<h2>device_open</h2>

<strong>Function</strong> - Establish a connection to a device.

<h3>SYNOPSIS</h3>

<strong>#include&ltdevice/device.h&gt</strong>

<strong>kern_return_t device_open</strong>

<strong>(mach_port_t</strong> <var>master_port</var>,

<strong>mach_port_t</strong> <var>ledger</var>,

<strong>dev_mode_t</strong> <var>mode</var>,

<strong>security_token_t</strong> <var>security_id</var>,

<strong>dev_name_t</strong> <var>name</var>,

<strong>mach_port_t</strong> <var>device</var><strong>);</strong>

<strong>#include&ltdevice/device_request.h&gt</strong>

<strong>kern_return_t device_open_request</strong>

<strong>(mach_port_t</strong> <var>master_port</var>,

<strong>mach_port_t</strong> <var>reply_port</var>,

<strong>mach_port_t</strong> <var>ledger</var>,

<strong>dev_mode_t</strong> <var>mode</var>,

<strong>security_token_t</strong> <var>security_id</var>,

<strong>dev_name_t</strong> <var>name</var><strong>);</strong>

<strong>kern_return_t ds_device_open_reply</strong>

<strong>(mach_port_t</strong> <var>reply_port</var>,

<strong>kern_return_t</strong> <var>return_code</var>,

<strong>mach_port_t</strong> <var>device</var><strong>);</strong>

<h3>PARAMETERS</h3>

<dt> <var>master_port</var>

[in device-master send right]

The master device port. This port is

provided to the bootstrap task.

<dt> <var>reply_port</var>

[in reply receive (to be converted to send-once) right]

The port to

which a reply is to be sent when the device is open.

<dt> <var>ledger</var>

[pointer to a ledger send right]

Resource ledger from which the device will draw its resources.

<dt> <var>mode</var>

[in scalar]

Opening mode. This is the bit-wise <strong>OR</strong> of the following

values:

<dt> <strong>D_READ</strong>

Read access

<dt> <strong>D_WRITE</strong>

Write access

<dt> <strong>D_NODELAY</strong>

Do not delay on open

<dt> <var>security_id</var>

[in scalar]

The security ID that tasks attempting to use this device port

must have. A zero value indicates all identities.

<dt> <var>name</var>

[pointer to in array of <var>char</var>]

Name of the device to open.

<dt> <var>return_code</var>

[in scalar]

Status of the open.

<dt> <var>device</var>

[out device send right, in for asynchronous form]

The returned device

port.

<h3>DESCRIPTION</h3>

The <strong>device_open</strong> function opens a device object. The

open operation of the

device is invoked, if the device is not already open. The open

count for the device

is incremented. Each open for a device returns a port, the allowed

operations upon which being governed by <var>mode</var>. The port is not

distinct.

<h3>RETURN VALUES</h3>

Only generic errors apply.

<h3>RELATED INFORMATION</h3>

Functions:

<a href="device_close.html"><strong>device_close</strong></a>,

<a href="device_reply_server.html"><strong>device_reply_server</strong></a>.