Document how to use devicetree aliases to assign a stable
bus number to a spi bus.
Signed-off-by: Christer Weinigel <christer@xxxxxxxxxxx>
---
Trivial documentation change.
Not having used devicetree that much it was surprisingly hard to
figure out how to assign a stable bus number to a spi bus. Add a
simple example that shows how to do that.
Mark Cced as the SPI maintainer. Or should trivial documentation
fixes like this be addressed to someone else?
/Christer
Documentation/devicetree/bindings/spi/spi-bus.txt | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt b/Documentation/devicetree/bindings/spi/spi-bus.txt
index 42d5954..c35c4c2 100644
--- a/Documentation/devicetree/bindings/spi/spi-bus.txt
+++ b/Documentation/devicetree/bindings/spi/spi-bus.txt
@@ -94,3 +94,13 @@ SPI example for an MPC5200 SPI bus:
reg = <1>;
};
};
+
+Normally SPI buses are assigned dynamic bus numbers starting at 32766
+and counting downwards. It is possible to assign the bus number
+statically using devicetee aliases. For example, on the MPC5200 the
+"spi@f00" device above is connected to the "soc" bus. To set its
+bus_num to 1 add an aliases entry like this:
+
+ aliases {
+ spi1 = "/soc/spi@f00";
+ };
--
1.9.1
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