arch/tiva: Serial TIOCxBRK BSD-compatible BREAK support #8475
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In the lower half UART driver for Tiva architecture (TM4C12x), adding the TIOCxBRK ioctl calls, which allow an application to transmit a BSD compatible line BREAK. TIOCSBRK starts the BREAK and TIOCCBRK ends it. This architecture supports BSD-style BREAK in hardware. We write to the BRK bit (bit 0) of the UART Line Control register (UARTLCRH) to start the BREAK, which begins after the UART finishes shifting out the current character in progress, if any, including its stop bit(s), and continues indefinitely until we write to the BRK bit again to stop the BREAK. * arch/arm/src/tiva/Kconfig (config TIVA_UART_BREAKS): New. Appears as CONFIG_TIVA_UART_BREAKS in code. * arch/arm/src/tiva/common/tiva_serial.c (struct up_dev_s): Add new field 'brk' to indicate line break in progress when built with CONFIG_TIVA_UART_BREAKS. (up_ioctl): Add cases for TIOCSBRK to turn BSD-compatible break on unconditionally and TIOCCBRK to turn break off unconditionally. (up_txint): Block enabling TX interrupt if line break in progress. This is similar to the STM32F7 implementation.
Your input on this (previously on the mailing list) has been tremendously helpful. Thanks for all your help! |
xiaoxiang781216
approved these changes
Feb 8, 2023
acassis
approved these changes
Feb 8, 2023
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Summary
In the lower half UART driver for Tiva architecture (TM4C12x), adding the
TIOCxBRKioctl calls, which allow an application to transmit a BSD compatible line BREAK.TIOCSBRKstarts the BREAK andTIOCCBRKends it.This architecture supports BSD-style BREAK in hardware. We write to the BRK bit (bit 0) of the UART Line Control register (UARTLCRH) to start the BREAK, which begins after the UART finishes shifting out the current character in progress, if any, including its stop bit(s), and continues indefinitely until we write to the BRK bit again to stop the BREAK.
Impact
When new Kconfig option
TIVA_UART_BREAKSis activated,TIOCSBRKandTIOCCBRKioctl calls are supported on Tiva architectures. When not activated, no effect.Testing
Custom board.