The following existing MMC host controller bindings use slot subnodes:
Documentation/devicetree/bindings/mmc/synopsys-dw-mshc.txt
Documentation/devicetree/bindings/mmc/k3-dw-mshc.txt
Documentation/devicetree/bindings/mmc/exynos-dw-mshc.txt
Documentation/devicetree/bindings/mmc/socfpga-dw-mshc.txt
Documentation/devicetree/bindings/mmc/atmel-hsmci.txt
Documentation/devicetree/bindings/mmc/rockchip-dw-mshc.txt
This commit documents this practice in the standard mmc bindings documentation.
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
Documentation/devicetree/bindings/mmc/mmc.txt | 46 ++++++++++++++++++++++++++-
1 file changed, 45 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/mmc/mmc.txt b/Documentation/devicetree/bindings/mmc/mmc.txt
index 9dce540..44c9e53 100644
--- a/Documentation/devicetree/bindings/mmc/mmc.txt
+++ b/Documentation/devicetree/bindings/mmc/mmc.txt
@@ -60,7 +60,31 @@ 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 slot subnodes
+--------------------
+
+Some hosts have multiple MMC slots connected to a single MMC host, in this
+case each slot gets its own subnode representing the slot:
+
+Required host node properties when using slots:
+- #address-cells: should be one. The cell is the slot id.
+- #size-cells: should be zero.
+
+Required slot subnode properties:
+- reg: Must contain the MMC host slot number of the slot this subnode
+ describes. Slot numbers start at 0.
+
+Optional slot subnode properties:
+Any of the optional host node properties can be used inside a slot node too,
+if a property is specified at both the host and the slot level the slot
+level takes precedence.
+
+
+Examples
+--------
+
+Basic example:
sdhci@ab000000 {
compatible = "sdhci";
@@ -74,3 +98,23 @@ sdhci@ab000000 {
keep-power-in-suspend;
enable-sdio-wakeup;
}
+
+Example with slot subnodes:
+
+mmc0: mmc@f0008000 {
+ compatible = "atmel,hsmci";
+ reg = <0xf0008000 0x600>;
+ interrupts = <12 4>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ slot@0 {
+ reg = <0>;
+ bus-width = <4>;
+ cd-gpios = <&pioD 15 0>
+ cd-inverted;
+ };
+ slot@1 {
+ reg = <1>;
+ bus-width = <4>;
+ };
+};
--
2.0.0
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