Drive Tiering

[中文]

Note

The driver layered model is applicable to all peripherals. This section takes UART as an example to explain.

Example

The following figure lists the files related to UART driver implementation.

- armino
    - middleware
        - driver
            - include
                - uart.h
            - uart
                - uart_driver.c
                - uart_driver.h
                - uart_statis.c
                - uart_statis.h
        - arch
            - bk7237
                - soc
                    - uart_cap.h
                    - uart_reg.h
                    - uart_struct.h
                - hal
                    - uart_ll.c
                    - uart_ll.h
            - common
                - hal
                    - include
                        - uart_hal.h
                        - uart_types.h
                    - uart_hal.c
                - soc
                    - include
                        - uart_hw.h

Tiering Overview

UART (Drive is divided into drive layer), HAL (Hardware abstraction layer), LL (Register interface layer) and SOC (Register definition layer):

Layer	Function Overview
drive	Expose APIs, which are stable and backward compatible The hardware can only be accessed through this layer’s API Depends on HAL, usually a subset of HAL functions Internal implementations are usually platform independent Can rely on OS and other components of Beken SDK
HAL	Abstraction of hardware, providing a set of stable and comprehensive API interfaces Generally, it has better performance and takes less resources. When transplanting Beken chip operation to other software platforms, you can consider only transplanting the HAL layer. HAL interfaces on different boards are usually consistent The HAL layer interface does not promise stability, and the code based on HAL layer migration may face compatibility problems after HAL upgrade Only rely on LL/SOC and print relevant codes No direct register operation is involved
LL	It is usually a simple wrapper for register access to make the program more readable Usually implemented as inline function The implementation is as simple as possible
SoC	Provide register definition

Document description

Layer	Header file name	Function Overview
Driver	uart_types.h uart.h uart_driver.c uart_driver.h uart_statis.c uart_statis.h	UART API Type Definition UART API statement UART Drive implementation UART Drive private data types and macro definitions UART Driver statistics related information UART Similar definitions related to driver statistics
HAL	uart_hal.h uart_hal.c uart_ll.h	Hardware abstraction layer API statement, shared by different boards UART Hardware Abstraction Layer Interface Implementation Packaging register access interface, making the deposit code more readable
SoC	uart_reg.h uart_struct.h uart_cap.h	Register macro definition, board dependent Define register in the form of C structure Hardware capability parameters