ddi_cb_register(9F) Kernel Functions for Drivers ddi_cb_register(9F)
NAME
ddi_cb_register, ddi_cb_unregister - register and unregister a device driver callback handler
SYNOPSIS
#include <sys/sunddi.h>
int ddi_cb_register(dev_info_t *dip, ddi_cb_flags_t flags,
ddi_cb_func_t cbfunc, void *arg1, void *arg2,
ddi_cb_handle_t * ret_hdlp);
int ddi_cb_unregister(ddi_cb_handle_t hdl);
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI).
PARAMETERS
ddi_cb_register()
dip Pointer to the dev_info structure.
flags Flags to determine which callback events can be handled.
cbfunc Callback handler function.
arg1 First argument to the callback handler.
arg2 Second (optional) argument to the callback handler.
ret_hdlp Pointer to return a handle to the registered callback.
ddi_cb_unregister()
hdl Handle to the registered callback handler that is to be unregistered.
DESCRIPTION
The ddi_cb_register() function installs a callback handler which processes various actions that require the driver's attention while it is
attached. The driver specifies which callback actions it can handle through the flags parameter. With each relevant action, the specified
callback function passes the arg1 and arg2 arguments along with the description of each callback event to the driver.
The ddi_cb_unregister() function removes a previously installed callback handler and prevents future processing of actions.
The flags parameter consists of the following:
DDI_CB_FLAG_INTR The device driver participates in interrupt resource management. The device driver may receive additional interrupt
resources from the system, but only because it can accept callback notices informing it when it has more or less
resources available. Callback notices can occur at anytime after the driver is attached. Interrupt availability varies
based on the overall needs of the system.
The cdfunc is a callback handler with the following prototype:
typedef int (*ddi_cb_func_t)(dev_info_t *dip,
ddi_cb_action_t action, void *cbarg,
void *arg1, void *arg2);
The cbfunc routine with the arguments dip, action, cbarg, arg1 and arg2 is called upon receipt of any callbacks for which the driver is
registered. The callback handler returns DDI_SUCCESS if the callback was handled successfully, DDI_ENOTSUP if it received a callback
action that it did not know how to process, or DDI_FAILURE if it has an internal failure while processing an action.
The action parameter can be one of the following:
DDI_CB_INTR_ADD For interrupt resource management, the driver has more available interrupts. The driver can allocate more interrupt
vectors and then set up more interrupt handling functions by using ddi_intr_alloc(9F).
DDI_CB_INTR_REMOVE For interrupt resource management, the driver has fewer available interrupts. The driver must release any previously
allocated interrupts in excess of what is now available by using ddi_intr_free(9F).
The cbarg parameter points to an action-specific argument. Each class of registered actions specifies its own data structure that a call-
back handler should dereference when it receives those actions.
The cbarg parameter is defined as an integer in the case of DDI_CB_INTR_ADD and DDI_CB_INTR_REMOVE actions. The callback handler should
cast the cbarg parameter to an integer. The integer represents how many interrupts have been added or removed from the total number avail-
able to the device driver.
If a driver participates in interrupt resource management, it must register a callback with the DDI_CB_FLAG_INTR flag. The driver then
receives the actions DDI_CB_INTR_ADD and DDI_CB_INTR_REMOVE whenever its interrupt availability has changed. The callback handler should
use the interrupt functions ddi_intr_alloc(9F) and ddi_intr_free(9F) functions to respond accordingly. A driver is not required to allocate
all interrupts that are available to it, but it is required to manage its allocations so that it never uses more interrupts than are cur-
rently available.
RETURN VALUES
The ddi_cb_register() and ddi_cb_unregister() functions return:
DDI_SUCCESS on success
DDI_EINVAL An invalid parameter was given when registering a callback handler, or an invalid handle was given when unregistering.
DDI_EALREADY An attempt was made to register a callback handler while a previous registration still exists.
The cbfunc routine must return:
DDI_SUCCESS on success
DDI_ENOTSUP The device does not support the operation
DDI_FAILURE Implementation specific failure
CONTEXT
These functions can be called from kernel, non-interrupt context.
