iommu/arm-smmu-v3: Add command queue batching helpers

As more functions will implement command queue batching, add two helpers
to simplify building a command list.
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Will Deacon <will@kernel.org>

drivers/iommu/arm-smmu-v3.c

@@ -548,6 +548,11 @@ struct arm_smmu_cmdq {
 	atomic_t			lock;
 };
 
+struct arm_smmu_cmdq_batch {
+	u64				cmds[CMDQ_BATCH_ENTRIES * CMDQ_ENT_DWORDS];
+	int				num;
+};
+
 struct arm_smmu_evtq {
 	struct arm_smmu_queue		q;
 	u32				max_stalls;
@@ -1482,6 +1487,24 @@ static int arm_smmu_cmdq_issue_sync(struct arm_smmu_device *smmu)
 	return arm_smmu_cmdq_issue_cmdlist(smmu, NULL, 0, true);
 }
 
+static void arm_smmu_cmdq_batch_add(struct arm_smmu_device *smmu,
+				    struct arm_smmu_cmdq_batch *cmds,
+				    struct arm_smmu_cmdq_ent *cmd)
+{
+	if (cmds->num == CMDQ_BATCH_ENTRIES) {
+		arm_smmu_cmdq_issue_cmdlist(smmu, cmds->cmds, cmds->num, false);
+		cmds->num = 0;
+	}
+	arm_smmu_cmdq_build_cmd(&cmds->cmds[cmds->num * CMDQ_ENT_DWORDS], cmd);
+	cmds->num++;
+}
+
+static int arm_smmu_cmdq_batch_submit(struct arm_smmu_device *smmu,
+				      struct arm_smmu_cmdq_batch *cmds)
+{
+	return arm_smmu_cmdq_issue_cmdlist(smmu, cmds->cmds, cmds->num, true);
+}
+
 /* Context descriptor manipulation functions */
 static void arm_smmu_sync_cd(struct arm_smmu_domain *smmu_domain,
 			     int ssid, bool leaf)
@@ -2220,10 +2243,9 @@ static void arm_smmu_tlb_inv_range(unsigned long iova, size_t size,
 				   size_t granule, bool leaf,
 				   struct arm_smmu_domain *smmu_domain)
 {
-	u64 cmds[CMDQ_BATCH_ENTRIES * CMDQ_ENT_DWORDS];
 	struct arm_smmu_device *smmu = smmu_domain->smmu;
 	unsigned long start = iova, end = iova + size;
-	int i = 0;
+	struct arm_smmu_cmdq_batch cmds = {};
 	struct arm_smmu_cmdq_ent cmd = {
 		.tlbi = {
 			.leaf	= leaf,
@@ -2242,18 +2264,11 @@ static void arm_smmu_tlb_inv_range(unsigned long iova, size_t size,
 	}
 
 	while (iova < end) {
-		if (i == CMDQ_BATCH_ENTRIES) {
-			arm_smmu_cmdq_issue_cmdlist(smmu, cmds, i, false);
-			i = 0;
-		}
-
 		cmd.tlbi.addr = iova;
-		arm_smmu_cmdq_build_cmd(&cmds[i * CMDQ_ENT_DWORDS], &cmd);
+		arm_smmu_cmdq_batch_add(smmu, &cmds, &cmd);
 		iova += granule;
-		i++;
 	}
-
-	arm_smmu_cmdq_issue_cmdlist(smmu, cmds, i, true);
+	arm_smmu_cmdq_batch_submit(smmu, &cmds);
 
 	/*
 	 * Unfortunately, this can't be leaf-only since we may have