(clk);
+
+	return 0;
+}
+
+static void clk_gate_disable_clear(struct clk_hw *clk)
+{
+	clk_gate_clear_bit(clk);
+}
+
+struct clk_hw_ops clk_gate_set_enable_ops = {

const?

Yup.

quoted

quoted

+	.recalc_rate = clk_gate_get_rate,
+	.enable = clk_gate_enable_set,
+	.disable = clk_gate_disable_clear,
+};
+EXPORT_SYMBOL_GPL(clk_gate_set_enable_ops);
+
+static int clk_gate_enable_clear(struct clk_hw *clk)
+{
+	clk_gate_clear_bit(clk);
+
+	return 0;
+}
+
+static void clk_gate_disable_set(struct clk_hw *clk)
+{
+	clk_gate_set_bit(clk);
+}

Are these wrapper functions really needed? Just assign set_bit and
clear_bit functions directly to the ops structs. Only the ops struct
name is exposed to the user.

I used the wrappers because the .enable method has to return an int, but 
the disable needs to return void.  It's either that or open code the 
set/clear in each.

Okay. I missed that detail...

Rob