#PHP SERIAL PORT COMMUNICATION LINUX KERNEL DRIVER#
Registered by TTY driver when client is defined.
Only in-kernel controller implementation.
The Serdev allows a device to be attached on UART without known the line disciplines limitations:
"drivers" are registered when a port is opened.
the associated ressources (GPIOs and interrupts, regulators, clocks, audio interface) are not described in the kernel space, which impacts power management.
#PHP SERIAL PORT COMMUNICATION LINUX KERNEL DRIVERS#
"drivers" are not kernel drivers but user space daemons.
the devices are encoded in the user space rather than in the firmware (Device Tree of ACPI).
Since kernel 4.12 version, the serial device bus (also called Serdev) has been introduced in the TTY framework to improve the interface offered to devices attached to a serial port (ex: Bluetooth, NFC, FM Radio and GPS devices), as the line disciplines "drivers" have some known limitations:
Converter modules: the converter modules, or mapping disciplines, translate, or map, input and output characters.
The line disciplines also perform most of the error handling and status monitoring for the TTY drivers. They perform all the transformations that occur on the inbound and outbound data streams.
Line disciplines: the line disciplines provide editing, job control, and special character interpretation.
The services are flow control and special semantics when a port is being opened. They perform the actual input and output to the adapter by providing services to the modules above it.
TTY drivers: TTY drivers, or hardware disciplines, directly control the hardware ( TTY devices) or pseudo-hardware (PTY devices).
The TTY subsystem supports three main types of modules: Modules can be added and removed dynamically for each TTY. A module is a set of processing rules that govern the interface for communication between the computer and an asynchronous device. To perform its tasks, the TTY subsystem is composed of modules, also called disciplines. The TTY special file (ttyX filesystem entry) supports the controlling terminal interface. The synchronous mode of the STM32 USART peripheral is not supported by the TTY subsystem.Ī controlling terminal manages the input and output operations of a group of processes.
controlling jobs and terminal access by using the concept of controlling terminal.
interpreting the data by recognizing special characters and adapting to national languages.
controlling the physical flow of data on asynchronous lines (including the transmission speed, character size, and line availability).
The TTY subsytem controls the communication between UART devices and the programs using these devices.