spi: add SPI_MOSI_IDLE_LOW mode bit

Some spi controller switch the mosi line to high, whenever they are
idle. This may not be desired in all use cases. For example neopixel
leds can get confused and flicker due to misinterpreting the idle state.
Therefore, we introduce a new spi-mode bit, with which the idle behaviour
can be overwritten on a per device basis.

Signed-off-by: Boerge Struempfel <boerge.struempfel@gmail.com>
Link: https://lore.kernel.org/r/20230530141641.1155691-2-boerge.struempfel@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/include/uapi/linux/spi/spi.h b/include/uapi/linux/spi/spi.h
index 9d5f580597039e9cf798bb9e62ad18b248dffb61..ca56e477d161906257d023de03bf3df01f998d18 100644 (file)
--- a/include/uapi/linux/spi/spi.h
+++ b/include/uapi/linux/spi/spi.h
@@ -28,6 +28,7 @@
 #define        SPI_RX_OCTAL            _BITUL(14)      /* receive with 8 wires */
 #define        SPI_3WIRE_HIZ           _BITUL(15)      /* high impedance turnaround */
 #define        SPI_RX_CPHA_FLIP        _BITUL(16)      /* flip CPHA on Rx only xfer */
+#define SPI_MOSI_IDLE_LOW      _BITUL(17)      /* leave mosi line low when idle */
 
 /*
  * All the bits defined above should be covered by SPI_MODE_USER_MASK.
@@ -37,6 +38,6 @@
  * These bits must not overlap. A static assert check should make sure of that.
  * If adding extra bits, make sure to increase the bit index below as well.
  */
-#define SPI_MODE_USER_MASK     (_BITUL(17) - 1)
+#define SPI_MODE_USER_MASK     (_BITUL(18) - 1)
 
 #endif /* _UAPI_SPI_H */