mapdev_access(9E)

NAME

mapdev_access − device mapping access entry point

SYNOPSIS

#include <sys/sunddi.h>

int prefixmapdev_access(ddi_mapdev_handle_t handle, void ∗devprivate, off_t offset);

INTERFACE LEVEL

Solaris DDI specific (Solaris DDI).

ARGUMENTS

handle An opaque pointer to a device mapping.

devprivate Driver private mapping data from ddi_mapdev(9F).

offset The offset within device memory at which the access occurred.

DESCRIPTION

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.

RETURN VALUES

mapdev_access() should return 0 on success, -1 if there was a hardware error, or the return value from ddi_mapdev_intercept() or ddi_mapdev_nointercept().

CONTEXT

This function is called from user context only.

EXAMPLES

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)
{
interr;
/∗ 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));
}

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