man pages section 9: DDI and DKI Driver Entry Points

prop_op(9E)

Name

prop_op– report driver property information

Synopsis

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



int prefixprop_op(dev_t dev, dev_info_t *dip, 
     ddi_prop_op_t prop_op, int flags, char *name, caddr_t valuep, 
     int *lengthp);

Interface Level

Solaris DDI specific (Solaris DDI). This entry point is required, but it can be ddi_prop_op(9F).

ARGUMENTS

dev

Device number associated with this device.

dip

A pointer to the device information structure for this device.

prop_op

Property operator. Valid operators are:

PROP_LEN: Get property length only. (valuep unaffected).
PROP_LEN_AND_VAL_BUF: Get length and value into caller's buffer. (valuep used as input).
PROP_LEN_AND_VAL_ALLOC: Get length and value into allocated buffer. (valuep returned as pointer to pointer to allocated buffer).

flags

The only possible flag value is:

DDI_PROP_DONTPASS: Do not pass request to parent if property not found.

name

Pointer to name of property to be interrogated.

valuep

If prop_op is PROP_LEN_AND_VAL_BUF, this should be a pointer to the user's buffer. If prop_op is PROP_LEN_AND_VAL_ALLOC, this should be the address of a pointer.

lengthp

On exit, *lengthp will contain the property length. If prop_op is PROP_LEN_AND_VAL_BUF then lengthp should point to an int that contains the length of caller's buffer, before calling prop_op().

Description

prop_op() is an entry point which reports the values of certain properties of the driver or device to the system. Each driver must have a prefix prop_op entry point, but most drivers that do not need to create or manage their own properties can use ddi_prop_op() for this entry point. Then the driver can use ddi_prop_update(9F) to create properties for its device.

Return Values

prop_op() should return:

DDI_PROP_SUCCESS: Property found and returned.
DDI_PROP_NOT_FOUND: Property not found.
DDI_PROP_UNDEFINED: Prop explicitly undefined.
DDI_PROP_NO_MEMORY: Property found, but unable to allocate memory. lengthp has the correct property length.
DDI_PROP_BUF_TOO_SMALL: Property found, but the supplied buffer is too small. lengthp has the correct property length.

Examples

Example 1 Using `prop_op()` to Report Property Information

In the following example, prop_op() intercepts requests for the temperature property. The driver tracks changes to temperature using a variable in the state structure in order to avoid frequent calls to ddi_prop_update(9F). The temperature property is only updated when a request is made for this property. It then uses the system routine ddi_prop_op(9F) to process the property request. If the property request is not specific to a device, the driver does not intercept the request. This is indicated when the value of the dev parameter is equal to DDI_DEV_T_ANY.

int temperature;	/* current device temperature */
 .
 .
 .
static int
xxprop_op(dev_t dev, dev_info_t *dip, ddi_prop_op_t prop_op,
     int flags, char *name, caddr_t valuep, int *lengthp)
{
			int  instance;
			struct xxstate *xsp;
     if (dev == DDI_DEV_T_ANY)
				goto skip;
     instance = getminor(dev);
     xsp = ddi_get_soft_state(statep, instance);
     if (xsp == NULL)
				return (DDI_PROP_NOT_FOUND);
     if (strcmp(name, "temperature") == 0) {
				ddi_prop_update_int(dev, dip,\
           "temperature", temperature);
     }
		       /*	other cases...	*/
     skip:
     return (ddi_prop_op(dev, dip, prop_op, flags,\ 
             name, valuep, lengthp));
}