EXAMPLES
Example 1 ddi_cb_register
/*
* attach(9F) routine.
*
* Creates soft state, registers callback handler, initializes
* hardware, and sets up interrupt handling for the driver.
*/
xx_attach(dev_info_t *dip, ddi_attach_cmd_t cmd)
{
xx_state_t *statep = NULL;
xx_intr_t *intrs = NULL;
ddi_intr_handle_t *hdls;
ddi_cb_handle_t cb_hdl;
int instance;
int type;
int types;
int nintrs;
int nactual;
int inum;
/* Get device instance */
instance = ddi_get_instance(dip);
switch (cmd) {
case DDI_ATTACH:
/* Get soft state */
if (ddi_soft_state_zalloc(state_list, instance) != 0)
return (DDI_FAILURE);
statep = ddi_get_soft_state(state_list, instance);
ddi_set_driver_private(dip, (caddr_t)statep);
statep->dip = dip;
/* Initialize hardware */
xx_initialize(statep);
/* Register callback handler */
if (ddi_cb_register(dip, DDI_CB_FLAG_INTR, xx_cbfunc,
statep, NULL, &cb_hdl) != 0) {
ddi_soft_state_free(state_list, instance);
return (DDI_FAILURE);
}
statep->cb_hdl = cb_hdl;
/* Select interrupt type */
ddi_intr_get_supported_types(dip, &types);
if (types & DDI_INTR_TYPE_MSIX) {
type = DDI_INTR_TYPE_MSIX;
} else if (types & DDI_INTR_TYPE_MSI) {
type = DDI_INTR_TYPE_MSI;
} else {
type = DDI_INTR_TYPE_FIXED;
}
statep->type = type;
/* Get number of supported interrupts */
ddi_intr_get_nintrs(dip, type, &nintrs);
/* Allocate interrupt handle array */
statep->hdls_size = nintrs * sizeof (ddi_intr_handle_t);
hdls = kmem_zalloc(statep->hdls_size, KMEM_SLEEP);
/* Allocate interrupt setup array */
statep->intrs_size = nintrs * sizeof (xx_intr_t);
statep->intrs = kmem_zalloc(statep->intrs_size, KMEM_SLEEP);
/* Allocate interrupt vectors */
ddi_intr_alloc(dip, hdls, type, 0, nintrs, &nactual, 0);
statep->nactual = nactual;
/* Configure interrupt handling */
xx_setup_interrupts(statep, nactual, statep->intrs);
/* Install and enable interrupt handlers */
for (inum = 0; inum < nactual; inum++) {
ddi_intr_add_handler(&statep->hdls[inum],
statep->intrs[inum].inthandler,
statep->intrs[inum].arg1,
statep->intrs[inum].arg2);
ddi_intr_enable(statep->hdls[inum]);
}
break;
case DDI_RESUME:
/* Get soft state */
statep = ddi_get_soft_state(state_list, instance);
if (statep == NULL)
return (DDI_FAILURE);
/* Resume hardware */
xx_resume(statep);
break;
}
return (DDI_SUCESS);
}
/*
* detach(9F) routine.
*
* Stops the hardware, disables interrupt handling, unregisters
* a callback handler, and destroys the soft state for the driver.
*/
xx_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
{
xx_state_t *statep = NULL;
int instance;
int inum;
/* Get device instance */
instance = ddi_get_instance(dip);
switch (cmd) {
case DDI_DETACH:
/* Get soft state */
statep = ddi_get_soft_state(state_list, instance);
if (statep == NULL)
return (DDI_FAILURE);
/* Stop device */
xx_uninitialize(statep);
/* Disable and free interrupts */
for (inum = 0; inum < statep->nactual; inum++) {
ddi_intr_disable(statep->hdls[inum]);
ddi_intr_remove_handler(statep->hdls[inum]);
ddi_intr_free(statep->hdls[inum]);
}
/* Unregister callback handler */
ddi_cb_unregister(statep->cb_hdl);
/* Free interrupt handle array */
kmem_free(statep->hdls, statep->hdls_size);
/* Free interrupt setup array */
kmem_free(statep->intrs, statep->intrs_size);
/* Free soft state */
ddi_soft_state_free(state_list, instance);
break;
case DDI_SUSPEND:
/* Get soft state */
statep = ddi_get_soft_state(state_list, instance);
if (statep == NULL)
return (DDI_FAILURE);
/* Suspend hardware */
xx_quiesce(statep);
break;
}
return (DDI_SUCCESS);
}
/*
* (*ddi_cbfunc)() routine.
