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


NAME


ddi_intr_dup_handler - reuse interrupt handler and arguments for MSI-X
interrupts

SYNOPSIS


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

int ddi_intr_dup_handler(ddi_intr_handle_t primary, int vector,
ddi_intr_handle_t *new);


INTERFACE LEVEL


Solaris DDI specific (Solaris DDI).

PARAMETERS


primary
Original DDI interrupt handle


vector
Interrupt number to duplicate


new
Pointer to new DDI interrupt handle


DESCRIPTION


The ddi_intr_dup_handler() function is a feature for MSI-X interrupts
that allows an unallocated interrupt vector of a device to use a
previously initialized or added primary MSI-X interrupt vector in order
to share the same vector address, vector data, interrupt handler, and
handler arguments. This feature allows a driver to alias the resources
provided by the Solaris Operating System to the unallocated interrupt
vectors on an associated device. For example, if 2 MSI-X interrupts were
allocated to a driver and 32 interrupts were supported on the device, the
driver could alias the 2 interrupts it received to the 30 remaining on
the device.


The ddi_intr_dup_handler() function must be called after the primary
interrupt handle has been added to the system or enabled by
ddi_intr_add_handler(9F) and ddi_intr_enable(9F) calls, respectively. If
successful, the function returns the new interrupt handle for a given
vector in the new argument passed to the function. The new interrupt
handle must not have been previously allocated with ddi_intr_alloc(9F).
Otherwise, the ddi_intr_dup_handler() call will fail.


The only supported calls on dup-ed interrupt handles are
ddi_intr_set_mask(9F), ddi_intr_clr_mask(9F), ddi_intr_get_pending(9F),
ddi_intr_enable(9F), ddi_intr_disable(9F), and ddi_intr_free(9F).


A call to ddi_intr_dup_handler() does not imply that the interrupt source
is automatically enabled. Initially, the dup-ed handle is in the disabled
state and must be enabled before it can be used by calling
ddi_intr_enable(). Likewise, ddi_intr_disable() must be called to
disable the enabled dup-ed interrupt source.


A dup-ed interrupt is removed by calling ddi_intr_free() after it has
been disabled. The ddi_intr_remove_handler(9F) call is not required for a
dup-ed handle.


Before removing the original MSI-X interrupt handler, all dup-ed
interrupt handlers associated with this MSI-X interrupt must have been
disabled and freed. Otherwise, calls to ddi_intr_remove_handler() will
fail with DDI_FAILURE.


See the EXAMPLES section for code that illustrates the use of the
ddi_intr_dup_handler() function.

RETURN VALUES


The ddi_intr_dup_handler() function returns:

DDI_SUCCESS
On success.

Note that the interface should be verified to ensure that
the return value is not equal to DDI_SUCCESS. Incomplete
checking for failure codes could result in inconsistent
behavior among platforms.


DDI_EINVAL
On encountering invalid input parameters. DDI_EINVAL is
also returned if a dup is attempted from a dup-ed
interrupt or if the hardware device is found not to
support MSI-X interrupts.


DDI_FAILURE
On any implementation specific failure.


EXAMPLES


Example 1: Using the ddi_intr_dup_handler() function



int
add_msix_interrupts(intr_state_t *state)
{
int x, y;

/*
* For this example, assume the device supports multiple
* interrupt vectors, but only request to be allocated
* 1 MSI-X to use and then dup the rest.
*/
if (ddi_intr_get_nintrs(state->dip, DDI_INTR_TYPE_MSIX,
&state->intr_count) != DDI_SUCCESS) {
cmn_err(CE_WARN, "Failed to retrieve the MSI-X interrupt count");
return (DDI_FAILURE);
}

state->intr_size = state->intr_count * sizeof (ddi_intr_handle_t);
state->intr_htable = kmem_zalloc(state->intr_size, KM_SLEEP);

