Calling ipa_cmd_pipeline_clear() after stopping the channel
underlying the AP<-modem RX endpoint can lead to a deadlock.

This occurs in the ->runtime_suspend device power operation for the
IPA driver.  While this callback is in progress, any other requests
for power will block until the callback returns.

Stopping the AP<-modem RX channel does not prevent the modem from
sending another packet to this endpoint.  If a packet arrives for an
RX channel when the channel is stopped, an SUSPEND IPA interrupt
condition will be pending.  Handling an IPA interrupt requires
power, so ipa_isr_thread() calls pm_runtime_get_sync() first thing.

The problem occurs because a "pipeline clear" command will not
complete while such a SUSPEND interrupt condition exists.  So the
SUSPEND IPA interrupt handler won't proceed until it gets power;
that won't happen until the ->runtime_suspend callback (and its
"pipeline clear" command) completes; and that can't happen while
the SUSPEND interrupt condition exists.

It turns out that in this case there is no need to use the "pipeline
clear" command.  There are scenarios in which clearing the pipeline
is required while suspending, but those are not (yet) supported
upstream.  So a simple fix, avoiding the potential deadlock, is to
stop calling ipa_cmd_pipeline_clear() in ipa_endpoint_suspend().
This removes the only user of ipa_cmd_pipeline_clear(), so get rid
of that function.  It can be restored again whenever it's needed.

This is basically a manual revert along with an explanation for
commit 6cb63ea6 ("net: ipa: introduce ipa_cmd_tag_process()").

Fixes: 6cb63ea6 ("net: ipa: introduce ipa_cmd_tag_process()")
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

The IPA setup_complete flag is set at the end of ipa_setup(), when
the setup phase of initialization has completed successfully.  This
occurs as part of driver probe processing, or (if "modem-init" is
specified in the DTS file) it is triggered by the "ipa-setup-ready"
SMP2P interrupt generated by the modem.

In the latter case, it's possible for driver shutdown (or remove) to
begin while setup processing is underway, and this can't be allowed.
The problem is that the setup_complete flag is not adequate to signal
that setup is underway.

If setup_complete is set, it will never be un-set, so that case is
not a problem.  But if setup_complete is false, there's a chance
setup is underway.

Because setup is triggered by an interrupt on a "modem-init" system,
there is a simple way to ensure the value of setup_complete is safe
to read.  The threaded handler--if it is executing--will complete as
part of a request to disable the "ipa-modem-ready" interrupt.  This
means that ipa_setup() (which is called from the handler) will run
to completion if it was underway, or will never be called otherwise.

The request to disable the "ipa-setup-ready" interrupt is currently
made within ipa_modem_stop().  Instead, disable the interrupt
outside that function in the two places it's called.  In the case of
ipa_remove(), this ensures the setup_complete flag is safe to read
before we read it.

Rename ipa_smp2p_disable() to be ipa_smp2p_irq_disable_setup(), to be
more specific about its effect.

Fixes: 530f9216 ("soc: qcom: ipa: AP/modem communications")
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

We currently maintain a "disabled" Boolean flag to determine whether
the "ipa-setup-ready" SMP2P IRQ handler does anything.  That flag
must be accessed under protection of a mutex.

Instead, disable the SMP2P interrupt when requested, which prevents
the interrupt handler from ever being called.  More importantly, it
synchronizes a thread disabling the interrupt with the completion of
the interrupt handler in case they run concurrently.

Use the IPA setup_complete flag rather than the disabled flag in the
handler to determine whether to ignore any interrupts arriving after
the first.

Rename the "disabled" flag to be "setup_disabled", to be specific
about its purpose.

Fixes: 530f9216 ("soc: qcom: ipa: AP/modem communications")
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

The head-of-line blocking timer should only be modified when
head-of-line drop is disabled.

One of the steps in recovering from a modem crash is to enable
dropping of packets with timeout of 0 (immediate).  We don't know
how the modem configured its endpoints, so before we program the
timer, we need to ensure HOL_BLOCK is disabled.

Fixes: 84f9bd12 ("soc: qcom: ipa: IPA endpoints")
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Starting with IPA v4.5, the HOL_BLOCK_EN register must be written
twice when enabling head-of-line blocking avoidance.

