firmware: arm_scmi: Check for notification support

When registering protocol events, use the optional .is_notify_supported
callback provided by the protocol to check if that specific notification
type is available for that particular resource on the running system,
marking it as unsupported otherwise.

Then, when a notification enable request is received, return an error if
it was previously marked as unsuppported, so avoiding to send a needless
notification enable command and check the returned value for failure.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20240212123233.1230090-2-cristian.marussi@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Fix kernel doc warnings about return values

Kernel doc validation script still complains about the following:

|No description found for return value of 'scmi_get_protocol_device'
|No description found for return value of 'scmi_devm_notifier_register'
|No description found for return value of 'scmi_devm_notifier_unregister'

Fix adding missing Return kernel-doc statements.

Link: https://lore.kernel.org/r/20210712143504.33541-1-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Rename non devres notify_ops

Rename non devres managed notify_ops to use a naming pattern which exposes
the performed action verb as last token.

No functional change.

Link: https://lore.kernel.org/r/20210316124903.35011-37-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Make notify_priv really private

Notification private data is currently accessible via handle->notify_priv,
this data was indeed meant to be private to the notification core support
and not to be accessible by SCMI drivers. Make it private hiding it
inside instance descriptor struct scmi_info and accessible only via
dedicated helpers.

Link: https://lore.kernel.org/r/20210316124903.35011-36-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Convert events registration to protocol handles

Convert all refactored events registration routines to use protocol
handles.

In order to maintain bisectability and to allow protocols and drivers
to be later ported to the new protocol handle interface one by one,
introduce here also some transient code that will be removed later
in order to ease such transition.

Link: https://lore.kernel.org/r/20210316124903.35011-8-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Refactor events registration

Add a new refactored protocol events registration helper and invoke it
from the centralized initialization process triggered by get_ops() and
friends.

Also add a `get_num_sources` as a new optional callback amongst protocol
events operations. Finally remove events registration call-sites from
within the legacy protocol init routines.

Link: https://lore.kernel.org/r/20210316124903.35011-7-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Introduce new devres notification ops

Expose to the SCMI drivers a new alternative devres managed notifications
API based on protocol handles.

All drivers still keep using the old API, no functional change.

Link: https://lore.kernel.org/r/20210316124903.35011-6-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Make notifications aware of protocols users

Account for any active registered notifier against the proper related
protocol, do not consider pending event handlers, only active handlers
will concur to protocol usage accounting.

Link: https://lore.kernel.org/r/20210316124903.35011-5-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Fix missing destroy_workqueue()

destroy_workqueue is required before the return from scmi_notification_init
in case devm_kcalloc fails to allocate registered_protocols. Fix this by
simply moving registered_protocols allocation before alloc_workqueue.

Link: https://lore.kernel.org/r/20201110074221.41235-1-miaoqinglang@huawei.com
Fixes: bd31b249692e ("firmware: arm_scmi: Add notification dispatch and delivery")
Suggested-by: Cristian Marussi <cristian.marussi@arm.com>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Fix duplicate workqueue name

When more than a single SCMI device are present in the system, the
creation of the notification workqueue with the WQ_SYSFS flag will lead
to the following sysfs duplicate node warning:

sysfs: cannot create duplicate filename '/devices/virtual/workqueue/scmi_notify'
CPU: 0 PID: 20 Comm: kworker/0:1 Not tainted 5.9.0-gdf4dd84a3f7d #29
Hardware name: Broadcom STB (Flattened Device Tree)
Workqueue: events deferred_probe_work_func
Backtrace:
show_stack + 0x20/0x24
dump_stack + 0xbc/0xe0
sysfs_warn_dup + 0x70/0x80
sysfs_create_dir_ns + 0x15c/0x1a4
kobject_add_internal + 0x140/0x4d0
kobject_add + 0xc8/0x138
device_add + 0x1dc/0xc20
device_register + 0x24/0x28
workqueue_sysfs_register + 0xe4/0x1f0
alloc_workqueue + 0x448/0x6ac
scmi_notification_init + 0x78/0x1dc
scmi_probe + 0x268/0x4fc
platform_drv_probe + 0x70/0xc8
really_probe + 0x184/0x728
driver_probe_device + 0xa4/0x278
__device_attach_driver + 0xe8/0x148
bus_for_each_drv + 0x108/0x158
__device_attach + 0x190/0x234
device_initial_probe + 0x1c/0x20
bus_probe_device + 0xdc/0xec
deferred_probe_work_func + 0xd4/0x11c
process_one_work + 0x420/0x8f0
worker_thread + 0x4fc/0x91c
kthread + 0x21c/0x22c
ret_from_fork + 0x14/0x20
kobject_add_internal failed for scmi_notify with -EEXIST, don't try to
register things with the same name in the same directory.
arm-scmi brcm_scmi@1: SCMI Notifications - Initialization Failed.
arm-scmi brcm_scmi@1: SCMI Notifications NOT available.
arm-scmi brcm_scmi@1: SCMI Protocol v1.0 'brcm-scmi:' Firmware version 0x1

Fix this by using dev_name(handle->dev) which guarantees that the name is
unique and this also helps correlate which notification workqueue corresponds
to which SCMI device instance.

