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#include <sys/sunddi.h>
int prefixmapdev_access(ddi_mapdev_handle_t handle, void *devprivate, off_t offset);
Solaris DDI specific (Solaris DDI).
mapdev_access() is called when an access is made to a mapping that has either been newly created with ddi_mapdev(9F) or that has been enabled with a call to ddi_mapdev_intercept(9F) .
mapdev_access() is passed the handle of the mapped object on which an access has occurred. This handle uniquely identifies the mapping and is used as an argument to ddi_mapdev_intercept(9F) or ddi_mapdev_nointercept(9F) to control whether or not future accesses to the mapping will cause mapdev_access() to be called. In general, mapdev_access() should call ddi_mapdev_intercept() on the mapping that is currently in use and then call ddi_mapdev_nointercept() on the mapping that generated this call to mapdev_access(). This will ensure that a call to mapdev_access() will be generated for the current mapping next time it is accessed.
mapdev_access() must at least call ddi_mapdev_nointercept() with offset passed in in order for the access to succeed. A request to allow accesses affects the entire page containing the offset.
Accesses to portions of mappings that have been disabled by a call to ddi_mapdev_nointercept() will not generate a call to mapdev_access(). A subsequent call to ddi_mapdev_intercept() will enable mapdev_access() to be called again.
A non-zero return value from mapdev_access() will cause the corresponding operation to fail. The failure may result in a SIGSEGV or SIGBUS signal being delivered to the process.
This function is called from user context
only.
The following shows an example of managing a device context that is one page in length.
ddi_mapdev_handle_t cur_hdl;
static int
xxmapdev_access(ddi_mapdev_handle_t handle, void *devprivate,
off_t offset)
{
int err;
/* enable calls to mapdev_access for the current mapping */
if (cur_hdl != NULL) {
if ((err = ddi_mapdev_intercept(cur_hdl, off, 0)) != 0)
return (err);
}
/* Switch device context - device dependent*/
...
/* Make handle the new current mapping */
cur_hdl = handle;
/*
* Disable callbacks and complete the access for the
* mapping that generated this callback.
*/
return (ddi_mapdev_nointercept(handle, off, 0));
}