[PATCH v10 02/15] iommu/arm-smmu-v3: Add Q_POS() macro

[Pranjal Shrivastava <praan@google.com>]

From: Nicolin Chen <nicolinc@nvidia.com>

A queue position, the wrap bit combined with the index, is Q_WRP | Q_IDX.
It is a (max_n_shift + 1)-bit value that wraps at twice the queue capacity.
queue_inc_cons(), queue_sync_cons_ovf(), and queue_inc_prod_n() currently
compute such positions by open-coding the two macros at each call site.

Add a Q_POS() macro and switch the open-coded sites to it.

A subsequent change will apply Q_POS() to a position difference, to count
the entries that a queue pointer moved past.

No functional change intended.

Assisted-by: Claude:claude-fable-5
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Pranjal Shrivastava <praan@google.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 11 +++++------
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  2 ++
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 270e6617a19a..06b7de2e6e4b 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -181,8 +181,8 @@ static void queue_sync_cons_out(struct arm_smmu_queue *q)
 
 static void queue_inc_cons(struct arm_smmu_ll_queue *q)
 {
-	u32 cons = (Q_WRP(q, q->cons) | Q_IDX(q, q->cons)) + 1;
-	q->cons = Q_OVF(q->cons) | Q_WRP(q, cons) | Q_IDX(q, cons);
+	u32 cons = Q_POS(q, q->cons) + 1;
+	q->cons = Q_OVF(q->cons) | Q_POS(q, cons);
 }
 
 static void queue_sync_cons_ovf(struct arm_smmu_queue *q)
@@ -192,8 +192,7 @@ static void queue_sync_cons_ovf(struct arm_smmu_queue *q)
 	if (likely(Q_OVF(llq->prod) == Q_OVF(llq->cons)))
 		return;
 
-	llq->cons = Q_OVF(llq->prod) | Q_WRP(llq, llq->cons) |
-		      Q_IDX(llq, llq->cons);
+	llq->cons = Q_OVF(llq->prod) | Q_POS(llq, llq->cons);
 	queue_sync_cons_out(q);
 }
 
@@ -218,8 +217,8 @@ static int queue_sync_prod_in(struct arm_smmu_queue *q)
 
 static u32 queue_inc_prod_n(struct arm_smmu_ll_queue *q, int n)
 {
-	u32 prod = (Q_WRP(q, q->prod) | Q_IDX(q, q->prod)) + n;
-	return Q_OVF(q->prod) | Q_WRP(q, prod) | Q_IDX(q, prod);
+	u32 prod = Q_POS(q, q->prod) + n;
+	return Q_OVF(q->prod) | Q_POS(q, prod);
 }
 
 static void queue_poll_init(struct arm_smmu_device *smmu,
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
index dd2fee2f560e..84e618a7fa9e 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -187,6 +187,8 @@ struct arm_vsmmu;
 
 #define Q_IDX(llq, p)			((p) & ((1 << (llq)->max_n_shift) - 1))
 #define Q_WRP(llq, p)			((p) & (1 << (llq)->max_n_shift))
+/* A position is Q_WRP | Q_IDX, wrapping at twice the queue capacity */
+#define Q_POS(llq, p)			(Q_WRP(llq, p) | Q_IDX(llq, p))
 #define Q_OVERFLOW_FLAG			(1U << 31)
 #define Q_OVF(p)			((p) & Q_OVERFLOW_FLAG)
 #define Q_ENT(q, p)			((q)->base +			\
-- 
2.55.0.979.g7e5102b832-goog