User input is buffered anyway, so it's pointless to set the UART_LSR_OE bit.
Instead, wait for the guest kernel to consume the current input and send a new
character when the guest is ready.

This fixes the following warnings in guest kernels:

[  207.485000] ttyS0: 1 input overrun(s)

Reported-by: Asias He <asias.hejun@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

This patch fixes 8250 device initial state for registers and IRQ based on what
Qemu does.

Signed-off-by: Pekka Enberg <penberg@kernel.org>

This patch implements 16550A FIFO support to the serial console emulation
layer. There's still a bug lurking somewhere which the hypervisor in some busy
loop taking up 100% of CPU. However, this patch is a definite improvement over
the previous hacks.

Signed-off-by: Pekka Enberg <penberg@kernel.org>

This patch implements missing register emulation as per "UART register to port
conversion table" here:

  http://www.lammertbies.nl/comm/info/serial-uart.html



Signed-off-by: Pekka Enberg <penberg@kernel.org>

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

This patch cleans up receive emulation by separating the stdin polling and
reading logic from the interrupt logic. The patch also fixes the interrupt
injection code to inject one type of interrupt at a time.

Signed-off-by: Pekka Enberg <penberg@kernel.org>

We need to reset the counter to zero before we inject an interrupt to the
guest.

Signed-off-by: Pekka Enberg <penberg@kernel.org>

This patch fixes the "too much work for irq4" problems caused by the fact that
we never set the UART_IIR_NO_INT flag in the emulation layer. This makes the
interrupt handler in the guest kernel process as much as possible which
triggers a warning.

Signed-off-by: Pekka Enberg <penberg@kernel.org>

This patch fixes the 8250 serial emulation to not have undefined ioports but
rather make them explicitly disabled.

Signed-off-by: Pekka Enberg <penberg@kernel.org>

Signed-off-by: Pekka Enberg <penberg@kernel.org>

Signed-off-by: Pekka Enberg <penberg@kernel.org>

Otherwise it causes kernel to do additional timeout
waiting for THR being empty.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

Signed-off-by: Pekka Enberg <penberg@kernel.org>

This patch fixes 8250 emulation to inject interrupts to guest so we actually
see what's sent to the serial console.

Signed-off-by: Pekka Enberg <penberg@kernel.org>

The 8250 emulation is no longer there to just support early_printk() so rename
the source file to reflect that.

Signed-off-by: Pekka Enberg <penberg@kernel.org>

This patch implement support for injecting interrupts from the userspace
hypervisor to the guest.

Signed-off-by: Pekka Enberg <penberg@kernel.org>

This patch enables the THRI ("transmission holding register empty") bit in the
IIR register to make sure the guest doesn't think we have data waiting for it.

Signed-off-by: Pekka Enberg <penberg@kernel.org>

Signed-off-by: Pekka Enberg <penberg@kernel.org>

Signed-off-by: Pekka Enberg <penberg@kernel.org>

Signed-off-by: Pekka Enberg <penberg@kernel.org>

Signed-off-by: Pekka Enberg <penberg@kernel.org>

This patch adds a 'count' argument to ioport__register() to allow callers to
register a range of ioports.

Signed-off-by: Pekka Enberg <penberg@kernel.org>

This patch adds some more ioport emulation code so that I can boot a Linux
kernel cleanly with "--ioport-debug" command line option enabled.

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

Signed-off-by: Asias He <asias.hejun@gmail.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

Make sure we flush stdout for early printk so that we can see what's really
going on when a kernel gets stuck.

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

Use similar constants and variable names as in arch/x86/kernel/early_printk.c
in the Linux kernel.

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>