Create a simple helper function that indicates whether a channel has
been initialized.  This abstacts/hides the details of how this is
determined.

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

This patch actually fixes a bug, though it doesn't affect the two
platforms supported currently.  The fix implements GSI memory
pointers a bit differently.

For IPA version 4.5 and above, the address space for almost all GSI
registers is adjusted downward by a fixed amount.  This is currently
handled by adjusting the I/O virtual address pointer after it has
been mapped.  The bug is that the pointer is not "de-adjusted" as it
should be when it's unmapped.

This patch fixes that error, but it does so by maintaining one "raw"
pointer for the mapped memory range.  This is assigned when the
memory is mapped and used to unmap the memory.  This pointer is also
used to access the two registers that do *not* sit in the "adjusted"
memory space.

Rather than adjusting *that* pointer, we maintain a separate pointer
that's an adjusted copy of the "raw" pointer, and that is used for
most GSI register accesses.

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

An event ring's state only needs to be known when it is allocated,
reset, or deallocated.  We check an event ring's state both before
and after performing an event ring control command that changes
its state.  These are only issued at startup and shutdown, so there
is very little value in caching the state.

Stop recording a copy of the channel's last known state, and instead
fetch the true state from hardware whenever it's needed.  In such
cases, *do* record the state in a local variable, in case an error
message reports it (so the value reported is the value seen).

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

When stopping a channel, gsi_channel_stop() will ensure NAPI
polling is complete when it calls napi_disable().  So there is no
need to call napi_synchronize() in that case.

Move the call to napi_synchronize() out of __gsi_channel_stop()
and into gsi_channel_suspend(), so it's only used where needed.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Move the mutex calls out of gsi_channel_stop_retry() and into
__gsi_channel_stop(), to make the latter more semantically similar
to __gsi_channel_start().

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

In gsi_channel_setup(), we check to see if the configuration data
contains any information about channels that are not supported by
the hardware.  If one is found, we abort the setup process, but
the error code (ret) is not set in this case.  Fix this bug.

Fixes: 650d1603825d8 ("soc: qcom: ipa: the generic software interface")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20210204010655.15619-1-elder@linaro.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Transactions to send data for a network device can be allocated at
any time up until the point the TX queue is stopped.  It is possible
for ipa_start_xmit() to be called in one context just before a
the transmit queue is stopped in another.

Update gsi_channel_trans_last() so that for TX channels the
allocated and pending transaction lists are checked--in addition
to the completed and polled lists--to determine the "last"
transaction.  This means any transaction that has been allocated
before the TX queue is stopped will be allowed to complete before
we conclude the channel is quiesced.

Rework the function a bit to use a list pointer and gotos.

Signed-off-by: Alex Elder <elder@linaro.org>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

No completion interrupts will occur while an endpoint is suspended,
nor when a channel has been stopped for suspend.  So there's no need
to disable the interrupt during suspend and re-enable it when
resuming.  Without any interrupts occurring, there is no need to
disable/re-enable NAPI for channel suspend/resume either.

We'll only enable NAPI and the interrupt when we first start the
channel, and disable it again only when it's "really" stopped.

To accomplish this, move the enable/disable calls out of
__gsi_channel_start() and __gsi_channel_stop(), and into
gsi_channel_start() and gsi_channel_stop() instead.

Add a call to napi_synchronize() to gsi_channel_suspend(), to ensure
NAPI polling is done before moving on.

Signed-off-by: Alex Elder <elder@linaro.org>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Disable both the I/O completion interrupt and NAPI polling on a
channel *after* we successfully stop it rather than before.  This
ensures a completion occurring just before the channel is stopped
gets processed.

Enable NAPI polling and the interrupt *before* starting a channel
rather than after, to be symmetric.  A stopped channel won't
generate any completion interrupts anyway.

Enable NAPI before the interrupt and disable it afterward.

Signed-off-by: Alex Elder <elder@linaro.org>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>