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


Solaris DDI specific (Solaris 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);
}


SEE ALSO


devmap_access(9E), devmap_do_ctxmgt(9F), devmap_callback_ctl(9S)


Writing Device Drivers


January 14, 1997 DEVMAP_DEFAULT_ACCESS(9F)