[PATCH V3 4/4] doc: lpspi: Document DT bindings for LPSPI slave mode

[Clark Wang <xiaoning.wang@nxp.com>]

Add introductions of interrupt-parent and spi-slave.

Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
---
Change log:
V2:
 - No change.
V3:
 - Keep the description of "fsl,imx8qxp-spi" in spi-fsl-lpspi.txt.
---
 Documentation/devicetree/bindings/spi/spi-fsl-lpspi.txt | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/spi-fsl-lpspi.txt b/Documentation/devicetree/bindings/spi/spi-fsl-lpspi.txt
index 8d178a4503cf..6cc3c6fe25a3 100644
--- a/Documentation/devicetree/bindings/spi/spi-fsl-lpspi.txt
+++ b/Documentation/devicetree/bindings/spi/spi-fsl-lpspi.txt
@@ -5,8 +5,11 @@ Required properties:
   - "fsl,imx7ulp-spi" for LPSPI compatible with the one integrated on i.MX7ULP soc
   - "fsl,imx8qxp-spi" for LPSPI compatible with the one integrated on i.MX8QXP soc
 - reg : address and length of the lpspi master registers
+- interrupt-parent : core interrupt controller
 - interrupts : lpspi interrupt
 - clocks : lpspi clock specifier
+- spi-slave : spi slave mode support. In slave mode, add this attribute without
+	      value. In master mode, remove it.
 
 Examples:
 
@@ -16,4 +19,5 @@ lpspi2: lpspi@40290000 {
 	interrupt-parent = <&intc>;
 	interrupts = <GIC_SPI 28 IRQ_TYPE_LEVEL_HIGH>;
 	clocks = <&clks IMX7ULP_CLK_LPSPI2>;
+	spi-slave;
 };
-- 
2.17.1