PCI(9) BSD Kernel Developer's Manual PCI(9)NAME
PCI, pci_activate, pci_bus_devorder, pci_chipset_tag_create,
pci_chipset_tag_destroy, pci_conf_read, pci_conf_write, pci_conf_print,
pci_conf_capture, pci_conf_restore, pci_find_device, pci_get_capability,
pci_mapreg_type, pci_mapreg_map, pci_mapreg_info, pci_intr_map,
pci_intr_string, pci_intr_evcnt, pci_intr_establish,
pci_intr_disestablish, pci_get_powerstate, pci_set_powerstate,
pci_vpd_read, pci_vpd_write, pci_make_tag, pci_decompose_tag,
pci_findvendor, pci_devinfo, PCI_VENDOR, PCI_PRODUCT, PCI_REVISION —
Peripheral Component Interconnect
SYNOPSIS
#include <sys/bus.h>
#include <dev/pci/pcivar.h>
#include <dev/pci/pcireg.h>
#include <dev/pci/pcidevs.h>
int
pci_bus_devorder(pci_chipset_tag_t pc, int bus, uint8_t *devs,
int maxdevs);
int
pci_activate(pci_chipset_tag_t pc, pcitag_t tag, device_t dev,
int (*wakeup)(pci_chipset_tag_t pc, pcitag_t tag,
device_t dev, pcireg_t reg));
int
pci_chipset_tag_create(pci_chipset_tag_t opc, uint64_t present,
const struct pci_overrides *ov, void *ctx, pci_chipset_tag_t *pcp);
void
pci_chipset_tag_destroy(pci_chipset_tag_t pc);
pcireg_t
pci_conf_read(pci_chipset_tag_t pc, pcitag_t tag, int reg);
void
pci_conf_write(pci_chipset_tag_t pc, pcitag_t tag, int reg,
pcireg_t val);
void
pci_conf_print(pci_chipset_tag_t pc, pcitag_t tag,
void (*func)(pci_chipset_tag_t, pcitag_t, const pcireg_t *));
void
pci_conf_capture(pci_chipset_tag_t pc, pcitag_t tag,
struct pci_conf_state *);
void
pci_conf_restore(pci_chipset_tag_t pc, pcitag_t tag,
struct pci_conf_state *);
int
pci_find_device(struct pci_attach_args *pa,
int (*func)(const struct pci_attach_args *));
int
pci_get_capability(pci_chipset_tag_t pc, pcitag_t tag, int capid,
int *offsetp, pcireg_t *valuep);
pcireg_t
pci_mapreg_type(pci_chipset_tag_t pc, pcitag_t tag, int reg);
int
pci_mapreg_map(const struct pci_attach_args *pa, int reg, pcireg_t type,
int busflags, bus_space_tag_t *tagp, bus_space_handle_t *handlep,
bus_addr_t *basep, bus_size_t *sizep);
int
pci_mapreg_info(pci_chipset_tag_t pc, pcitag_t tag, int reg,
pcireg_t type, bus_addr_t *basep, bus_size_t *sizep, int *flagsp);
int
pci_find_rom(const struct pci_attach_args *pa, bus_space_tag_t bst,
bus_space_handle_t bsh, int code, bus_space_handle_t *handlep,
bus_space_size_t *sizep);
int
pci_intr_map(const struct pci_attach_args *pa, pci_intr_handle_t *ih);
const char *
pci_intr_string(pci_chipset_tag_t pc, pci_intr_handle_t ih);
const struct evcnt *
pci_intr_evcnt(pci_chipset_tag_t pc, pci_intr_handle_t ih);
void *
pci_intr_establish(pci_chipset_tag_t pc, pci_intr_handle_t ih, int level,
int (*handler)(void *), void *arg);
void
pci_intr_disestablish(pci_chipset_tag_t pc, void *ih);
int
pci_set_powerstate(pci_chipset_tag_t pc, pcitag_t tag,
pcireg_t newstate);
int
pci_get_powerstate(pci_chipset_tag_t pc, pcitag_t tag, pcireg_t *state);
int
pci_vpd_read(pci_chipset_tag_t pc, pcitag_t tag, int offset, int count,
pcireg_t *data);
int
pci_vpd_write(pci_chipset_tag_t pc, pcitag_t tag, int offset, int count,
pcireg_t *data);
pcitag_t
pci_make_tag(pci_chipset_tag_t pc, int bus, int device, int function);
void
pci_decompose_tag(pci_chipset_tag_t pc, pcitag_t tag, int *busp,
int *devicep, int *functionp);
char *
pci_findvendor(pcireg_t id);
void
pci_devinfo(pcireg_t id, pcireg_t class, int show, char *cp, size_t len);
void
pci_aprint_devinfo(struct pci_attach_args *pa, const char *naive);
int
PCI_VENDOR(pcireg_t id);
int
PCI_PRODUCT(pcireg_t id);
int
PCI_REVISION(pcireg_t id);
DESCRIPTION
The machine-independent PCI subsystem provides support for PCI devices.
The PCI bus was initially developed by Intel in the early 1990's to
replace the ISA bus for interfacing with their Pentium processor. The
PCI specification is widely regarded as well designed, and the PCI bus
has found widespread acceptance in machines ranging from Apple's PowerPC-
based systems to Sun's UltraSPARC-based machines.
