mmc: pwrseq: Document DT bindings for the simple MMC power sequence

[karo-tx-linux.git] / Documentation / devicetree / bindings / mmc / mmc.txt

diff --git a/Documentation/devicetree/bindings/mmc/mmc.txt b/Documentation/devicetree/bindings/mmc/mmc.txt
index bac131169c076f7a8ca097b6475125deb1d330c3..438899e8829b7d5c077f81af5eff316c54329411 100644 (file)
--- a/Documentation/devicetree/bindings/mmc/mmc.txt
+++ b/Documentation/devicetree/bindings/mmc/mmc.txt
@@ -65,6 +65,18 @@ Optional SDIO properties:
 - enable-sdio-wakeup: Enables wake up of host system on SDIO IRQ assertion
 
 
+MMC power sequences:
+--------------------
+
+System on chip designs may specify a specific MMC power sequence. To
+successfully detect an (e)MMC/SD/SDIO card, that power sequence must be
+maintained while initializing the card.
+
+Optional property:
+- mmc-pwrseq: phandle to the MMC power sequence node. See "mmc-pwrseq-*"
+       for documentation of MMC power sequence bindings.
+
+
 Use of Function subnodes
 ------------------------
 
@@ -101,6 +113,7 @@ sdhci@ab000000 {
        max-frequency = <50000000>;
        keep-power-in-suspend;
        enable-sdio-wakeup;
+       mmc-pwrseq = <&sdhci0_pwrseq>
 }
 
 Example with sdio function subnode:
@@ -114,6 +127,7 @@ mmc3: mmc@01c12000 {
        vmmc-supply = <&reg_vmmc3>;
        bus-width = <4>;
        non-removable;
+       mmc-pwrseq = <&sdhci0_pwrseq>
        status = "okay";
 
        brcmf: bcrmf@1 {