drm/xe: Clarify 'gt' retrieval for primary tile

There are a bunch of places in the driver where we need to perform
non-GT MMIO against the platform's primary tile (display code, top-level
interrupt enable/disable, driver initialization, etc.).  Rename
'to_gt()' to 'xe_primary_mmio_gt()' to clarify that we're trying to get
a primary MMIO handle for these top-level operations.

In the future we need to move away from xe_gt as the target for MMIO
operations (most of which are completely unrelated to GT).

v2:
 - s/xe_primary_mmio_gt/xe_root_mmio_gt/ for more consistency with how
   we refer to tile 0.  (Lucas)
v3:
 - Tweak comment on xe_root_mmio_gt().  (Lucas)

Acked-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20230601215244.678611-16-matthew.d.roper@intel.com
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_device.c

@@ -355,7 +355,7 @@ static void device_kill_persistent_engines(struct xe_device *xe,
 
 void xe_device_wmb(struct xe_device *xe)
 {
-	struct xe_gt *gt = xe_device_get_gt(xe, 0);
+	struct xe_gt *gt = xe_root_mmio_gt(xe);
 
 	wmb();
 	if (IS_DGFX(xe))

drivers/gpu/drm/xe/xe_device.h

@@ -66,9 +66,18 @@ static inline struct xe_gt *xe_device_get_gt(struct xe_device *xe, u8 gt_id)
 }
 
 /*
- * FIXME: Placeholder until multi-gt lands. Once that lands, kill this function.
+ * Provide a GT structure suitable for performing non-GT MMIO operations against
+ * the primary tile.  Primarily intended for early tile initialization, display
+ * handling, top-most interrupt enable/disable, etc.  Since anything using the
+ * MMIO handle returned by this function doesn't need GSI offset translation,
+ * we'll return the primary GT from the root tile.
+ *
+ * FIXME: Fix the driver design so that 'gt' isn't the target of all MMIO
+ * operations.
+ *
+ * Returns the primary gt of the root tile.
  */
-static inline struct xe_gt *to_gt(struct xe_device *xe)
+static inline struct xe_gt *xe_root_mmio_gt(struct xe_device *xe)
 {
 	return &xe_device_get_root_tile(xe)->primary_gt;
 }

drivers/gpu/drm/xe/xe_irq.c

@@ -284,7 +284,7 @@ static void gt_irq_handler(struct xe_device *xe, struct xe_gt *gt,
 static irqreturn_t xelp_irq_handler(int irq, void *arg)
 {
 	struct xe_device *xe = arg;
-	struct xe_gt *gt = xe_device_get_gt(xe, 0);	/* Only 1 GT here */
+	struct xe_gt *gt = xe_root_mmio_gt(xe);
 	u32 master_ctl, gu_misc_iir;
 	long unsigned int intr_dw[2];
 	u32 identity[32];
@@ -306,7 +306,7 @@ static irqreturn_t xelp_irq_handler(int irq, void *arg)
 
 static u32 dg1_intr_disable(struct xe_device *xe)
 {
-	struct xe_gt *gt = xe_device_get_gt(xe, 0);
+	struct xe_gt *gt = xe_root_mmio_gt(xe);
 	u32 val;
 
 	/* First disable interrupts */
@@ -324,7 +324,7 @@ static u32 dg1_intr_disable(struct xe_device *xe)
 
 static void dg1_intr_enable(struct xe_device *xe, bool stall)
 {
-	struct xe_gt *gt = xe_device_get_gt(xe, 0);
+	struct xe_gt *gt = xe_root_mmio_gt(xe);
 
 	xe_mmio_write32(gt, DG1_MSTR_TILE_INTR, DG1_MSTR_IRQ);
 	if (stall)

drivers/gpu/drm/xe/xe_mmio.c

@@ -328,7 +328,7 @@ int xe_mmio_probe_vram(struct xe_device *xe)
 
 static void xe_mmio_probe_tiles(struct xe_device *xe)
 {
-	struct xe_gt *gt = &xe_device_get_root_tile(xe)->primary_gt;
+	struct xe_gt *gt = xe_root_mmio_gt(xe);
 	u32 mtcfg;
 	u8 adj_tile_count;
 	u8 id;
@@ -380,7 +380,7 @@ static void mmio_fini(struct drm_device *drm, void *arg)
 int xe_mmio_init(struct xe_device *xe)
 {
 	struct xe_tile *root_tile = xe_device_get_root_tile(xe);
-	struct xe_gt *gt = xe_device_get_gt(xe, 0);
+	struct xe_gt *gt = xe_root_mmio_gt(xe);
 	const int mmio_bar = 0;
 	int err;
 
@@ -439,7 +439,7 @@ int xe_mmio_ioctl(struct drm_device *dev, void *data,
 		  struct drm_file *file)
 {
 	struct xe_device *xe = to_xe_device(dev);
-	struct xe_gt *gt = xe_device_get_gt(xe, 0);
+	struct xe_gt *gt = xe_root_mmio_gt(xe);
 	struct drm_xe_mmio *args = data;
 	unsigned int bits_flag, bytes;
 	struct xe_reg reg;

drivers/gpu/drm/xe/xe_query.c

@@ -259,7 +259,7 @@ static int query_gts(struct xe_device *xe, struct drm_xe_device_query *query)
 static int query_hwconfig(struct xe_device *xe,
 			  struct drm_xe_device_query *query)
 {
-	struct xe_gt *gt = xe_device_get_gt(xe, 0);
+	struct xe_gt *gt = xe_root_mmio_gt(xe);
 	size_t size = xe_guc_hwconfig_size(&gt->uc.guc);
 	void __user *query_ptr = u64_to_user_ptr(query->data);
 	void *hwconfig;

drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c

@@ -54,7 +54,7 @@ bool xe_ttm_stolen_cpu_access_needs_ggtt(struct xe_device *xe)
 static s64 detect_bar2_dgfx(struct xe_device *xe, struct xe_ttm_stolen_mgr *mgr)
 {
 	struct xe_tile *tile = xe_device_get_root_tile(xe);
-	struct xe_gt *mmio = &tile->primary_gt;
+	struct xe_gt *mmio = xe_root_mmio_gt(xe);
 	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
 	u64 stolen_size;
 	u64 tile_offset;
@@ -92,7 +92,7 @@ static u32 detect_bar2_integrated(struct xe_device *xe, struct xe_ttm_stolen_mgr
 	u32 stolen_size;
 	u32 ggc, gms;
 
-	ggc = xe_mmio_read32(to_gt(xe), GGC);
+	ggc = xe_mmio_read32(xe_root_mmio_gt(xe), GGC);
 
 	/* check GGMS, should be fixed 0x3 (8MB) */
 	if (drm_WARN_ON(&xe->drm, (ggc & GGMS_MASK) != GGMS_MASK))