Fixes: 84f9bd12 ("soc: qcom: ipa: IPA endpoints")
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

The source group count was mistakenly assigned to both dst and src loops.
Fix it to make IPA probe and work again.

Fixes: 4fd704b3 ("net: ipa: record number of groups in data")
Acked-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Reviewed-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20211111183724.593478-1-konrad.dybcio@somainline.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Now that SCM can be a loadable module, we have to add another
dependency to avoid link failures when ipa or adreno-gpu are
built-in:

aarch64-linux-ld: drivers/net/ipa/ipa_main.o: in function `ipa_probe':
ipa_main.c:(.text+0xfc4): undefined reference to `qcom_scm_is_available'

ld.lld: error: undefined symbol: qcom_scm_is_available
>>> referenced by adreno_gpu.c
>>>               gpu/drm/msm/adreno/adreno_gpu.o:(adreno_zap_shader_load) in archive drivers/built-in.a

This can happen when CONFIG_ARCH_QCOM is disabled and we don't select
QCOM_MDT_LOADER, but some other module selects QCOM_SCM. Ideally we'd
use a similar dependency here to what we have for QCOM_RPROC_COMMON,
but that causes dependency loops from other things selecting QCOM_SCM.

This appears to be an endless problem, so try something different this
time:

 - CONFIG_QCOM_SCM becomes a hidden symbol that nothing 'depends on'
   but that is simply selected by all of its users

 - All the stubs in include/linux/qcom_scm.h can go away

 - arm-smccc.h needs to provide a stub for __arm_smccc_smc() to
   allow compile-testing QCOM_SCM on all architectures.

 - To avoid a circular dependency chain involving RESET_CONTROLLER
   and PINCTRL_SUNXI, drop the 'select RESET_CONTROLLER' statement.
   According to my testing this still builds fine, and the QCOM
   platform selects this symbol already.

Acked-by: Kalle Valo <kvalo@codeaurora.org>
Acked-by: Alex Elder <elder@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

There is an off-by-one problem in ipa_table_init_add(), when
initializing filter tables.

In that function, the number of filter table entries is determined
based on the number of set bits in the filter map.  However that
count does *not* include the extra "slot" in the filter table that
holds the filter map itself.  Meanwhile, ipa_table_addr() *does*
include the filter map in the memory it returns, but because the
count it's provided doesn't include it, it includes one too few
table entries.

Fix this by including the extra slot for the filter map in the count
computed in ipa_table_init_add().

Note: ipa_filter_reset_table() does not have this problem; it resets
filter table entries one by one, but does not overwrite the filter
bitmap.

Fixes: 2b9feef2 ("soc: qcom: ipa: filter and routing tables")
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Finally, rename "ipa_clock.c" to be "ipa_power.c" and "ipa_clock.h"
to be "ipa_power.h".

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

Rename a number of functions to clarify that there is no longer a
notion of an "IPA clock," but rather that the functions are more
generally related to IPA power management.

  ipa_clock_enable() -> ipa_power_enable()
  ipa_clock_disable() -> ipa_power_disable()
  ipa_clock_rate() -> ipa_core_clock_rate()
  ipa_clock_init() -> ipa_power_init()
  ipa_clock_exit() -> ipa_power_exit()

Rename the ipa_clock structure to be ipa_power.  Rename all
variables and fields using that structure type "power" rather
than "clock".

Rename the ipa_clock_data structure to be ipa_power_data, and more
broadly, just substitute "power" for "clock" in places that
previously represented things related to the "IPA clock".

Update comments throughout.

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

Use runtime power management autosuspend.

Up until this point, we only suspended the IPA hardware for system
suspend; now we'll suspend it aggressively using runtime power
management, setting the initial autosuspend delay to half a second
of inactivity.

Replace pm_runtime_put() calls with pm_runtime_put_autosuspend(),
call pm_runtime_mark_last_busy() before each of those.  In places
where we're shutting things down, or decrementing power references
for errors, use pm_runtime_put_noidle() instead.

Finally, remove ipa_runtime_idle(), so the ->runtime_suspend
callback will occur if idle.

