zephyr-cp: enable BLE on the Raspberry Pi Pico W

Same CYW43439 as the Pico 2 W, and the shared-bus HCI driver needed no
board-specific work, so this is the Pico 2 W change applied to the RP2040
board:

- overlay: hang the infineon,cyw43-bt-hci node off the stock
  infineon,airoc-wifi node and point zephyr,bt-hci at it.
- overlay: the settings partition had the same defect as the Pico 2 W's --
  originally 2K at 0x180800, neither erase-sector aligned nor big enough
  for one of the RP2040's 4K sectors; main has since made it one aligned
  4K sector at 0x17f000, which is still one short of the two nvs_mount()
  insists on, so bt_enable() fails before opening the HCI driver. Give
  settings two sectors at 0x17e000, taken from the code partition. nvm
  and circuitpy stay at 0x180000 and 0x181000 to match ports/raspberrypi
  (cptools/check_partitions.py checks this), so CIRCUITPY is not moved.
- conf: BT_EXT_ADV=n, since this controller rejects the Bluetooth 5
  extended advertising commands, plus a deeper system workqueue stack.

HW_STACK_PROTECTION is deliberately left off here: it earned its place on
the Cortex-M33 but costs RAM, and this is the constrained board.

Builds at 68.67% flash and 84.32% RAM of 264K, so BLE fits with about 42K
to spare.

Verified on hardware after the "ranges" fix (now on main): the adapter
comes up as WiFi MAC + 2 and a legacy LE scan returns nearby advertisers.
That run used the earlier layout with settings at 0x181000; the 0x17e000
placement is build-tested only.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: tyeth

ports/zephyr-cp/boards/raspberrypi/rpi_pico_w_zephyr/autogen_board_info.toml

@@ -3,7 +3,7 @@ name = "Raspberry Pi Foundation Raspberry Pi Pico"
 
 [modules]
 __future__ = true
-_bleio = false
+_bleio = true # Zephyr board has _bleio
 _eve = false
 _pew = false
 _pixelmap = false

ports/zephyr-cp/boards/raspberrypi/rpi_pico_w_zephyr/board.conf

@@ -20,3 +20,12 @@ CONFIG_MBEDTLS_ENTROPY_C=y
 CONFIG_MBEDTLS_CTR_DRBG_C=y
 
 CONFIG_TEST_RANDOM_GENERATOR=y
+
+# Bluetooth over the shared gSPI bus (CONFIG_BT itself comes from the
+# zephyr,bt-hci chosen node in the overlay).
+#
+# The CYW43439's BT controller firmware does not implement the Bluetooth 5
+# extended advertising/scanning commands, and the port defaults BT_EXT_ADV on,
+# so turn it off here and let the host use the legacy 0x200B/0x200C commands.
+CONFIG_BT_EXT_ADV=n
+CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=4096

ports/zephyr-cp/boards/raspberrypi/rpi_pico_w_zephyr/board.overlay

@@ -1,3 +1,58 @@
 /* Partition layout is owned by the mcuboot fork (dts/raspberrypi/rpi_pico.dtsi)
  * and applied to this image by sysbuild. This overlay only adds board/app config. */
+
+/*
+ * Settings partition: one exception to the layout above. sysbuild prepends the
+ * adaboot layout (dts/raspberrypi/rpi_pico_w.dtsi) to this overlay, so what
+ * is set here wins.
+ *
+ * The settings partition backs Bluetooth bond keys via NVS, so it must be
+ * erase-sector aligned and hold at least two of the RP2040's 4K sectors.
+ * The layout gives it one (0x17f000, 4K); nvs_mount() rejects a single sector
+ * with -EINVAL, which makes bt_enable() fail before ever opening the HCI
+ * driver and surfaces as a bare OSError from "import _bleio".
+ *
+ * nvm and the filesystem must stay where ports/raspberrypi puts them
+ * (cptools/check_partitions.py enforces this), so the second sector comes out
+ * of the code partition, not out of the CIRCUITPY drive. The code partition
+ * still starts at 0x100, after the second stage bootloader.
+ */
+&code_partition {
+	reg = <0x100 (0x17e000 - 0x100)>;
+};
+
+/delete-node/ &storage_partition;
+
+&flash0 {
+	partitions {
+		storage_partition: partition@17e000 {
+			compatible = "zephyr,mapped-partition";
+			label = "storage";
+			reg = <0x17e000 0x2000>;
+		};
+	};
+};
+
+/*
+ * Bluetooth. Same CYW43439 as the Pico 2 W: HCI is not on a UART, it shares
+ * the WiFi gSPI bus, so hang the shared-bus HCI transport off the board's
+ * stock infineon,airoc-wifi node and point the host at it. CONFIG_BT then
+ * enables itself via the zephyr,bt-hci chosen (see
+ * ../../../internal-modules/circuitpython-kconfig/Kconfig).
+ */
+&pio0_spi0 {
+	airoc-wifi@0 {
+		cyw43_bt_hci: cyw43_bt_hci {
+			compatible = "infineon,cyw43-bt-hci";
+			status = "okay";
+		};
+	};
+};
+
+/ {
+	chosen {
+		zephyr,bt-hci = &cyw43_bt_hci;
+	};
+};
+
 #include "../../../app.overlay"