Ubuntu Manpage: pci — generic PCI driver

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NAME

       pci — generic PCI driver

SYNOPSIS

       device pci

DESCRIPTION

       The  pci  driver  provides a way for userland programs to read and write PCI configuration registers.  It
       also provides a way for userland programs to get a list of all PCI devices, or all PCI devices that match
       various patterns.

       Since the pci driver provides a write interface for PCI configuration  registers,  system  administrators
       should  exercise  caution  when  granting  access to the pci device.  If used improperly, this driver can
       allow userland applications to crash a machine or cause data loss.

       The pci driver implements the PCI bus in the kernel.  It enumerates any devices on the PCI bus and  gives
       PCI  client  drivers  the chance to attach to them.  It assigns resources to children, when the BIOS does
       not.  It takes care of routing interrupts when necessary.  It reprobes the unattached PCI  children  when
       PCI client drivers are dynamically loaded at runtime.

KERNEL CONFIGURATION

       The  pci device is included in the kernel as described in the SYNOPSIS section.  The pci driver cannot be
       built as a kld(4).

IOCTLS

The following ioctl(2) calls are supported by the pci driver. They are defined in the header file
<sys/pciio.h>.

PCIOCGETCONF This ioctl(2) takes a pci_conf_io structure. It allows the user to retrieve information
on all PCI devices in the system, or on PCI devices matching patterns supplied by the
user. The call may set errno to any value specified in either copyin(9) or copyout(9).
The pci_conf_io structure consists of a number of fields:

pat_buf_len The length, in bytes, of the buffer filled with user-supplied patterns.

num_patterns The number of user-supplied patterns.

patterns Pointer to a buffer filled with user-supplied patterns. patterns is a
pointer to num_patterns pci_match_conf structures. The pci_match_conf
structure consists of the following elements:

pc_sel PCI domain, bus, slot and function.

pd_name PCI device driver name.

pd_unit PCI device driver unit number.

pc_vendor PCI vendor ID.

pc_device PCI device ID.

pc_class PCI device class.

flags The flags describe which of the fields the kernel should match
against. A device must match all specified fields in order to
be returned. The match flags are enumerated in the
pci_getconf_flags structure. Hopefully the flag values are
obvious enough that they do not need to described in detail.

match_buf_len Length of the matches buffer allocated by the user to hold the results of
the PCIOCGETCONF query.

num_matches Number of matches returned by the kernel.

matches Buffer containing matching devices returned by the kernel. The items in
this buffer are of type pci_conf, which consists of the following items:

pc_sel PCI domain, bus, slot and function.

pc_hdr PCI header type.

pc_subvendor PCI subvendor ID.

pc_subdevice PCI subdevice ID.

pc_vendor PCI vendor ID.

pc_device PCI device ID.

pc_class PCI device class.

pc_subclass PCI device subclass.

pc_progif PCI device programming interface.

pc_revid PCI revision ID.

pd_name Driver name.

pd_unit Driver unit number.

offset The offset is passed in by the user to tell the kernel where it should
start traversing the device list. The value passed out by the kernel
points to the record immediately after the last one returned. The user
may pass the value returned by the kernel in subsequent calls to the
PCIOCGETCONF ioctl. If the user does not intend to use the offset, it
must be set to zero.

generation PCI configuration generation. This value only needs to be set if the
offset is set. The kernel will compare the current generation number of
its internal device list to the generation passed in by the user to
determine whether its device list has changed since the user last called
the PCIOCGETCONF ioctl. If the device list has changed, a status of
PCI_GETCONF_LIST_CHANGED will be passed back.

status The status tells the user the disposition of his request for a device
list. The possible status values are:

PCI_GETCONF_LAST_DEVICE
This means that there are no more devices in the PCI device list after
the ones returned in the matches buffer.

PCI_GETCONF_LIST_CHANGED
This status tells the user that the PCI device list has changed since his
last call to the PCIOCGETCONF ioctl and he must reset the offset and
generation to zero to start over at the beginning of the list.

PCI_GETCONF_MORE_DEVS
This tells the user that his buffer was not large enough to hold all of
the remaining devices in the device list that possibly match his
criteria. It is possible for this status to be returned, even when none
of the remaining devices in the list would match the user's criteria.

PCI_GETCONF_ERROR
This indicates a general error while servicing the user's request. If
the pat_buf_len is not equal to num_patterns times sizeof(struct
pci_match_conf), errno will be set to EINVAL.

PCIOCREAD This ioctl(2) reads the PCI configuration registers specified by the passed-in pci_io
structure. The pci_io structure consists of the following fields:

pi_sel A pcisel structure which specifies the domain, bus, slot and function the user
would like to query. If the specific bus is not found, errno will be set to
ENODEV and -1 returned from the ioctl.

pi_reg The PCI configuration register the user would like to access.

pi_width The width, in bytes, of the data the user would like to read. This value may
be either 1, 2, or 4. 3-byte reads and reads larger than 4 bytes are not
supported. If an invalid width is passed, errno will be set to EINVAL.

pi_data The data returned by the kernel.

PCIOCWRITE This ioctl(2) allows users to write to the PCI specified in the passed-in pci_io
structure. The pci_io structure is described above. The limitations on data width
described for reading registers, above, also apply to writing PCI configuration
registers.

FILES

       /dev/pci  Character device for the pci driver.

HISTORY

       The  pci  driver  (not  the  kernel's PCI support code) first appeared in FreeBSD 2.2, and was written by
       Stefan Esser and Garrett Wollman.  Support for device listing and matching was re-implemented by  Kenneth
       Merry, and first appeared in FreeBSD 3.0.

AUTHORS

       Kenneth Merry <ken@FreeBSD.org>

BUGS

       It  is  not  possible  for  users  to specify an accurate offset into the device list without calling the
       PCIOCGETCONF at least once, since they have no way of knowing the current  generation  number  otherwise.
       This  probably is not a serious problem, though, since users can easily narrow their search by specifying
       a pattern or patterns for the kernel to match against.

Debian                                           January 3, 2008                                          PCI(4)