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

The only remaining user of the ipa_clock_{get,put}() interface is
ipa_isr_thread().  Replace calls to ipa_clock_get() there calling
pm_runtime_get_sync() instead.  And call pm_runtime_put() there
rather than ipa_clock_put().  Warn if we ever get an error.

With that, we can get rid of ipa_clock_get() and ipa_clock_put().

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

When we open or close the modem network device we need to ensure the
hardware is powered.  Replace the callers of ipa_clock_get() found
in ipa_open() and ipa_stop() with calls to pm_runtime_get_sync().
If an error is returned, simply return that error to the caller
(without any error or warning message).  This could conceivably
occur if the function was called while the system was suspended,
but that really shouldn't happen.  Replace corresponding calls to
ipa_clock_put() with pm_runtime_put() also.

If the modem crashes we also need to ensure the hardware is powered
to recover.  If getting power returns an error there's not much we
can do, but at least report the error.  (Ideally the remoteproc SSR
code would ensure the AP was not suspended when it sends the
notification, but that is not (yet) the case.)

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

Replace the ipa_clock_get() call in ipa_uc_clock() when taking the
"proxy" clock reference for the microcontroller with a call to
pm_runtime_get_sync().  Replace calls of ipa_clock_put() for the
microcontroller with pm_runtime_put() calls instead.

There is a chance we get an error when taking the microcontroller
power reference.  This is an unlikely scenario, where system suspend
is initiated just before we learn the modem is booting.  For now
we'll just accept that this could occur, and report it if it does.

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

If the "modem-init" Device Tree property is present for a platform,
the modem performs early IPA hardware initialization, and signals
this is complete with an "ipa-setup-ready" SMP2P interrupt.  This
triggers a call to ipa_setup(), which requires the hardware to be
powered.

Replace the call to ipa_clock_get() in this case with a call to
pm_runtime_get_sync().  And replace the corresponding calls to
ipa_clock_put() with calls to pm_runtime_put() instead.

There is a chance we get an error when taking this power reference.
This is an unlikely scenario, where system suspend is initiated just
before the modem signals it has finished initializing the IPA
hardware.  For now we'll just accept that this could occur, and
report it if it does.

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

We need the hardware to be powered starting at the config stage of
initialization when the IPA driver probes.  And we need it powered
when the driver is removed, at least until the deconfig stage has
completed.

Replace callers of ipa_clock_get() in ipa_probe() and ipa_exit(),
calling pm_runtime_get_sync() instead.  Replace the corresponding
callers of ipa_clock_put(), calling pm_runtime_put() instead.

The only error we expect when getting power would occur when the
system is suspended.  The ->probe and ->remove driver callbacks
won't be called when suspended, so issue a WARN() call if an error
is seen getting power.

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

Jakub Kicinski pointed out a race condition in ipa_start_xmit() in a
recently-accepted series of patches:
  https://lore.kernel.org/netdev/20210812195035.2816276-1-elder@linaro.org/


We are stopping the modem TX queue in that function if the power
state is not active.  We restart the TX queue again once hardware
resume is complete.

  TX path                       Power Management
  -------                       ----------------
  pm_runtime_get(); no power    Start resume
  Stop TX queue                      ...
  pm_runtime_put()              Resume complete
  return NETDEV_TX_BUSY         Start TX queue

  pm_runtime_get()
  Power present, transmit
  pm_runtime_put()              (auto-suspend)

The issue is that the power management (resume) activity and the
network transmit activity can occur concurrently, and there's a
chance the queue will be stopped *after* it has been started again.

  TX path                       Power Management
  -------                       ----------------
                                Resume underway
  pm_runtime_get(); no power         ...
                                Resume complete
                                Start TX queue
  Stop TX queue       <-- No more transmits after this
  pm_runtime_put()
  return NETDEV_TX_BUSY

We address this using a STARTED flag to indicate when the TX queue
has been started from the resume path, and a spinlock to make the
flag and queue updates happen atomically.

  TX path                       Power Management
  -------                       ----------------
                                Resume underway
  pm_runtime_get(); no power    Resume complete
                                start TX queue     \
  If STARTED flag is *not* set:                     > atomic
      Stop TX queue             set STARTED flag   /
  pm_runtime_put()
  return NETDEV_TX_BUSY

A second flag is used to address a different race that involves
another path requesting power.

