IEEE1284_GET_IRQ_FD(3)

okay bestie, pull up a chair 🫶 you just landed on ieee1284_get_irq_fd(3) — that's the one from the Functions section of the manual, and it's all about interrupt notification. Let's get into it. 💖

---

🌸 NAME 🌸

ieee1284_get_irq_fd, ieee1284_clear_irq — interrupt notification, aka "hey bestie, tell me when the port pokes me" 💅

---

✨ SYNOPSIS ✨

#include <ieee1284.h>

int ieee1284_get_irq_fd(struct parport *port);

int ieee1284_clear_irq(struct parport *port, unsigned int *count);

---

🦋 DESCRIPTION 🦋

So here's the vibe. If the port has a configured interrupt line and the port type supports interrupt notification, then you can literally get yourself a file descriptor that works with select(2) or poll(2). 😌

Any event — readable, writable, or exception — means an interrupt has been triggered. That's it, that's the signal. 🔔

⚠️ No operations other than select or poll may be performed on the file descriptor. Not even a lil peek. Do NOT.

The port must be open in order to call ieee1284_get_irq_fd, and it must be claimed when you're using select or poll. Two separate conditions, both required, no skipping. ✋

Also, and this is important:

• The caller must not close the file descriptor 🙅‍♀️
• The caller may not use it at all when the port is not claimed

Then, once an interrupt has been detected, the caller must call ieee1284_clear_irq to clear the interrupt condition. 🧹 And here's the cute part: at that moment you can grab the number of interrupts raised by supplying a non-NULL count. 🌟

---

💅 RETURN VALUE 💅

For ieee1284_get_irq_fd 🌈

If the return value is negative then it's an error code (listed below). Otherwise? It's a valid file descriptor, and you're so back. 👑

• E1284_NOTAVAIL — No such file descriptor is available. 😭
• E1284_INVALIDPORT — The port parameter is invalid (for instance, perhaps the port is not open). 🙈

For ieee1284_clear_irq 🎀

• E1284_OK — The interrupt has been cleared. And if count was not NULL, the count of interrupts has been atomically stored to count and reset. Slay. ✨
• E1284_NOTAVAIL — The count parameter was not NULL but interrupt counting is not supported on this type of port. The interrupt has been cleared, though, so don't cry. 🫶
• E1284_SYS — There was a problem clearing the interrupt. 💀
• E1284_INVALIDPORT — The port parameter is invalid (for instance, perhaps the port is not claimed). 🙈

---

👑 AUTHOR 👑

Tim Waugh <twaugh@redhat.com>

• Author. 💜

---

🧚 COPYRIGHT 🧚

Copyright © 2001-2003 Tim Waugh

---

and that's the whole page, bestie, no notes. this one shipped as part of the 09/18/2007 release of the IEEE1284_GET_IRQ_FD(3) page — iconic date, iconic energy, go clear some interrupts responsibly 💖✨🦋