STRUCT REG_DEFAULT(9)

💖 NAME 💖

okay so bestie, we’re looking at struct reg_default(9) from the Kernel API Manual, and it is literally the struct for a register’s default value. It’s giving “what should this register be when we start?” energy 💅

✨ SYNOPSIS ✨

struct reg_default {
    unsigned int reg;
    unsigned int def;
};

👑 Members 👑

• reg — register address.
• def — register default value.

🦋 Description 🦋

so we use an array of structs rather than a simple array because so many modern devices have very sparse register maps. that’s the whole reason, and honestly it makes sense — sparse register maps are the vibe this thing is built for ✨

🌈 SEE ALSO 🌈

• Kernel file: ./include/linux/regmap.h.
• Structs and polling helpers: struct reg_sequence(9), regmap_read_poll_timeout(9), regmap_read_poll_timeout_atomic(9), regmap_field_read_poll_timeout(9), struct regmap_range(9), struct regmap_access_table(9), struct regmap_config(9), struct regmap_range_cfg(9), struct regmap_sdw_mbq_cfg(9), struct regmap_bus(9).
• regmap_init crew: regmap_init(9), regmap_init_i2c(9), regmap_init_mdio(9), regmap_init_sccb(9), regmap_init_slimbus(9), regmap_init_spi(9), regmap_init_spmi_base(9), regmap_init_spmi_ext(9), regmap_init_w1(9), regmap_init_mmio_clk(9), regmap_init_mmio(9), regmap_init_ac97(9), regmap_init_sdw(9), regmap_init_sdw_mbq(9), regmap_init_sdw_mbq_cfg(9), regmap_init_i3c(9), regmap_init_spi_avmm(9), regmap_init_fsi(9).
• devm_regmap_init crew: devm_regmap_init(9), devm_regmap_init_i2c(9), devm_regmap_init_mdio(9), devm_regmap_init_sccb(9), devm_regmap_init_spi(9), devm_regmap_init_spmi_base(9), devm_regmap_init_spmi_ext(9), devm_regmap_init_w1(9), devm_regmap_init_mmio_clk(9), devm_regmap_init_mmio(9), devm_regmap_init_ac97(9), devm_regmap_init_sdw(9), devm_regmap_init_sdw_mbq(9), devm_regmap_init_sdw_mbq_cfg(9), devm_regmap_init_slimbus(9), devm_regmap_init_i3c(9), devm_regmap_init_spi_avmm(9), devm_regmap_init_fsi(9).
• IRQ/field structs: struct reg_field(9), struct regmap_irq_type(9), struct regmap_irq(9), struct regmap_irq_chip(9).

mwah 💋 this page’s source/version is ./include/linux, it’s dated October 2026, and the page itself is struct reg_default(9) — bye bestie, slay your register defaults 🎀