watchdog: fix syntactic kernel-doc issues

The command 'find drivers/watchdog | xargs ./scripts/kernel-doc -none'
reports a number of kernel-doc warnings in the watchdog subsystem.

Address the kernel-doc warnings that were purely syntactic issues with
kernel-doc comments.

The remaining kernel-doc warnings are of type "Excess function parameter"
and "Function parameter or member not described". These warnings would
need to be addressed in a second pass with a bit more insight into the
APIs and purpose of the functions in the watchdog subsystem.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210322065337.617-1-lukas.bulwahn@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

mei: fix kdoc in the driver

Over time the functions were renamed,
but this was not always reflected in kdoc, fix that.

Signed-off-by: Tamar Mashiah <tamar.mashiah@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Link: https://lore.kernel.org/r/20210621193756.134027-1-tomas.winkler@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

mei: bus: change remove callback to return void

The driver core ignores the return value of mei_cl_device_remove() so
passing an error value doesn't solve any problem. As most mei drivers'
remove callbacks return 0 unconditionally and returning a different value
doesn't have any effect, change this prototype to return void and return 0
unconditionally in mei_cl_device_remove(). The only driver that could
return an error value is modified to emit an explicit warning in the error
case.

Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Link: https://lore.kernel.org/r/20210208073705.428185-3-uwe@kleine-koenig.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

watchdog: mei_wdt: request stop on unregister

The MEI bus has a special behavior on suspend it destroys
all the attached devices, this is due to the fact that also
firmware context is not persistent across power flows.

If watchdog on MEI bus is ticking before suspending the firmware
times out and reports that the OS is missing watchdog tick.
Send the stop command to the firmware on watchdog unregistered
to eliminate the false event on suspend.
This does not make the things worse from the user-space perspective
as a user-space should re-open watchdog device after
suspending before this patch.

Cc: <stable@vger.kernel.org>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210124114938.373885-1-tomas.winkler@intel.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

watchdog: mei_wdt: no need to check return value of debugfs_create functions

When calling debugfs functions, there is no need to ever check the
return value. The function can work or not, but the code logic should
never do something different based on this.

Cc: Tomas Winkler <tomas.winkler@intel.com>
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: linux-watchdog@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

watchdog: mei_wdt: drop warning after registering device

The core will print out details now.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

watchdog: mei_wdt: no need to check return value of debugfs_create functions

When calling debugfs functions, there is no need to ever check the
return value. The function can work or not, but the code logic should
never do something different based on this.

Cc: Tomas Winkler <tomas.winkler@intel.com>
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: linux-watchdog@vger.kernel.org
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

watchdog: add SPDX identifiers for watchdog subsystem

- Add SPDX identifier
- Remove boiler plate license text
- If MODULE_LICENSE and boiler plate does not match, go for boiler plate
license

Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Acked-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Acked-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Acked-by: Keiji Hayashibara <hayashibara.keiji@socionext.com>
Acked-by: Johannes Thumshirn <jth@kernel.org>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Mans Rullgard <mans@mansr.com>
Acked-by: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Acked-by: Tomas Winkler <tomas.winkler@intel.com>
Acked-by: Patrice Chotard <patrice.chotard@st.com>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

watchdog: mei_wdt: don't use of variable length array

Fixes sparse warning:
drivers/watchdog/mei_wdt.c:530:18: warning: Variable length array is used

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Reviewed-by: Alexander Usyskin <alexander.usyskin@intel.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

watchdog: mei_wdt: constify mei_cl_device_id

mei_cl_device_id are not supposed to change at runtime. All functions
working with mei_cl_device_id provided by <linux/mei_cl_bus.h> work
with const mei_cl_device_id. So mark the non-const structs as const.

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

watchdog: mei_wdt: request stop on reboot to prevent false positive event

Systemd on reboot enables shutdown watchdog that leaves the watchdog
device open to ensure that even if power down process get stuck the
platform reboots nonetheless.
The iamt_wdt is an alarm-only watchdog and can't reboot system, but the
FW will generate an alarm event reboot was completed in time, as the
watchdog is not automatically disabled during power cycle.
So we should request stop watchdog on reboot to eliminate wrong alarm
from the FW.

Cc: <stable@vger.kernel.org>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

mei: bus: split RX and async notification callbacks

Split callbacks for RX and async notification events on mei bus to
eliminate synchronization problems and to open way for RX optimizations.

Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

mei: bus: remove rx callback context

The callback context is redunant as all the information can be
retrived from the device struture of its private data.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

watchdog: mei_wdt: use module_mei_cl_driver macro

Replace boilerplate driver registration with module_mei_cl_driver macro.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

watchdog: mei_wdt: re-register device on event

For Intel SKL platform the ME device can inform the host via
asynchronous notification that the watchdog feature was activated
on the device. The activation doesn't require reboot.
In that case the driver registers the watchdog device with the kernel.

Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

watchdog: mei_wdt: add activation debugfs entry

Add entry for displaying whether the device has activated or
deactivated watchdog fw application.

cat <debugfs>/mei_wdt/activation
activated | deactivated

Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

watchdog: mei_wdt: register wd device only if required

For Intel Broadwell and newer platforms, the ME device can inform
the host whether the watchdog functionality is activated or not.
If the watchdog functionality is not activated then the watchdog interface
can be not registered and eliminate unnecessary pings and hence lower the
power consumption by avoiding waking up the device.
The feature can be deactivated also without reboot
in that case the watchdog device should be unregistered at runtime.

The information regarding the deactivation is reported
in the ping response command. In runtime case the unregistration
has to be run from a worker so that the ping initiated by the watchdog
core completes. Otherwise the flow will deadlock on watchdog
core mutex which both ping and unregistration acquire.

Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

watchdog: mei_wdt: add status debugfs entry

Add entry for displaying current watchdog internal state

cat <debugfs>/mei_wdt/state
IDLE|START|RUNNING|STOPPING

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

watchdog: mei_wdt: implement MEI iAMT watchdog driver

Create a driver with the generic watchdog interface
for the MEI iAMT watchdog device.

Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>