i2c_smbus_xfer(9)

✨ i2c_smbus_xfer ✨

okay bestie, welcome to the Kernel API Manual entry for i2c_smbus_xfer — it's giving "one function to rule all the SMBus protocols" and honestly? iconic. 💅

💖 NAME 💖

i2c_smbus_xfer — execute SMBus protocol operations. that's it, that's the whole job description, and she does it flawlessly. 🎀

🌸 SYNOPSIS 🌸

s32 i2c_smbus_xfer (struct i2c_adapter *adapter , u16 addr , unsigned
short flags , char read_write , u8 command , int protocol , union
i2c_smbus_data *data );

like, look at all those parameters. she's high-maintenance but she's worth it. 🔥

🦋 ARGUMENTS 🦋

okay so here's the whole cast of characters, and every single one of them matters:

• adapter — your handle to the I2C bus. think of it as the group chat you're posting into. 🫶
• addr — the address of the SMBus slave on that bus. that's who you're @-ing. 📍
• flags — I2C_CLIENT_* flags. usually zero or I2C_CLIENT_PEC. lowkey optional, highkey relevant. ✨
• read_write — either I2C_SMBUS_READ or I2C_SMBUS_WRITE. pick a lane, bestie. 🙈
• command — a byte interpreted by the slave, for the protocols which use such bytes. iykyk. 💀
• protocol — the SMBus protocol operation you want to execute, such as I2C_SMBUS_PROC_CALL. this is the main character of the whole call, ngl. 👑
• data — the data to be read or written. the payload, the moment, the content. 🍓

🌈 DESCRIPTION 🌈

so what does she actually do? this executes an SMBus protocol operation, and returns a negative errno code — else zero on success. that's the whole vibe check: negative errno = not slay, zero = slay. ⭐

fr fr, watch that return value. a negative errno is the function telling you something went sideways, and zero is the green flag. 🟢

💜 SEE ALSO 💜

the whole squad, in order, no one left out:

• Kernel file ./drivers/i2c/i2c-core-smbus.c
• i2c_smbus_pec(9)
• i2c_smbus_read_byte(9)
• i2c_smbus_write_byte(9)
• i2c_smbus_read_byte_data(9)
• i2c_smbus_write_byte_data(9)
• i2c_smbus_read_word_data(9)
• i2c_smbus_write_word_data(9)
• i2c_smbus_read_block_data(9)
• i2c_smbus_write_block_data(9)
• i2c_smbus_read_i2c_block_data_or_emulated(9)
• i2c_new_smbus_alert_device(9)

and that's the page, bestie!! 🧚💖 brought to you by the fine folks over at ./drivers/i2c, stamped October 2026, and officially filed under i2c_smbus_xfer(9). mwah, go read your errno values, ily. 💜🦋🌸