[PATCH v2 2/2] clk: add accuracy support for fixed clock

Boris BREZILLON
2013-11-27T12:47:30Z

This patch adds support for accuracy retrieval on fixed clocks.
It also adds a new dt property called 'clock-accuracy' to define the clock
accuracy.

This can be usefull for oscillator (RC, crystal, ...) definitions which are
always given an accuracy characteristic.

Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
---
.../devicetree/bindings/clock/fixed-clock.txt | 3 ++
drivers/clk/clk-fixed-rate.c | 43 +++++++++++++++++---
include/linux/clk-provider.h | 4 ++
3 files changed, 44 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/clock/fixed-clock.txt b/Documentation/devicetree/bindings/clock/fixed-clock.txt
index 0b1fe78..48ea0ad 100644
--- a/Documentation/devicetree/bindings/clock/fixed-clock.txt
+++ b/Documentation/devicetree/bindings/clock/fixed-clock.txt
@@ -10,6 +10,8 @@ Required properties:
- clock-frequency : frequency of clock in Hz. Should be a single cell.

Optional properties:
+- clock-accuracy : accuracy of clock in ppb (parts per billion).
+ Should be a single cell.
- gpios : From common gpio binding; gpio connection to clock enable pin.
- clock-output-names : From common clock binding.

@@ -18,4 +20,5 @@ Example:
compatible = "fixed-clock";
#clock-cells = <0>;
clock-frequency = <1000000000>;
+ clock-accuracy = <100>;
};
diff --git a/drivers/clk/clk-fixed-rate.c b/drivers/clk/clk-fixed-rate.c
index 1ed591a..0fc56ab 100644
--- a/drivers/clk/clk-fixed-rate.c
+++ b/drivers/clk/clk-fixed-rate.c
@@ -34,22 +34,31 @@ static unsigned long clk_fixed_rate_recalc_rate(struct clk_hw *hw,
return to_clk_fixed_rate(hw)->fixed_rate;
}

+static unsigned long clk_fixed_rate_recalc_accuracy(struct clk_hw *hw,
+ unsigned long parent_accuracy)
+{
+ return to_clk_fixed_rate(hw)->fixed_accuracy;
+}
+
const struct clk_ops clk_fixed_rate_ops = {
.recalc_rate = clk_fixed_rate_recalc_rate,
+ .recalc_accuracy = clk_fixed_rate_recalc_accuracy,
};
EXPORT_SYMBOL_GPL(clk_fixed_rate_ops);

/**
- * clk_register_fixed_rate - register fixed-rate clock with the clock framework
+ * clk_register_fixed_rate_with_accuracy - register fixed-rate clock with the
+ * clock framework
* @dev: device that is registering this clock
* @name: name of this clock
* @parent_name: name of clock's parent
* @flags: framework-specific flags
* @fixed_rate: non-adjustable clock rate
+ * @fixed_accuracy: non-adjustable clock rate
*/
-struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
- const char *parent_name, unsigned long flags,
- unsigned long fixed_rate)
+struct clk *clk_register_fixed_rate_with_accuracy(struct device *dev,
+ const char *name, const char *parent_name, unsigned long flags,
+ unsigned long fixed_rate, unsigned long fixed_accuracy)
{
struct clk_fixed_rate *fixed;
struct clk *clk;
@@ -70,16 +79,33 @@ struct clk *clk_register_fixed_rate(struct device *dev, const char *name,

/* struct clk_fixed_rate assignments */
fixed->fixed_rate = fixed_rate;
+ fixed->fixed_accuracy = fixed_accuracy;
fixed->hw.init = &init;

/* register the clock */
clk = clk_register(dev, &fixed->hw);
-
if (IS_ERR(clk))
kfree(fixed);

return clk;
}
+EXPORT_SYMBOL_GPL(clk_register_fixed_rate_with_accuracy);
+
+/**
+ * clk_register_fixed_rate - register fixed-rate clock with the clock framework
+ * @dev: device that is registering this clock
+ * @name: name of this clock
+ * @parent_name: name of clock's parent
+ * @flags: framework-specific flags
+ * @fixed_rate: non-adjustable clock rate
+ */
+struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
+ const char *parent_name, unsigned long flags,
+ unsigned long fixed_rate)
+{
+ return clk_register_fixed_rate_with_accuracy(dev, name, parent_name,
+ flags, fixed_rate, 0);
+}
EXPORT_SYMBOL_GPL(clk_register_fixed_rate);

#ifdef CONFIG_OF
@@ -91,13 +117,18 @@ void of_fixed_clk_setup(struct device_node *node)
struct clk *clk;
const char *clk_name = node->name;
u32 rate;
+ u32 accuracy = 0;

if (of_property_read_u32(node, "clock-frequency", &rate))
return;

+ of_property_read_u32(node, "clock-accuracy", &accuracy);
+
of_property_read_string(node, "clock-output-names", &clk_name);

- clk = clk_register_fixed_rate(NULL, clk_name, NULL, CLK_IS_ROOT, rate);
+ clk = clk_register_fixed_rate_with_accuracy(NULL, clk_name, NULL,
+ CLK_IS_ROOT, rate,
+ accuracy);
if (!IS_ERR(clk))
of_clk_add_provider(node, of_clk_src_simple_get, clk);
}
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 16d182c..5429f5d 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -204,6 +204,7 @@ struct clk_hw {
struct clk_fixed_rate {
struct clk_hw hw;
unsigned long fixed_rate;
+ unsigned long fixed_accuracy;
u8 flags;
};

@@ -211,6 +212,9 @@ extern const struct clk_ops clk_fixed_rate_ops;
struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
const char *parent_name, unsigned long flags,
unsigned long fixed_rate);
+struct clk *clk_register_fixed_rate_with_accuracy(struct device *dev,
+ const char *name, const char *parent_name, unsigned long flags,
+ unsigned long fixed_rate, unsigned long fixed_accuracy);

void of_fixed_clk_setup(struct device_node *np);

--
1.7.9.5