SVR5

drv_open(D3)

drv_open -- obtain a channel handle for subsequent access by layered driver

Synopsis

   #include <sys/types.h>
   #include <sys/ddi.h>
   
   int drv_open(rm_key_t key, channel_t channelp,
                 int oflags, struct cred_t *crp,
                 chan_handle_t* *chan_handle_p);

Description

drv_open( ) obtains a channel handle that a layered driver can use to access this driver's entry points. The layered driver can use this handle as an argument to the do_biostart(D3), do_devinfo(D3), do_ioctl(D3), and drv_close(D3) functions.

Arguments

key: Resource manager key for the driver
channelp: Channel number used to select subcomponents and/or operating modes of this device instance. This value is passed to the open(D2) entry point routine.
oflags: Flags to pass to the open( ) entry point routine. See the open(D2) manual page for a list of valid values.
crp: Pointer to the user credential structure. This value is passed to the open(D2) entry point routine.
chan_handle_p: Will be updated to the actual channel number that will be used by other functions if the underlying device uses device indirection.

Return values

The drv_open( ) function returns 0 for success, or the appropriate non-zero error number from errnos(D5).

Usage

Each drv_open( ) call must be matched by a corresponding drv_close(D3) call, although the target driver only receives one close(D2) call per channel, called when the last outstanding drv_open( ) call has been ended with a call to drv_close( ).

Context and synchronization

User or blockable context.

Hardware applicability

All

Version applicability

ddi: 8, 8mp

References

do_biostart(D3), do_devinfo(D3), do_ioctl(D3), drv_attach(D3), drv_close(D3)

``Layered device drivers'' in HDK Technical Reference