subdev_8255_cb_init(9)

subdev_8255_cb_init(9) — Kernel API Manual ✨

Okay bestie, this is the Kernel API Manual page for subdev_8255_cb_init, and it is literally giving “wire up a DIO subdevice that drives an 8255 through a callback” energy. 💅

🎀 NAME 🎀

subdev_8255_cb_init — initialize DIO subdevice for driving callback-mapped 8255. ✨

🌸 SYNOPSIS 🌸

int subdev_8255_cb_init (struct comedi_device *dev , struct
       comedi_subdevice *s , int (*io)(struct comedi_device *dev, int dir, int
       port, int data, unsigned long context) , unsigned long context );

🫶 ARGUMENTS 🫶

• dev — the comedi device that owns the subdevice. 👑
• s — the comedi subdevice you’re initializing. 💖
• io — the register I/O call-back function. 🔥
• context — the call-back context. 🎀

🦋 DESCRIPTION 🦋

This initializes a comedi subdevice as a DIO subdevice driving an 8255 chip. Iconic. 💅

The prototype of the I/O call-back function is of the following form:

int my_8255_callback(struct comedi_device *dev, int dir, int port, int
       data, unsigned long context);

In that callback, dev and context match the values passed to this function, the direction is 0 for read or 1 for write, and data is the value to be written. It should return 0 if writing or the value read if reading. Periodt. ✨

⭐ RETURN ⭐

• -ENOMEM — if failed to allocate memory. 😭
• zero — on success. 🎉

🌈 SEE ALSO 🌈

• Kernel file ./drivers/comedi/drivers/comedi_8255.c
• subdev_8255_io_init(9)
• subdev_8255_mm_init(9)
• subdev_8255_regbase(9)

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Cute sign-off bestie: source/version is ./drivers/comedi/drivers, date is October 2026, manual is subdev_8255_cb_init(9). Mwah 💋✨