[PATCH v2 0/5] clk: dt: bindings for mux, divider & gate clocks

[PATCH v2 0/5] clk: dt: bindings for mux, divider & gate clocks

[Mike Turquette]

This series introduces binding definitions for common register-mapped
clock multiplexer, divider and gate IP blocks along with the
corresponding setup functions for matching DT data.  The bindings are
similar to the struct definitions but please don't hold that against the
binding: the struct definitions closely model the hardware register
layout.

This version incorporates review comments from the last RFC and includes
the basic gate clock as well. This version is not considered RFC and
hopefully can be agreed upon for 3.11, review comments notwithstanding.

Also this second version of the series converts the divider
implementation to use a bitmask internally. The registration APIs are
not changed so existing users are not affected. This gives us a cleaner
binding and a more flexible representation for more exotic hardware
designs.

I'm currently looking at the best way to match and setup these basic
clocks without requiring every platform to write a small clock driver
that matches the basic types. That is missing from this series but can
be merged later as a separate change.

Testing was done on OMAP4460 Panda ES using the experimental out-of-tree
OMAP CCF conversion patches posted recently.

Heiko, enough changed here such that I did not keep your Acked-by's and
Tested-by's. But I am happy to take them again :-)

Mike Turquette (5):
  clk: divider: replace bitfield width with mask
  clk: of: helper for determining number of parent clocks
  clk: dt: binding for basic multiplexer clock
  clk: dt: binding for basic divider clock
  clk: dt: binding for basic gate clock

 .../devicetree/bindings/clock/divider-clock.txt    |  87 +++++++++++++++
 .../devicetree/bindings/clock/gate-clock.txt       |  34 ++++++
 .../devicetree/bindings/clock/mux-clock.txt        |  77 +++++++++++++
 arch/arm/mach-imx/clk-busy.c                       |   2 +-
 drivers/clk/clk-divider.c                          | 121 ++++++++++++++++++---
 drivers/clk/clk-gate.c                             |  40 +++++++
 drivers/clk/clk-mux.c                              |  62 ++++++++++-
 drivers/clk/clk.c                                  |   6 +
 drivers/clk/mxs/clk-div.c                          |   2 +-
 include/linux/clk-private.h                        |   2 +-
 include/linux/clk-provider.h                       |  12 +-
 11 files changed, 422 insertions(+), 23 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/clock/divider-clock.txt
 create mode 100644 Documentation/devicetree/bindings/clock/gate-clock.txt
 create mode 100644 Documentation/devicetree/bindings/clock/mux-clock.txt

-- 
1.8.1.2

[PATCH v2 1/5] clk: divider: replace bitfield width with mask

[Mike Turquette]

The forthcoming Device Tree binding for the divider clock type will use
a bitfield mask instead of bitfield width, which is what the current
basic divider implementation uses.

This patch replaces the u8 width in struct clk_divider with a u32 mask.
The divider code is updated to use the bit mask internally but the two
registration functions still accept the width to maintain compatibility
with existing users.

Also updated in this patch is the clk-private.h divider macro and two
Freescale clock divider implementations that are based on struct
clk_divider.

Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
---
No change since v1, new patch

 arch/arm/mach-imx/clk-busy.c |  2 +-
 drivers/clk/clk-divider.c    | 31 +++++++++++++++----------------
 drivers/clk/mxs/clk-div.c    |  2 +-
 include/linux/clk-private.h  |  2 +-
 include/linux/clk-provider.h |  2 +-
 5 files changed, 19 insertions(+), 20 deletions(-)

diff --git a/arch/arm/mach-imx/clk-busy.c b/arch/arm/mach-imx/clk-busy.c
index 4bb1bc4..bc88e38 100644
--- a/arch/arm/mach-imx/clk-busy.c
+++ b/arch/arm/mach-imx/clk-busy.c
@@ -95,7 +95,7 @@ struct clk *imx_clk_busy_divider(const char *name, const char *parent_name,
 
 	busy->div.reg = reg;
 	busy->div.shift = shift;
-	busy->div.width = width;
+	busy->div.mask = BIT(width) - 1;
 	busy->div.lock = &imx_ccm_lock;
 	busy->div_ops = &clk_divider_ops;
 
diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
index 6d55eb2..ac9cb7f 100644
--- a/drivers/clk/clk-divider.c
+++ b/drivers/clk/clk-divider.c
@@ -30,8 +30,6 @@
 
 #define to_clk_divider(_hw) container_of(_hw, struct clk_divider, hw)
 
-#define div_mask(d)	((1 << ((d)->width)) - 1)
-
 static unsigned int _get_table_maxdiv(const struct clk_div_table *table)
 {
 	unsigned int maxdiv = 0;
@@ -46,12 +44,12 @@ static unsigned int _get_table_maxdiv(const struct clk_div_table *table)
 static unsigned int _get_maxdiv(struct clk_divider *divider)
 {
 	if (divider->flags & CLK_DIVIDER_ONE_BASED)
-		return div_mask(divider);
+		return divider->mask;
 	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
-		return 1 << div_mask(divider);
+		return 1 << divider->mask;
 	if (divider->table)
 		return _get_table_maxdiv(divider->table);
-	return div_mask(divider) + 1;
+	return divider->mask + 1;
 }
 
 static unsigned int _get_table_div(const struct clk_div_table *table,
@@ -105,7 +103,7 @@ static unsigned long clk_divider_recalc_rate(struct clk_hw *hw,
 	unsigned int div, val;
 
 	val = readl(divider->reg) >> divider->shift;
-	val &= div_mask(divider);
+	val &= divider->mask;
 
 	div = _get_div(divider, val);
 	if (!div) {
@@ -221,17 +219,17 @@ static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
 	div = parent_rate / rate;
 	value = _get_val(divider, div);
 
