drm/i915: Prepare for multiple gt platforms

On a multi-tile platform, each tile has its own registers + GGTT space,
and BAR 0 is extended to cover all of them.  Probe the tiles
individually.

Add some basic plumbing to support more than one dynamically allocated
struct intel_gt.  Up to four gts are supported in i915->gts[], with slot
zero shadowing the existing i915->gt to enable source compatibility with
legacy driver paths.  A for_each_gt macro is added to iterate over the
GTs and will be used by upcoming patches that convert various parts of
the driver to be multi-gt aware.

Check how many extra GT tiles are available on the system and setup
register access for all of them. We can detect how may GT tiles are
available by reading a register on the root tile. The same register
returns the tile ID on all tiles.

Signed-off-by: Abdiel Janulgue <abdiel.janulgue@gmail.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
index c0fa41e4c803..e66479d33bc3 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
@@ -128,7 +128,14 @@ static const struct intel_wakeref_ops wf_ops = {
 
 void intel_gt_pm_init_early(struct intel_gt *gt)
 {
-	intel_wakeref_init(&gt->wakeref, gt->uncore->rpm, &wf_ops);
+	/*
+	 * We access the runtime_pm structure via gt->i915 here rather than
+	 * gt->uncore as we do elsewhere in the file because gt->uncore is not
+	 * yet initialized for all tiles at this point in the driver startup.
+	 * runtime_pm is per-device rather than per-tile, so this is still the
+	 * correct structure.
+	 */
+	intel_wakeref_init(&gt->wakeref, &gt->i915->runtime_pm, &wf_ops);
 	seqcount_mutex_init(&gt->stats.lock, &gt->wakeref.mutex);
 }