/* Allocate one MSI-X interrupt handle */
if (ddi_intr_alloc(state->dip, state->intr_htable,
DDI_INTR_TYPE_MSIX, state->inum, 1, &state->actual,
DDI_INTR_ALLOC_STRICT) != DDI_SUCCESS) {
cmn_err(CE_WARN, "Failed to allocate MSI-X interrupt");
kmem_free(state->intr_htable, state->intr_size);
return (DDI_FAILURE);
}

/* Get the count of how many MSI-X interrupts we dup */
state->dup_cnt = state->intr_count - state->actual;

if (ddi_intr_get_pri(state->intr_htable[0],
&state->intr_pri) != DDI_SUCCESS) {
cmn_err(CE_WARN, "Failed to get interrupt priority");
goto error1;
}

/* Make sure the MSI-X priority is below 'high level' */
if (state->intr_pri >= ddi_intr_get_hilevel_pri()) {
cmn_err(CE_WARN, "Interrupt PRI is too high");
goto error1;
}

/*
* Add the handler for the interrupt
*/
if (ddi_intr_add_handler(state->intr_htable[0],
(ddi_intr_handler_t *)intr_isr, (caddr_t)state,
NULL) != DDI_SUCCESS) {
cmn_err(CE_WARN, "Failed to add interrupt handler");
goto error1;
}

/* Enable the main MSI-X handle first */
if (ddi_intr_enable(state->intr_htable[0]) != DDI_SUCCESS) {
cmn_err(CE_WARN, "Failed to enable interrupt");
goto error2;
}

/*
* Create and enable dups of the original MSI-X handler, note
* that the inum we are using starts at 0.
*/
for (x = 1; x < state->dup_cnt; x++) {
if (ddi_intr_dup_handler(state->intr_htable[0],
state->inum + x, &state->intr_htable[x]) != DDI_SUCCESS) {
for (y = x - 1; y > 0; y--) {
(void) ddi_intr_disable(state->intr_htable[y]);
(void) ddi_intr_free(state->intr_htable[y]);
}

goto error2;
}
if (ddi_intr_enable(state->intr_htable[x]) != DDI_SUCCESS) {
for (y = x; y > 0; y--) {
(void) ddi_intr_disable(state->intr_htable[y]);
(void) ddi_intr_free(state->intr_htable[y]);
}

goto error2;
}
}

return (DDI_SUCCESS);

error2:
(void) ddi_intr_remove_handler(state->intr_htable[0]);
error1:
(void) ddi_intr_free(state->intr_htable[0]);

kmem_free(state->intr_htable, state->intr_size);
return (DDI_FAILURE);
}

void
remove_msix_interrupts(intr_state_t *state)
{
int x;

/*
* Disable all the handles and free the dup-ed handles
* before we can remove the main MSI-X interrupt handle.
*/
for (x = 1; x < state->dup_cnt; x++) {
(void) ddi_intr_disable(state->intr_htable[x]);
(void) ddi_intr_free(state->intr_htable[x]);
}

/*
* We can remove and free the main MSI-X handler now
* that all the dups have been freed.
*/
(void) ddi_intr_disable(state->intr_htable[0]);
(void) ddi_intr_remove_handler(state->intr_htable[0]);
(void) ddi_intr_free(state->intr_htable[0]);

kmem_free(state->intr_htable, state->intr_size);
}


CONTEXT


The ddi_intr_dup_handler() function can be called from kernel non-
interrupt context.

ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


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

SEE ALSO


attributes(5), ddi_intr_add_handler(9F), ddi_intr_alloc(9F),
ddi_intr_clr_mask(9F), ddi_intr_disable(9F), ddi_intr_enable(9F),
ddi_intr_free(9F), ddi_intr_get_pending(9F),
ddi_intr_get_supported_types(9F), ddi_intr_set_mask(9F)


Writing Device Drivers


May 9, 2006 DDI_INTR_DUP_HANDLER(9F)