From: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
While SDIO devices are runtime probable they sometimes need nonprobable
additional information on embedded systems, like an additional gpio
interrupt or a clock. This binding describes how to add child nodes to the
devicetree to supply this information.
Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
[hdegoede@xxxxxxxxxx: Documented the need for #address- and #size-cells]
[hdegoede@xxxxxxxxxx: Added a real world example]
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
Documentation/devicetree/bindings/mmc/mmc.txt | 48 ++++++++++++++++++++++++++-
1 file changed, 47 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/mmc/mmc.txt b/Documentation/devicetree/bindings/mmc/mmc.txt
index 3c18001..2f362c4 100644
--- a/Documentation/devicetree/bindings/mmc/mmc.txt
+++ b/Documentation/devicetree/bindings/mmc/mmc.txt
@@ -62,7 +62,31 @@ Optional SDIO properties:
- keep-power-in-suspend: Preserves card power during a suspend/resume cycle
- enable-sdio-wakeup: Enables wake up of host system on SDIO IRQ assertion
-Example:
+
+Use of Function subnodes
+------------------------
+
+On embedded systems the cards connected to a host may need additional
+properties. These can be specified in subnodes to the host controller node.
+The subnodes are identified by the standard 'reg' property.
+Which information exactly can be specified depends on the bindings for the
+SDIO function driver for the subnode, as specified by the compatible string.
+
+Required host node properties when using function subnodes:
+- #address-cells: should be one. The cell is the slot id.
+- #size-cells: should be zero.
+
+Required function subnode properties:
+- compatible: name of SDIO function following generic names recommended practice
+- reg: Must contain the SDIO function number of the function this subnode
+ describes. A value of 0 denotes the memory SD function, values from
+ 1 to 7 denote the SDIO functions.
+
+
+Examples
+--------
+
+Basic example:
sdhci@ab000000 {
compatible = "sdhci";
@@ -76,3 +100,25 @@ sdhci@ab000000 {
keep-power-in-suspend;
enable-sdio-wakeup;
}
+
+Example with sdio function subnode:
+
+mmc3: mmc@01c12000 {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ pinctrl-names = "default";
+ pinctrl-0 = <&mmc3_pins_a>;
+ vmmc-supply = <®_vmmc3>;
+ bus-width = <4>;
+ non-removable;
+ status = "okay";
+
+ brcmf: bcrmf@1 {
+ reg = <1>;
+ compatible = "brcm,bcm43xx-fmac";
+ interrupt-parent = <&pio>;
+ interrupts = <10 8>; /* PH10 / EINT10 */
+ interrupt-names = "host-wake";
+ };
+};
--
2.0.0
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