illumos: manual page: pci_report

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

illumos DDI specific (illumos 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 indicated 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 applicable 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\n",
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 negotiates 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\n",
ddi_driver_name(dip), ddi_get_instance(dip));

ATTRIBUTES