INTRENABLE(10.2) INTRENABLE(10.2)
NAME
intrenable, intrdisable - enable (disable) an interrupt handler
SYNOPSIS
void intrenable(int v, void (*f)(Ureg*, void*), void* a, int tbdf, char
*name)
void intrdisable(int v, void (*f)(Ureg*, void*), void* a, int tbdf,
char *name)
DESCRIPTION
Intrenable registers f to be called by the kernel's interrupt con‐
troller driver each time an interrupt denoted by v occurs, and unmasks
the corresponding interrupt in the interrupt controller. The encoding
of v is platform-dependent; it is often an interrupt vector number, but
can be more complex. Tbdf is a platform-dependent value that might
further qualify v. It might for instance denote the type of bus, bus
instance, device number and function (following the PCI device indexing
scheme), hence its name, but can have platform-dependent meaning. Name
is a string that should uniquely identify the corresponding device (eg,
"uart0"); again it is usually platform-dependent. Intrenable supports
sharing of interrupt levels when the hardware does.
Almost invariably f is a function defined in a device driver to carry
out the device-specific work associated with a given interrupt. The
pointer a is passed to f; typically it points to the driver's data for
a given device or controller. It also passes f a Ureg* value that con‐
tains the registers saved by the interrupt handler (the contents are
platform specific; see the platform's include file ureg.h).
F is invoked by underlying code in the kernel that is invoked directly
from the hardware vectors. It is therefore not running in any process
(see kproc(10.2); indeed, on many platforms the current process pointer
(up) will be nil. There are many restrictions on kernel functions run‐
ning outside a process, but a fundamental one is that they must not
sleep(10.2), although they often call wakeup to signal the occurrence
of an event associated with the interrupt. Qio(10.2) and other manual
pages note which functions are safe for f to call.
The interrupt controller driver does whatever is required to acknowl‐
edge or dismiss the interrupt signal in the interrupt controller,
before calling f, for edge-triggered interrupts, and after calling f
for level-triggered ones. F is responsible for deal with the cause of
the interrupt in the device, including any acknowledgement required in
the device, before it returns.
Intrdisable removes any registration previously made by intrenable with
matching parameters, and if no other interrupt is active on v, it masks
the interrupt in the controller. Device drivers that are not dynami‐
cally configured tend to call intrenable during reset or initialisation
(see dev(10.2)), but can call it at any appropriate time, and instead
of calling intrdisable they can simply enable or disable interrupts in
the device as required.
SOURCE
/os/*/trap.c
SEE ALSO
malloc(10.2), qio(10.2), sleep(10.2), splhi(10.2)
INTRENABLE(10.2)
