The goal is to use devcoredump infrastructure to report error states
captured at the crash time.

The error state will contain useful information for GPU hang debug, such
as INSTDONE registers and the current buffers getting executed, as well
as any other information that helps user space and allow later replays of
the error.

The proposal here is to avoid a Xe only error_state like i915 and use
a standard dev_coredump infrastructure to expose the error state.

For our own case, the data is only useful if it is a snapshot of the
time when the GPU crash has happened, since we reset the GPU immediately
after and the registers might have changed. So the proposal here is to
have an internal snapshot to be printed out later.

Also, usually a subsequent GPU hang can be only a cause of the initial
one. So we only save the 'first' hang. The dev_coredump has a delayed
work queue where it remove the coredump and free all the data within a
few moments of the error. When that happens we also reset our capture
state and allow further snapshots.

Right now this infra only print out the time of the hang. More information
will be migrated here on subsequent work. Also, in order to organize the
dump better, the goal is to propose dev_coredump changes itself to allow
multiple files and different controls. But for now we start Xe usage of
it without any dependency on dev_coredump core changes.

v2: Add dma_fence annotation for capture that might happen during long
    running. (Thomas and Matt)
    Use xe->drm.primary->index on drm_info msg. (Jani)
v3: checkpatch fixes
v4: Fix building and locking issues found by Francois.
    Actually let's kill all of the locking in here. gt_reset serialization
    already guarantee that there will be only one capture at the same time.
    Also, the devcoredump has its own locking to protect the free and reads
    and drivers don't need to duplicate it.
    Besides this, the dma_fence locking was pushed to a following patch
    since it is not needed in this one.
    Fix a use after free identified by KASAN: Do not stash the faulty_engine
    since that will be freed somewhere else.
v5: Fix Uptime - ktime_get_boottime actually returns the Uptime. (Francois)

Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Francois Dugast <francois.dugast@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>