*
* Adapt interrupt usage when availability changes.
*/
int
xx_cbfunc(dev_info_t *dip, ddi_cb_action_t cbaction, void *cbarg,
void *arg1, void *arg2)
{
xx_state_t *statep = (xx_state_t *)arg1;
int count;
int inum;
int nactual;
switch (cbaction) {
case DDI_CB_INTR_ADD:
case DDI_CB_INTR_REMOVE:
/* Get change in availability */
count = (int)(uintptr_t)cbarg;
/* Suspend hardware */
xx_quiesce(statep);
/* Tear down previous interrupt handling */
for (inum = 0; inum < statep->nactual; inum++) {
ddi_intr_disable(statep->hdls[inum]);
ddi_intr_remove_handler(statep->hdls[inum]);
}
/* Adjust interrupt vector allocations */
if (cbaction == DDI_CB_INTR_ADD) {
/* Allocate additional interrupt vectors */
ddi_intr_alloc(dip, statep->hdls, statep->type,
statep->nactual, count, &nactual, 0);
/* Update actual count of available interrupts */
statep->nactual += nactual;
} else {
/* Free removed interrupt vectors */
for (inum = statep->nactual - count;
inum < statep->nactual; inum++) {
ddi_intr_free(statep->hdls[inum]);
}
/* Update actual count of available interrupts */
statep->nactual -= count;
}
/* Configure interrupt handling */
xx_setup_interrupts(statep, statep->nactual, statep->intrs);
/* Install and enable interrupt handlers */
for (inum = 0; inum < statep->nactual; inum++) {
ddi_intr_add_handler(&statep->hdls[inum],
statep->intrs[inum].inthandler,
statep->intrs[inum].arg1,
statep->intrs[inum].arg2);
ddi_intr_enable(statep->hdls[inum]);
}
/* Resume hardware */
xx_resume(statep);
break;
default:
return (DDI_ENOTSUP);
}
return (DDI_SUCCESS);
}
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Private |
+-----------------------------+-----------------------------+
|MT-Level |Unsafe |
+-----------------------------+-----------------------------+
SEE ALSO
attributes(5), ddi_intr_alloc(9F), ddi_intr_free(9F), ddi_intr_set_nreq(9F)
NOTES
Users of these interfaces that register for DDI_CB_FLAG_INTR become participants in interrupt resource management. With that participation
comes a responsibility to properly adjust interrupt usage. In the case of a DDI_CB_INTR_ADD action, the system guarantees that a driver can
allocate a total number of interrupt resources up to its new number of available interrupts. The total number of interrupt resources is the
sum of all resources allocated by the function ddi_intr_alloc(9F), minus all previously released by the function ddi_intr_free(9F). In the
case of a DDI_CB_INTR_REMOVE action, the driver might have more interrupts allocated than are now currently available. It is necessary for
the driver to release the excess interrupts, or it will have a negative impact on the interrupt availability for other drivers in the sys-
tem.
A failure to release interrupts in response to a DDI_CB_INTR_REMOVE callback generates the following warning on the system console:
WARNING: <driver><instance>: failed to release interrupts for
IRM (nintrs = ##, navail=##).
Participation in interrupt resource management ends when a driver uses the ddi_cb_unregister() function to unregister its callback func-
tion. The callback function must still operate properly until after the call to the ddi_cb_unregister() function completes. If addinter-
rupts were given to the driver because of its participation, then a final use of the callback function occurs to release the additional
interrupts. The call to the ddi_cb_unregister() function blocks until the final use of the registered callback function is finished.
SunOS 5.11 30 Jan 2009 ddi_cb_register(9F)