1 files changed, 111 insertions, 9 deletions

diff --git a/src/device/device.c b/src/device/device.c
index 3ed64da34a..633346ede0 100644
--- a/src/device/device.c
+++ b/src/device/device.c
@@ -594,6 +594,19 @@ static void update_bridge_resource(const struct device *bridge, struct resource
 			bridge_res->limit = child_res->limit;
 
 		/*
+		 * Propagate the downstream resource request to allocate above 4G boundary to
+		 * upstream bridge resource. This ensures that during pass 2, the resource
+		 * allocator at domain level has a global view of all the downstream device
+		 * requirements and thus address space is allocated as per updated flags in the
+		 * bridge resource.
+		 *
+		 * Since the bridge resource is a single window, all the downstream resources of
+		 * this bridge resource will be allocated space above 4G boundary.
+		 */
+		if (child_res->flags & IORESOURCE_ABOVE_4G)
+			bridge_res->flags |= IORESOURCE_ABOVE_4G;
+
+		/*
 		 * Alignment value of 0 means that the child resource has no alignment
 		 * requirements and so the base value remains unchanged here.
 		 */
@@ -687,24 +700,98 @@ static void compute_domain_resources(const struct device *domain)
 	}
 }
 
-static void initialize_memranges(struct memranges *ranges, const struct resource *res,
-				 unsigned long memrange_type)
+/*
+ * If the resource base is set to the limit, then it means that the resource is invalid and
+ * hence cannot be used for allocation.
+ */
+static bool is_resource_invalid(const struct resource *res)
+{
+	return res->base == res->limit;
+}
+
+/*
+ * This function initializes memranges for domain device. If the resource crosses 4G boundary,
+ * then this function splits it into two ranges -- one for the window below 4G and the other for
+ * the window above 4G. The latter range has IORESOURCE_ABOVE_4G flag set to satisfy resource
+ * requests from downstream devices for allocations above 4G.
+ */
+static void initialize_domain_memranges(struct memranges *ranges, const struct resource *res,
+					unsigned long memrange_type)
 {
 	resource_t res_base;
 	resource_t res_limit;
+	const resource_t limit_4g = 0xffffffff;
 
 	memranges_init_empty(ranges, NULL, 0);
 
-	if (res == NULL)
+	if ((res == NULL) || is_resource_invalid(res))
 		return;
 
 	res_base = res->base;
 	res_limit = res->limit;
 
-	if (res_base == res_limit)
+	/*
+	 * Split the resource into two separate ranges if it crosses the 4G boundary. Memrange
+	 * type is set differently to ensure that memrange does not merge these two ranges. For
+	 * the range above 4G boundary, given memrange type is ORed with IORESOURCE_ABOVE_4G.
+	 */
+	if (res_base <= limit_4g) {
+
+		resource_t range_limit;
+
+		/* Clip the resource limit at 4G boundary if necessary. */
+		range_limit = MIN(res_limit, limit_4g);
+		memranges_insert(ranges, res_base, range_limit - res_base + 1, memrange_type);
+
+		/*
+		 * If the resource lies completely below the 4G boundary, nothing more needs to
+		 * be done.
+		 */
+		if (res_limit <= limit_4g)
+			return;
+
+		/*
+		 * If the resource window crosses the 4G boundary, then update res_base to add
+		 * another entry for the range above the boundary.
+		 */
+		res_base = limit_4g + 1;
+	}
+
+	if (res_base > res_limit)
 		return;
 
-	memranges_insert(ranges, res_base, res_limit - res_base + 1, memrange_type);
+	/*
+	 * If resource lies completely above the 4G boundary or if the resource was clipped to
+	 * add two separate ranges, the range above 4G boundary has the resource flag
+	 * IORESOURCE_ABOVE_4G set. This allows domain to handle any downstream requests for
+	 * resource allocation above 4G differently.
+	 */
+	memranges_insert(ranges, res_base, res_limit - res_base + 1,
+			 memrange_type | IORESOURCE_ABOVE_4G);
+}
+
+/*
+ * This function initializes memranges for bridge device. Unlike domain, bridge does not need to
+ * care about resource window crossing 4G boundary. This is handled by the resource allocator at
+ * domain level to ensure that all downstream bridges are allocated space either above or below
+ * 4G boundary as per the state of IORESOURCE_ABOVE_4G for the respective bridge resource.
+ *
+ * So, this function creates a single range of the entire resource window available for the
+ * bridge resource. Thus all downstream resources of the bridge for the given resource type get
+ * allocated space from the same window. If there is any downstream resource of the bridge which
+ * requests allocation above 4G, then all other downstream resources of the same type under the
+ * bridge get allocated above 4G.
+ */
+static void initialize_bridge_memranges(struct memranges *ranges, const struct resource *res,
+					unsigned long memrange_type)
+{
+
+	memranges_init_empty(ranges, NULL, 0);
+
+	if ((res == NULL) || is_resource_invalid(res))
+		return;
+
+	memranges_insert(ranges, res->base, res->limit - res->base + 1, memrange_type);
 }
 
 static void print_resource_ranges(const struct memranges *ranges)
@@ -834,10 +921,12 @@ static void setup_resource_ranges(const struct device *dev, const struct resourc
 		dev_path(dev), resource2str(res), res->base, res->size, res->align,
 		res->gran, res->limit);
 
-	initialize_memranges(ranges, res, type);
-
-	if (dev->path.type == DEVICE_PATH_DOMAIN)
+	if (dev->path.type == DEVICE_PATH_DOMAIN) {
+		initialize_domain_memranges(ranges, res, type);
 		constrain_domain_resources(dev->link_list, ranges, type);
+	} else {
+		initialize_bridge_memranges(ranges, res, type);
+	}
 
 	print_resource_ranges(ranges);
 }
@@ -943,12 +1032,25 @@ static void allocate_domain_resources(const struct device *domain)
 	 * Domain does not distinguish between mem and prefmem resources. Thus, the resource
 	 * allocation at domain level considers mem and prefmem together when finding the best
 	 * fit based on the biggest resource requirement.
+	 *
+	 * However, resource requests for allocation above 4G boundary need to be handled
+	 * separately if the domain resource window crosses this boundary. There is a single
+	 * window for resource of type IORESOURCE_MEM. When creating memranges, this resource
+	 * is split into two separate ranges -- one for the window below 4G boundary and other
+	 * for the window above 4G boundary (with IORESOURCE_ABOVE_4G flag set). Thus, when
+	 * allocating child resources, requests for below and above the 4G boundary are handled
+	 * separately by setting the type_mask and type_match to allocate_child_resources()
+	 * accordingly.
 	 */
 	res = find_domain_resource(domain, IORESOURCE_MEM);
 	if (res) {
 		setup_resource_ranges(domain, res, IORESOURCE_MEM, &ranges);
-		allocate_child_resources(domain->link_list, &ranges, IORESOURCE_TYPE_MASK,
+		allocate_child_resources(domain->link_list, &ranges,
+					 IORESOURCE_TYPE_MASK | IORESOURCE_ABOVE_4G,
 					 IORESOURCE_MEM);
+		allocate_child_resources(domain->link_list, &ranges,
+					 IORESOURCE_TYPE_MASK | IORESOURCE_ABOVE_4G,
+					 IORESOURCE_MEM | IORESOURCE_ABOVE_4G);
 		cleanup_resource_ranges(domain, &ranges, res);
 	}