Link: https://lore.kernel.org/r/20201014021737.287340-1-f.fainelli@gmail.com
Fixes: bd31b249692e ("firmware: arm_scmi: Add notification dispatch and delivery")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
[sudeep.holla: trimmed backtrace to remove all unwanted hexcodes and timestamps]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Fix locking in notifications

When a protocol registers its events, the notification core takes care
to rescan the hashtable of pending event handlers and activate all the
possibly existent handlers referring to any of the events that are just
registered by the new protocol. When a pending handler becomes active
the core requests and enables the corresponding events in the SCMI
firmware.

If, for whatever reason, the enable fails, such invalid event handler
must be finally removed and freed. Let us ensure to use the
scmi_put_active_handler() helper which handles properly the needed
additional locking.

Failing to properly acquire all the needed mutexes exposes a race that
leads to the following splat being observed:

WARNING: CPU: 0 PID: 388 at lib/refcount.c:28 refcount_warn_saturate+0xf8/0x148
Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development
Platform, BIOS EDK II Jun 30 2020
pstate: 40000005 (nZcv daif -PAN -UAO BTYPE=--)
pc : refcount_warn_saturate+0xf8/0x148
lr : refcount_warn_saturate+0xf8/0x148
Call trace:
refcount_warn_saturate+0xf8/0x148
scmi_put_handler_unlocked.isra.10+0x204/0x208
scmi_put_handler+0x50/0xa0
scmi_unregister_notifier+0x1bc/0x240
scmi_notify_tester_remove+0x4c/0x68 [dummy_scmi_consumer]
scmi_dev_remove+0x54/0x68
device_release_driver_internal+0x114/0x1e8
driver_detach+0x58/0xe8
bus_remove_driver+0x88/0xe0
driver_unregister+0x38/0x68
scmi_driver_unregister+0x1c/0x28
scmi_drv_exit+0x1c/0xae0 [dummy_scmi_consumer]
__arm64_sys_delete_module+0x1a4/0x268
el0_svc_common.constprop.3+0x94/0x178
do_el0_svc+0x2c/0x98
el0_sync_handler+0x148/0x1a8
el0_sync+0x158/0x180

Link: https://lore.kernel.org/r/20201013133109.49821-1-cristian.marussi@arm.com
Fixes: e7c215f358a35 ("firmware: arm_scmi: Add notification callbacks-registration")
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Constify static scmi-ops

These are never modified, so make them const to allow the compiler to
put them in read-only memory.

Link: https://lore.kernel.org/r/20200906230452.33410-4-rikard.falkeborn@gmail.com
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Remove fixed size fields from reports/scmi_event_header

Event reports are used to convey information describing events to the
registered user-callbacks: they are necessarily derived from the underlying
raw SCMI events' messages but they are not meant to expose or directly
mirror any of those messages data layout, which belong to the protocol
layer.

Using fixed size types for report fields, mirroring messages structure,
is at odd with this: get rid of them using more generic, equivalent,
typing.

Substitute scmi_event_header fixed size fields with generic types too and
shuffle around fields definitions to minimize implicit padding while
adapting involved functions.

Link: https://lore.kernel.org/r/20200710133919.39792-3-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Remove unneeded __packed attribute

Remove __packed attribute from struct scmi_event_header.

Link: https://lore.kernel.org/r/20200710133919.39792-2-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add notification dispatch and delivery

Add the core SCMI notifications dispatch and delivery support logic
which is able to dispatch well-known received events from the Rx
interrupt handler to the dedicated deferred worker. From there, it will
deliver the events to the registered users' callbacks.

Dispatch and delivery support is just added here, still not enabled.

Link: https://lore.kernel.org/r/20200701155348.52864-4-cristian.marussi@arm.com
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add notification callbacks-registration

Add the core SCMI notifications callbacks-registration support: allow
users to register their own callbacks against the desired events.

Whenever a registration request is issued against a still non existent
event, mark such request as pending for later processing, in order to
account for possible late initializations of SCMI Protocols associated
to loadable drivers.

Link: https://lore.kernel.org/r/20200701155348.52864-3-cristian.marussi@arm.com
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

firmware: arm_scmi: Add notification protocol-registration

Add the core SCMI notifications protocol-registration support: allow
protocols to register their own set of supported events, during their
initialization phase. Notification core can track multiple platform
instances by their handles.

Link: https://lore.kernel.org/r/20200701155348.52864-2-cristian.marussi@arm.com
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>