Tribblix: manual page: devmap_default

DEVMAP_DEFAULT_ACCESS(9F) Kernel Functions for Drivers

NAME

devmap_default_access - default driver memory access function

SYNOPSIS

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

int devmap_default_access(devmap_cookie_t dhp, void *pvtp,
offset_t off, size_t len, uint_t type, uint_t rw);

INTERFACE LEVEL

illumos DDI specific (illumos DDI).

PARAMETERS

dhp
An opaque mapping handle that the system uses to describe
the mapping.

pvtp
Driver private mapping data.

off
User offset within the logical device memory at which the
access begins.

len
Length (in bytes) of the memory being accessed.

type
Type of access operation.

rw
Type of access.

DESCRIPTION

devmap_default_access() is a function providing the semantics of
devmap_access(9E). The drivers call devmap_default_access() to handle
the mappings that do not support context switching. The drivers
should call devmap_do_ctxmgt(9F) for the mappings that support
context management.

devmap_default_access() can either be called from devmap_access(9E)
or be used as the devmap_access(9E) entry point. The arguments dhp,
pvtp, off, len, type, and rw are provided by the devmap_access(9E)
entry point and must not be modified.

RETURN VALUES

0
Successful completion.

Non-zero
An error occurred.

CONTEXT

devmap_default_access() must be called from the driver's
devmap_access(9E) entry point.

EXAMPLES

Example 1: Using devmap_default_access in devmap_access.

The following shows an example of using devmap_default_access() in
the devmap_access(9E) entry point.

...
#define OFF_DO_CTXMGT 0x40000000
#define OFF_NORMAL 0x40100000
#define CTXMGT_SIZE 0x100000
#define NORMAL_SIZE 0x100000

/*
* Driver devmap_contextmgt(9E) callback function.
*/
static int
xx_context_mgt(devmap_cookie_t dhp, void *pvtp, offset_t offset,
size_t length, uint_t type, uint_t rw)
{
......
/*
* see devmap_contextmgt(9E) for an example
*/
}

/*
* Driver devmap_access(9E) entry point
*/
static int
xxdevmap_access(devmap_cookie_t dhp, void *pvtp, offset_t off,
size_t len, uint_t type, uint_t rw)
{
offset_t diff;
int err;

/*
* check if off is within the range that supports
* context management.
*/
if ((diff = off - OFF_DO_CTXMG) >= 0 && diff < CTXMGT_SIZE) {
/*
* calculates the length for context switching
*/
if ((len + off) > (OFF_DO_CTXMGT + CTXMGT_SIZE))
return (-1);
/*
* perform context switching
*/
err = devmap_do_ctxmgt(dhp, pvtp, off, len, type,
rw, xx_context_mgt);
/*
* check if off is within the range that does normal
* memory mapping.
*/
} else if ((diff = off - OFF_NORMAL) >= 0 && diff < NORMAL_SIZE) {
if ((len + off) > (OFF_NORMAL + NORMAL_SIZE))
return (-1);
err = devmap_default_access(dhp, pvtp, off, len, type, rw);
} else
return (-1);

return (err);
}