dt-bindings: sdhci-of-at91: add the microchip,sdcal-inverted property

Add the specific microchip,sdcal-inverted property to at91 sdhci
device binding.
This optional property describes how the SoC SDCAL pin is connected.
It could be handled at SiP, SoM or board level.

This property read by at91 sdhci driver will allow to put in place a
software workaround that would reduce power consumption.

Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt b/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt
index 1b662d7171a0f0b3c6b730df034bfbdb09676b11..503c6dbac1b271024e30b8ac28f98bff0bbff9aa 100644 (file)
--- a/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt
+++ b/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt
@@ -9,6 +9,11 @@ Required properties:
 - clocks:              Phandlers to the clocks.
 - clock-names:         Must be "hclock", "multclk", "baseclk";
 
+Optional properties:
+- microchip,sdcal-inverted: when present, polarity on the SDCAL SoC pin is
+  inverted. The default polarity for this signal is described in the datasheet.
+  For instance on SAMA5D2, the pin is usually tied to the GND with a resistor
+  and a capacitor (see "SDMMC I/O Calibration" chapter).
 
 Example: