diff options
Diffstat (limited to 'include/dm/ofnode_decl.h')
| -rw-r--r-- | include/dm/ofnode_decl.h | 37 |
1 files changed, 33 insertions, 4 deletions
diff --git a/include/dm/ofnode_decl.h b/include/dm/ofnode_decl.h index 266253d5e33..5c2115aab0b 100644 --- a/include/dm/ofnode_decl.h +++ b/include/dm/ofnode_decl.h @@ -31,18 +31,47 @@ * this increases code size slightly due to the subtraction. Since it offers no * real benefit, the approach described here seems best. * - * For now these points use constant types, since we don't allow writing - * the DT. + * Where multiple trees are in use, this works without any trouble with live + * tree, except for aliases, such as ofnode_path("mmc0"), which only work on the + * control FDT. When the flat tree is in use, the trees are registered and a + * 'tree ID' is encoded into the top bits of @of_offset - see immediately below + * for the associated macro definitions. Note that 64-bit machines use the same + * encoding, even though there is more space available. This is partly because + * the FDT format contains 32-bit values for things like the string-table + * offset, therefore 64-bit offsets cannot be supported anyway. + * + * For the multiple-tree case, an invalid offset (i.e. with of_offset < 0) is + * still invalid. It does not contain a tree ID. So there is no way of knowing + * which tree produced the invalid offset. * * @np: Pointer to device node, used for live tree * @of_offset: Pointer into flat device tree, used for flat tree. Note that this * is not a really a pointer to a node: it is an offset value. See above. */ typedef union ofnode_union { - const struct device_node *np; + struct device_node *np; long of_offset; } ofnode; +/* shift for the tree ID within of_offset */ +#define OF_TREE_SHIFT 28 + +/* mask to obtain the device tree offset from of_offset */ +#define OF_TREE_MASK ((1 << OF_TREE_SHIFT) - 1) + +/* encode a tree ID and node offset into an of_offset value */ +#define OFTREE_NODE(tree_id, offs) ((tree_id) << OF_TREE_SHIFT | (offs)) + +/* decode the node offset from an of_offset value */ +#define OFTREE_OFFSET(of_offs) ((of_offs) & OF_TREE_MASK) + +/* decode the tree ID from an of_offset value */ +#define OFTREE_TREE_ID(of_offs) ((of_offs) >> OF_TREE_SHIFT) + +/* encode a node offset in the tree given by another node's of_offset value */ +#define OFTREE_MAKE_NODE(other_of_offset, offs) \ + (((offs) & OF_TREE_MASK) | ((other_of_offset) & ~OF_TREE_MASK)) + /** * struct ofprop - reference to a property of a device tree node * @@ -57,7 +86,7 @@ typedef union ofnode_union { * * @node: Pointer to device node * @offset: Pointer into flat device tree, used for flat tree. - * @prop: Pointer to property, used for live treee. + * @prop: Pointer to property, used for live tree. */ struct ofprop { |