illumos: manual page: ddi_prop

DDI_PROP_EXISTS(9F) Kernel Functions for Drivers DDI_PROP_EXISTS(9F)

NAME

ddi_prop_exists - check for the existence of a property

SYNOPSIS

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

int ddi_prop_exists(dev_t match_dev, dev_info_t *dip, uint_t flags,
char *name);

INTERFACE LEVEL

illumos DDI specific (illumos DDI).

PARAMETERS

match_dev
Device number associated with property or DDI_DEV_T_ANY.

dip
Pointer to the device info node of device whose property
list should be searched.

flags
Possible flag values are some combination of:

DDI_PROP_DONTPASS
Do not pass request to parent device
information node if the property is
not found.

DDI_PROP_NOTPROM
Do not look at PROM properties
(ignored on platforms that do not
support PROM properties).

name
String containing the name of the property.

DESCRIPTION

ddi_prop_exists() checks for the existence of a property regardless of
the property value data type.

Properties are searched for based on the dip, name, and match_dev. The
property search order is as follows:

1. Search software properties created by the driver.

2. Search the software properties created by the system (or nexus
nodes in the device info tree).

3. Search the driver global properties list.

4. If DDI_PROP_NOTPROM is not set, search the PROM properties (if
they exist).

5. If DDI_PROP_DONTPASS is not set, pass this request to the
parent device information node.

6. Return 0 if not found and 1 if found.

Usually, the match_dev argument should be set to the actual device number
that this property is associated with. However, if the match_dev
argument is DDI_DEV_T_ANY, then ddi_prop_exists() will match the request
regardless of the match_dev the property was created with. That is the
first property whose name matches name will be returned. If a property
was created with match_dev set to DDI_DEV_T_NONE then the only way to
look up this property is with a match_dev set to DDI_DEV_T_ANY. PROM
properties are always created with match_dev set to DDI_DEV_T_NONE.

name must always be set to the name of the property being looked up.

RETURN VALUES

ddi_prop_exists() returns 1 if the property exists and 0 otherwise.

CONTEXT

These functions can be called from user or kernel context.

EXAMPLES

Example 1: : Using ddi_prop_exists()

The following example demonstrates the use of ddi_prop_exists().

/*
* Enable "whizzy" mode if the "whizzy-mode" property exists
*/
if (ddi_prop_exists(xx_dev, xx_dip, DDI_PROP_NOTPROM,
"whizzy-mode") == 1) {
xx_enable_whizzy_mode(xx_dip);
} else {
xx_disable_whizzy_mode(xx_dip);
}