src/sys/dev/uart/uart_tty.c, branch releng/12.4

add support for console resuming, implement it for uart, use on x86

2018-05-29T16:16:24Z

This change adds a new optional console method cn_resume and a kernel console interface cnresume. Consoles that may need to re-initialize their hardware after suspend (e.g., because firmware does not care to do it) will implement cn_resume. Note that it is called in rather early environment not unlike early boot, so the same restrictions apply. Platform specific code, for platforms that support hardware suspend, should call cnresume early after resume, before any console output is expected. This change fixes a problem with a system of mine failing to resume when a serial console is used. I found that the serial port was in a strange configuration and an attempt to write to it likely resulted in an infinite loop. To avoid adding cn_resume method to every console driver, CONSOLE_DRIVER macro has been extended to support optional methods. Reviewed by: imp, mav MFC after: 3 weeks Differential Revision: https://reviews.freebsd.org/D15552

sys/dev: further adoption of SPDX licensing ID tags.

2017-11-27T14:52:40Z

Mainly focus on files that use BSD 2-Clause license, however the tool I was using misidentified many licenses so this was mostly a manual - error prone - task. The Software Package Data Exchange (SPDX) group provides a specification to make it easier for automated tools to detect and summarize well known opensource licenses. We are gradually adopting the specification, noting that the tags are considered only advisory and do not, in any way, superceed or replace the license texts.

- Make the code consistent with itself style-wise and bring it closer

2016-01-25T22:58:06Z

to style(9). - Mark unused arguments as such. - Make the ttystates table const.

Fix tty_drain() and, thus, TIOCDRAIN of the current tty(4) incarnation

2016-01-19T23:34:27Z

to actually wait until the TX FIFOs of UARTs have be drained before returning. This is done by bringing the equivalent of the TS_BUSY flag found in the previous implementation back in an ABI-preserving way. Reported and tested by: Patrick Powell Most likely, drivers for USB-serial-adapters likewise incorporating TX FIFOs as well as other terminal devices that buffer output in some form should also provide implementations of tsw_busy. MFC after: 3 days

Provide the tty-layer mutex when initializing the pps api. This allows

2015-08-08T20:11:47Z

time_pps_fetch() to be used in blocking mode. Also, don't init the pps api for system devices (consoles) that provide a custom attach routine. The device may actually be a keyboard or other non- tty device. If it wants to do pps processing (unlikely) it must handle everything for itself. (In reality, only a sun keyboard uses a custom attach routine, and it doesn't make a good pps device.)

Do not prevent processes from making changes to the baudrate or the

2014-04-05T22:25:10Z

CLOCAL and HUPCL control flags. There are legit reasons for allowing those to be changed. When /etc/ttys has the "3wire" type (without a baudrate) for the serial port that is the low-level console, then this change has no effect. Obtained from: Juniper Networks, Inc.

Pass the actual baudrate to tty_init_console(). This defines the initial

2014-03-11T03:20:10Z

baudrate of the device special file, and makes sure that on open(2) the UART is programmed with the correct baudrate. This then eliminates the need in uart_tty_param() to override the speed setting.

Plumb the cn_grab and cn_ungrab routines down into the uart

2013-12-21T16:23:31Z

clients. Mask RX interrupts while grabbed on the atmel serial driver. This UART interrupts every character. When interrupts are enabled at the mountroot> prompt, this means the ISR eats the characters. Rather than try to create a cooperative buffering system for the low level kernel console, instead just mask out the ISR. For NS8250 and decsendents this isn't needed, since interrupts only happen after 14 or more characters (depending on the fifo settings). Plumb such that these are optional so there's no change in behavior for all the other UART clients. ddb worked on this platform because all interrupts were disabled while it was running, so this problem wasn't noticed. The mountroot> issue has been around for a very very long time. MFC after: 3 days

kern cons: introduce infrastructure for console grabbing by kernel

2011-12-17T15:08:43Z

At the moment grab and ungrab methods of all console drivers are no-ops. Current intended meaning of the calls is that the kernel takes control of console input. In the future the semantics may be extended to mean that the calling thread takes full ownership of the console (e.g. console output from other threads could be suspended). Inspired by: bde MFC after: 2 months

In uart_tty_outwakeup(), check CTS/RTS flow control settings and

2011-01-24T18:34:16Z

prevent sending data when CTS is de-asserted. In uart_tty_intr(), call uart_tty_outwakeup() when the CTS signal changed, knowing that uart_tty_outwakeup() will do the right thing for flow control. This avoids redundant conditionals. PR: kern/148644 Submitted by: John Wehle MFC after: 3 days