new file mode 100644
@@ -0,0 +1,20 @@
+* The simple MMC power sequence provider
+
+The purpose of the simple MMC power sequence provider is to supports a set of
+common properties between various SOC designs. It thus enables us to use the
+same provider for several SOC designs.
+
+Required properties:
+- compatible : contains "mmc-pwrseq-simple".
+
+Optional properties:
+- reset-gpios : contains a GPIO specifier. The reset GPIO is asserted at
+ initialization and prior we start the power up procedure of the card. It
+ will be de-asserted right after the power has been provided to the card.
+
+Example:
+
+ sdhci0_pwrseq {
+ compatible = "mmc-pwrseq-simple";
+ reset-gpios = <&gpio1 12 0>;
+ }
@@ -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 = <®_vmmc3>;
bus-width = <4>;
non-removable;
+ mmc-pwrseq = <&sdhci0_pwrseq>
status = "okay";
brcmf: bcrmf@1 {
To support SOCs which specifies specific MMC power sequences, document some MMC DT bindings to be able to describe these hardwares. Let's also document bindings for a simple MMC power sequence provider, which purpose is to support a set of common properties between various SOCs. In this initial step, let's also document a top level description of the MMC power sequence and describe the compatible string used for the simple MMC power sequence provider. The simple MMC power sequence provider will initially support a reset GPIO. From several earlier posted patches, it's clear that such hardware exists. Especially some WLAN chips which are attached to an SDIO interface may use a GPIO reset. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> --- Changes in v3: - Folded in all documentation into this patch, to get the big picture. - Make it clear that we support one reset GPIO. --- .../devicetree/bindings/mmc/mmc-pwrseq-simple.txt | 20 ++++++++++++++++++++ Documentation/devicetree/bindings/mmc/mmc.txt | 14 ++++++++++++++ 2 files changed, 34 insertions(+) create mode 100644 Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt