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Name

Synopsis

#include <sys/sunddi.h>

int ddi_mapdev_intercept(ddi_mapdev_handle_t handle, off_t offset, off_t len);

int ddi_mapdev_nointercept(ddi_mapdev_handle_t handle, off_t offset, off_t len);

Interface Level

Arguments

handle

An opaque pointer to a device mapping handle.

offset

An offset in bytes within device memory.

len

Length in bytes.

Description

ddi_mapdev_intercept() and ddi_mapdev_nointercept() control whether or not user accesses to device mappings created by ddi_mapdev(9F) in the specified range will generate calls to the mapdev_access(9E) entry point. ddi_mapdev_intercept() tells the system to intercept the user access and notify the driver to invalidate the mapping translations. ddi_mapdev_nointercept() tells the system to not intercept the user access and allow it to proceed by validating the mapping translations.

For both routines, the range to be affected is defined by the offset and len arguments. Requests affect the entire page containing the offset and all pages up to and including the page containing the last byte as indicated by offset + len.

Supplying a value of 0 for the len argument affects all addresses from the offset to the end of the mapping. Supplying a value of 0 for the offset argument and a value of 0 for len argument affect all addresses in the mapping.

To manage a device context, a device driver would call ddi_mapdev_intercept() on the context about to be switched out, switch contexts, and then call ddi_mapdev_nointercept() on the context switched in.

Return Values

ddi_mapdev_intercept() and ddi_mapdev_nointercept() return zero on success and non-zero on failure.

Example

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)
{
    int err;

    /* enable access callbacks for the current mapping */
    if (cur_hdl != NULL) {
        if ((err = ddi_mapdev_intercept(cur_hdl, offset, 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, offset, 0));
}

Context

These routines can be called from user or kernel context only.

See Also

Table of Contents

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• Arguments
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