[PATCH 1/2] spi: dual and quad support(device tree)

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




Add spi-tx-nbits and spi-rx-nbits for spi slave node.
 spi-tx-nbits:Number of bits used for MOSI(writting)
 spi-rx-nbits:Number of bits used for MISO(reading)
Support for spi-tx/rx-nbits in SPI framework has been picked[1].
[1]: http://comments.gmane.org/gmane.linux.kernel.spi.devel/14420
Commit Id:f477b7fb13df2b843997559ff34e87d054ba6538

Signed-off-by: wangyuhang <wangyuhang2014@xxxxxxxxx>
---
 Documentation/devicetree/bindings/spi/spi-bus.txt |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt b/Documentation/devicetree/bindings/spi/spi-bus.txt
index 296015e..145ba96 100644
--- a/Documentation/devicetree/bindings/spi/spi-bus.txt
+++ b/Documentation/devicetree/bindings/spi/spi-bus.txt
@@ -55,6 +55,20 @@ contain the following properties.
     		chip select active high
 - spi-3wire       - (optional) Empty property indicating device requires
     		    3-wire mode.
+- spi-tx-nbits    - (optional) Number of bits used for MOSI(writting)
+- spi-rx-nbits    - (optional) Number of bits used for MISO(reading)
+
+So if for example the slave has 4 wires for writting and 2 wires for reading,
+and the spi-tx/rx-nbits property should be set as follows:
+
+spi-tx-nbits = <4>;
+spi-rx-nbits = <2>;
+
+Now the value that spi-tx-nbits and spi-rx-nbits can receive is only
+1(single), 2(dual) and 4(quad). If you don't set spi-tx-nbits or spi-rx-nbits,
+spi_device mode will be set in single(1 wire) as default. Another point, if
+property:spi-3wire is set, spi-tx/rx-nbits is forbidden to set to <2 or 4>,
+otherwise, an errro will return.
 
 If a gpio chipselect is used for the SPI slave the gpio number will be passed
 via the cs_gpio
-- 
1.7.9.5

--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]
  Powered by Linux