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Kernel Functions for Drivers

ddi_prop_exists(9F)

INTERFACE LEVEL
PARAMETERS
DESCRIPTION
RETURN VALUES
CONTEXT
EXAMPLES
SEE ALSO

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);

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:

Search software properties created by the driver.
Search the software properties created by the system (or nexus nodes in the device info tree).
Search the driver global properties list.
If DDI_PROP_NOTPROM is not set, search the PROM properties (if they exist).
If DDI_PROP_DONTPASS is not set, pass this request to the parent device information node.
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); }