-	if (value > div_mask(divider))
-		value = div_mask(divider);
+	if (value > divider->mask)
+		value = divider->mask;
 
 	if (divider->lock)
 		spin_lock_irqsave(divider->lock, flags);
 
 	if (divider->flags & CLK_DIVIDER_HIWORD_MASK) {
-		val = div_mask(divider) << (divider->shift + 16);
+		val = divider->mask << (divider->shift + 16);
 	} else {
 		val = readl(divider->reg);
-		val &= ~(div_mask(divider) << divider->shift);
+		val &= ~(divider->mask << divider->shift);
 	}
 	val |= value << divider->shift;
 	writel(val, divider->reg);
@@ -251,7 +249,7 @@ EXPORT_SYMBOL_GPL(clk_divider_ops);
 
 static struct clk *_register_divider(struct device *dev, const char *name,
 		const char *parent_name, unsigned long flags,
-		void __iomem *reg, u8 shift, u8 width,
+		void __iomem *reg, u8 shift, u32 mask,
 		u8 clk_divider_flags, const struct clk_div_table *table,
 		spinlock_t *lock)
 {
@@ -260,8 +258,9 @@ static struct clk *_register_divider(struct device *dev, const char *name,
 	struct clk_init_data init;
 
 	if (clk_divider_flags & CLK_DIVIDER_HIWORD_MASK) {
-		if (width + shift > 16) {
-			pr_warn("divider value exceeds LOWORD field\n");
+		if ((mask << shift) & 0xffff0000) {
+			pr_warn("%s: divider value exceeds LOWORD field\n",
+					__func__);
 			return ERR_PTR(-EINVAL);
 		}
 	}
@@ -282,7 +281,7 @@ static struct clk *_register_divider(struct device *dev, const char *name,
 	/* struct clk_divider assignments */
 	div->reg = reg;
 	div->shift = shift;
-	div->width = width;
+	div->mask = mask;
 	div->flags = clk_divider_flags;
 	div->lock = lock;
 	div->hw.init = &init;
@@ -315,7 +314,7 @@ struct clk *clk_register_divider(struct device *dev, const char *name,
 		u8 clk_divider_flags, spinlock_t *lock)
 {
 	return _register_divider(dev, name, parent_name, flags, reg, shift,
-			width, clk_divider_flags, NULL, lock);
+			((1 << width) - 1), clk_divider_flags, NULL, lock);
 }
 
 /**
@@ -339,5 +338,5 @@ struct clk *clk_register_divider_table(struct device *dev, const char *name,
 		spinlock_t *lock)
 {
 	return _register_divider(dev, name, parent_name, flags, reg, shift,
-			width, clk_divider_flags, table, lock);
+			((1 << width) - 1), clk_divider_flags, table, lock);
 }
diff --git a/drivers/clk/mxs/clk-div.c b/drivers/clk/mxs/clk-div.c
index 90e1da9..af2428e 100644
--- a/drivers/clk/mxs/clk-div.c
+++ b/drivers/clk/mxs/clk-div.c
@@ -96,7 +96,7 @@ struct clk *mxs_clk_div(const char *name, const char *parent_name,
 
 	div->divider.reg = reg;
 	div->divider.shift = shift;
-	div->divider.width = width;
+	div->divider.mask = BIT(width) - 1;
 	div->divider.flags = CLK_DIVIDER_ONE_BASED;
 	div->divider.lock = &mxs_lock;
 	div->divider.hw.init = &init;
diff --git a/include/linux/clk-private.h b/include/linux/clk-private.h
index dd7adff..67a3069 100644
--- a/include/linux/clk-private.h
+++ b/include/linux/clk-private.h
@@ -119,7 +119,7 @@ struct clk {
 		},						\
 		.reg = _reg,					\
 		.shift = _shift,				\
-		.width = _width,				\
+		.mask = ((1 << _width) - 1),			\
 		.flags = _divider_flags,			\
 		.table = _table,				\
 		.lock = _lock,					\
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 1ec14a7..4920fd1 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -271,7 +271,7 @@ struct clk_divider {
 	struct clk_hw	hw;
 	void __iomem	*reg;
 	u8		shift;
-	u8		width;
+	u32		mask;
 	u8		flags;
 	const struct clk_div_table	*table;
 	spinlock_t	*lock;
-- 
1.8.1.2

[PATCH v2 1/5] clk: divider: replace bitfield width with mask

[Shawn Guo]

On Sun, Jun 16, 2013 at 07:58:21PM -0700, Mike Turquette wrote:
> The forthcoming Device Tree binding for the divider clock type will use
> a bitfield mask instead of bitfield width, which is what the current
> basic divider implementation uses.
> 
> This patch replaces the u8 width in struct clk_divider with a u32 mask.
> The divider code is updated to use the bit mask internally but the two
> registration functions still accept the width to maintain compatibility
> with existing users.
> 
> Also updated in this patch is the clk-private.h divider macro and two
> Freescale clock divider implementations that are based on struct
> clk_divider.
> 
> Cc: Sascha Hauer <kernel@pengutronix.de>
> Cc: Shawn Guo <shawn.guo@linaro.org>
> Signed-off-by: Mike Turquette <mturquette@linaro.org>
> ---
> No change since v1, new patch
> 
>  arch/arm/mach-imx/clk-busy.c |  2 +-
>  drivers/clk/clk-divider.c    | 31 +++++++++++++++----------------
>  drivers/clk/mxs/clk-div.c    |  2 +-
>  include/linux/clk-private.h  |  2 +-
>  include/linux/clk-provider.h |  2 +-
>  5 files changed, 19 insertions(+), 20 deletions(-)

On imx and mxs,

Tested-by: Shawn Guo <shawn.guo@linaro.org>

[PATCH v2 2/5] clk: of: helper for determining number of parent clocks

[Mike Turquette]

Walks the "clocks" array of parent clock phandles and returns the
number.

