mmc: core: parse voltage from device-tree

Add function to support getting voltage from device-tree.
If voltage-range is specified in device-tree node, this function
will parse it and return the available voltage mask.

Signed-off-by: Haijun Zhang <haijun.zhang@freescale.com>
Acked-by: Anton Vorontsov <anton@enomsg.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/mmc/fsl-esdhc.txt b/Documentation/devicetree/bindings/mmc/fsl-esdhc.txt
index bd9be0b5bc20..b7943f3f9995 100644
--- a/Documentation/devicetree/bindings/mmc/fsl-esdhc.txt
+++ b/Documentation/devicetree/bindings/mmc/fsl-esdhc.txt
@@ -19,6 +19,9 @@ Optional properties:
     "bus-width = <1>" property.
   - sdhci,auto-cmd12: specifies that a controller can only handle auto
     CMD12.
+  - voltage-ranges : two cells are required, first cell specifies minimum
+    slot voltage (mV), second cell specifies maximum slot voltage (mV).
+    Several ranges could be specified.
 
 Example:
 
@@ -29,4 +32,5 @@ sdhci@2e000 {
         interrupt-parent = <&ipic>;
         /* Filled in by U-Boot */
         clock-frequency = <0>;
+        voltage-ranges = <3300 3300>;
 };