Bluetooth device tree configuration

Article purpose

本文介绍如何配置“蓝牙” 将外围设备“(或与框架关联的外围设备)”分配给 Linux^® OS.

使用 设备树机制 执行配置。

在我们的平台上选择的蓝牙配套芯片是赛普拉斯(Cypress)芯片

Bluetooth DT bindings documentation

The Bluetooth 树绑定由以下部分组成：

• STM32 USART设备树绑定
• 用作从属设备所连接的主机USART设备的子节点 的Cypress设备。

Bluetooth DT configuration

此硬件描述是STM32微处理器设备树文件（扩展名为.dtsi）和板设备树文件（扩展名为.dts）的组合。有关设备树文件拆分的说明，请参见设备树

Bluetooth DT configuration (STM32 level)

USART外设节点位于``stm32mp157c.dtsi

• 这是一组属性，对于给定的STM32器件而言可能不变，例如：寄存器地址，时钟，复位...

在 Serial TTY device tree configuration中说明了USART DT配置。

Article purpose

This article explains how to configure Bluetooth when the peripheral (or peripheral associated to the framework) is assigned to the Linux^® OS.

The configuration is performed using the device tree mechanism .

The Bluetooth companion chip chosen on our platform is a Cypress chip

Bluetooth DT bindings documentation

The Bluetooth tree bindings are composed of:

• STM32 USART device tree bindings
• The Cypress device, used as child node of the host USART device to which the slave device is attached.

Bluetooth DT configuration

This hardware description is a combination of the STM32 microprocessor device tree files (.dtsi extension) and board device tree files (.dts extension). See the device tree for an explanation of the device tree file split.

Bluetooth DT configuration (STM32 level)

The USART peripheral node is located in stm32mp151.dtsi

• This is a set of properties that may not vary for given STM32 device, such as: registers address, clock, reset...

The USART DT configuration is explained in Serial TTY device tree configuration

Bluetooth DT configuration (board level)

&usart2 {
       ... 
       uart-has-rtscts;                                     /* enable hardware flow control */
       ...
       bluetooth {                                            /* node of Bluetooth companion chip */         
               shutdown-gpios = <&gpioz 6 GPIO_ACTIVE_HIGH>;  /* GPIO specifier, used to enable the BT module */
               compatible = "brcm,bcm43438-bt";
               max-speed = <3000000>;
       };
};

Specific properties for USART:

• uart-has-rtscts; bool flag to enable hardware flow control

How to configure Bluetooth using CubeMX

The STM32CubeMX tool can be used to configure the STM32MPU device and get the corresponding platform configuration device tree files.
The STM32CubeMX may not support all the properties described in the above DT bindings documentation paragraph. If so, the tool inserts user sections in the generated device tree. These sections can then be edited to add some properties and they are preserved from one generation to another. Refer to STM32CubeMX user manual for further information.

References