We need the tty fixes in here for other patches to be based on.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Since IRQs might be muxed on some parts, we need to pay attention when we
are freeing them.
Otherwise we get the ugly WARNING "Trying to free already-free IRQ 20".

Fixes: 628c534ae735 ("serial: sh-sci: Improve support for separate TEI and DRI interrupts")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Most RX/TX-specific DMA functions are prefixed with "sci_dma_[rt]x_".
Rename the exceptions to increase consistency.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When submitting a DMA request fails in sci_dma_rx_complete(), the driver
tries to fall back to PIO, but that does not work: no more data will be
received, or the kernel will even crash.

Fix this similar as in (but not identical to) sci_submit_rx():
  - On SCIF, PIO cannot take over if any DMA transactions are pending,
    hence they must be terminated first.
  - All active cookies must be invalidated, else rx_timer_fn() may
    trigger a NULL pointer dereference.
  - Restarting the port is not needed, as it is already running, but
    serial port interrupts must be directed back from the DMA engine to
    the CPU.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Extract the functionality to direct new serial port interrupts back to
the CPU into its own helper, to prepare for using it from a second
callsite.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The cookies and channel pointer for the DMA receive channel are
invalidated in two places, and one more is planned.
Extract this functionality in a common helper.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

On (H)SCIF, sci_submit_rx() is called in the receive interrupt handler.
Hence if DMA submission fails, the interrupt handler should resume
handling reception using PIO, else no more data is received.

Make sci_submit_rx() return an error indicator, so the receive interrupt
handler can act appropriately.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When falling back to PIO, active_rx must be set to a different value
than cookie_rx[i], else sci_dma_rx_find_active() will incorrectly find a
match, leading to a NULL pointer dereference in rx_timer_fn() later.

Use zero instead, which is the same value as after driver
initialization.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Some callers of sci_submit_rx() hold the port spinlock, others don't.
During fallback to PIO, the driver needs to obtain the port spinlock.
If the lock was already held, spinlock recursion is detected, causing a
deadlock: BUG: spinlock recursion on CPU#0.

Fix this by adding a flag parameter to sci_submit_rx() for the caller to
indicate the port spinlock is already held, so spinlock recursion can be
avoided.

Move the spin_lock_irqsave() up, so all DMA disable steps are protected,
which is safe as the recently introduced dmaengine_terminate_async() can
be called in atomic context.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

We want the tty/serial fixes in here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>