  TX path            Other path              Power Management
  -------            ----------              ----------------
                     pm_runtime_get_sync()   Resume
                                             Start TX queue   \ atomic
                                             Set STARTED flag /
                     (do its thing)
                     pm_runtime_put()
                                             (auto-suspend)
  pm_runtime_get()                           Mark delayed resume
  STARTED *is* set, so
    do *not* stop TX queue  <-- Queue should be stopped here
  pm_runtime_put()
  return NETDEV_TX_BUSY                      Suspend done, resume
                                             Resume complete
  pm_runtime_get()
  Stop TX queue
    (STARTED is *not* set)                   Start TX queue   \ atomic
  pm_runtime_put()                           Set STARTED flag /
  return NETDEV_TX_BUSY

So a STOPPED flag is set in the transmit path when it has stopped
the TX queue, and this pair of operations is also protected by the
spinlock.  The resume path only restarts the TX queue if the STOPPED
flag is set.  This case isn't a major problem, but it avoids the
"non-trivial amount of useless work" done by the networking stack
when NETDEV_TX_BUSY is returned.

Fixes: 6b51f802 ("net: ipa: ensure hardware has power in ipa_start_xmit()")
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Currently a clock reference is taken whenever the ->ndo_open
callback for the modem netdev is called.  That reference is dropped
when the device is closed, in ipa_stop().

We no longer need this, because ipa_start_xmit() now handles the
situation where the hardware power state is not active.

Drop the clock reference in ipa_open() when we're done, and take a
new reference in ipa_stop() before we begin closing the interface.

Finally (and unrelated, but trivial), change the return type of
ipa_start_xmit() to be netdev_tx_t instead of int.

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

Currently we stop the modem netdev transmit queue when suspending
the hardware.  For system suspend this ensured we'd never attempt
to transmit while attempting to suspend the modem endpoints.

For runtime suspend, the IPA hardware might get suspended while the
system is operating.  In that case we want an attempt to transmit a
packet to cause the hardware to resume if necessary.  But if we
disable the queue this cannot happen.

So stop disabling the queue on suspend.  In case we end up disabling
it in ipa_start_xmit() (see the previous commit), we still arrange
to start the TX queue on resume.

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

We need to ensure the hardware is powered when we transmit a packet.
But if it's not, we can't block to wait for it.  So asynchronously
request power in ipa_start_xmit(), and only proceed if the return
value indicates the power state is active.

If the hardware is not active, a runtime resume request will have
been initiated.  In that case, stop the network stack from further
transmit attempts until the resume completes.  Return NETDEV_TX_BUSY,
to retry sending the packet once the queue is restarted.

If the power request returns an error (other than -EINPROGRESS,
which just means a resume requested elsewhere isn't complete), just
drop the packet.

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

Create a new work structure in the modem private data, and use it to
re-enable the modem network device transmit queue when resuming.

This is needed by the next patch, which stops the TX queue if IPA
power isn't active when a transmit request arrives.  Packets will
start arriving the instant the TX queue is enabled, but resuming
isn't complete until ipa_modem_resume() returns.  This way we're
sure to be resumed before transmits are allowed again.

Cancel it before calling ipa_stop() in ipa_modem_stop() to ensure
the transmit queue restart completes before it gets stopped there.

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

Add a new flag that is set when the hardware is suspended due to a
system suspend operation, distingishing it from runtime suspend.
Use it in the SUSPEND IPA interrupt handler to determine whether to
trigger a system resume because of the event.  Define new suspend
and resume power management callback functions to set and clear the
new flag, respectively.

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

Move the call to enable the IPA interrupt as a wakeup interrupt into
ipa_power_setup(), disable it in ipa_power_teardown().

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

It isn't required, but all callers of ipa_aggr_granularity_val()
pass a constant value (IPA_AGGR_GRANULARITY) as the usec argument.
Two of those callers are in ipa_validate_build(), with the result
being passed to BUILD_BUG_ON().

Evidently the "sparc64-linux-gcc" compiler (at least) doesn't always
inline ipa_aggr_granularity_val(), so the result of the function is
not constant at compile time, and that leads to build errors.

