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Date: Thu, 1 Aug 2013 17:03:45 +0200
From: Boris BREZILLON <b.brezillon@...rkiz.com>
To: Mike Turquette <mturquette@...aro.org>,
Russell King <linux@....linux.org.uk>,
Rob Landley <rob@...dley.net>,
Rob Herring <rob.herring@...xeda.com>
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
devicetree@...r.kernel.org, linux-doc@...r.kernel.org,
Boris BREZILLON <b.brezillon@...rkiz.com>
Subject: [RFC PATCH 2/2] clk: add accuracy support for fixed clock
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.
---
.../devicetree/bindings/clock/fixed-clock.txt | 3 ++
drivers/clk/clk-fixed-rate.c | 41 +++++++++++++++++---
include/linux/clk-provider.h | 3 ++
3 files changed, 42 insertions(+), 5 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 dc58fbd..f716bf3 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;
@@ -70,6 +79,7 @@ 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 */
@@ -81,6 +91,22 @@ struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
return clk;
}
+/**
+ * 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);
+}
+
#ifdef CONFIG_OF
/**
* of_fixed_clk_setup() - Setup function for simple fixed rate clock
@@ -90,13 +116,18 @@ 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 2127fbc..b379e50 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -203,6 +203,9 @@ 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
--
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