Signed-off-by: Mike Turquette <mturquette@linaro.org>
---
No change since v1

 drivers/clk/clk.c            | 6 ++++++
 include/linux/clk-provider.h | 1 +
 2 files changed, 7 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index edf3fe1..a9feab6 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2081,6 +2081,12 @@ struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec)
 	return clk;
 }
 
+int of_clk_get_parent_count(struct device_node *np)
+{
+	return of_count_phandle_with_args(np, "clocks", "#clock-cells");
+}
+EXPORT_SYMBOL_GPL(of_clk_get_parent_count);
+
 const char *of_clk_get_parent_name(struct device_node *np, int index)
 {
 	struct of_phandle_args clkspec;
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 4920fd1..8730cb9 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -457,6 +457,7 @@ void of_clk_del_provider(struct device_node *np);
 struct clk *of_clk_src_simple_get(struct of_phandle_args *clkspec,
 				  void *data);
 struct clk *of_clk_src_onecell_get(struct of_phandle_args *clkspec, void *data);
+int of_clk_get_parent_count(struct device_node *np);
 const char *of_clk_get_parent_name(struct device_node *np, int index);
 
 void of_clk_init(const struct of_device_id *matches);
-- 
1.8.1.2

[PATCH v2 3/5] clk: dt: binding for basic multiplexer clock

[Mike Turquette]

Device Tree binding for the basic clock multiplexer, plus the setup
function to register the clock.  Based on the existing fixed-clock
binding.

Includes minor beautification of clk-provider.h where some whitespace is
added and of_fixed_factor_clock_setup is relocated to maintain a
consistent style.

Signed-off-by: Mike Turquette <mturquette@linaro.org>
---
Changes since v1:
* pass shift value into clk_register_mux_table
* s/multiplexor/multiplexer/
* removed debug prints
* mask is u32, shift is u8
* DT property names use dashes instead of underscores
* DT property names are more verbose
* shift property is optional in binding and can be auto-generated from a
  full 32-bit mask

 .../devicetree/bindings/clock/mux-clock.txt        | 77 ++++++++++++++++++++++
 drivers/clk/clk-mux.c                              | 62 ++++++++++++++++-
 include/linux/clk-provider.h                       |  5 +-
 3 files changed, 142 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/clock/mux-clock.txt

diff --git a/Documentation/devicetree/bindings/clock/mux-clock.txt b/Documentation/devicetree/bindings/clock/mux-clock.txt
new file mode 100644
index 0000000..8fa370e
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/mux-clock.txt
@@ -0,0 +1,77 @@
+Binding for simple mux clock.
+
+This binding uses the common clock binding[1].  It assumes a
+register-mapped multiplexer with multiple input clock signals or
+parents, one of which can be selected as output.  This clock does not
+gate or adjust the parent rate via a divider or multiplier.
+
+By default the "clocks" property lists the parents in the same order
+as they are programmed into the regster.  E.g:
+
+	clocks = <&foo_clock>, <&bar_clock>, <&baz_clock>;
+
+results in programming the register as follows:
+
+register value		selected parent clock
+0			foo_clock
+1			bar_clock
+2			baz_clock
+
+Some clock controller IPs do not allow a value of zero to be programmed
+into the register, instead indexing begins at 1.  The optional property
+"index_one" modified the scheme as follows:
+
+register value		selected clock parent
+1			foo_clock
+2			bar_clock
+3			baz_clock
+
+Additionally an optional table of bit and parent pairs may be supplied
+like so:
+
+	table = <&foo_clock 0x0>, <&bar_clock, 0x2>, <&baz_clock, 0x4>;
+
+where the first value in the pair is the parent clock and the second
+value is the bitfield to be programmed into the register.
+
+The binding must provide the register to control the mux and the mask
+for the corresponding control bits.  Optionally the number of bits to
+shift that mask if necessary.  If the shift value is missing it is the
+same as supplying a zero shift.
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+Required properties:
+- compatible : shall be "mux-clock".
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : link phandles of parent clocks
+- reg : base address for register controlling adjustable mux
+- bit-mask : arbitrary bitmask for programming the adjustable mux
+
+Optional properties:
+- clock-output-names : From common clock binding.
+- table : array of integer pairs defining parents & bitfield values
+- bit-shift : number of bits to shift the bit-mask, defaults to
+  (ffs(mask) - 1) if not present
+- index-starts-at-one : valid input select programming starts at 1, not
+  zero
+
+Examples:
+	clock: clock at 4a008100 {
+		compatible = "mux-clock";
+		#clock-cells = <0>;
+		clocks = <&clock_foo>, <&clock_bar>, <&clock_baz>;
+		reg = <0x4a008100 0x4>
+		mask = <0x3>;
+		index_one;
+	};
+
+	clock: clock at 4a008100 {
+		#clock-cells = <0>;
+		compatible = "mux-clock";
+		clocks = <&clock_foo>, <&clock_bar>, <&clock_baz>;
+		reg = <0x4a008100 0x4>;
+		mask = <0x3>;
+		shift = <0>;
+		table = <&clock_foo 1>, <&clock_bar 2>, <&clock_baz 3>;
+	};
diff --git a/drivers/clk/clk-mux.c b/drivers/clk/clk-mux.c
index 614444c..a640228 100644
--- a/drivers/clk/clk-mux.c
+++ b/drivers/clk/clk-mux.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
  * Copyright (C) 2011 Richard Zhao, Linaro <richard.zhao@linaro.org>
- * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
+ * Copyright (C) 2011-2013 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
  *
  * 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
@@ -16,6 +16,8 @@
 #include <linux/slab.h>
 #include <linux/io.h>
 #include <linux/err.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
 
