[Minios-devel] [UNIKRAFT PATCH 2/8] lib/fdt: Introduce a helper of fdt_get_cells

[Wei Chen <wei.chen@xxxxxxx>]

In device tree, we always use fdt_address_cells, fdt_size_cells
and fdt_interrupt_cells to get cells' size. fdt_get_cells will
reduce the redundant code for this *_cells APIs.
If fdt_get_cells could not find the property in current node,
in previous implement, it will return 2 arbitrarily. In this patch
it will try to find the property in parent node.

Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
Signed-off-by: Jianyong Wu <jianyong.wu@xxxxxxx>
---
 lib/fdt/fdt_ro.c         | 22 ++++++++++++++++++++++
 lib/fdt/include/libfdt.h | 20 ++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/lib/fdt/fdt_ro.c b/lib/fdt/fdt_ro.c
index 9077cff..9afede3 100644
--- a/lib/fdt/fdt_ro.c
+++ b/lib/fdt/fdt_ro.c
@@ -456,6 +456,28 @@ int fdt_getprop_u32_by_offset(const void *fdt, int offset,
        return -FDT_ERR_NOTFOUND;
 }
 
+int fdt_get_cells(const void *fdt, const char *prop, int nodeoffset)
+{
+       int val;
+
+       do {
+               /* Find whether the property exists in this node */
+               if (!fdt_getprop_u32_by_offset(fdt, nodeoffset,
+                               prop, (uint32_t *)&val))
+                       break;
+               /* If not, try to find in parent node */
+               nodeoffset = fdt_parent_offset(fdt, nodeoffset);
+       } while (nodeoffset >= 0);
+
+       if (nodeoffset < 0)
+               return nodeoffset;
+
+       if ((val <= 0) || (val > FDT_MAX_NCELLS))
+               return -FDT_ERR_BADNCELLS;
+
+       return val;
+}
+
 int fdt_supernode_atdepth_offset(const void *fdt, int nodeoffset,
                                 int supernodedepth, int *nodedepth)
 {
diff --git a/lib/fdt/include/libfdt.h b/lib/fdt/include/libfdt.h
index 1383f42..bda6456 100644
--- a/lib/fdt/include/libfdt.h
+++ b/lib/fdt/include/libfdt.h
@@ -1082,6 +1082,26 @@ const char *fdt_stringlist_get(const void *fdt, int 
nodeoffset,
  */
 #define FDT_MAX_NCELLS         4
 
+/**
+ * fdt_get_cells - 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 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
+ *     -FDT_ERR_BADMAGIC,
+ *     -FDT_ERR_BADVERSION,
+ *     -FDT_ERR_BADSTATE,
+ *     -FDT_ERR_BADSTRUCTURE,
+ *     -FDT_ERR_TRUNCATED, standard meanings
+ */
+int fdt_get_cells(const void *fdt, const char *prop, int nodeoffset);
+
 /**
  * fdt_address_cells - retrieve address size for a bus represented in the tree
  * @fdt: pointer to the device tree blob
-- 
2.17.1


_______________________________________________
Minios-devel mailing list
Minios-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/minios-devel