DEVMAP_MAP(9E) Driver Entry Points DEVMAP_MAP(9E)


devmap_map - device mapping create entry point


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

int prefixdevmap_map(devmap_cookie_t dhp, dev_t dev,
uint_t flags, offset_t off, size_t len, void **pvtp);


illumos DDI specific (illumos DDI).


An opaque mapping handle that the system uses to describe the
mapping currently being created.

The device whose memory is to be mapped.

Flags indicating type of mapping. Possible values are:

Changes are private.

Changes should be shared.

User offset within the logical device memory at which the
mapping begins.

Length (in bytes) of the memory to be mapped.

A pointer to be filled in by device drivers with the driver
private mapping data.


The devmap_map() entry point is an optional routine that allows drivers
to perform additional processing or to allocate private resources during
the mapping setup time. For example, in order for device drivers to
support context switching, the drivers allocate private mapping data and
associate the private data with the mapping parameters in the
devmap_map() entry point.

The system calls devmap_map() after the user mapping to device physical
memory has been established. (For example, after the devmap(9E) entry
point is called.)

devmap_map() receives a pointer to the driver private data for this
mapping in pvtp. The system expects the driver to allocate its private
data and set *pvtp to the allocated data. The driver must store off and
len, which define the range of the mapping, in its private data. Later,
when the system calls devmap_unmap(9E), the driver will use the off and
len stored in pvtp to check if the entire mapping, or just a part of it,
is being unmapped. If only a part of the mapping is being unmapped, the
driver must allocate a new private data for the remaining mapping before
freeing the old private data. The driver will receive *pvtp in
subsequent event notification callbacks.

If the driver support context switching, it should store the mapping
handle dhp in its private data *pvtp for later use in devmap_unload(9F).

For a driver that supports context switching, flags indicates whether or
not the driver should allocate a private context for the mapping. For
example, a driver may allocate a memory region to store the device
context if flags is set to MAP_PRIVATE.


devmap_map() returns the following values:

Successful completion.

An error occurred.


Example 1 devmap_map()implementation

The following shows an example implementation for devmap_map().

static int
xxdevmap_map(devmap_cookie_t dhp, dev_t dev, uint_t flags, \
offset_t off,size_t len, void **pvtp)
struct xx_resources *pvt;
struct xx_context *this_context;
struct xx_softc *softc;
softc = ddi_get_soft_state(statep, getminor(dev));

this_context = get_context(softc, off, len);

/* allocate resources for the mapping - Device dependent */
pvt = kmem_zalloc(sizeof (struct xx_resources), KM_SLEEP);

pvt->off = off;
pvt->len = len;
pvt->dhp = dhp;
pvt->ctx = this_context;
*pvtp = pvt;


devmap_unmap(9E), devmap_unload(9F), devmap_callback_ctl(9S)

Writing Device Drivers

illumos January 7, 1997 DEVMAP_MAP(9E)