 /*
  * DOC: basic adjustable multiplexer clock that cannot gate
@@ -166,3 +168,61 @@ struct clk *clk_register_mux(struct device *dev, const char *name,
 				      flags, reg, shift, mask, clk_mux_flags,
 				      NULL, lock);
 }
+
+#ifdef CONFIG_OF
+/**
+ * of_mux_clk_setup() - Setup function for simple mux rate clock
+ */
+void of_mux_clk_setup(struct device_node *node)
+{
+	struct clk *clk;
+	const char *clk_name = node->name;
+	void __iomem *reg;
+	int num_parents;
+	const char **parent_names;
+	int i;
+	u8 clk_mux_flags = 0;
+	u32 mask = 0;
+	u8 shift = 0;
+
+	of_property_read_string(node, "clock-output-names", &clk_name);
+
+	num_parents = of_clk_get_parent_count(node);
+	if (num_parents < 1) {
+		pr_err("%s: mux-clock %s must have parent(s)\n",
+				__func__, node->name);
+		return;
+	}
+
+	parent_names = kzalloc((sizeof(char*) * num_parents),
+			GFP_KERNEL);
+
+	for (i = 0; i < num_parents; i++)
+		parent_names[i] = of_clk_get_parent_name(node, i);
+
+	reg = of_iomap(node, 0);
+
+	if (of_property_read_u32(node, "bit-mask", &mask)) {
+		pr_err("%s: missing bit-mask property for %s\n", __func__, node->name);
+		return;
+	}
+
+	if (of_property_read_u8(node, "bit-shift", &shift)) {
+		shift = __ffs(mask);
+		pr_debug("%s: bit-shift property defaults to 0x%x for %s\n",
+				__func__, shift, node->name);
+	}
+
+	if (of_property_read_bool(node, "index-starts-at-one"))
+		clk_mux_flags |= CLK_MUX_INDEX_ONE;
+
+	clk = clk_register_mux_table(NULL, clk_name, parent_names, num_parents,
+			0, reg, shift, mask, clk_mux_flags,
+			NULL, NULL);
+
+	if (!IS_ERR(clk))
+		of_clk_add_provider(node, of_clk_src_simple_get, clk);
+}
+EXPORT_SYMBOL_GPL(of_mux_clk_setup);
+CLK_OF_DECLARE(mux_clk, "mux-clock", of_mux_clk_setup);
+#endif
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 8730cb9..24a04b8 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -340,7 +340,7 @@ struct clk *clk_register_mux_table(struct device *dev, const char *name,
 		void __iomem *reg, u8 shift, u32 mask,
 		u8 clk_mux_flags, u32 *table, spinlock_t *lock);
 
-void of_fixed_factor_clk_setup(struct device_node *node);
+void of_mux_clk_setup(struct device_node *node);
 
 /**
  * struct clk_fixed_factor - fixed multiplier and divider clock
@@ -361,10 +361,13 @@ struct clk_fixed_factor {
 };
 
 extern struct clk_ops clk_fixed_factor_ops;
+
 struct clk *clk_register_fixed_factor(struct device *dev, const char *name,
 		const char *parent_name, unsigned long flags,
 		unsigned int mult, unsigned int div);
 
+void of_fixed_factor_clk_setup(struct device_node *node);
+
 /***
  * struct clk_composite - aggregate clock of mux, divider and gate clocks
  *
-- 
1.8.1.2

[PATCH v2 3/5] clk: dt: binding for basic multiplexer clock

[Heiko Stübner]

Am Montag, 17. Juni 2013, 04:58:23 schrieb Mike Turquette:
> Device Tree binding for the basic clock multiplexer, plus the setup
> function to register the clock.  Based on the existing fixed-clock
> binding.
> 
> Includes minor beautification of clk-provider.h where some whitespace is
> added and of_fixed_factor_clock_setup is relocated to maintain a
> consistent style.
> 
> Signed-off-by: Mike Turquette <mturquette@linaro.org>
> ---

> +void of_mux_clk_setup(struct device_node *node)
> +{
> +	struct clk *clk;
> +	const char *clk_name = node->name;
> +	void __iomem *reg;
> +	int num_parents;
> +	const char **parent_names;
> +	int i;
> +	u8 clk_mux_flags = 0;
> +	u32 mask = 0;
> +	u8 shift = 0;
> +
> +	of_property_read_string(node, "clock-output-names", &clk_name);
> +
> +	num_parents = of_clk_get_parent_count(node);
> +	if (num_parents < 1) {
> +		pr_err("%s: mux-clock %s must have parent(s)\n",
> +				__func__, node->name);
> +		return;
> +	}
> +
> +	parent_names = kzalloc((sizeof(char*) * num_parents),
> +			GFP_KERNEL);
> +
> +	for (i = 0; i < num_parents; i++)
> +		parent_names[i] = of_clk_get_parent_name(node, i);
> +
> +	reg = of_iomap(node, 0);
> +
> +	if (of_property_read_u32(node, "bit-mask", &mask)) {
> +		pr_err("%s: missing bit-mask property for %s\n", __func__, node-
>name);
> +		return;
> +	}
> +
> +	if (of_property_read_u8(node, "bit-shift", &shift)) {
> +		shift = __ffs(mask);
> +		pr_debug("%s: bit-shift property defaults to 0x%x for %s\n",
> +				__func__, shift, node->name);
> +	}

I'm not really sure if either I am or the code is doing something wrong.
For me here of_property_read_u8 is always setting shift to 0, with bit-shift 
values normally being <8>, <15> etc.

When I change the type of shift to u32 and use the corresponding 
of_property_read_u32 everything works fine.

And when I switch both function and var back to u8 again, it again reads 0 for 
everything.


For reference one of my muxes looks like:

		mux_uart2: mux-uart2 at 20000080 {
			compatible = "mux-clock";
			reg = <0x20000080 0x04>;
			clocks = <&clk_gates1 12>, <&dummy>, <&xin24m>;
			bit-mask = <0x3>;
			bit-shift = <8>;
			hiword-mask;
			#clock-cells = <0>;
		};

Same is of course also true for the divider-clock.


Very confused,
Heiko


> +
> +	if (of_property_read_bool(node, "index-starts-at-one"))
> +		clk_mux_flags |= CLK_MUX_INDEX_ONE;
> +
> +	clk = clk_register_mux_table(NULL, clk_name, parent_names, num_parents,
> +			0, reg, shift, mask, clk_mux_flags,
> +			NULL, NULL);
> +
> +	if (!IS_ERR(clk))
> +		of_clk_add_provider(node, of_clk_src_simple_get, clk);
> +}
> +EXPORT_SYMBOL_GPL(of_mux_clk_setup);
> +CLK_OF_DECLARE(mux_clk, "mux-clock", of_mux_clk_setup);
> +#endif
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index 8730cb9..24a04b8 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -340,7 +340,7 @@ struct clk *clk_register_mux_table(struct device *dev,
> const char *name, void __iomem *reg, u8 shift, u32 mask,
>  		u8 clk_mux_flags, u32 *table, spinlock_t *lock);
> 
> -void of_fixed_factor_clk_setup(struct device_node *node);
> +void of_mux_clk_setup(struct device_node *node);
> 
>  /**
>   * struct clk_fixed_factor - fixed multiplier and divider clock
> @@ -361,10 +361,13 @@ struct clk_fixed_factor {
>  };
> 
>  extern struct clk_ops clk_fixed_factor_ops;
> +
>  struct clk *clk_register_fixed_factor(struct device *dev, const char
> *name, const char *parent_name, unsigned long flags,
>  		unsigned int mult, unsigned int div);
> 
> +void of_fixed_factor_clk_setup(struct device_node *node);
> +
>  /***
>   * struct clk_composite - aggregate clock of mux, divider and gate clocks
>   *

