4.3. M.2 Wi-Fi and Bluetooth module setup

This application note describes the Android build system modifications required to integrate third-party M.2 Wi-Fi and Bluetooth modules.

Warning

This guide assumes the kernel already includes the required drivers and device tree overlays. For kernel configuration, see Build Instructions.

4.3.1. Introduction

The AM62Px-SK and AM62x-SK Evaluation Modules (EVMs) include an M.2 Key E connector that supports Wi-Fi and Bluetooth combo modules. These modules typically use:

Secure Digital Input/Output (SDIO) interface for Wi-Fi
Universal Asynchronous Receiver-Transmitter (UART) interface for Bluetooth

This guide lists the files you need to change in the Android build system to add support for a new Wi-Fi and Bluetooth module.

4.3.2. Wi-Fi firmware setup

Note

Depending on your Wi-Fi module, you might also need to change the Wi-Fi Hardware Abstraction Layer (HAL) configuration in device/ti/am62x/shared/wifi/. The default configuration uses TI-specific libraries (lib_driver_cmd_ti). For other modules, you might need to update BoardConfig.mk to use the appropriate driver library (e.g., lib_driver_cmd_nl80211 for generic NL80211 drivers).

4.3.2.1. Adding firmware files

Copy the firmware files to the appropriate directory:

$ cp <firmware_file> \
    ${YOUR_PATH}/ti-aosp-16/vendor/ti/am62x/wifi/vendor/firmware/<vendor_dir>/

Common vendor directories:

mrvl/ for Marvell (now NXP Semiconductors)
ti-connectivity/ for TI
brcm/ for Broadcom/Cypress
nxp/ for NXP Semiconductors Bluetooth firmware

4.3.2.2. Change Android.bp

Edit vendor/ti/am62x/wifi/Android.bp and add a prebuilt_firmware module.

prebuilt_firmware {
    name: "<package_name>",
    vendor: true,
    src: "vendor/firmware/<vendor_dir>/<firmware_file>",
    filename: "<firmware_file>",
    sub_dir: "<vendor_dir>",
    proprietary: true,
}

4.3.2.3. Change the product Makefile

Edit vendor/ti/am62x/am62x.mk and add the firmware to PRODUCT_PACKAGES.

PRODUCT_PACKAGES += \
    <package_name>

4.3.3. Bluetooth configuration

M.2 Wi-Fi and Bluetooth combo modules typically use UART for Bluetooth communication. Change the following files to enable Bluetooth.

4.3.3.1. Change device_vendor.mk

Edit device/ti/am62x/shared/bluetooth/device_vendor.mk to enable Bluetooth permissions and HAL.

Change from disabled Bluetooth:

PRODUCT_COPY_FILES += \
    device/generic/car/common/android.hardware.disable.xml:$(TARGET_COPY_OUT_VENDOR)/etc/permissions/android.hardware.bluetooth.xml \
    device/generic/car/common/android.hardware.disable.xml:$(TARGET_COPY_OUT_VENDOR)/etc/permissions/android.hardware.bluetooth_le.xml

To enabled Bluetooth:

# Bluetooth configuration

# Enable Bluetooth permissions
PRODUCT_COPY_FILES += \
    frameworks/native/data/etc/android.hardware.bluetooth.xml:$(TARGET_COPY_OUT_VENDOR)/etc/permissions/android.hardware.bluetooth.xml \
    frameworks/native/data/etc/android.hardware.bluetooth_le.xml:$(TARGET_COPY_OUT_VENDOR)/etc/permissions/android.hardware.bluetooth_le.xml

# Bluetooth HAL (AIDL)
PRODUCT_PACKAGES += \
    android.hardware.bluetooth-service.default

4.3.3.2. Change product.prop

Edit device/ti/am62x/product.prop and add Bluetooth properties.

