drm/xe: Add xe_gt_clock_interval_to_ms helper

Add helper to convert GT clock ticks to msec. Useful for determining if
timeouts occur by examing GT clock ticks.

v6:
- s/nom/n , s/dom/d (Jonathan)
- include math64 (CI)

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240611144053.2805091-6-matthew.brost@intel.com

drivers/gpu/drm/xe/xe_gt_clock.c

@@ -3,6 +3,8 @@
  * Copyright © 2022 Intel Corporation
  */
 
+#include <linux/math64.h>
+
 #include "xe_gt_clock.h"
 
 #include "regs/xe_gt_regs.h"
@@ -79,3 +81,21 @@ int xe_gt_clock_init(struct xe_gt *gt)
 	gt->info.reference_clock = freq;
 	return 0;
 }
+
+static u64 div_u64_roundup(u64 n, u32 d)
+{
+	return div_u64(n + d - 1, d);
+}
+
+/**
+ * xe_gt_clock_interval_to_ms - Convert sampled GT clock ticks to msec
+ *
+ * @gt: the &xe_gt
+ * @count: count of GT clock ticks
+ *
+ * Returns: time in msec
+ */
+u64 xe_gt_clock_interval_to_ms(struct xe_gt *gt, u64 count)
+{
+	return div_u64_roundup(count * MSEC_PER_SEC, gt->info.reference_clock);
+}

drivers/gpu/drm/xe/xe_gt_clock.h

@@ -11,5 +11,6 @@
 struct xe_gt;
 
 int xe_gt_clock_init(struct xe_gt *gt);
+u64 xe_gt_clock_interval_to_ms(struct xe_gt *gt, u64 count);
 
 #endif