[PATCH v2 3/5] clk: dt: binding for basic multiplexer clock

[Heiko Stübner]

Am Dienstag, 18. Juni 2013, 02:53:59 schrieb Heiko St?bner:
> Am Montag, 17. Juni 2013, 04:58:23 schrieb Mike Turquette:
> > Device Tree binding for the basic clock multiplexer, plus the setup
> > function to register the clock.  Based on the existing fixed-clock
> > binding.
> > 
> > Includes minor beautification of clk-provider.h where some whitespace is
> > added and of_fixed_factor_clock_setup is relocated to maintain a
> > consistent style.
> > 
> > Signed-off-by: Mike Turquette <mturquette@linaro.org>
> > ---
> > 
> > +void of_mux_clk_setup(struct device_node *node)
> > +{
> > +	struct clk *clk;
> > +	const char *clk_name = node->name;
> > +	void __iomem *reg;
> > +	int num_parents;
> > +	const char **parent_names;
> > +	int i;
> > +	u8 clk_mux_flags = 0;
> > +	u32 mask = 0;
> > +	u8 shift = 0;
> > +
> > +	of_property_read_string(node, "clock-output-names", &clk_name);
> > +
> > +	num_parents = of_clk_get_parent_count(node);
> > +	if (num_parents < 1) {
> > +		pr_err("%s: mux-clock %s must have parent(s)\n",
> > +				__func__, node->name);
> > +		return;
> > +	}
> > +
> > +	parent_names = kzalloc((sizeof(char*) * num_parents),
> > +			GFP_KERNEL);
> > +
> > +	for (i = 0; i < num_parents; i++)
> > +		parent_names[i] = of_clk_get_parent_name(node, i);
> > +
> > +	reg = of_iomap(node, 0);
> > +
> > +	if (of_property_read_u32(node, "bit-mask", &mask)) {
> > +		pr_err("%s: missing bit-mask property for %s\n", __func__, node-
> >
> >name);
> >
> > +		return;
> > +	}
> > +
> > +	if (of_property_read_u8(node, "bit-shift", &shift)) {
> > +		shift = __ffs(mask);
> > +		pr_debug("%s: bit-shift property defaults to 0x%x for %s\n",
> > +				__func__, shift, node->name);
> > +	}
> 
> I'm not really sure if either I am or the code is doing something wrong.
> For me here of_property_read_u8 is always setting shift to 0, with
> bit-shift values normally being <8>, <15> etc.
> 
> When I change the type of shift to u32 and use the corresponding
> of_property_read_u32 everything works fine.
> 
> And when I switch both function and var back to u8 again, it again reads 0
> for everything.
> 
> 
> For reference one of my muxes looks like:
> 
> 		mux_uart2: mux-uart2 at 20000080 {
> 			compatible = "mux-clock";
> 			reg = <0x20000080 0x04>;
> 			clocks = <&clk_gates1 12>, <&dummy>, <&xin24m>;
> 			bit-mask = <0x3>;
> 			bit-shift = <8>;
> 			hiword-mask;
> 			#clock-cells = <0>;
> 		};
> 
> Same is of course also true for the divider-clock.
> 

found the issue ... the same missing "/bits/ 8" mentioned in the divider 
review causes of_property_read_u8 to return wrong values.

So the binding example should probably include this, i.e.

			bit-shift = /bits/ 8 <6>;


Heiko

[PATCH v2 4/5] clk: dt: binding for basic divider clock

[Mike Turquette]

Devicetree binding for the basic clock divider, plus the setup function
to register the clock.  Based on the existing fixed-clock binding.

Signed-off-by: Mike Turquette <mturquette@linaro.org>
---
Changes since v1:
* mask is u32, shift is u8
* use bit mask instead of bitfield width
* DT property names use dashes instead of underscores
* DT property names are more verbose
* added minimum/maximum divider values to binding
* shift property is optional in binding and can be auto-generated from a
  full 32-bit mask

 .../devicetree/bindings/clock/divider-clock.txt    | 87 +++++++++++++++++++++
 drivers/clk/clk-divider.c                          | 90 +++++++++++++++++++++-
 include/linux/clk-provider.h                       |  2 +
 3 files changed, 178 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/devicetree/bindings/clock/divider-clock.txt

