Packet transmission for the stellaris ethernet controller can be triggered
in one of two ways:
* by setting a threshold value in the THR register; when the FIFO
fill level reaches the threshold, the h/w starts transmitting.
Software has to finish filling the FIFO before the transmit
process completes to avoid a (silent) underrun
* by software writing to the TR register to explicitly trigger
transmission
Since QEMU transmits packets instantaneously (from the guest's
point of view), implement "transmit based on threshold" with
our existing mechanism of "transmit as soon as we have the whole
packet", with the additional wrinkle that we don't transmit if
the packet size is below the specified threshold, and implement
"transmit by specific request" properly.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
The datasheet is clear that the frame length written to the DATA
register is actually stored in the TX FIFO; this means we don't
need to keep both tx_frame_len and tx_fifo_len state separately.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
The PADEN bit in the transmit control register enables padding of short
data packets out to the required minimum length. However a typo here
meant we were adjusting tx_fifo_len rather than tx_frame_len, so the
padding didn't actually happen. Fix this bug.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: qemu-stable@nongnu.org
The current tx_fifo code has a corner case where the guest can overrun
the fifo buffer: if automatic CRCs are disabled we allow the guest to write
the CRC word even if there isn't actually space for it in the FIFO.
The datasheet is unclear about exactly how the hardware deals with this
situation; the most plausible answer seems to be that the CRC word is
just lost.
Implement this fix by separating the "can we stuff another word in the
FIFO" logic from the "should we transmit the packet now" check. This
also moves us closer to the real hardware, which has a number of ways
it can be configured to trigger sending the packet, some of which we
don't implement.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: qemu-stable@nongnu.org
Add a cast to avoid an unintended sign extension that
would mean we returned 0xffffffff in the high 32 bits
for an IA0 read if bit 31 in the MAC address was 1.
(This is harmless since we'll only be doing 4 byte
reads, but it could be confusing, so best avoided.)
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Message-id: 1392647854-8067-3-git-send-email-peter.maydell@linaro.org
Drop freeing stellaris_enet_state - that is done by QOM later on unref.
Both MemoryRegion init and savevm registration happen in SysBusDevice
initfn currently, so move them into an unrealizefn for now.
Signed-off-by: Andreas Färber <afaerber@suse.de>
