illumos: manual page: mc

MC_IOCTL(9E) Driver Entry Points MC_IOCTL(9E)

NAME

mc_ioctl - device specific I/O control operation

SYNOPSIS

#include <sys/types.h>
#include <sys/stream.h>
#include <sys/stropts.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>

void
prefix_m_ioctl(void *driver, queue_t *wq, mblk_t *mp);

INTERFACE LEVEL

illumos DDI Specific

PARAMETERS

driver A pointer to the driver's private data that was passed in via the
m_pdata member of the mac_register(9S) structure to the
mac_register(9F) function.

wq A pointer to a STREAMS write-side queue that the ioctl request was
received upon.

mp A pointer to a message block structure that contains the I/O
control request.

DESCRIPTION

The mc_ioctl() entry point is an optional GLDv3 entry point. It provides a
means for device-specific I/O control operations to be initiated. In
general, this entry point is not recommended for most devices and is
unimplemented.

The I/O control interface is not like a traditional character or block
device's ioctl(9E) entry point, rather it is a STREAMS-based I/O control
operation. The data pointer of the mp argument is a iocblk(9S) structure.
After handling the message, the driver will need to reply to the message,
which is usually done by using the miocack(9F) and miocnak(9F) functions to
prepare mp.

The device driver can access its soft state by casting the value pointed to
in driver. The driver should be careful and ensure that it performs any
necessary locking to access members of that structure while processing the
I/O control operation.

RETURN VALUES

Return information is not conveyed by the return value of this function,
rather it is encoded in the iocblk(9S) structure in the mp argument.

EXAMPLES

The following example shows how a device driver might structure its
mc_ioctl() entry point.

#include <sys/types.h>
#include <sys/stream.h>
#include <sys/stropts.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>

/*
* Note, this example merely shows the structure of this function. It does not
* actively handle any device-specific ioctls and instead returns failure for
* every one. This is the most common case. Note, miocnak(9F) takes care of
* calling putnext(9F) for us.
*/
static void
example_m_ioctl(void *arg, queue_t *wq, mblk_t *mp)
{
miocnak(wq, mp, 0, EINVAL);
}