diff --git a/Documentation/devicetree/bindings/clock/divider-clock.txt b/Documentation/devicetree/bindings/clock/divider-clock.txt
new file mode 100644
index 0000000..96bea07
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/divider-clock.txt
@@ -0,0 +1,87 @@
+Binding for simple divider clock.
+
+This binding uses the common clock binding[1].  It assumes a
+register-mapped adjustable clock rate divider that does not gate and has
+only one input clock or parent.  By default the value programmed into
+the register is one less than the actual divisor value.  E.g:
+
+register value		actual divisor value
+0			1
+1			2
+2			3
+
+This assumption may be modified by the following optional properties:
+
+index-starts-at-one - valid divisor values start at 1, not the default
+of 0.  E.g:
+register value		actual divisor value
+1			1
+2			2
+3			3
+
+index-power-of-two - valid divisor values are powers of two.  E.g:
+register value		actual divisor value
+0			1
+1			2
+2			4
+
+index-allow-zero - same as index_one, but zero is divide-by-1.  E.g:
+register value		actual divisor value
+0			1
+1			1
+2			2
+
+Additionally a table of valid dividers may be supplied like so:
+
+	table = <4 0>, <8, 1>;
+
+where the first value in the pair is the divider and the second value is
+the programmed register bitfield.
+
+The binding must also provide the register to control the divider and
+the mask for the corresponding control bits.  Optionally the number of
+bits to shift that mask, if necessary.  If the shift value is missing it
+is the same as supplying a zero shift.
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+Required properties:
+- compatible : shall be "divider-clock".
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : link to phandle of parent clock
+- reg : base address for register controlling adjustable divider
+- bit-mask : arbitrary bitmask for programming the adjustable divider
+
+Optional properties:
+- clock-output-names : from common clock binding.
+- table : array of integer pairs defining divisors & bitfield values
+- bit-shift : number of bits to shift the bit-mask, defaults to
+  (ffs(mask) - 1) if not present
+- minimum-divider : min divisor for dividing the input clock rate, only
+  needed if the first divisor is offset from the default value
+- maximum-divider : max divisor for dividing the input clock rate, only
+  needed if the max divisor is less than (mask + 1).
+- index-starts-at-one : valid divisor programming starts at 1, not zero
+- index-power-of-two : valid divisor programming must be a power of two
+- index-allow-zero : implies index-one, and programming zero results in
+  divide-by-one
+
+Examples:
+	clock_foo: clock_foo at 4a008100 {
+		compatible = "divider-clock";
+		#clock-cells = <0>;
+		clocks = <&clock_baz>;
+		reg = <0x4a008100 0x4>
+		mask = <0x3>
+		maximum-divider = <3>
+	};
+
+	clock_bar: clock_bar at 4a008108 {
+		#clock-cells = <0>;
+		compatible = "divider-clock";
+		clocks = <&clock_foo>;
+		reg = <0x4a008108 0x4>;
+		mask = <0x1>;
+		shift = <0>;
+		table = < 4 0 >, < 8 1 >;
+	};
diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
index ac9cb7f..8c42c7f 100644
--- a/drivers/clk/clk-divider.c
+++ b/drivers/clk/clk-divider.c
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
  * Copyright (C) 2011 Richard Zhao, Linaro <richard.zhao@linaro.org>
- * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
+ * Copyright (C) 2011-2013 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
  *
  * 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
@@ -17,6 +17,8 @@
 #include <linux/err.h>
 #include <linux/string.h>
 #include <linux/log2.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
 
 /*
  * DOC: basic adjustable divider clock that cannot gate
@@ -340,3 +342,89 @@ struct clk *clk_register_divider_table(struct device *dev, const char *name,
 	return _register_divider(dev, name, parent_name, flags, reg, shift,
 			((1 << width) - 1), clk_divider_flags, table, lock);
 }
+
+#ifdef CONFIG_OF
+struct clk_div_table *of_clk_get_div_table(struct device_node *node)
+{
+	int i;
+	int table_size = 0;
+	struct clk_div_table *table;
+	u32 pair[2];
+
+	table_size = of_count_phandle_with_args(node, "table", "#clock-cells");
+
+	if (table_size < 1)
+		return NULL;
+
+	table = kzalloc(sizeof(struct clk_div_table) * table_size, GFP_KERNEL);
+	if (!table) {
+		pr_err("%s: unable to allocate memory for %s table\n", __func__, node->name);
+		return NULL;
+	}
+
+	for (i = 0; i < table_size; i++) {
+		if (!of_property_read_u32_array(node, "table", pair, ARRAY_SIZE(pair))) {
+			table[i].val = pair[0];
+			table[i].div = pair[1];
+		}
+	}
+
+	return table;
+}
+
+/**
+ * of_divider_clk_setup() - Setup function for simple div rate clock
+ */
+void of_divider_clk_setup(struct device_node *node)
+{
+	struct clk *clk;
+	const char *clk_name = node->name;
+	void __iomem *reg;
+	const char *parent_name;
+	u8 clk_divider_flags = 0;
+	u32 mask = 0;
+	u8 shift = 0;
+	struct clk_div_table *table;
+
+	of_property_read_string(node, "clock-output-names", &clk_name);
+
+	parent_name = of_clk_get_parent_name(node, 0);
+
+	reg = of_iomap(node, 0);
+
+	if (of_property_read_u32(node, "bit-mask", &mask)) {
+		pr_err("%s: missing bit-mask property for %s\n", __func__, node->name);
+		return;
+	}
+
+	if (of_property_read_u8(node, "bit-shift", &shift)) {
+		shift = __ffs(mask);
+		pr_debug("%s: bit-shift property defaults to 0x%x for %s\n",
+				__func__, shift, node->name);
+	}
+
+	if (of_property_read_bool(node, "index-starts-at-one"))
+		clk_divider_flags |= CLK_DIVIDER_ONE_BASED;
+
+	if (of_property_read_bool(node, "index-power-of-two"))
+		clk_divider_flags |= CLK_DIVIDER_POWER_OF_TWO;
+
+	if (of_property_read_bool(node, "index-allow-zero"))
+		clk_divider_flags |= CLK_DIVIDER_ALLOW_ZERO;
+
+	table = of_clk_get_div_table(node);
+	if (IS_ERR(table))
+		return;
+
+	clk = _register_divider(NULL, clk_name,
+			parent_name, 0,
+			reg, shift, mask,
+			clk_divider_flags, table,
+			NULL);
+
+	if (!IS_ERR(clk))
+		of_clk_add_provider(node, of_clk_src_simple_get, clk);
+}
+EXPORT_SYMBOL_GPL(of_divider_clk_setup);
+CLK_OF_DECLARE(divider_clk, "divider-clock", of_divider_clk_setup);
+#endif
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 24a04b8..723ce69 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -293,6 +293,8 @@ struct clk *clk_register_divider_table(struct device *dev, const char *name,
 		u8 clk_divider_flags, const struct clk_div_table *table,
 		spinlock_t *lock);
 
+void of_divider_clk_setup(struct device_node *node);
+
 /**
  * struct clk_mux - multiplexer clock
  *
-- 
1.8.1.2

[PATCH v2 4/5] clk: dt: binding for basic divider clock

[Heiko Stübner]

