STRUCT I2C_ATR(9)

🌸 NAME 🌸

struct i2c_atr — bestie, it's literally the I2C ATR instance 👑

So like, this whole page lives in the Kernel API Manual (yes, the real one, we're fancy now 💅). And the star of the show is struct i2c_atr, the actual instance of an I2C ATR. Iconic behavior only.

✨ SYNOPSIS ✨

struct i2c_atr {
    struct i2c_adapter *parent;
    struct device *dev;
    const struct i2c_atr_ops *ops;
    void *priv;
    struct i2c_algorithm algo;
    struct mutex lock;
    struct lock_class_key lock_key;
    int max_adapters;
    u32 flags;
    struct i2c_atr_alias_pool *alias_pool;
    struct notifier_block i2c_nb;
    struct i2c_adapter *adapter[];
};

Look at her. Struct royalty. The [] at the end is giving flexible array member main character energy 🫶

🎀 Members 🎀

• parent — the parent struct i2c_adapter. Every queen has a mothership 💖
• dev — the device that owns this I2C ATR instance. Like, the whole thing belongs to this device, no cap.
• ops — a struct i2c_atr_ops. The vibe/behavior pack.
• priv — private driver data, and you set it with i2c_atr_set_driver_data. Secret stash, iykyk 🙈
• algo — the struct i2c_algorithm for adapters.
• lock — the lock for the I2C bus segment (peep struct i2c_lock_operations if you wanna go deeper). Protect the bus, protect your peace 🔒
• lock_key — the lock key for lock. It's lock's plus-one.
• max_adapters — maximum number of adapters this I2C ATR can have. Set the limit, bestie 🚦
• flags — flags for ATR.
• alias_pool — an optional common pool of available client aliases. Optional!! Not mandatory, she's flexible ✨
• i2c_nb — the notifier for remote client add & del events. She's on notification duty 📣
• adapter — array of adapters. Plural. A whole squad 🌈

🦋 SEE ALSO 🦋

The kernel file ./drivers/i2c/i2c-atr.c is where it all goes down, and you're gonna want to meet the whole friend group too:

• struct i2c_atr_alias_pair(9)
• struct i2c_atr_alias_pool(9)
• struct i2c_atr_chan(9)

Ngl, if you're poking at ATR internals you should fr fr read the source alongside this. The struct doesn't gatekeep, but context is everything 💜

Okay that's the whole page, bestie — go slay some I2C 🧚💫 This masterpiece came from ./drivers/i2c, dated October 2026, so you know it's fresh 🔥