man/man9f/devmap_setup.9f

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 DEVMAP_SETUP 9F "Jan 22, 1997"
 NAME
devmap_setup, ddi_devmap_segmap - set up a user mapping to device memory using
the devmap framework
 SYNOPSIS
#include <sys/ddi.h>
#include <sys/sunddi.h>


int devmap_setup(dev_t dev, offset_t off, ddi_as_handle_t as,
 caddr_t *addrp, size_tlen, uint_t prot, uint_t maxprot,
 uint_t flags, cred_t *cred);


int ddi_devmap_segmap(dev_t dev, off_t off, ddi_as_handle_t as,
 caddr_t *addrp, off_tlen, uint_t prot, uint_t maxprot,
 uint_t flags, cred_t *cred);


 INTERFACE LEVEL
illumos DDI specific (illumos DDI).
 PARAMETERS
dev

Device whose memory is to be mapped.


off

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


as

An opaque data structure that describes the address space into which the device
memory should be mapped.


addrp

Pointer to the starting address in the address space into which the device
memory should be mapped.


len

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


prot

A bit field that specifies the protections. Some possible settings combinations
are:
PROT_READ

Read access is desired.


PROT_WRITE

Write access is desired.


PROT_EXEC

Execute access is desired.


PROT_USER

User-level access is desired (the mapping is being done as a result of a
mmap(2) system call).


PROT_ALL

All access is desired.


maxprot

Maximum protection flag possible for attempted mapping; the PROT_WRITE
bit may be masked out if the user opened the special file read-only.


flags

Flags indicating type of mapping. The following flags can be specified:
MAP_PRIVATE

Changes are private.


MAP_SHARED

Changes should be shared.


MAP_FIXED

The user specified an address in *addrp rather than letting the system
choose an address.


cred

Pointer to the user credential structure.


 DESCRIPTION
devmap_setup() and ddi_devmap_segmap() allow device drivers to use
the devmap framework to set up user mappings to device memory. The devmap
framework provides several advantages over the default device mapping framework
that is used by ddi_segmap(9F) or ddi_segmap_setup(9F). Device
drivers should use the devmap framework, if the driver wants to:


use an optimal MMU pagesize to minimize address translations,


conserve kernel resources,


receive callbacks to manage events on the mapping,


export kernel memory to applications,


set up device contexts for the user mapping if the device requires context
switching,


assign device access attributes to the user mapping, or


change the maximum protection for the mapping.


devmap_setup() must be called in the segmap(9E) entry point to
establish the mapping for the application. ddi_devmap_segmap() can be
called in, or be used as, the segmap(9E) entry point. The differences
between devmap_setup() and ddi_devmap_segmap() are in the data
type used for off and len.

When setting up the mapping, devmap_setup() and
ddi_devmap_segmap() call the devmap(9E) entry point to validate the
range to be mapped. The devmap(9E) entry point also translates the
logical offset (as seen by the application) to the corresponding physical
offset within the device address space. If the driver does not provide its own
devmap(9E) entry point, EINVAL will be returned to the
mmap(2) system call.
 RETURN VALUES
0

Successful completion.


Non-zero

An error occurred. The return value of devmap_setup() and
ddi_devmap_segmap() should be used directly in the segmap(9E)
entry point.


 CONTEXT
devmap_setup() and ddi_devmap_segmap() can be called from user or
kernel context only.
 SEE ALSO
mmap(2), devmap(9E), segmap(9E), ddi_segmap(9F),
ddi_segmap_setup(9F), cb_ops(9S)

Writing Device Drivers