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.
SEE ALSO¶
pciconf(8)
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.