of_map_id(9)

🌸 NAME 🌸

Bestie, this page is of_map_id from the Kernel API Manual (section 9, iykyk), and its whole vibe is: translate an ID through a downstream mapping. Periodt. 💅

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✨ SYNOPSIS ✨

Okay so here’s the exact signature, and yes the punctuation is doing the most, so leave it alone:

int of_map_id (const struct device_node *np , u32 id , const char
*map_name , const char *cells_name , const char *map_mask_name , struct
device_node * const *filter_np , struct of_phandle_args *arg );

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🎀 ARGUMENTS 🎀

• np — root complex device node. That’s the starting point, bestie.
• id — device ID to map.
• map_name — property name of the map to use.
• cells_name — property name of target specifier cells.
• map_mask_name — optional property name of the mask to use.
• filter_np — pointer to an optional filter node, or NULL to allow bypass. If non-NULL, the map property must exist (-ENODEV if absent). If *filter_np is also non-NULL, only entries targeting that node match. So yeah, filtering is a whole mood.
• arg — pointer to a struct of_phandle_args for the result. On success, arg->args_count will be set to the number of output specifier cells as defined by cells_name in the target node, and arg->args[0..args_count-1] will contain the translated output specifier values. If a map entry was matched, arg->np will be set to the target node with a reference held that the caller must release with of_node_put. Important: caller, you gotta release it. No ghosting references. 😭

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💅 DESCRIPTION 💅

Given a device ID, look up the appropriate implementation-defined platform ID and/or the target device which receives transactions on that ID, as per the "iommu-map" and "msi-map" bindings.

It’s literally giving “ID goes in, mapped ID and/or target device comes out.” 🦋

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🦋 RETURN 🦋

0 on success or a standard error code on failure. Slay when it’s 0, check the error code when it’s not. 💀

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👑 SEE ALSO 👑

The whole friend group is huge, and every single one made the list. The kernel file is ./drivers/of/base.c:

• Kernel file: ./drivers/of/base.c
• of_find_all_nodes(9), __of_device_is_compatible(9), of_machine_compatible_match(9), of_machine_read_compatible(9), of_machine_read_model(9), of_machine_get_match(9), of_machine_get_match_data(9)
• __of_device_is_available(9), __of_device_is_reserved(9), of_device_is_available(9), __of_device_is_fail(9), of_device_is_big_endian(9)
• of_get_parent(9), of_get_next_parent(9), of_get_next_child(9), of_get_next_child_with_prefix(9), of_get_next_available_child(9), of_get_next_reserved_child(9), of_get_next_cpu_node(9)
• of_get_compatible_child(9), of_get_child_by_name(9), of_get_available_child_by_name(9)
• of_find_node_opts_by_path(9), of_find_node_by_name(9), of_find_node_by_type(9), of_find_compatible_node(9), of_find_node_with_property(9), of_match_node(9), of_find_matching_node_and_match(9), of_alias_from_compatible(9)
• of_find_node_by_phandle(9), of_parse_phandle_with_args_map(9), of_count_phandle_with_args(9)
• __of_add_property(9), of_add_property(9), of_remove_property(9), of_alias_scan(9), of_alias_get_id(9), of_alias_get_highest_id(9)
• of_console_check(9), of_find_next_cache_node(9), of_find_last_cache_level(9), of_map_iommu_id(9), of_map_msi_id(9)

xoxo, your of_map_id(9) bestie 💖 — source/version: ./drivers/of 🌈 date: October 2026 🎀