boards: nxp: rd_rw612_bga: enable support for flash

Enable support for the mx25u51245g flash chip present on the
RD RW612 BGA. Support has been verified with the following samples:

- samples/drivers/flash_shell
- tests/drivers/flash/common

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>

boards/nxp/rd_rw612_bga/doc/index.rst

@@ -45,6 +45,8 @@ Supported Features
 +-----------+------------+-----------------------------------+
 | I2C       | on-chip    | i2c                               |
 +-----------+------------+-----------------------------------+
+| FLEXSPI   | on-chip    | flash                             |
++-----------+------------+-----------------------------------+
 | TRNG      | on-chip    | entropy                           |
 +-----------+------------+-----------------------------------+
 | WWDT      | on-chip    | watchdog                          |

boards/nxp/rd_rw612_bga/rd_rw612_bga-pinctrl.dtsi

@@ -31,4 +31,22 @@
 			bias-pull-up;
 		};
 	};
+
+	pinmux_flexspi: pinmux_flexspi {
+		group0 {
+			pinmux = <IO_MUX_QUAD_SPI_FLASH_IO28
+				IO_MUX_QUAD_SPI_FLASH_IO30
+				IO_MUX_QUAD_SPI_FLASH_IO31
+				IO_MUX_QUAD_SPI_FLASH_IO32
+				IO_MUX_QUAD_SPI_FLASH_IO33
+				IO_MUX_QUAD_SPI_FLASH_IO34>;
+			slew-rate = "ultra";
+		};
+
+		group1 {
+			pinmux = <IO_MUX_QUAD_SPI_FLASH_IO29>;
+			slew-rate = "ultra";
+			bias-pull-down;
+		};
+	};
 };

boards/nxp/rd_rw612_bga/rd_rw612_bga.dtsi

@@ -77,14 +77,22 @@ arduino_i2c: &flexcomm2 {
 };
 
 &flexspi {
+	status = "okay";
+	ahb-bufferable;
+	ahb-prefetch;
+	ahb-cacheable;
+	ahb-read-addr-opt;
+	rx-clock-source = <1>;
+	pinctrl-0 = <&pinmux_flexspi>;
+	pinctrl-names = "default";
 	status = "okay";
 	mx25u51245g: mx25u51245g@0 {
 		compatible = "nxp,imx-flexspi-nor";
 		spi-max-frequency = <133000000>;
 		reg = <0>;
 		/* MX25UM51245G is 64MB, 512MBit flash part */
 		size = <DT_SIZE_M(64 * 8)>;
-		status = "disabled";
+		status = "okay";
 		jedec-id = [c2 25 3a];
 		erase-block-size = <4096>;
 		write-block-size = <1>;