Define the function with the __always_inline attribute to avoid the
errors.  We can see by inspection that the value passed is never
zero, so we can just remove its WARN_ON() call.

Fixes: 5bc55884 ("net: ipa: use WARN_ON() rather than assertions")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20210811135948.2634264-1-elder@linaro.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Now that ipa_clock_get_additional() is a trivial wrapper around
pm_runtime_get_if_active(), just open-code it in its only caller
and delete the function.

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

The runtime power management core code maintains a usage count.  This
count mirrors the IPA clock reference count, and there's no need to
maintain both.  So get rid of the IPA clock reference count and just
rely on the runtime PM usage count to determine when the hardware
should be suspended or resumed.

Use pm_runtime_get_if_active() in ipa_clock_get_additional().  We
care whether power is active, regardless of whether it's in use, so
pass true for its ign_usage_count argument.

The IPA clock mutex is just used to make enabling/disabling the
clock and updating the reference count occur atomically.  Without
the reference count, there's no need for the mutex, so get rid of
that too.

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

Suspending the IPA hardware is now managed by the runtime PM core
code.  The ->runtime_idle callback returns a non-zero value, so it
will never suspend except when forced.  As a result, there's no need
to take an extra "do not suspend" clock reference.

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

Use the runtime power management core to cause hardware suspend and
resume to occur.  Enable it in ipa_clock_init() (without autosuspend),
and disable it in ipa_clock_exit().

Use ipa_runtime_suspend() as the ->runtime_suspend power operation,
and arrange for it to be called by having ipa_clock_get() call
pm_runtime_get_sync() when the first clock reference is taken.
Similarly, use ipa_runtime_resume() as the ->runtime_resume power
operation, and pm_runtime_put() when the last IPA clock reference
is dropped.

Introduce ipa_runtime_idle() as the ->runtime_idle power operation,
and have it return a non-zero value; this way suspend will never
occur except when forced.

Use pm_runtime_force_suspend() and pm_runtime_force_resume() as the
system suspend and resume callbacks, and remove ipa_suspend() and
ipa_resume().

Store a pointer to the device structure passed to ipa_clock_init(),
so it can be used by ipa_clock_exit() to disable runtime power
management.

For now we preserve IPA clock reference counting.

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

Introduce ipa_runtime_suspend() and ipa_runtime_resume(), which
encapsulate the activities necessary for suspending and resuming
the IPA hardware.  Call these functions from ipa_clock_get() and
ipa_clock_put() when the first reference is taken or last one is
dropped.

When the very first clock reference is taken (for ipa_config()),
setup isn't complete yet, so (as before) only the core clock gets
enabled.

When the last clock reference is dropped (after ipa_deconfig()),
ipa_teardown() will have made the setup_complete flag false, so
there too, the core clock will be stopped without affecting GSI
or the endpoints.

Otherwise these new functions will perform the desired suspend and
resume actions once setup is complete.

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

Disable the IPA clock rather than dropping a reference to it in the
system suspend callback.  This forces the suspend to occur without
affecting existing references.

Similarly, enable the clock rather than taking a reference in
ipa_resume(), forcing a resume without changing the reference count.

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

We currently assume no errors occur when enabling or disabling the
IPA core clock and interconnects.  And although this commit exposes
errors that could occur, we generally assume this won't happen in
practice.

This commit changes ipa_clock_get() and ipa_clock_put() so each
returns a value.  The values returned are meant to mimic what the
runtime power management functions return, so we can set up error
handling here before we make the switch.  Have ipa_clock_get()
increment the reference count even if it returns an error, to match
the behavior of pm_runtime_get().

More details follow.

When taking a reference in ipa_clock_get(), return 0 for the first
reference, 1 for subsequent references, or a negative error code if
an error occurs.  Note that if ipa_clock_get() returns an error, we
must not touch hardware; in some cases such errors now cause entire
blocks of code to be skipped.

When dropping a reference in ipa_clock_put(), we return 0 or an
error code.  The error would come from ipa_clock_disable(), which
now returns what ipa_interconnect_disable() returns (either 0 or a
negative error code).  For now, callers ignore the return value;
if an error occurs, a message will have already been logged, and
little more can actually be done to improve the situation.

