man pages section 9: DDI and DKI Driver Entry Points

devmap_unmap(9E)

Name

devmap_unmap– device mapping unmap entry point

Synopsis

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



void prefixdevmap_unmap(devmap_cookie_t dhp, void *pvtp, 
     offset_t off, size_tlen, devmap_cookie_t new_dhp1, 
     void **new_pvtp1, devmap_cookie_tnew_dhp2, void **new_pvtp2);

Interface Level

Solaris DDI specific (Solaris DDI).

ARGUMENTS

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 unmapping begins.
len: Length (in bytes) of the memory being unmapped.
new_dhp1: The opaque mapping handle that the system uses to describe the new region that ends at (off - 1) . new_dhp1 may be NULL.
new_pvtp1: A pointer to be filled in by the driver with the driver private mapping data for the new region that ends at (off – 1); ignored if new_dhp1 is NULL.
new_dhp2: The opaque mapping handle that the system uses to describe the new region that begins at (off + len); new_dhp2 may be NULL.
new_pvtp2: A pointer to be filled in by the driver with the driver private mapping data for the new region that begins at (off + len); ignored if new_dhp2 is NULL.

Description

devmap_unmap() is called when the system removes the mapping in the range [ off, off + len ], such as in the munmap(2) or exit(2) system calls. Device drivers use devmap_unmap() to free up the resources allocated in devmap_map(9E).

dhp is the mapping handle that uniquely identifies the mapping. The driver stores the mapping attributes in the driver's private data, pvtp, when the mapping is created. See devmap_map(9E) for details.

off and len define the range to be affected by devmap_unmap(). This range is within the boundary of the mapping described by dhp.

If the range [ off, off + len ] covers the entire mapping, the system passes NULL to new_dhp1, new_pvtp1, new_dhp2, and new_pvtp2. The system expects device drivers to free all resources allocated for this mapping.

If off is at the beginning of the mapping and len does not cover the entire mapping, the system sets NULL to new_dhp1 and to new_pvtp1. The system expects the drivers to allocate new driver private data for the region that starts at off + len and to set *new_pvtp2 to point to it. new_dhp2 is the mapping handle of the newly mapped object.

If off is not at the beginning of the mapping, but off + len is at the end of the mapping the system passes NULL to new_dhp2 and new_pvtp2. The system then expects the drivers to allocate new driver private data for the region that begins at the beginning of the mapping (for example, stored in pvtp) and to set *new_pvtp1 to point to it. new_dhp1 is the mapping handle of the newly mapped object.

The drivers should free up the driver private data, pvtp, previously allocated in devmap_map(9E) before returning to the system.

Examples

Example 1 `devmap_unmap()` implementation

static void
xxdevmap_unmap(devmap_cookie_t dhp, void *pvtp, offset_t off,
    size_t len, devmap_cookie_t new_dhp1, void **new_pvtp1,
    devmap_cookie_t new_dhp2, void **new_pvtp2)
{
    struct xxpvtdata *ptmp;
    struct xxpvtdata *p = (struct xxpvtdata *)pvtp;
    struct xx_softc  *softc = p->softc;
    mutex_enter(&softc->mutex);
    /*
     * If new_dhp1 is not NULL, create a new driver private data
     * for the region from the beginning of old mapping to off.
     */
    if (new_dhp1 != NULL) {
        ptmp = kmem_zalloc(sizeof (struct xxpvtdata), KM_SLEEP);
        ptmp->dhp = new_dhp1;
        ptmp->off = pvtp->off;
        ptmp->len = off - pvtp->off;
        *new_pvtp1 = ptmp;
    }

    /*
     * If new_dhp2 is not NULL, create a new driver private data
     * for the region from off+len to the end of the old mapping.
     */
    if (new_dhp2 != NULL) {
        ptmp = kmem_zalloc(sizeof (struct xxpvtdata), KM_SLEEP);
        ptmp->off = off + len;
        ptmp->len = pvpt->len - (off + len - pvtp->off);
        ptmp->dhp = new_dhp2;
        *new_pvtp2 = ptmp;
    }

    /* Destroy the driver private data - Device dependent */
    ...
    kmem_free(pvtp, sizeof (struct xxpvtdata));
    mutex_exit(&softc->mutex);
}