[ Upstream commit 5468cbcddf47f674829c6ada190283108a63d7b5 ]

In gsi_channel_stop(), there's a check to see if the channel might
have entered STOPPED state since a previous call, which might have
timed out before stopping completed.

That check actually belongs in gsi_channel_stop_command(), which is
called repeatedly by gsi_channel_stop() for RX channels.

Fixes: 650d1603825d ("soc: qcom: ipa: the generic software interface")
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit 195ef57f870070cb02f2f3b99a63d69e8e8f798e ]

In gsi_channel_start() there is harmless-looking comment "Clear the
channel's event ring interrupt in case it's pending".  The intent
was to avoid getting spurious interrupts when first bringing up a
channel.

However we now use channel stop/start to implement suspend and
resume, and an interrupt pending at the time we resume is actually
something we don't want to ignore.

The very first time we bring up the channel we do not expect an
interrupt to be pending, and even if it were, the effect would
simply be to schedule NAPI on that channel, which would find nothing
to do, which is not a problem.

Stop clearing any pending IEOB interrupt in gsi_channel_start().
That leaves one caller of the trivial function gsi_isr_ieob_clear().
Get rid of that function and just open-code it in gsi_isr_ieob()
instead.

This fixes a problem where suspend/resume IPA v4.2 would get stuck
when resuming after a suspend.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

The iteration count value used in gsi_channel_poll() is intended to
limit poll iterations to the budget supplied as an argument.  But
it's never updated.

Fix this bug by incrementing the count each time through the loop.

Reported-by: Sharath Chandra Vurukala <sharathv@codeaurora.com>
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Zero the result code stored in a field of the scratch 0 register
before issuing a generic EE command.  This just guarantees that
the value we read later was actually written as a result of the
command.

Also add the definitions of two more possible result codes that can
be returned when issuing flow control enable or disable commands:
  INCORRECT_CHANNEL_STATE: - channel must be in started state
  INCORRECT_DIRECTION - flow control is only valid for TX channels

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

An error message about limiting the number of TREs used prints the
wrong value.  Fix this bug.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch includes "gsi.c", which implements the generic software
interface (GSI) for IPA.  The generic software interface abstracts
channels, which provide a means of transferring data either from the
AP to the IPA, or from the IPA to the AP.  A ring buffer of "transfer
elements" (TREs) is used to describe data transfers to perform.  The
AP writes a doorbell register associated with a channel to let it know
it has added new entries (for an AP->IPA channel) or has finished
processing entries (for an IPA->AP channel).

Each channel also has an event ring buffer, used by the IPA to
communicate information about events related to a channel (for
example, the completion of TREs).  The IPA writes its own doorbell
register, which triggers an interrupt on the AP, to signal that
new event information has arrived.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>