Example configuration (adjust profiles based on your module capabilities):

# Bluetooth configuration
# Set the Bluetooth Class of Device
# Service Field: 0x5A -> 90
#    Bit 17: Networking
#    Bit 19: Capturing
#    Bit 20: Object Transfer
#    Bit 22: Telephony
# MAJOR_CLASS: 0x01 -> 1 (Computer)
# MINOR_CLASS: 0x04 -> 4 (Desktop workstation)
bluetooth.device.class_of_device=90,1,4

# Set supported Bluetooth profiles to enabled
bluetooth.profile.asha.central.enabled?=true
bluetooth.profile.a2dp.source.enabled?=true
bluetooth.profile.avrcp.target.enabled?=true
bluetooth.profile.gatt.enabled?=true
bluetooth.profile.hfp.ag.enabled?=true
bluetooth.profile.hid.device.enabled?=true
bluetooth.profile.hid.host.enabled?=true
bluetooth.profile.map.server.enabled?=true
bluetooth.profile.opp.enabled?=true
bluetooth.profile.pan.nap.enabled?=true
bluetooth.profile.pan.panu.enabled?=true
bluetooth.profile.pbap.server.enabled?=true

# Disable LeAudio profiles (requires specific hardware support)
bluetooth.profile.bap.broadcast.assist.enabled=false
bluetooth.profile.bap.unicast.client.enabled=false
bluetooth.profile.bas.client.enabled=false
bluetooth.profile.ccp.server.enabled=false
bluetooth.profile.csip.set_coordinator.enabled=false
bluetooth.profile.hap.client.enabled=false
bluetooth.profile.vcp.controller.enabled=false

Note

The bluetooth.profile.*.enabled?=true syntax (with ?) enables the profile by default but allows overriding. Profiles disabled with =false (without ?) cannot be overridden.

4.3.3.3. Change ueventd.rc

Edit device/ti/am62x/am62x/ueventd.am62x.rc and add UART permissions:

# Bluetooth UART
/dev/ttyS1    0660   bluetooth  bluetooth

Note

The UART device name (ttyS1, ttyS2, and so on) depends on your device tree overlay configuration.

4.3.3.4. Change file_contexts

Edit device/ti/am62x/sepolicy/common/file_contexts and add:

# Bluetooth UART
/dev/ttyS1                      u:object_r:hci_attach_dev:s0

4.3.3.5. Adding SELinux policy

Create device/ti/am62x/sepolicy/common/hal_bluetooth_default.te:

# Allow Bluetooth HAL to access UART device
allow hal_bluetooth_default hci_attach_dev:chr_file rw_file_perms;

4.3.4. Build and flash

4.3.4.1. Rebuild the Android image

$ cd ${YOUR_PATH}/ti-aosp-16
$ source build/envsetup.sh
$ lunch <BUILD_TARGET>
$ m

4.3.4.2. Flash the device

After building, flash the device again following the standard flashing procedure documented in Flashing Instruction.

4.3.4.3. Configure the device tree blob overlay (DTBO)

After flashing, configure the DTBO index from U-Boot:

=> env set adtbo_idx <your_dtbo_index>
=> saveenv
=> reset

See Device Tree Overlay Support for the list of available DTBO overlays and their indices.

4.3.5. Summary

Change the following files to add Wi-Fi and Bluetooth support:

File	Purpose
`vendor/ti/am62x/wifi/Android.bp`	Add prebuilt_firmware module for Wi-Fi/BT firmware
`vendor/ti/am62x/am62x.mk`	Add firmware to PRODUCT_PACKAGES
`device/ti/am62x/shared/bluetooth/device_vendor.mk`	Enable Bluetooth permissions XML and HAL
`device/ti/am62x/product.prop`	Add Bluetooth properties (class of device, profiles)
`device/ti/am62x/am62x/ueventd.am62x.rc`	Set UART device permissions for Bluetooth
`device/ti/am62x/sepolicy/common/file_contexts`	Add SELinux context for Bluetooth UART
`device/ti/am62x/sepolicy/common/hal_bluetooth_default.te`	Add SELinux policy for Bluetooth HAL UART access