From 72479f6bf9a62eb21e966e657a4cd25060d8dde5 Mon Sep 17 00:00:00 2001
From: Ruslan Bukin <br@FreeBSD.org>
Date: Fri, 9 Oct 2020 13:11:14 +0000
Subject: [PATCH] Add iommu_get_dev_ctx() helper that allows to instantiate an
 iommu context for a given device_t.

Submitted by:	andrew
Reviewed by:	kib
Sponsored by:	DARPA, AFRL
---
 sys/dev/iommu/busdma_iommu.c | 24 +++++++++++++++++-------
 sys/dev/iommu/iommu.h        |  1 +
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/sys/dev/iommu/busdma_iommu.c b/sys/dev/iommu/busdma_iommu.c
index d82a3ac97072..959238b33445 100644
--- a/sys/dev/iommu/busdma_iommu.c
+++ b/sys/dev/iommu/busdma_iommu.c
@@ -269,14 +269,12 @@ iommu_instantiate_ctx(struct iommu_unit *unit, device_t dev, bool rmrr)
 	return (ctx);
 }
 
-bus_dma_tag_t
-iommu_get_dma_tag(device_t dev, device_t child)
+struct iommu_ctx *
+iommu_get_dev_ctx(device_t dev)
 {
 	struct iommu_unit *unit;
-	struct iommu_ctx *ctx;
-	bus_dma_tag_t res;
 
-	unit = iommu_find(child, bootverbose);
+	unit = iommu_find(dev, bootverbose);
 	/* Not in scope of any IOMMU ? */
 	if (unit == NULL)
 		return (NULL);
@@ -288,8 +286,20 @@ iommu_get_dma_tag(device_t dev, device_t child)
 	dmar_instantiate_rmrr_ctxs(unit);
 #endif
 
-	ctx = iommu_instantiate_ctx(unit, child, false);
-	res = ctx == NULL ? NULL : (bus_dma_tag_t)ctx->tag;
+	return (iommu_instantiate_ctx(unit, dev, false));
+}
+
+bus_dma_tag_t
+iommu_get_dma_tag(device_t dev, device_t child)
+{
+	struct iommu_ctx *ctx;
+	bus_dma_tag_t res;
+
+	ctx = iommu_get_dev_ctx(child);
+	if (ctx == NULL)
+		return (NULL);
+
+	res = (bus_dma_tag_t)ctx->tag;
 	return (res);
 }
 
diff --git a/sys/dev/iommu/iommu.h b/sys/dev/iommu/iommu.h
index 6dfb23410722..dfb4c3073e58 100644
--- a/sys/dev/iommu/iommu.h
+++ b/sys/dev/iommu/iommu.h
@@ -233,6 +233,7 @@ int bus_dma_iommu_load_ident(bus_dma_tag_t dmat, bus_dmamap_t map,
     vm_paddr_t start, vm_size_t length, int flags);
 
 bus_dma_tag_t iommu_get_dma_tag(device_t dev, device_t child);
+struct iommu_ctx *iommu_get_dev_ctx(device_t dev);
 
 SYSCTL_DECL(_hw_iommu);