drm/xe/mmio: Use single logic for waiting functions

The implementations for xe_mmio_wait32() and xe_mmio_wait32_not() are
almost identical. Let us avoid duplication of logic by having them
calling a common __xe_mmio_wait32() function.
Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240723120120.5443-2-gustavo.sousa@intel.com

drivers/gpu/drm/xe/xe_mmio.c

@@ -333,37 +333,24 @@ u64 xe_mmio_read64_2x32(struct xe_gt *gt, struct xe_reg reg)
 	return (u64)udw << 32 | ldw;
 }
 
-/**
- * xe_mmio_wait32() - Wait for a register to match the desired masked value
- * @gt: MMIO target GT
- * @reg: register to read value from
- * @mask: mask to be applied to the value read from the register
- * @val: desired value after applying the mask
- * @timeout_us: time out after this period of time. Wait logic tries to be
- * smart, applying an exponential backoff until @timeout_us is reached.
- * @out_val: if not NULL, points where to store the last unmasked value
- * @atomic: needs to be true if calling from an atomic context
- *
- * This function polls for the desired masked value and returns zero on success
- * or -ETIMEDOUT if timed out.
- *
- * Note that @timeout_us represents the minimum amount of time to wait before
- * giving up. The actual time taken by this function can be a little more than
- * @timeout_us for different reasons, specially in non-atomic contexts. Thus,
- * it is possible that this function succeeds even after @timeout_us has passed.
- */
-int xe_mmio_wait32(struct xe_gt *gt, struct xe_reg reg, u32 mask, u32 val, u32 timeout_us,
-		   u32 *out_val, bool atomic)
+static int __xe_mmio_wait32(struct xe_gt *gt, struct xe_reg reg, u32 mask, u32 val, u32 timeout_us,
+			    u32 *out_val, bool atomic, bool expect_match)
 {
 	ktime_t cur = ktime_get_raw();
 	const ktime_t end = ktime_add_us(cur, timeout_us);
 	int ret = -ETIMEDOUT;
 	s64 wait = 10;
 	u32 read;
+	bool check;
 
 	for (;;) {
 		read = xe_mmio_read32(gt, reg);
-		if ((read & mask) == val) {
+
+		check = (read & mask) == val;
+		if (!expect_match)
+			check = !check;
+
+		if (check) {
 			ret = 0;
 			break;
 		}
@@ -384,7 +371,12 @@ int xe_mmio_wait32(struct xe_gt *gt, struct xe_reg reg, u32 mask, u32 val, u32 t
 
 	if (ret != 0) {
 		read = xe_mmio_read32(gt, reg);
-		if ((read & mask) == val)
+
+		check = (read & mask) == val;
+		if (!expect_match)
+			check = !check;
+
+		if (check)
 			ret = 0;
 	}
 
@@ -395,62 +387,45 @@ int xe_mmio_wait32(struct xe_gt *gt, struct xe_reg reg, u32 mask, u32 val, u32 t
 }
 
 /**
- * xe_mmio_wait32_not() - Wait for a register to return anything other than the given masked value
+ * xe_mmio_wait32() - Wait for a register to match the desired masked value
  * @gt: MMIO target GT
  * @reg: register to read value from
  * @mask: mask to be applied to the value read from the register
- * @val: value to match after applying the mask
+ * @val: desired value after applying the mask
  * @timeout_us: time out after this period of time. Wait logic tries to be
  * smart, applying an exponential backoff until @timeout_us is reached.
  * @out_val: if not NULL, points where to store the last unmasked value
  * @atomic: needs to be true if calling from an atomic context
  *
- * This function polls for a masked value to change from a given value and
- * returns zero on success or -ETIMEDOUT if timed out.
+ * This function polls for the desired masked value and returns zero on success
+ * or -ETIMEDOUT if timed out.
  *
  * Note that @timeout_us represents the minimum amount of time to wait before
  * giving up. The actual time taken by this function can be a little more than
  * @timeout_us for different reasons, specially in non-atomic contexts. Thus,
  * it is possible that this function succeeds even after @timeout_us has passed.
  */
+int xe_mmio_wait32(struct xe_gt *gt, struct xe_reg reg, u32 mask, u32 val, u32 timeout_us,
+		   u32 *out_val, bool atomic)
+{
+	return __xe_mmio_wait32(gt, reg, mask, val, timeout_us, out_val, atomic, true);
+}
+
+/**
+ * xe_mmio_wait32_not() - Wait for a register to return anything other than the given masked value
+ * @gt: MMIO target GT
+ * @reg: register to read value from
+ * @mask: mask to be applied to the value read from the register
+ * @val: value not to be matched after applying the mask
+ * @timeout_us: time out after this period of time
+ * @out_val: if not NULL, points where to store the last unmasked value
+ * @atomic: needs to be true if calling from an atomic context
+ *
+ * This function works exactly like xe_mmio_wait32() with the exception that
+ * @val is expected not to be matched.
+ */
 int xe_mmio_wait32_not(struct xe_gt *gt, struct xe_reg reg, u32 mask, u32 val, u32 timeout_us,
 		       u32 *out_val, bool atomic)
 {
-	ktime_t cur = ktime_get_raw();
-	const ktime_t end = ktime_add_us(cur, timeout_us);
-	int ret = -ETIMEDOUT;
-	s64 wait = 10;
-	u32 read;
-
-	for (;;) {
-		read = xe_mmio_read32(gt, reg);
-		if ((read & mask) != val) {
-			ret = 0;
-			break;
-		}
-
-		cur = ktime_get_raw();
-		if (!ktime_before(cur, end))
-			break;
-
-		if (ktime_after(ktime_add_us(cur, wait), end))
-			wait = ktime_us_delta(end, cur);
-
-		if (atomic)
-			udelay(wait);
-		else
-			usleep_range(wait, wait << 1);
-		wait <<= 1;
-	}
-
-	if (ret != 0) {
-		read = xe_mmio_read32(gt, reg);
-		if ((read & mask) != val)
-			ret = 0;
-	}
-
-	if (out_val)
-		*out_val = read;
-
-	return ret;
+	return __xe_mmio_wait32(gt, reg, mask, val, timeout_us, out_val, atomic, false);
 }