If the UART back-end blocks, buffer in the Tx FIFO to try again later.
This stops the IO-thread busy waiting on char back-ends (which causes
all sorts of performance problems).
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Message-id: 4bea048b3ab38425701d82ccc1ab92545c26b79c.1388626249.git.peter.crosthwaite@xilinx.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
The can_receive logic was only taking into account the RxFIFO
occupancy. RxFIFO population is only used for the echo and normal modes
however. Improve the logic to correctly return the true number of
receivable characters based on the current mode:
Normal mode: RxFIFO vacancy.
Remote loopback: TxFIFO vacancy.
Echo mode: The min of the TxFIFO and RxFIFO vacancies.
Local Loopback: Return non-zero (to implement droppage)
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Message-id: 36a58440c9ca5080151e95765c2c81342de8a8df.1388626249.git.peter.crosthwaite@xilinx.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This tx timer implementation is flawed. Despite the controller
attempting to time the guest visable assertion of the TX-empty status
bit (and corresponding interrupt) the controller is still transmitting
characters instantaneously. There is also no sense of multiple character
delay.
The only side effect of this timer is assertion of tx-empty status. So
just remove the timer completely and hold tx-empty as permanently
asserted (its reset status). This matches the actual behaviour of
instantaneous transmission.
While we are VMSD version bumping, add the tx_fifo as device state to
prepare for upcomming TxFIFO flow control. Implement the interrupt
generation logic for the TxFIFO occupancy.
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Message-id: 7a208a7eb8d79d6429fe28b1396c3104371807b2.1388626249.git.peter.crosthwaite@xilinx.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Some (interrupt) status register bits relating to the TxFIFO path were
not defined. Define them. This prepares support for proper Tx data path
flow control.
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Message-id: 2068b963f0af8cc834c353944e9fa816d950b163.1388626249.git.peter.crosthwaite@xilinx.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
The status register bits are always pure functions of other device
state. Move the generation of these bits to the update_status()
function to simplify. Makes developing much easier as theres now no need
to recheck status bits on all the changes to rx/tx fifo state.
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Message-id: 321994929f789096975104f99c55732774be4cae.1388626249.git.peter.crosthwaite@xilinx.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This should be rechecked on bus write accesses as such accesses may
change the underlying state that generates the interrupt. Particular
relevant for when the guest touches the interrupt status or mask.
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Message-id: 1c250cd61b7b8de492fbc8b79b8370958a56d83b.1388626249.git.peter.crosthwaite@xilinx.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Most code already used QEMUTimer without the redundant 'struct' keyword.
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
This is an autogenerated patch using scripts/switch-timer-api.
Switch the entire code base to using the new timer API.
Note this patch may introduce some line length issues.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
commit 1db8b5efe0 introduced an issue
where QEMU would segfault if you have an unattached Cadence UART.
Fix by guarding the flush-on-reset logic on there being a qemu_chr
attachment.
Reported-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Tested-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Message-id: 9009578ee10a50d994b2e10aa2840d73765f5968.1370577272.git.peter.crosthwaite@xilinx.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
