[PATCH v4 1/2] PCI: of: introduce of_pci_build_prop_ranges()

[Alex Elder <elder@riscstar.com>]

Move the bulk of what happens inside of_pci_prop_ranges() into
a helper function that builds up the value to be passed to
of_changeset_add_prop_u32_array().

This helper will be used in the next commit to build the ranges
property for a statically-defined PCI endpoint devicetree node
when it has a "pci-ep-bus" sub-node.

Tested-by: Andrea della Porta <andrea.porta@suse.com>
Signed-off-by: Alex Elder <elder@riscstar.com>
---
 drivers/pci/of_property.c | 126 +++++++++++++++++++++++++-------------
 1 file changed, 83 insertions(+), 43 deletions(-)

diff --git a/drivers/pci/of_property.c b/drivers/pci/of_property.c
index 702675672fbc5..b202f45b3660b 100644
--- a/drivers/pci/of_property.c
+++ b/drivers/pci/of_property.c
@@ -8,6 +8,10 @@
 #include <linux/of_irq.h>
 #include <linux/bitfield.h>
 #include <linux/bits.h>
+#include <linux/ioport.h>
+#include <linux/slab.h>
+#include <linux/wordpart.h>
+
 #include "pci.h"
 
 #define OF_PCI_ADDRESS_CELLS		3
@@ -104,60 +108,96 @@ static int of_pci_prop_bus_range(struct pci_dev *pdev,
 					       ARRAY_SIZE(bus_range));
 }
 
-static int of_pci_prop_ranges(struct pci_dev *pdev, struct of_changeset *ocs,
-			      struct device_node *np)
+/*
+ * Build a "ranges" property value that defines the mapping between
+ * child and parent PCI address space for each of the given PCI
+ * device's resources.
+ *
+ * Returns a dynamically allocated array of u32 devicetree cells, or
+ * a null pointer if allocation fails.  The cell array is built as a
+ * of_pci_prop_ranges structure consisting of 8 32-bit cells in host
+ * byte order.  It is suitable for use as the value of a PCI device
+ * node "ranges" property passed to of_changeset_add_prop_u32_array().
+ * The total number of cells in the array is returned in *count.
+ *
+ * Caller is responsible for ensuring the returned pointer gets freed.
+ */
+static u32 *of_pci_build_prop_ranges(struct pci_dev *pdev, u32 *count)
 {
-	struct of_pci_range_entry *rp;
+	bool bridge_device = pci_is_bridge(pdev);
+	struct of_pci_range_entry *entries;
+	struct of_pci_range_entry *ep;
+	u32 resource_count = 0;
 	struct resource *res;
-	int i, j, ret;
 	u32 flags, num;
-	u64 val64;
+	u32 first;
+	u32 i;
 
-	if (pci_is_bridge(pdev)) {
+	if (bridge_device) {
+		first = PCI_BRIDGE_RESOURCES;
 		num = PCI_BRIDGE_RESOURCE_NUM;
-		res = &pdev->resource[PCI_BRIDGE_RESOURCES];
 	} else {
+		first = PCI_STD_RESOURCES;
 		num = PCI_STD_NUM_BARS;
-		res = &pdev->resource[PCI_STD_RESOURCES];
 	}
 
-	rp = kzalloc_objs(*rp, num);
-	if (!rp)
+	/* First count how many resources will get a range property */
+	res = pci_resource_n(pdev, first);
+	for (i = 0; i < num; i++, res++)
+		if (resource_size(res) && !of_pci_get_addr_flags(res, &flags))
+			resource_count++;
+
+	entries = kzalloc_objs(*entries, resource_count);
+	if (!entries)
+		return NULL;
+
+	ep = entries;
+	res = pci_resource_n(pdev, first);
+	for (i = 0; i < num; i++, res++) {
+		u64 size = resource_size(res);
+
+		if (!size || of_pci_get_addr_flags(res, &flags))
+			continue;
+
+		/* Record the size in the range entry */
+		ep->size[0] = upper_32_bits(size);
+		ep->size[1] = lower_32_bits(size);
+
+		/* Record the parent bus address from the resource */
+		of_pci_set_address(pdev, ep->parent_addr,
+				   pci_bus_address(pdev, first + i),
+				   flags, false);
+
+		/*
+		 * For a bridge device, the child address matches the
+		 * parent address (including its flags cell).  For an
+		 * endpoint device, the (flags) cell contains the BAR
+		 * number, and the two address cells are zero.
+		 */
+		if (bridge_device)
+			memcpy(ep->child_addr, ep->parent_addr,
+			       sizeof(ep->child_addr));
+		else
+			ep->child_addr[0] = i;
+
+		ep++;
+	}
+	*count = resource_count * sizeof(*ep) / sizeof(u32);
+
+	return (u32 *)entries;
+}
+
+static int of_pci_prop_ranges(struct pci_dev *pdev, struct of_changeset *ocs,
+			      struct device_node *np)
+{
+	u32 *value;
+	u32 count;
+
+	value = of_pci_build_prop_ranges(pdev, &count);
+	if (!value)
 		return -ENOMEM;
 
-	for (i = 0, j = 0; j < num; j++) {
-		if (!resource_size(&res[j]))
-			continue;
-
-		if (of_pci_get_addr_flags(&res[j], &flags))
-			continue;
-
-		val64 = pci_bus_address(pdev, &res[j] - pdev->resource);
-		of_pci_set_address(pdev, rp[i].parent_addr, val64, flags,
-				   false);
-		if (pci_is_bridge(pdev)) {
-			memcpy(rp[i].child_addr, rp[i].parent_addr,
-			       sizeof(rp[i].child_addr));
-		} else {
-			/*
-			 * For endpoint device, the lower 64-bits of child
-			 * address is always zero.
-			 */
-			rp[i].child_addr[0] = j;
-		}
-
-		val64 = resource_size(&res[j]);
-		rp[i].size[0] = upper_32_bits(val64);
-		rp[i].size[1] = lower_32_bits(val64);
-
-		i++;
-	}
-
-	ret = of_changeset_add_prop_u32_array(ocs, np, "ranges", (u32 *)rp,
-					      i * sizeof(*rp) / sizeof(u32));
-	kfree(rp);
-
-	return ret;
+	return of_changeset_add_prop_u32_array(ocs, np, "ranges", value, count);
 }
 
 static int of_pci_prop_reg(struct pci_dev *pdev, struct of_changeset *ocs,
-- 
2.53.0