dts/bindings: qspi: Add stm32 qspi binding

qspi bus controller bindings for stm32 family.

Signed-off-by: Erwan Gouriou <[email protected]>

Author: erwango

dts/bindings/qspi/st,stm32-qspi.yaml

@@ -0,0 +1,40 @@
+# Copyright (c) 2020, Linaro limited
+# SPDX-License-Identifier: Apache-2.0
+
+description: |
+    STM32 QSPI device representation. A stm32 quadspi node would typically
+    looks to this:
+
+        &quadspi {
+            pinctrl-0 = <&quadspi_clk_pe10 &quadspi_ncs_pe11
+                         &quadspi_bk1_io0_pe12 &quadspi_bk1_io1_pe13
+                         &quadspi_bk1_io2_pe14 &quadspi_bk1_io3_pe15>;
+
+            dmas = <&dma1 5 5 0x0000 0x03>;
+            dma-names = "tx_rx";
+
+            status = "okay";
+        };
+
+compatible: "st,stm32-qspi"
+
+include: base.yaml
+
+bus: qspi
+
+properties:
+    reg:
+      required: true
+
+    interrupts:
+      required: true
+
+    dmas:
+      required: true
+
+    dma-names:
+      required: true
+
+    pinctrl-0:
+      type: phandles
+      required: true