[Minios-devel] [UNIKRAFT PATCHv4 4/9] plat/common: Introduce fdt_{address, size}_cells_or_parent helpers

[Jia He <justin.he@xxxxxxx>]

In some cases, devices need to find the "#address-cells" "size-cells"
properties recursively(node, parent, grandparent...).
This patch introduces two helpers to simplify the codes

Signed-off-by: Jia He <justin.he@xxxxxxx>
---
 plat/common/fdt.c         | 57 +++++++++++++++++++++++++++++++++++++++
 plat/common/include/fdt.h | 34 +++++++++++++++++++++++
 2 files changed, 91 insertions(+)

diff --git a/plat/common/fdt.c b/plat/common/fdt.c
index 916a263..6feec0a 100644
--- a/plat/common/fdt.c
+++ b/plat/common/fdt.c
@@ -99,3 +99,60 @@ int fdt_interrupt_cells(const void *fdt, int offset)
 
        return val;
 }
+
+int fdt_address_cells_or_parent(const void *fdt, int nodeoffset)
+{
+       int prop_len;
+       const fdt32_t *prop;
+
+       do {
+               /* Find whether the property exists in this node */
+               prop = fdt_getprop(fdt, nodeoffset,
+                               "#address-cells", &prop_len);
+               /* If not, try to find in parent node */
+               nodeoffset = fdt_parent_offset(fdt, nodeoffset);
+       } while (nodeoffset >= 0 && prop == NULL);
+
+       /* as per DT spec, set the address-cells to 2 if no such
+        * property anywhere in this node or parent
+        */
+       if (prop == NULL)
+               return 2;
+
+       if (nodeoffset < 0)
+               return nodeoffset;
+
+       if (prop_len >= (int)sizeof(fdt32_t))
+               return fdt32_to_cpu(prop[0]);
+
+       return -FDT_ERR_NOTFOUND;
+}
+
+int fdt_size_cells_or_parent(const void *fdt, int nodeoffset)
+{
+       int prop_len;
+       const fdt32_t *prop;
+
+       do {
+               /* Find whether the property exists in this node */
+               prop = fdt_getprop(fdt, nodeoffset,
+                               "#size-cells", &prop_len);
+                       break;
+               /* If not, try to find in parent node */
+               nodeoffset = fdt_parent_offset(fdt, nodeoffset);
+       } while (nodeoffset >= 0 && prop == NULL);
+
+       /* as per DT spec, set the size-cells to 1 if no such
+        * property anywhere in this node or parent
+        */
+       if (prop == NULL)
+               return 1;
+
+       if (nodeoffset < 0)
+               return nodeoffset;
+
+       if (prop_len >= (int)sizeof(fdt32_t))
+               return fdt32_to_cpu(prop[0]);
+
+       return -FDT_ERR_NOTFOUND;
+}
diff --git a/plat/common/include/fdt.h b/plat/common/include/fdt.h
index afc4753..969cd28 100644
--- a/plat/common/include/fdt.h
+++ b/plat/common/include/fdt.h
@@ -76,4 +76,38 @@ int fdt_getprop_u32_by_offset(const void *fdt, int 
nodeoffset,
  */
 int fdt_interrupt_cells(const void *fdt, int nodeoffset);
 
+/**
+ * fdt_address_cells_or_parent - retrieve cell size for a bus represented
+ * in the tree
+ * @fdt: pointer to the device tree blob
+ * @prop: cell name of the property containing the string list
+ * @nodeoffset: offset of the node to find the address size for
+ *
+ * When the node or parent has a valid #address-cells property, returns
+ * its value.
+ *
+ * returns:
+ *     0 <= n < FDT_MAX_NCELLS, on success
+ *      -FDT_ERR_BADNCELLS, if the node has a badly formatted or invalid
+ *             #address-cells property
+ */
+int fdt_address_cells_or_parent(const void *fdt, int nodeoffset);
+
+/**
+ * fdt_size_cells_or_parent - retrieve cell size for a bus represented
+ * in the tree
+ * @fdt: pointer to the device tree blob
+ * @prop: cell name of the property containing the string list
+ * @nodeoffset: offset of the node to find the address size for
+ *
+ * When the node or parent has a valid #size-cells property, returns its
+ * value.
+ *
+ * returns:
+ *     0 <= n < FDT_MAX_NCELLS, on success
+ *      -FDT_ERR_BADNCELLS, if the node has a badly formatted or invalid
+ *             #address-cells property
+ */
+int fdt_size_cells_or_parent(const void *fdt, int nodeoffset);
+
 #endif
-- 
2.17.1


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