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

NAME

       pci_report_pmcap - Report Power Management capability of a PCI device

SYNOPSIS

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

       int pci_report_pmcap(dev_info_t *dip,  int cap, void *arg);

INTERFACE LEVEL

       Solaris DDI specific (Solaris DDI)

PARAMETERS

       dip    Pointer to the device's dev_info structure

       cap    Power management capability

       arg    Argument for the capability

DESCRIPTION

       Some  PCI  devices  provide  power  management  capabilities  in  addition to those provided by the PCI Power Management Specification. The
       pci_report_pmcap() function reports those Power Management capabilities of the PCI device to  the  framework.  Framework  supports  dynamic
       changing  of  the  capability by allowing pci_report_pmcap() to be called multiple times. Following are the supported capabilities as indi-
       cated by the cap:

       PCI_PM_IDLESPEED -- The PCI_PM_IDLESPEED value indicates the lowest PCI clock speed that a device can tolerate when idle, and is   applica-
       ble  only  to  33  MHz PCI bus. arg represents the lowest possible idle speed in KHz (1 KHz is 1000 Hz). The integer value representing the
       speed should be cast to (void *)before passing as arg to pci_report_pmcap().

       The special values of arg are:

       PCI_PM_IDLESPEED_ANY	The device can tolerate any idle clock speed.

       PCI_PM_IDLESPEED_NONE	The device cannot tolerate slowing down of PCI clock even when idle.

       If the driver doesn't make this call, PCI_PM_IDLESPEED_NONE is assumed. In this case, one offending device can keep  the  entire  bus  from
       being power managed.

RETURN VALUES

       The pci_report_pmcap() function returns:

       DDI_SUCCESS    Successful reporting of the capability

       DDI_FAILURE    Failure to report capability because of invalid argument(s)

CONTEXT

       The pci_report_pmcap() function can be called from user, kernel and interrupt context.

EXAMPLES

       1.  A  device  driver  knows  that the device it controls works with any clock between DC and 33 MHz as specified in Section 4.2.3.1: Clock
       Specification  of the PCI Bus Specification Revision 2.1. The device driver makes the following call from its attach(9E):

	 if (pci_report_pmcap(dip, PCI_PM_IDLESPEED, PCI_PM_IDLESPEED_ANY) !=
		     DDI_SUCCESS)
			 cmn_err(CE_WARN, "%s%d: pci_report_pmcap failed
",
			     ddi_driver_name(dip), ddi_get_instance(dip));

       2. A device driver controls a 10/100 Mb Ethernet device which runs the device state machine on the chip from the PCI clock. For the  device
       state  machine to receive packets at 100 Mb, the PCI clock cannot drop below 4 MHz. The driver makes the following call whenever it negoti-
       ates a 100 Mb Ethernet connection:

	 if (pci_report_pmcap(dip,  PCI_PM_IDLESPEED, (void *)4000) !=
			DDI_SUCCESS)
			 cmn_err(CE_WARN, "%s%d: pci_report_pmcap failed
",
			     ddi_driver_name(dip), ddi_get_instance(dip));

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Committed 		   |
       +-----------------------------+-----------------------------+

SEE ALSO

       Writing Device Drivers

       PCI Bus Power Management Interface Specification Version 1.1

       PCI Bus Specification Revision 2.1

SunOS 5.11							  13 August 1999					      pci_report_pmcap(9F)