ALTERA_JTAG_UART(4) | Device Drivers Manual | ALTERA_JTAG_UART(4) |
NAME¶
altera_jtag_uart
—
SYNOPSIS¶
device altera_jtag_uart
In /boot/device.hints:
hint.altera_jtag_uart.0.at="nexus0"
hint.altera_jtag_uart.0.maddr=0x7f000000
hint.altera_jtag_uart.0.msize=0x40
hint.altera_jtag_uart.0.irq=0
hint.altera_jtag_uart.1.at="nexus0"
hint.altera_jtag_uart.1.maddr=0x7f001000
hint.altera_jtag_uart.1.msize=0x40
DESCRIPTION¶
Thealtera_jtag_uart
device driver provides support for
the Altera JTAG UART core, which allows multiple UART-like streams to be
carried over JTAG. altera_jtag_uart
allows JTAG UART
streams to be attached to both the low-level console interface, used for
direct kernel input and output, and the tty(4) layer, to be
used with ttys(5) and login(1). Sequential
Altera JTAG UART devices will appear as ttyu0
,
ttyu1
, etc.
HARDWARE¶
Altera JTAG UART devices can be connected to using Altera's nios2-terminal program, with the instance selected using the--instance
argument on the management host.
altera_jtag_uart
supports JTAG UART cores with or
without interrupt lines connected; if the irq
portion
of the device.hints entry is omitted, the driver will
poll rather than configure interrupts.
SEE ALSO¶
login(1), tty(4), ttys(5)Altera Embedded Peripherals IP User Guide, Altera Corporation, http://www.altera.com/literature/ug/ug_embedded_ip.pdf, June 2011.
HISTORY¶
Thealtera_jtag_uart
device driver first appeared in
FreeBSD 10.0.
AUTHORS¶
Thealtera_jtag_uart
device driver and this manual page
were developed by SRI International and the University of Cambridge Computer
Laboratory under DARPA/AFRL contract (FA8750-10-C-0237)
(“CTSRD”), as part of the DARPA CRASH research programme. This
device driver was written by Robert N. M. Watson.
BUGS¶
altera_jtag_uart
must dynamically poll to detect when
JTAG is present, in order to disable flow control in the event that there is
no receiving endpoint. Otherwise, the boot may hang waiting for the JTAG
client to be attached, and user processes attached to JTAG UART devices might
block indefinitely. However, there is no way to flush the output buffer once
JTAG is detected to have disappeared; this means that a small amount of stale
output data will remain in the output buffer, being displayed by
nios2-terminal
when it is connected. Loss of JTAG will
not generate a hang-up event, as that is rarely the desired behaviour.
nios2-terminal
does not place the
client-side TTY in raw mode, and so by default will not pass all control
characters through to the UART.
August 18, 2012 | Linux 4.19.0-10-amd64 |