spi: xilinx: add description of new property xlnx,num-transfer-bits

This property is used to set the number of bits per transfer (bits_per_word).

Xilinx' IP core allows either 8, 16 or 32, and is non changeable on runtime,
only when instantiating the core.

Signed-off-by: Alvaro Gamez Machado <alvaro.gamez@hazent.com>
Link: https://lore.kernel.org/r/20191024110757.25820-2-alvaro.gamez@hazent.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/Documentation/devicetree/bindings/spi/spi-xilinx.txt b/Documentation/devicetree/bindings/spi/spi-xilinx.txt
index dc924a5f71db042c5c702374442c08710a4e5fec..5f4ed3e5c9942cb407bcc8e92026142042257a98 100644 (file)
--- a/Documentation/devicetree/bindings/spi/spi-xilinx.txt
+++ b/Documentation/devicetree/bindings/spi/spi-xilinx.txt
@@ -8,7 +8,8 @@ Required properties:
                          number.
 
 Optional properties:
-- xlnx,num-ss-bits     : Number of chip selects used.
+- xlnx,num-ss-bits      : Number of chip selects used.
+- xlnx,num-transfer-bits : Number of bits per transfer. This will be 8 if not specified
 
 Example:
        axi_quad_spi@41e00000 {
@@ -17,5 +18,6 @@ Example:
                        interrupts = <0 31 1>;
                        reg = <0x41e00000 0x10000>;
                        xlnx,num-ss-bits = <0x1>;
+                       xlnx,num-transfer-bits = <32>;
        };