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

The ipa->flags field is only ever used in "ipa_clock.c", related to
suspend/resume activity.

Move the definition of the ipa_flag enumerated type to "ipa_clock.c".
And move the flags field from the ipa structure and to the ipa_clock
structure.  Rename the type and its values to include "power" or
"POWER" in the name.

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

Move ipa_suspend_handler() into "ipa_clock.c" from "ipa_main.c", to
group with the reset of the suspend/resume code.  This IPA interrupt
is triggered if an IPA RX endpoint is suspended but has a packet to
be delivered.

Introduce ipa_power_setup() and ipa_power_teardown() to add and
remove the handler for the IPA SUSPEND interrupt at the same place
as before, while allowing the handler to remain private.

The "power" naming convention will be adopted elsewhere in this
file as well (soon).

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

Move ipa_suspend() and ipa_resume(), as well as the definition of
the ipa_pm_ops structure into "ipa_clock.c".  Make ipa_pm_ops public
and declare it as extern in "ipa_clock.h".

This is part of centralizing IPA power management functionality into
"ipa_clock.c" (the file will eventually get a name change).

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

Rearrange messages reported when errors occur in the IPA clock code,
so that the specific interconnect is identified when an error occurs
enabling or disabling it, or the core clock is indicated when an
error occurs enabling it.

Have ipa_interconnect_disable() return zero or the negative error
value returned by the first interconnect that produced an error
when disabled.  For now, the callers ignore the returned value.

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

Assign the ipa->modem_netdev and endpoint->netdev pointers *before*
registering the network device.  As soon as the device is
registered it can be opened, and by that time we'll want those
pointers valid.

Similarly, don't make those pointers NULL until *after* the modem
network device is unregistered in ipa_modem_stop().

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

The modem network device is set up by ipa_modem_start().  But its
TX queue is not actually started and endpoints enabled until it is
opened.

So avoid stopping the modem network device TX queue and disabling
endpoints on suspend or stop unless the netdev is marked UP.  And
skip attempting to resume unless it is UP.

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

Three interconnects are defined for IPA version 4.9, but there
should only be two.  They should also use names that match what's
used for other platforms (and specified in the Device Tree binding).

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

Introduce new functions gsi_suspend() and gsi_resume(), which will
disable the GSI interrupt handler after all endpoints are suspended
and re-enable it before endpoints are resumed.  This will ensure no
GSI interrupt handler will fire when the hardware is suspended.

Here's a little further explanation.  There are seven GSI interrupt
types, and most are disabled except when needed.
  - These two are not used (never enabled):
      GSI_INTER_EE_CH_CTRL
      GSI_INTER_EE_EV_CTRL
  - These two are only used to implement channel and event ring
    commands, and are only enabled while a command is underway:
      GSI_CH_CTRL
      GSI_EV_CTRL
  - The IEOB interrupt signals I/O completion.  It will not fire
    when a channel is stopped (or "suspended").
      GSI_IEOB
  - This interrupt is used to allocate or halt modem channels,
    and is only enabled while such a command is underway.
      GSI_GLOB_EE
    However it also is used to signal certain errors, and this could
    occur at any time.
  - The general interrupt signals general errors, and could occur at
    any time.
      GSI_GENERAL

The purpose for this change is to ensure no global or general
interrupts fire due to errors while the hardware is suspended.
We enable the clock on resume, and at that time we can "handle"
(at least report) these error conditions.

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

The GSI IRQ handler could be triggered as soon as it is registered
with request_irq().  The handler function, gsi_isr(), touches
hardware, meaning the IPA clock must be operational.  The IPA clock
is not operating when the handler is registered (in gsi_irq_init()),
so this is a problem.

Move the call to request_irq() for the GSI interrupt handler into
gsi_irq_setup(), which is called when the IPA clock is known to be
operational (and furthermore, the GSI firmware will have been
loaded).  Request the IRQ at the end of that function, after all
interrupt types have been disabled and masked.

Move the matching free_irq() call into gsi_irq_teardown(), and get
rid of the now empty gsi_irq_exit(),

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