[coreboot-gerrit] [M] Change in coreboot[main]: commonlib/device_tree.c: Add read reg property helper

[Maximilian Brune (Code Review)]

Maximilian Brune has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/83457?usp=email )

Change subject: commonlib/device_tree.c: Add read reg property helper
......................................................................

commonlib/device_tree.c: Add read reg property helper

Add a helper function to read the reg property.

Signed-off-by: Maximilian Brune 
Change-Id: I7846eb8af390d709b0757262025cb819e9988699
---
M src/commonlib/device_tree.c
M src/commonlib/include/commonlib/device_tree.h
2 files changed, 56 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/57/83457/1

diff --git a/src/commonlib/device_tree.c b/src/commonlib/device_tree.c
index 0ec6ea9..37c0ecc 100644
--- a/src/commonlib/device_tree.c
+++ b/src/commonlib/device_tree.c
@@ -981,6 +981,60 @@
  */

/*
+ * dt_read_reg_prop reads the reg property inside a node
+ *
+ * @params node           device tree node to read reg property from
+ * @params addr_cells     number of cells used for one address
+ * @params size_cells     number of cells used for one size
+ * @params regions        all regions that are read inside the reg property are saved inside
+ *                        this array
+ * @params regions_count  maximum number of entries that can be saved inside the regions array.
+ *
+ * Returns: Either 0 on error or returns the number of regions put into the regions array.
+ */
+size_t dt_read_reg_prop(struct device_tree_node *node, u32 addr_cells, u32 size_cells,
+		        struct device_tree_region regions[], size_t regions_count)
+{
+	struct device_tree_property *prop;
+	bool found = false;
+	list_for_each(prop, node->properties, list_node)
+		if (!strcmp("reg", prop->prop.name))
+			found = true;
+
+	if (!found) {
+		printk(BIOS_DEBUG, "no reg property found\n");
+		return 0;
+	}
+
+	// we found the reg property, no need to parse all regions in 'reg'
+	size_t count = prop->prop.size / (4 * addr_cells + 4 * size_cells);
+	if (count > regions_count) {
+		printk(BIOS_ERR, "reg property has more entries (%zd) than regions array can hold (%zd)\n", count, regions_count);
+		count = regions_count;
+	}
+	if (addr_cells > 2 || size_cells > 2) {
+		printk(BIOS_ERR, "addr_cells (%d) or size_cells (%d) bigger than 2\n",
+				  addr_cells, size_cells);
+		return 0;
+	}
+	uint32_t *ptr = prop->prop.data;
+	for (int i = 0; i < count; i++) {
+		if (addr_cells == 1)
+			regions[i].addr = be32dec(ptr);
+		else if (addr_cells == 2)
+			regions[i].addr = be64dec(ptr);
+		ptr += addr_cells;
+		if (size_cells == 1)
+			regions[i].size = be32dec(ptr);
+		else if (size_cells == 2)
+			regions[i].size = be64dec(ptr);
+		ptr += size_cells;
+	}
+
+	return count; // return the number of regions found in the reg property
+}
+
+/*
  * Read #address-cells and #size-cells properties from a node.
  *
  * @param node		The device tree node to read from.
diff --git a/src/commonlib/include/commonlib/device_tree.h b/src/commonlib/include/commonlib/device_tree.h
index 81377fa..225ef3e 100644
--- a/src/commonlib/include/commonlib/device_tree.h
+++ b/src/commonlib/include/commonlib/device_tree.h
@@ -147,6 +147,8 @@
 /* Flatten a device tree into the buffer pointed to by dest. */
 void dt_flatten(const struct device_tree *tree, void *dest);
 void dt_print_node(const struct device_tree_node *node);
+size_t dt_read_reg_prop(struct device_tree_node *node, u32 addr_cells, u32 size_cells,
+		        struct device_tree_region regions[], size_t regions_count);
 /* Read #address-cells and #size-cells properties from a node. */
 void dt_read_cell_props(const struct device_tree_node *node, u32 *addrcp,
    		u32 *sizecp);