pci_device_read

Get the ID of the nth capability that a device supports

Synopsis:

#include <pci/pci.h>

pci_err_t pci_device_read_capid( pci_bdf_t bdf,
                                 pci_capid_t *capid,
                                 uint_t idx );

Arguments:

bdf: The Bus/Device/Function associated with a device.
capid: A pointer to a location where the function can store the capability ID.
idx: The index of the capability.

Library:

libpci

Use the -l pci option to qcc to link against this library.

Description:

You can use pci_device_read_capid() and pci_device_find_capid() to identify which capabilities the device identified by bdf supports. The pci_device_read_capid() function obtains the capability ID for the nth capability (specified by idx and starting at 0) that the device identified by bdf supports.

Note: This function doesn't cause a capability module to be loaded.

The purpose of this function is to obtain the capability index for a capability that the software wishes to enable for the device. You'll use this index when you call pci_device_read_cap().

You can use pci_device_read_capid() to easily loop with an incrementing idx value and obtain the pci_capid_t at that index. If *capid is for a desired capability, you can then read the capability with pci_device_read_cap() and the current idx value.

Returns:

PCI_ERR_OK: Success; *capid holds the ID of the capability at the specified idx.
PCI_ERR_ENOENT: The capability at idx doesn't exist. This usually means the end of the devices capability list, but if idx is 0, it means that the device has no capabilities.
PCI_ERR_EIO: A malformed capability “next” pointer was encountered.

If any error occurs, you should consider the contents of *capid to be invalid data.

Classification:

QNX Neutrino

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	No
Thread	Yes