查看“Serial TTY line discipline”的源代码

本文提供有关 Linux® TTY 框架的信息。 它说明了如何使用线路规则激活“ UART”接口，以及如何从用户和内核空间访问它。<br />

==Framework purpose==
UART是几种设备类型（例如蓝牙，NFC，FM收音机和GPS设备）的通用接口。 <br/>
从内核版本4.12开始，TTY框架中引入了串行设备总线（也称为Serdev），以改善提供给连接到串行端口的设备的接口。 请参考 [[Serial TTY overview]]文章，以详细了解TTY框架的用途。尽管如此，仍然有可能（即使不推荐）使用行规“驱动程序”。
本文重点介绍提供给连接到串行端口的设备的线路规范接口。

==System overview==
[[File:Serial TTY Line Discipline overview.png|center|link=]]
<br/>

===Components description===
''从客户端应用程序到硬件''
* 应用程序：客户应用程序，用于从串行端口上连接的外围设备读取/写入数据。

* [[TTY tools]]: Linux社区提供的工具，例 '''stty''', '''ldattach''', '''inputattach''', '''tty''', '''ttys''', '''agetty''', '''mingetty''', '''kermit''' and '''minicom'''.

* Termios: API<ref name="termios API">[http://man7.org/linux/man-pages/man3/termios.3.html termios API], Linux Programmer's Manual termios API Documentation (user land API with serial devices)</ref> 提供使用串行驱动程序开发应用程序的接口。
*客户端子系统：'''TTY'''内核的内核子系统客户端（示例：蓝牙设备）

* TTY框架：高层TTY结构管理，包括 {{CodeSource | Linux kernel | drivers/tty/tty_io.c | '''tty character device driver'''}}, {{CodeSource | Linux kernel | drivers/tty | '''TTY core functions'''}}, [[Serial TTY line discipline| '''line discipline''']].

* 串行框架：低级串行驱动程序管理，包括{{CodeSource | Linux kernel | drivers/tty/serial/serial_core.c | '''serial core''' functions}}.

* USART驱动程序：{{CodeSource | Linux kernel | drivers/tty/serial/stm32-usart.c | stm32-usart}} '“低级串行驱动程序'”，用于所有stm32系列设备。
* [[USART internal peripheral| STM32 USART]]: ''' STM32前端IP''' 通过串行端口连接到外部设备

===APIs description===

The TTY provides only '''character device interface''' (named /dev/ttyX) to user space.
The main API for user space TTY client applications is provided by the portable POSIX terminal interface termios, which relies on /dev/ttyX interface for TTY link configuration.<br/>

The '''termios API'''<ref name="termios API"/> is a user land API, and its functions describe a general terminal interface that is provided to control asynchronous communications ports. <br/>

The POSIX termios API abstracts the low-level details of the hardware, and provides a simple yet complete programming interface that can be used for advanced projects. It is a wrapper on '''character device API''' <ref> [http://bootlin.com/doc/accessing-hardware.pdf Character device API overview], ''Accessing hardware from userspace'' training, Bootlin documentation</ref> ioctl operations.<br/>

{{Info|A [[Serial TTY line discipline|'''line discipline''']] driver can be used when a serial interface is needed at kernel level.}}
For example, a kernel driver maybe needed to control an external device through an U(S)ART port.
{{ReviewsComments|FGA W1941: I rephrased above note, can you please double-ckeck ?}}
* The '''line discipline''' will be responsible for:
** creating this new kernel API
** routing data flow between serial core and new kernel API <br/>

{{ReviewsComments|FGA W1941: No how to use section, nor examples ? Is it deliberate ?<br/>
FGA W1941: Maybe worth pointing out some existing examples in the kernel ?}}

==References==
<references />

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[[Category:Serial TTY|6]]
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