@@ -55,6 +55,20 @@ contain the following properties.
chip select active high
- spi-3wire - (optional) Empty property indicating device requires
+- 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