clk: add clock-indices support

Add a property called clock-indices to allow clock-output-names
to be used where the index used to lookup a clock is not a 1:1
mapping to the array position in the clock-output-names

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

2 files changed, 36 insertions, 1 deletions

diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt
index 7c52c29d99fa..700e7aac3717 100644
--- a/Documentation/devicetree/bindings/clock/clock-bindings.txt
+++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt
@@ -44,6 +44,23 @@ For example:
   clocks by index. The names should reflect the clock output signal
   names for the device.
 
+clock-indices:     If the identifyng number for the clocks in the node
+                   is not linear from zero, then the this mapping allows
+                   the mapping of identifiers into the clock-output-names
+                   array.
+
+For example, if we have two clocks <&oscillator 1> and <&oscillator 3>:
+
+        oscillator {
+                compatible = "myclocktype";
+                #clock-cells = <1>;
+                clock-indices = <1>, <3>;
+                clock-output-names = "clka", "clkb";
+        }
+
+        This ensures we do not have any empty nodes in clock-output-names
+
+
 ==Clock consumers==
 
 Required properties:
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index ea2ca9ff2677..a6f079d23eaa 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2496,8 +2496,12 @@ 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;
+        struct property *prop;
         const char *clk_name;
+        const __be32 *vp;
+        u32 pv;
         int rc;
+        int count;
 
         if (index < 0)
                 return NULL;
@@ -2507,8 +2511,22 @@ const char *of_clk_get_parent_name(struct device_node *np, int index)
         if (rc)
                 return NULL;
 
+        index = clkspec.args_count ? clkspec.args[0] : 0;
+        count = 0;
+
+        /* if there is an indices property, use it to transfer the index
+         * specified into an array offset for the clock-output-names property.
+         */
+        of_property_for_each_u32(clkspec.np, "clock-indices", prop, vp, pv) {
+                if (index == pv) {
+                        index = count;
+                        break;
+                }
+                count++;
+        }
+
         if (of_property_read_string_index(clkspec.np, "clock-output-names",
-                                          clkspec.args_count ? clkspec.args[0] : 0,
+                                          index,
                                           &clk_name) < 0)
                 clk_name = clkspec.np->name;