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.

Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

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 0b1fe7824093..48ea0ad8ad46 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 1ed591ab8b1d..0fc56ab6e844 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 16d182c28ce6..5429f5db5037 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);