PROP_OP(9E) Driver Entry Points PROP_OP(9E)

prop_op - report driver property information

#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);

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

Device number associated with this device.


A pointer to the device information structure for this device.


Property operator. Valid operators are:


Get property length only. (valuep unaffected).


Get length and value into caller's buffer. (valuep used as input).


Get length and value into allocated buffer. (valuep returned as pointer to pointer to allocated buffer).


The only possible flag value is:


Do not pass request to parent if property not found.


Pointer to name of property to be interrogated.


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.


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().

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.

prop_op() should return:


Property found and returned.


Property not found.


Prop explicitly undefined.


Property found, but unable to allocate memory. lengthp has the correct property length.


Property found, but the supplied buffer is too small. lengthp has the correct property length.

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...	*/
     return (ddi_prop_op(dev, dip, prop_op, flags,\
             name, valuep, lengthp));

Intro(9E), ddi_prop_op(9F), ddi_prop_update(9F)

Writing Device Drivers

July 8, 1996 OmniOS