Commit a31edf1e authored by Sascha Hauer's avatar Sascha Hauer Committed by Ulf Hansson

mmc: Add SDIO function subnode DT documentation

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: default avatarSascha Hauer <>
[ Documented the need for #address- and #size-cells]
[ Added a real world example]
Signed-off-by: default avatarHans de Goede <>
Signed-off-by: default avatarUlf Hansson <>
parent 9b449e99
......@@ -64,7 +64,31 @@ 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
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.
Basic example:
sdhci@ab000000 {
compatible = "sdhci";
......@@ -78,3 +102,25 @@ sdhci@ab000000 {
Example with sdio function subnode:
mmc3: mmc@01c12000 {
#address-cells = <1>;
#size-cells = <0>;
pinctrl-names = "default";
pinctrl-0 = <&mmc3_pins_a>;
vmmc-supply = <&reg_vmmc3>;
bus-width = <4>;
status = "okay";
brcmf: bcrmf@1 {
reg = <1>;
compatible = "brcm,bcm43xx-fmac";
interrupt-parent = <&pio>;
interrupts = <10 8>; /* PH10 / EINT10 */
interrupt-names = "host-wake";
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