boards: shields: add support for renesas DA14531 Pmod

Add support for the Renesas US159 Pmod board that contains a DA14531
Bluetooth LE SoC.

Signed-off-by: Ian Morris <ian.d.morris@outlook.com>

boards/shields/renesas_us159_da14531evz/Kconfig.shield

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+# Copyright (c) 2024 Renesas Electronics Corporation
+# SPDX-License-Identifier: Apache-2.0
+
+config SHIELD_RENESAS_US159_DA14531EVZ
+	def_bool $(shields_list_contains,renesas_us159_da14531evz)

boards/shields/renesas_us159_da14531evz/boards/ek_ra8m1.overlay

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+/*
+ * Copyright (c) 2024 Renesas Electronics Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&pinctrl {
+	sci0_default: sci0_default {
+		group1 {
+			/* tx */
+			psels = <RA_PSEL(RA_PSEL_SCI_0, 6, 9)>;
+			drive-strength = "medium";
+		};
+		group2 {
+			/* rx, rts, cts */
+			psels = <RA_PSEL(RA_PSEL_SCI_0, 6, 10)>,
+					<RA_PSEL(RA_PSEL_SCI_0, 6, 12)>,
+					<RA_PSEL(RA_PSEL_SCI_0, 6, 13)>;
+		};
+	};
+};
+
+&sci0 {
+	pinctrl-0 = <&sci0_default>;
+	pinctrl-names = "default";
+	status = "okay";
+	uart0: uart {
+		current-speed = <115200>;
+		hw-flow-control;
+		status = "okay";
+	};
+};

boards/shields/renesas_us159_da14531evz/doc/index.rst

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+.. _renesas_us159_da14531evz_shield:
+
+Renesas DA14531 Pmod Board
+##########################
+
+Overview
+********
+
+The Renesas US159 DA14531EVZ carries a `DA14531MOD`_ Bluetooth LE module
+in a `Digilent Pmod`_ |trade| form factor.
+
+.. figure:: us159-da14531evz-pmod.webp
+   :align: center
+   :alt: Renesas US159 DA14531EVZ Pmod
+
+   Renesas US159 DA14531EVZ Pmod (Credit: Renesas Electronics)
+
+Requirements
+************
+
+This shield can only be used with a board that provides a Pmod |trade|
+socket and defines the ``pmod_serial`` node label (see :ref:`shields` for
+more details).
+
+The DA14531 Module contained on the shield must be programmed with a binary
+file that supports the HCI interface over UART, with hardware flow control
+enabled.
+
+The `Renesas SmartBond Flash Programmer`_ tool can be used to download a
+suitable binary and then program it into the DA14531 via the SWD header
+present on the Pmod board. Once the tool has been installed, open it and
+press the "Search Online" button. The required binary file can be selected
+for download as follows:
+
+.. figure:: da14531-hci-hw-flow-binary.webp
+   :align: center
+   :alt: DA14531 HCI Binary File Selection
+
+   Selecting the DA14531 HCI Binary File for Download
+
+Press the "Program" button to program the binary file into the DA14531 Module.
+
+For more information about interfacing to the DA14531 and the US159 DA14531EVZ
+Pmod, see the following documentation:
+
+- `DA14531MOD Datasheet`_
+- `US159 DA14531EVZ Pmod`_
+
+Programming
+***********
+
+Set ``--shield renesas_us159_da14531evz`` when you invoke ``west build``. For
+example:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/bluetooth/beacon
+   :board: ek_ra8m1
+   :shield: renesas_us159_da14531evz
+   :goals: build
+
+References
+**********
+
+.. target-notes::
+
+.. _DA14531MOD:
+   https://www.renesas.com/us/en/products/wireless-connectivity/bluetooth-low-energy/da14531mod-smartbond-tiny-bluetooth-low-energy-module
+
+.. _Digilent Pmod:
+   https://digilent.com/reference/pmod/start
+
+.. _Renesas SmartBond Flash Programmer:
+   https://www.renesas.com/us/en/software-tool/smartbond-flash-programmer
+
+.. _DA14531MOD Datasheet:
+   https://www.renesas.com/us/en/document/dst/da14531-module-datasheet?r=1601921
+
+.. _US159 DA14531EVZ Pmod:
+   https://www.renesas.com/en/products/wireless-connectivity/bluetooth-low-energy/us159-da14531evz-low-power-bluetooth-pmod-board-renesas-quickconnect-iot

boards/shields/renesas_us159_da14531evz/renesas_us159_da14531evz.overlay

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+/*
+ * Copyright (c) 2024 Renesas Electronics Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	chosen {
+		zephyr,bt-hci = &bt_hci_uart;
+	};
+};
+
+&pmod_serial {
+	status = "okay";
+
+	bt_hci_uart: bt_hci_uart {
+		compatible = "zephyr,bt-hci-uart";
+		status = "okay";
+
+		da1453x {
+			compatible = "renesas,bt-hci-da1453x";
+			status = "okay";
+			reset-gpios = <&pmod_header 5 GPIO_ACTIVE_LOW>;
+		};
+	};
+};