Revert "net: wwan: iosm: enable runtime pm support for 7560"

Runtime power management support breaks Intel LTE modem where dmesg dump
showes timeout errors:

```
[ 72.027442] iosm 0000:01:00.0: msg timeout
[ 72.531638] iosm 0000:01:00.0: msg timeout
[ 73.035414] iosm 0000:01:00.0: msg timeout
[ 73.540359] iosm 0000:01:00.0: msg timeout
```

Furthermore, when shutting down with `poweroff` and modem attached, the
system rebooted instead of powering down as expected. The modem works
again only after power cycling.

Revert runtime power management support for IOSM driver as introduced by
commit e4f5073d53be6c ("net: wwan: iosm: enable runtime pm support for
7560").

Fixes: e4f5073d53be ("net: wwan: iosm: enable runtime pm support for 7560")
Reported-by: Martin <mwolf@adiumentum.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217996
Link: https://lore.kernel.org/r/267abf02-4b60-4a2e-92cd-709e3da6f7d3@gmail.com/
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: wwan: iosm: enable runtime pm support for 7560

Adds runtime pm support for 7560.

As part of probe procedure auto suspend is enabled and auto suspend
delay is set to 5000 ms for runtime pm use. Later auto flag is set
to power manage the device at run time.

On successful communication establishment between host and device the
device usage counter is dropped and request to put the device into
sleep state (suspend).

In TX path, the device usage counter is raised and device is moved out
of sleep(resume) for data transmission. In RX path, if the device has
some data to be sent it request host platform to change the power state
by giving PCI PME message.

Signed-off-by: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: wwan: make debugfs optional

Debugfs interface is optional for the regular modem use. Some distros
and users will want to disable this feature for security or kernel
size reasons. So add a configuration option that allows to completely
disable the debugfs interface of the WWAN devices.

A primary considered use case for this option was embedded firmwares.
For example, in OpenWrt, you can not completely disable debugfs, as a
lot of wireless stuff can only be configured and monitored with the
debugfs knobs. At the same time, reducing the size of a kernel and
modules is an essential task in the world of embedded software.
Disabling the WWAN and IOSM debugfs interfaces allows us to save 50K
(x86-64 build) of space for module storage. Not much, but already
considerable when you only have 16MB of storage.

So it is hard to just disable whole debugfs. Users need some fine
grained set of options to control which debugfs interface is important
and should be available and which is not.

The new configuration symbol is enabled by default and is hidden under
the EXPERT option. So a regular user would not be bothered by another
one configuration question. While an embedded distro maintainer will be
able to a little more reduce the final image size.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Acked-by: M Chetan Kumar <m.chetan.kumar@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: wwan: iosm: move debugfs knobs into a subdir

The modem traces collection is a device (and so driver) specific option.
Therefore, move the related debugfs files into a driver-specific
subdirectory under the common per WWAN device directory.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Acked-by: M Chetan Kumar <m.chetan.kumar@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: wwan: iosm: allow trace port be uninitialized

Collecting modem firmware traces is optional for the regular modem use.
There are not many reasons for aborting device initialization due to an
inability to initialize the trace port and (or) its debugfs interface.
So, demote the initialization failure erro message into a warning and do
not break the initialization sequence in this case. Rework packet
processing and deinitialization so that they do not crash in case of
uninitialized trace port.

This change is mainly a preparation for an upcoming configuration option
introduction that will help disable driver debugfs functionality.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Acked-by: M Chetan Kumar <m.chetan.kumar@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: wwan: iosm: consolidate trace port init code

Move the channel related structures initialization from
ipc_imem_channel_init() to ipc_trace_init() and call it directly. On the
one hand, this makes the trace port initialization symmetric to the
deitialization, that is, it removes the additional wrapper.

On the other hand, this change consolidates the trace port related code
into a single source file, what facilitates an upcoming disabling of
this functionality by a user choise.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Acked-by: M Chetan Kumar <m.chetan.kumar@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: wwan: iosm: device trace collection using relayfs

This patch brings in support for device trace collection.
It implements relayfs interface for pushing device trace
from kernel space to user space.

Driver gets the debugfs base directory associated to WWAN
Device and creates trace_control and trace debugfs for
device tracing. Both trace_control & trace debugfs are
created under /sys/kernel/debug/wwan/wwan0/.

In order to collect device trace on trace0 interface, user
need to write 1 to trace_ctl interface.

Signed-off-by: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>