of_property_read_u64(9)

💅 of_property_read_u64(9) — the kernel API manual, but make it make sense

okay so bestie, this is of_property_read_u64(9), and yes the name is a mouthful but it's literally just "go find a property and read a 64-bit number out of it". we're in the kernel API manual, this is device-tree territory, and it's giving very demure, very mindful, very drivers/of. let's go 🎀

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✨ NAME ✨

of_property_read_u64 — find a property and read a 64 bit integer out of it. that's it. that's the whole vibe. 💖

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🌸 SYNOPSIS 🌸

int of_property_read_u64 (const struct device_node *np , const char
*propname , u64 *out_value );

like, three args, one int coming back at you, no drama. 🦋

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🫶 ARGUMENTS 🫶

• np — the device node you're reading the property value from. this is your main character. 👑
• propname — the name of the property you're searching for. iykyk, you gotta know what you're looking for. 🔍
• out_value — a pointer to the return value. and listen — it only gets modified if the return value is 0. so if you're out here assuming it got written, no bestie, check that return first. 💀

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🧚 DESCRIPTION 🧚

so the whole thing is: search for a property inside a device node, then read a 64-bit value out of it. lowkey simple, highkey useful. ✨

the out_value is modified only if a valid u64 value can actually be decoded. no valid decode = no touchy. hands off. 🙈

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🔥 RETURN 🔥

• 0 on success — slay, you got your value 💅
• -EINVAL if the property does not exist — it's not there, bestie, it's just not 😭
• -ENODATA if the property does not have a value — the property is there but it's giving nothing. empty. void. 🕳️
• -EOVERFLOW if the property data isn't large enough — too small to hold a u64, we can't work with that 🫠

fr fr, check your return code. the out_value write is conditional and that is not a drill. ⚠️

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🌈 SEE ALSO 🌈

the kernel file lives at ./drivers/of/property.c, and here's the whole friend group 🫂:

• of_property_read_bool(9)
• of_graph_is_present(9)
• of_property_count_elems_of_size(9)
• of_find_property_value_of_size(9)
• of_property_read_u8_index(9)
• of_property_read_u16_index(9)
• of_property_read_u32_index(9)
• of_property_read_u64_index(9)
• of_property_read_variable_u8_array(9)
• of_property_read_variable_u16_array(9)
• of_property_read_variable_u32_array(9)
• of_property_read_variable_u64_array(9)
• of_property_read_string(9)
• of_property_match_string(9)
• of_property_read_string_helper(9)
• of_graph_parse_endpoint(9)
• of_graph_get_port_by_id(9)
• of_graph_get_next_port(9)
• of_graph_get_next_port_endpoint(9)
• of_graph_get_next_endpoint(9)
• of_graph_get_endpoint_by_regs(9)
• of_graph_get_remote_endpoint(9)
• of_graph_get_port_parent(9)
• of_graph_get_remote_port_parent(9)
• of_graph_get_remote_port(9)
• of_graph_get_endpoint_count(9)
• of_graph_get_port_count(9)
• of_graph_get_remote_node(9)
• parse_prop_cells(9)
• parse_suffix_prop_cells(9)
• struct supplier_bindings(9)
• of_link_property(9)

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and that's the whole page, bestie 🎀 this one's from ./drivers/of, dated October 2026, and it goes by of_property_read_u64(9) — periodt. 💜✨