DDI_INTR_ALLOC(9F) Kernel Functions for Drivers DDI_INTR_ALLOC(9F)

NAME

ddi_intr_alloc, ddi_intr_free - allocate or free interrupts for a given
interrupt type

SYNOPSIS

#include <sys/types.h>
#include <sys/conf.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>

int ddi_intr_alloc(dev_info_t *dip, ddi_intr_handle_t *h_array, int type,
int inum, int count, int *actualp, int behavior);


int ddi_intr_free(ddi_intr_handle_t h);

INTERFACE LEVEL

illumos DDI specific (illumos DDI).

PARAMETERS

ddi_intr_alloc()

dip
Pointer to the dev_info structure


h_array
Pointer to an array of DDI interrupt handles


type
Interrupt type


inum
Interrupt number


count
Number of interrupts requested. The count should not exceed
the total number of interrupts supported by the device, as
returned by a call to ddi_intr_get_nintrs(9F).


actualp
Pointer to the number of interrupts actually allocated


behavior
Flag to determine the allocation algorithm


ddi_intr_free()

h
DDI interrupt handle

DESCRIPTION

The ddi_intr_alloc() function allocates interrupts of the interrupt type
given by the type argument beginning at the interrupt number inum. If
ddi_intr_alloc() allocates any interrupts, it returns the actual number
of interrupts allocated in the integer pointed to by the actualp argument
and returns the number of interrupt handles in the interrupt handle array
pointed to by the h_array argument.


Specific interrupts are always specified by the combination of interrupt
type and inum. For legacy devices, inum refers to the nth interrupt,
typically as defined by the devices interrupts property. For PCI fixed
interrupts, inum refers to the interrupt number. The inum is the relative
interrupt vector number, from 0 to 31 for MSI, from 0 to 2047 for MSI-X.
The first interrupt vector is 0. The last relative vector is 31 for MSI
or 2047 for MSI-X.


The h_array must be pre-allocated by the caller as a count sized array of
ddi_intr_handle_t's.


If MSI interrupts are being allocated, the count argument passed should
be a number between 1 and 32, specified as a power of two. If count is
not specified as a power of two, the error DDI_EINVAL is returned.


The behavior flag controls the interrupt allocation algorithm. It takes
one of two input values: DDI_INTR_ALLOC_NORMAL or DDI_INTR_ALLOC_STRICT.
If the count value used is greater than NINTRs, then the call fails with
DDI_EINVAL unconditionally. When set to DDI_INTR_ALLOC_STRICT, the call
succeeds if and only if count interrupts are allocated. Otherwise, the
call fails, and the number of available interrupts is returned in
actualp. When set to DDI_INTR_ALLOC_NORMAL, the call succeeds if at least
one interrupt is allocated, and the number of allocated interrupts is
returned in actualp.


The handle for each allocated interrupt, if any, is returned in the array
of handles given by the h_array argument.


The ddi_intr_free() function releases the system resources and interrupt
vectors associated with the ddi_intr_handle_t h, including any resources
associated with the handle h itself. Once freed, the handle h should not
be used in any further calls.


The ddi_intr_free() function should be called once for each handle in the
handle array.

RETURN VALUES

The ddi_intr_alloc() and ddi_intr_free() functions return:

DDI_SUCCESS
On success.


DDI_EAGAIN
Not enough interrupt resources.


DDI_EINVAL
On encountering invalid input parameters.


DDI_INTR_NOTFOUND
On failure to find the interrupt.


DDI_FAILURE
On any implementation specific failure.

CONTEXT

The ddi_intr_alloc() and ddi_intr_free() functions can be called from
kernel non-interrupt context.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Committed |
+--------------------+-----------------+

SEE ALSO

attributes(7), ddi_intr_add_handler(9F), ddi_intr_block_enable(9F),
ddi_intr_disable(9F), ddi_intr_enable(9F), ddi_intr_get_cap(9F),
ddi_intr_get_nintrs(9F), ddi_intr_get_pri(9F),
ddi_intr_get_supported_types(9F), ddi_intr_remove_handler(9F)


Writing Device Drivers

NOTES

Consumers of these interfaces should verify that the return value is not
equal to DDI_SUCCESS. Incomplete checking for failure codes could result
in inconsistent behavior among platforms.


If a device driver that uses MSI and MSI-X interrupts resets the device,
the device might reset its configuration space modifications. Such a
reset could cause a device driver to lose any MSI and MSI-X interrupt
usage settings that have been applied.


April 23, 2008 DDI_INTR_ALLOC(9F)