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ddi_cb_register, ddi_cb_unregister - register and unregister a device driver callback handler

#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);

illumos DDI specific (illumos DDI). ddi_cb_register() dip flags cbfunc arg1 arg2 ret_hdlp

ddi_cb_unregister() hdl

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 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

DDI_CB_INTR_REMOVE

The cbarg parameter points to an action-specific argument. Each class of registered actions specifies its own data structure that a callback 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 available 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 currently available.

The ddi_cb_register() and ddi_cb_unregister() functions return: DDI_SUCCESS DDI_EINVAL DDI_EALREADY

The cbfunc routine must return: DDI_SUCCESS

DDI_ENOTSUP DDI_FAILURE These functions can be called from kernel, non-interrupt context. Example 1 ddi_cb_register

/*
 * attach(9E) 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_SUCCESS);
 }

 /*
 * detach(9E) 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);
 }

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

ATTRIBUTE TYPE ATTRIBUTE VALUE

Interface Stability Private

MT-Level Unsafe

attributes (7), ddi_intr_alloc (9F), ddi_intr_free (9F), ddi_intr_set_nreq (9F) 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 system.

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 function. The callback function must still operate properly until after the call to the ddi_cb_unregister() function completes. If addinterrupts 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.