Hi Mike,

Am Montag, 17. Juni 2013, 04:58:24 schrieb Mike Turquette:
> Devicetree binding for the basic clock divider, plus the setup function
> to register the clock.  Based on the existing fixed-clock binding.
> 
> Signed-off-by: Mike Turquette <mturquette@linaro.org>
> ---
> Changes since v1:
> * mask is u32, shift is u8
> * use bit mask instead of bitfield width
> * DT property names use dashes instead of underscores
> * DT property names are more verbose
> * added minimum/maximum divider values to binding
> * shift property is optional in binding and can be auto-generated from a
>   full 32-bit mask
> 
>  .../devicetree/bindings/clock/divider-clock.txt    | 87
> +++++++++++++++++++++ drivers/clk/clk-divider.c                          |
> 90 +++++++++++++++++++++- include/linux/clk-provider.h                    
>   |  2 +
>  3 files changed, 178 insertions(+), 1 deletion(-)
>  create mode 100644
> Documentation/devicetree/bindings/clock/divider-clock.txt
> 
> diff --git a/Documentation/devicetree/bindings/clock/divider-clock.txt
> b/Documentation/devicetree/bindings/clock/divider-clock.txt new file mode
> 100644
> index 0000000..96bea07
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/divider-clock.txt
> @@ -0,0 +1,87 @@
> +Binding for simple divider clock.
> +
> +This binding uses the common clock binding[1].  It assumes a
> +register-mapped adjustable clock rate divider that does not gate and has
> +only one input clock or parent.  By default the value programmed into
> +the register is one less than the actual divisor value.  E.g:
> +
> +register value		actual divisor value
> +0			1
> +1			2
> +2			3
> +
> +This assumption may be modified by the following optional properties:
> +
> +index-starts-at-one - valid divisor values start at 1, not the default
> +of 0.  E.g:
> +register value		actual divisor value
> +1			1
> +2			2
> +3			3
> +
> +index-power-of-two - valid divisor values are powers of two.  E.g:
> +register value		actual divisor value
> +0			1
> +1			2
> +2			4
> +
> +index-allow-zero - same as index_one, but zero is divide-by-1.  E.g:
> +register value		actual divisor value
> +0			1
> +1			1
> +2			2
> +
> +Additionally a table of valid dividers may be supplied like so:
> +
> +	table = <4 0>, <8, 1>;
> +
> +where the first value in the pair is the divider and the second value is
> +the programmed register bitfield.

this doesn't match the current code that is taking the first as bit-value
and the second as divider.


> +
> +The binding must also provide the register to control the divider and
> +the mask for the corresponding control bits.  Optionally the number of
> +bits to shift that mask, if necessary.  If the shift value is missing it
> +is the same as supplying a zero shift.
> +
> +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
> +
> +Required properties:
> +- compatible : shall be "divider-clock".
> +- #clock-cells : from common clock binding; shall be set to 0.
> +- clocks : link to phandle of parent clock
> +- reg : base address for register controlling adjustable divider
> +- bit-mask : arbitrary bitmask for programming the adjustable divider
> +
> +Optional properties:
> +- clock-output-names : from common clock binding.
> +- table : array of integer pairs defining divisors & bitfield values
> +- bit-shift : number of bits to shift the bit-mask, defaults to
> +  (ffs(mask) - 1) if not present
> +- minimum-divider : min divisor for dividing the input clock rate, only
> +  needed if the first divisor is offset from the default value
> +- maximum-divider : max divisor for dividing the input clock rate, only
> +  needed if the max divisor is less than (mask + 1).
> +- index-starts-at-one : valid divisor programming starts at 1, not zero
> +- index-power-of-two : valid divisor programming must be a power of two
> +- index-allow-zero : implies index-one, and programming zero results in
> +  divide-by-one
> +
> +Examples:
> +	clock_foo: clock_foo at 4a008100 {
> +		compatible = "divider-clock";
> +		#clock-cells = <0>;
> +		clocks = <&clock_baz>;
> +		reg = <0x4a008100 0x4>
> +		mask = <0x3>
> +		maximum-divider = <3>
> +	};
> +
> +	clock_bar: clock_bar at 4a008108 {
> +		#clock-cells = <0>;
> +		compatible = "divider-clock";
> +		clocks = <&clock_foo>;
> +		reg = <0x4a008108 0x4>;
> +		mask = <0x1>;
> +		shift = <0>;
> +		table = < 4 0 >, < 8 1 >;
> +	};

the shift and mask properties should probably also get their "bit-" additions.

Also, if you really want to use the u8 as type, it seems like the property
must also get a "/bits/ 8" prefix, making it:

			bit-shift = /bits/ 8 <6>;

so the example should probably reflect this. Without this the
of_property_read_u8 returns wrong values.


> diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
> index ac9cb7f..8c42c7f 100644
> --- a/drivers/clk/clk-divider.c
> +++ b/drivers/clk/clk-divider.c
> @@ -1,7 +1,7 @@
>  /*
>   * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
>   * Copyright (C) 2011 Richard Zhao, Linaro <richard.zhao@linaro.org>
> - * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd
> <mturquette@linaro.org> + * Copyright (C) 2011-2013 Mike Turquette, Linaro
> Ltd <mturquette@linaro.org> *
>   * 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
> @@ -17,6 +17,8 @@
>  #include <linux/err.h>
>  #include <linux/string.h>
>  #include <linux/log2.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> 
>  /*
>   * DOC: basic adjustable divider clock that cannot gate
> @@ -340,3 +342,89 @@ struct clk *clk_register_divider_table(struct device
> *dev, const char *name, return _register_divider(dev, name, parent_name,
> flags, reg, shift, ((1 << width) - 1), clk_divider_flags, table, lock);
>  }
> +
> +#ifdef CONFIG_OF
> +struct clk_div_table *of_clk_get_div_table(struct device_node *node)
> +{
> +	int i;
> +	int table_size = 0;
> +	struct clk_div_table *table;
> +	u32 pair[2];
> +
> +	table_size = of_count_phandle_with_args(node, "table", "#clock-cells");

I don't really understand what this should do ... especially what are the "#clock-cells" doing there?

Of course the function also doesn't work for my
			table = <2 0>, <4 1>, <8 2>, <16 3>;
table.


