* hurd/documentation.mdwn: add link to libirqhelp * hurd/libirqhelp.mdwn: new file --- hurd/documentation.mdwn | 1 + hurd/libirqhelp.mdwn | 66 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 67 insertions(+) create mode 100644 hurd/libirqhelp.mdwn
diff --git a/hurd/documentation.mdwn b/hurd/documentation.mdwn index 68914697..3a662ca4 100644 --- a/hurd/documentation.mdwn +++ b/hurd/documentation.mdwn @@ -78,6 +78,7 @@ is included in the section entitled * [[libnetfs]] -- short introductory material * [[libdiskfs]] * [[libihash]] + * [[libirqhelp]] * [[libpthread]] * [[libfshelp]] * [[libps]] diff --git a/hurd/libirqhelp.mdwn b/hurd/libirqhelp.mdwn new file mode 100644 index 00000000..e68a4812 --- /dev/null +++ b/hurd/libirqhelp.mdwn @@ -0,0 +1,66 @@ +[[!meta copyright="Copyright © 2024 Free Software Foundation, +Inc."]] + +[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable +id="license" text="Permission is granted to copy, distribute and/or modify this +document under the terms of the GNU Free Documentation License, Version 1.2 or +any later version published by the Free Software Foundation; with no Invariant +Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license +is included in the section entitled [[GNU Free Documentation +License|/fdl]]."]]"""]] + +[[!tag stable_URL]] + +Damien Zammit authored libirqhelp, which lets userspace attach and +handle interupts. Suppose, a user presses a key on his keyboard, then +the keyboard can send an interrupt request (an IRQ), to the the +processor. The CPU will try to interupt the program, so that a +callback handler can run instead. A brief overview of `x86` interrupt +information can be found on +[[wikipedia|https://en.wikipedia.org/wiki/Interrupt_request]]. The +[[osdev wiki|https://wiki.osdev.org/IOAPIC]] has more technical +information. The source for `libirqhelp` can be found in +`$hurd-src/libirqhelp/`. + +First you must call `irqhelp_init ();` Then you can install an +interupt handler with this function: + + struct irc * + irqhelp_install_interrupt_handler (int gsi, int bus, int dev, + int fun, void (*handler)(void*), + void *context); + +If `gsi` is `-1`, then ACPI will look up the global system interrupt. +If `bus`, `dev`, and `fun` are `-1`, then you must define `gsi` +(global system interrupt). You then use the returned `struct irc *` +to call the other functions. + +`struct irq`'s definition is: + + struct irq { + void (*handler)(void *); + void *context; + int gsi; + mach_port_t port; + bool enabled; + bool shutdown; + pthread_mutex_t irqlock; + pthread_cond_t irqcond; + }; + +If you want to use pthread, then set up this function, which installs +the handlers via pthread. `arg` is a `struct irc *`. + + void * irqhelp_server_loop (void *arg); + +You can enable an irq via: + + void irqhelp_enable_irq (struct irq *irq); + +You can disable an irq via: + + void irqhelp_disable_irq (struct irq *irq); + +You can deregister a handler via: + + error_t irqhelp_remove_interrupt_handler (struct irq *irq); -- 2.45.2
