drm/xe/pf: Access VF's register using dedicated MMIO view

Instead of creating ad-hoc new register definitions with altered
register addresses to mimic the VF's access to these registers,
prepare new MMIO instance per required VF, with shifted internal
location of the register map.  This will allow to use unmodified
register definitions in all calls to xe_mmio() functions.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patch.msgid.link/20251024205826.4652-1-michal.wajdeczko@intel.com

Author: mwajdecz

drivers/gpu/drm/xe/xe_gt_sriov_pf.c

@@ -158,39 +158,19 @@ void xe_gt_sriov_pf_init_hw(struct xe_gt *gt)
 	xe_gt_sriov_pf_service_update(gt);
 }
 
-static u32 pf_get_vf_regs_stride(struct xe_device *xe)
-{
-	return GRAPHICS_VERx100(xe) > 1200 ? 0x400 : 0x1000;
-}
-
-static struct xe_reg xe_reg_vf_to_pf(struct xe_reg vf_reg, unsigned int vfid, u32 stride)
-{
-	struct xe_reg pf_reg = vf_reg;
-
-	pf_reg.vf = 0;
-	pf_reg.addr += stride * vfid;
-
-	return pf_reg;
-}
-
 static void pf_clear_vf_scratch_regs(struct xe_gt *gt, unsigned int vfid)
 {
-	u32 stride = pf_get_vf_regs_stride(gt_to_xe(gt));
-	struct xe_reg scratch;
-	int n, count;
+	struct xe_mmio mmio;
+	int n;
+
+	xe_mmio_init_vf_view(&mmio, &gt->mmio, vfid);
 
 	if (xe_gt_is_media_type(gt)) {
-		count = MED_VF_SW_FLAG_COUNT;
-		for (n = 0; n < count; n++) {
-			scratch = xe_reg_vf_to_pf(MED_VF_SW_FLAG(n), vfid, stride);
-			xe_mmio_write32(&gt->mmio, scratch, 0);
-		}
+		for (n = 0; n < MED_VF_SW_FLAG_COUNT; n++)
+			xe_mmio_write32(&mmio, MED_VF_SW_FLAG(n), 0);
 	} else {
-		count = VF_SW_FLAG_COUNT;
-		for (n = 0; n < count; n++) {
-			scratch = xe_reg_vf_to_pf(VF_SW_FLAG(n), vfid, stride);
-			xe_mmio_write32(&gt->mmio, scratch, 0);
-		}
+		for (n = 0; n < VF_SW_FLAG_COUNT; n++)
+			xe_mmio_write32(&mmio, VF_SW_FLAG(n), 0);
 	}
 }
 

drivers/gpu/drm/xe/xe_mmio.c

@@ -379,3 +379,32 @@ int xe_mmio_wait32_not(struct xe_mmio *mmio, struct xe_reg reg, u32 mask, u32 va
 {
 	return __xe_mmio_wait32(mmio, reg, mask, val, timeout_us, out_val, atomic, false);
 }
+
+#ifdef CONFIG_PCI_IOV
+static size_t vf_regs_stride(struct xe_device *xe)
+{
+	return GRAPHICS_VERx100(xe) > 1200 ? 0x400 : 0x1000;
+}
+
+/**
+ * xe_mmio_init_vf_view() - Initialize an MMIO instance for accesses like the VF
+ * @mmio: the target &xe_mmio to initialize as VF's view
+ * @base: the source &xe_mmio to initialize from
+ * @vfid: the VF identifier
+ */
+void xe_mmio_init_vf_view(struct xe_mmio *mmio, const struct xe_mmio *base, unsigned int vfid)
+{
+	struct xe_tile *tile = base->tile;
+	struct xe_device *xe = tile->xe;
+	size_t offset = vf_regs_stride(xe) * vfid;
+
+	xe_assert(xe, IS_SRIOV_PF(xe));
+	xe_assert(xe, vfid);
+	xe_assert(xe, !base->sriov_vf_gt);
+	xe_assert(xe, base->regs_size > offset);
+
+	*mmio = *base;
+	mmio->regs += offset;
+	mmio->regs_size -= offset;
+}
+#endif

drivers/gpu/drm/xe/xe_mmio.h

@@ -42,4 +42,8 @@ static inline struct xe_mmio *xe_root_tile_mmio(struct xe_device *xe)
 	return &xe->tiles[0].mmio;
 }
 
+#ifdef CONFIG_PCI_IOV
+void xe_mmio_init_vf_view(struct xe_mmio *mmio, const struct xe_mmio *base, unsigned int vfid);
+#endif
+
 #endif