> +
> +	if (table_size < 1)
> +		return NULL;
> +
> +	table = kzalloc(sizeof(struct clk_div_table) * table_size, GFP_KERNEL);
> +	if (!table) {
> +		pr_err("%s: unable to allocate memory for %s table\n", __func__,
> node->name); +		return NULL;
> +	}
> +
> +	for (i = 0; i < table_size; i++) {
> +		if (!of_property_read_u32_array(node, "table", pair, ARRAY_SIZE(pair)))

wouldn't this always read the same values? It does not seem to iterate thru all the table entries.



> { +			table[i].val = pair[0];
> +			table[i].div = pair[1];
> +		}
> +	}
> +
> +	return table;
> +}
> +

how about:

struct clk_div_table *of_clk_get_div_table(struct device_node *node)
{
	int i;
	int table_size = 0;
	struct clk_div_table *table;
	const __be32 *list;

	list = of_get_property(node, "table", &table_size);
	table_size /= sizeof(*list);

	if (table_size < 2 || table_size % 2)
		return NULL;

	table_size /= 2;

	table = kzalloc(sizeof(struct clk_div_table) * table_size, GFP_KERNEL);
	if (!table) {
		pr_err("%s: unable to allocate memory for %s table\n", __func__, node->name);
		return NULL;
	}

	for (i = 0; i < table_size; i++) {
		table[i].div = be32_to_cpu(*list++);
		table[i].val = be32_to_cpu(*list++);
	}

	return table;
}


Heiko

[PATCH v2 5/5] clk: dt: binding for basic gate clock

[Mike Turquette]

Device Tree binding for the basic clock gate, plus the setup function to
register the clock.  Based on the existing fixed-clock binding.

A different approach to this was proposed in 2012[1] and a similar
binding was proposed more recently[2] if anyone wants some extra
reading.

[1] http://article.gmane.org/gmane.linux.documentation/5679
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2012-December/137878.html

Signed-off-by: Mike Turquette <mturquette@linaro.org>
---
No change since v1, new patch

 .../devicetree/bindings/clock/gate-clock.txt       | 34 ++++++++++++++++++
 drivers/clk/clk-gate.c                             | 40 ++++++++++++++++++++++
 include/linux/clk-provider.h                       |  2 ++
 3 files changed, 76 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/gate-clock.txt

diff --git a/Documentation/devicetree/bindings/clock/gate-clock.txt b/Documentation/devicetree/bindings/clock/gate-clock.txt
new file mode 100644
index 0000000..4f1c776
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/gate-clock.txt
@@ -0,0 +1,34 @@
+Binding for simple gate clock.
+
+This binding uses the common clock binding[1].  It assumes a
+register-mapped clock gate controlled by a single bit that has only one
+input clock or parent.  By default setting the specified bit gates the
+clock signal and clearing the bit ungates it.
+
+The binding must provide the register to control the gate and the bit
+shift for the corresponding gate control bit. Some clocks set the bit to
+gate the clock signal, and clear it to ungate the clock signal. The
+optional "set-bit-to-disable" specifies this behavior.
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+Required properties:
+- compatible : shall be "gate-clock".
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : link to phandle of parent clock
+- reg : base address for register controlling adjustable gate
+- bit-shift : bit shift for programming the clock gate
+
+Optional properties:
+- clock-output-names : from common clock binding.
+- set-bit-to-disable : inverts default gate programming. Setting the bit
+  gates the clock and clearing the bit ungates the clock.
+
+Examples:
+	clock_foo: clock_foo at 4a008100 {
+		compatible = "gate-clock";
+		#clock-cells = <0>;
+		clocks = <&clock_bar>;
+		reg = <0x4a008100 0x4>
+		bit-shift = <3>
+	};
diff --git a/drivers/clk/clk-gate.c b/drivers/clk/clk-gate.c
index 790306e..3cbf54e 100644
--- a/drivers/clk/clk-gate.c
+++ b/drivers/clk/clk-gate.c
@@ -15,6 +15,8 @@
 #include <linux/io.h>
 #include <linux/err.h>
 #include <linux/string.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
 
 /**
  * DOC: basic gatable clock which can gate and ungate it's ouput
@@ -161,3 +163,41 @@ struct clk *clk_register_gate(struct device *dev, const char *name,
 
 	return clk;
 }
+
+#ifdef CONFIG_OF
+/**
+ * of_gate_clk_setup() - Setup function for simple gate rate clock
+ */
+void of_gate_clk_setup(struct device_node *node)
+{
+	struct clk *clk;
+	const char *clk_name = node->name;
+	void __iomem *reg;
+	const char *parent_name;
+	u8 clk_gate_flags = 0;
+	u8 bit_idx = 0;
+
+	of_property_read_string(node, "clock-output-names", &clk_name);
+
+	parent_name = of_clk_get_parent_name(node, 0);
+
+	reg = of_iomap(node, 0);
+
+	if (of_property_read_u8(node, "bit-shift", &bit_idx)) {
+		pr_err("%s: missing bit-shift property for %s\n",
+				__func__, node->name);
+		return;
+	}
+
+	if (of_property_read_bool(node, "set-bit-to-disable"))
+		clk_gate_flags |= CLK_GATE_SET_TO_DISABLE;
+
+	clk = clk_register_gate(NULL, clk_name, parent_name, 0, reg, bit_idx,
+			clk_gate_flags, NULL);
+
+	if (!IS_ERR(clk))
+		of_clk_add_provider(node, of_clk_src_simple_get, clk);
+}
+EXPORT_SYMBOL_GPL(of_gate_clk_setup);
+CLK_OF_DECLARE(gate_clk, "gate-clock", of_gate_clk_setup);
+#endif
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 723ce69..4aeaedb 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -232,6 +232,8 @@ struct clk *clk_register_gate(struct device *dev, const char *name,
 		void __iomem *reg, u8 bit_idx,
 		u8 clk_gate_flags, spinlock_t *lock);
 
+void of_gate_clk_setup(struct device_node *node);
+
 struct clk_div_table {
 	unsigned int	val;
 	unsigned int	div;
-- 
1.8.1.2