drm/xe: Add helper macro to loop each DSS

Add helper macro to loop each DSS. This is a precursor patch to allow
for easier iteration through MCR registers and other per-DSS uses.
Signed-off-by: Zhanjun Dong <zhanjun.dong@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240314210735.258553-2-zhanjun.dong@intel.com

drivers/gpu/drm/xe/xe_gt_mcr.c

@@ -6,6 +6,7 @@
 #include "xe_gt_mcr.h"
 
 #include "regs/xe_gt_regs.h"
+#include "xe_assert.h"
 #include "xe_gt.h"
 #include "xe_gt_topology.h"
 #include "xe_gt_types.h"
@@ -294,14 +295,35 @@ static void init_steering_mslice(struct xe_gt *gt)
 	gt->steering[LNCF].instance_target = 0;		/* unused */
 }
 
-static void init_steering_dss(struct xe_gt *gt)
+static unsigned int dss_per_group(struct xe_gt *gt)
+{
+	return gt_to_xe(gt)->info.platform == XE_PVC ? 8 : 4;
+}
+
+/**
+ * xe_gt_mcr_get_dss_steering - Get the group/instance steering for a DSS
+ * @gt: GT structure
+ * @dss: DSS ID to obtain steering for
+ * @group: pointer to storage for steering group ID
+ * @instance: pointer to storage for steering instance ID
+ */
+void xe_gt_mcr_get_dss_steering(struct xe_gt *gt, unsigned int dss, u16 *group, u16 *instance)
 {
-	unsigned int dss = min(xe_dss_mask_group_ffs(gt->fuse_topo.g_dss_mask, 0, 0),
-			       xe_dss_mask_group_ffs(gt->fuse_topo.c_dss_mask, 0, 0));
-	unsigned int dss_per_grp = gt_to_xe(gt)->info.platform == XE_PVC ? 8 : 4;
+	int dss_per_grp = dss_per_group(gt);
+
+	xe_gt_assert(gt, dss < XE_MAX_DSS_FUSE_BITS);
+
+	*group = dss / dss_per_grp;
+	*instance = dss % dss_per_grp;
+}
 
-	gt->steering[DSS].group_target = dss / dss_per_grp;
-	gt->steering[DSS].instance_target = dss % dss_per_grp;
+static void init_steering_dss(struct xe_gt *gt)
+{
+	xe_gt_mcr_get_dss_steering(gt,
+				   min(xe_dss_mask_group_ffs(gt->fuse_topo.g_dss_mask, 0, 0),
+				       xe_dss_mask_group_ffs(gt->fuse_topo.c_dss_mask, 0, 0)),
+				   &gt->steering[DSS].group_target,
+				   &gt->steering[DSS].instance_target);
 }
 
 static void init_steering_oaddrm(struct xe_gt *gt)

drivers/gpu/drm/xe/xe_gt_mcr.h

@@ -7,6 +7,7 @@
 #define _XE_GT_MCR_H_
 
 #include "regs/xe_reg_defs.h"
+#include "xe_gt_topology.h"
 
 struct drm_printer;
 struct xe_gt;
@@ -25,5 +26,18 @@ void xe_gt_mcr_multicast_write(struct xe_gt *gt, struct xe_reg_mcr mcr_reg,
 			       u32 value);
 
 void xe_gt_mcr_steering_dump(struct xe_gt *gt, struct drm_printer *p);
+void xe_gt_mcr_get_dss_steering(struct xe_gt *gt, unsigned int dss, u16 *group, u16 *instance);
+
+/*
+ * Loop over each DSS and determine the group and instance IDs that
+ * should be used to steer MCR accesses toward this DSS.
+ * @dss: DSS ID to obtain steering for
+ * @gt: GT structure
+ * @group: steering group ID, data type: u16
+ * @instance: steering instance ID, data type: u16
+ */
+#define for_each_dss_steering(dss, gt, group, instance) \
+	for_each_dss((dss), (gt)) \
+		for_each_if((xe_gt_mcr_get_dss_steering((gt), (dss), &(group), &(instance)), true))
 
 #endif /* _XE_GT_MCR_H_ */

drivers/gpu/drm/xe/xe_gt_topology.c

@@ -11,9 +11,6 @@
 #include "xe_gt.h"
 #include "xe_mmio.h"
 
-#define XE_MAX_DSS_FUSE_BITS (32 * XE_MAX_DSS_FUSE_REGS)
-#define XE_MAX_EU_FUSE_BITS (32 * XE_MAX_EU_FUSE_REGS)
-
 static void
 load_dss_mask(struct xe_gt *gt, xe_dss_mask_t mask, int numregs, ...)
 {

drivers/gpu/drm/xe/xe_gt_topology.h

@@ -8,6 +8,17 @@
 
 #include "xe_gt_types.h"
 
+/*
+ * Loop over each DSS with the bit is 1 in geometry or compute mask
+ * @dss: iterated DSS bit from the DSS mask
+ * @gt: GT structure
+ */
+#define for_each_dss(dss, gt) \
+	for_each_or_bit((dss), \
+			(gt)->fuse_topo.g_dss_mask, \
+			(gt)->fuse_topo.c_dss_mask, \
+			XE_MAX_DSS_FUSE_BITS)
+
 struct drm_printer;
 
 void xe_gt_topology_init(struct xe_gt *gt);

drivers/gpu/drm/xe/xe_gt_types.h

@@ -25,10 +25,12 @@ enum xe_gt_type {
 };
 
 #define XE_MAX_DSS_FUSE_REGS	3
+#define XE_MAX_DSS_FUSE_BITS	(32 * XE_MAX_DSS_FUSE_REGS)
 #define XE_MAX_EU_FUSE_REGS	1
+#define XE_MAX_EU_FUSE_BITS	(32 * XE_MAX_EU_FUSE_REGS)
 
-typedef unsigned long xe_dss_mask_t[BITS_TO_LONGS(32 * XE_MAX_DSS_FUSE_REGS)];
-typedef unsigned long xe_eu_mask_t[BITS_TO_LONGS(32 * XE_MAX_EU_FUSE_REGS)];
+typedef unsigned long xe_dss_mask_t[BITS_TO_LONGS(XE_MAX_DSS_FUSE_BITS)];
+typedef unsigned long xe_eu_mask_t[BITS_TO_LONGS(XE_MAX_EU_FUSE_BITS)];
 
 struct xe_mmio_range {
 	u32 start;