The PCI bus is a multiplexed bus, allowing addresses and data on the same
pins for a reduced number of pins. Data transfers can be 8-bit, 16-bit
or 32-bit. A 64-bit extended PCI bus is also defined. Multi-byte trans‐
fers are little-endian. The PCI bus operates up to 33MHz and any device
on the bus can be the bus master.
AGP is a version of PCI optimised for high-throughput data rates, partic‐
ularly for accelerated frame buffers.
The PCI bus is a "plug and play" bus, in the sense that devices can be
configured dynamically by software. The PCI interface chip on a PCI
device bus presents a small window of registers into the PCI configura‐
tion space. These registers contain information about the device such as
the vendor and a product ID. The configuration registers can also be
written to by software to alter how the device interfaces to the PCI bus.
An important register in the configuration space is the Base Address Reg‐
ister (BAR). The BAR is written to by software to map the device regis‐
ters into a window of processor address space. Once this mapping is
done, the device registers can be accessed relative to the base address.
DATA TYPES
Drivers for devices attached to the PCI will make use of the following
data types:
pcireg_t
Configuration space register.
pci_chipset_tag_t
Chipset tag for the PCI bus.
pcitag_t
Configuration tag describing the location and function of the
PCI device. It contains the tuple ⟨bus, device, function⟩.
pci_intr_handle_t
The opaque handle describing an established interrupt handler.
struct pci_attach_args
Devices have their identity recorded in this structure. It con‐
tains the following members:
bus_space_tag_t pa_iot; /* pci i/o space tag */
bus_space_tag_t pa_memt; /* pci mem space tag */
bus_dma_tag_t pa_dmat; /* DMA tag */
pci_chipset_tag_t pa_pc;
int pa_flags; /* flags */
pcitag_t pa_tag;
pcireg_t pa_id;
pcireg_t pa_class;
struct pci_conf_state
Stores the PCI configuration state of a device. It contains the
following member:
pcireg_t reg[16]; /* pci conf register */
struct pci_overrides
Stores pointers to functions that override the architecture's
default pci(9) and pci_intr(9) implementation. It contains the
following members:
pcireg_t (*ov_conf_read)(void *,
pci_chipset_tag_t, pcitag_t, int);
void (*ov_conf_write)(void *,
pci_chipset_tag_t, pcitag_t, int, pcireg_t);
int (*ov_intr_map)(void *,
const struct pci_attach_args *, pci_intr_handle_t *);
const char *(*ov_intr_string)(void *,
pci_chipset_tag_t, pci_intr_handle_t);
const struct evcnt *(*ov_intr_evcnt)(void *,
pci_chipset_tag_t, pci_intr_handle_t);
void *(*ov_intr_establish)(void *,
pci_chipset_tag_t, pci_intr_handle_t,
int, int (*)(void *), void *);
void (*ov_intr_disestablish)(void *,
pci_chipset_tag_t, void *);
pcitag_t (*ov_make_tag)(void *,
pci_chipset_tag_t, int, int, int);
void (*ov_decompose_tag)(void *,
pci_chipset_tag_t, pcitag_t, int *, int *, int *);
FUNCTIONS
pci_bus_devorder(pc, bus, devs, maxdevs)
Tell how many devices a PCI bus driver should probe and in what
order. If maxdevs is less than or equal to zero, return 0 and
do not modify devs. Otherwise, return maxdevs or the number of
devices on bus to probe, whichever is less, and copy to devs
each of the PCI device numbers to probe in the order that they
should be probed. pci_bus_devorder() will not copy more than
maxdevs device numbers to devs.
pci_activate(pc, tag, dev, fun)
Attempt to bring the device to state D0. If the device is not
in the D0 state call fun to restore its state. If fun is NULL
then restoring from state D3 is going to fail.
pci_chipset_tag_create(opc, present, ov, ctx, pcp)
Create a copy of the tag opc at *pcp. Except for the behavior
overridden by ov, *pcp inherits the behavior of opc under PCI
calls.
ov contains function pointers corresponding to PCI routines.
Each function pointer has a corresponding bit in present, and if
that bit is 1, the function pointer overrides the corresponding
PCI call for the new tag. Any combination of these bits may be
set in present:
PCI_OVERRIDE_CONF_READ
PCI_OVERRIDE_CONF_WRITE
PCI_OVERRIDE_INTR_MAP
PCI_OVERRIDE_INTR_STRING
PCI_OVERRIDE_INTR_EVCNT
PCI_OVERRIDE_INTR_ESTABLISH
PCI_OVERRIDE_INTR_DISESTABLISH
PCI_OVERRIDE_MAKE_TAG
PCI_OVERRIDE_DECOMPOSE_TAG
pci_chipset_tag_create() does not copy ov. After a new tag is
created by pci_chipset_tag_create(), ov must not be destroyed
until after the tag is destroyed by pci_chipset_tag_destroy().
The first argument of every override-function is a void *, and
ctx is passed in that argument.
Return 0 if the call succeeds. Return EOPNOTSUPP if the archi‐
tecture does not support overrides. Return EINVAL if present is
0, if ov is NULL, or if present indicates that an override is
present, but the corresponding override in ov is NULL.
If the call does not succeed, *pcp is undefined.
pci_chipset_tag_destroy(pc)
Destroy a tag, pc, created by a prior call to
pci_chipset_tag_create(). If pc was not created by
pci_chipset_tag_create(), results are undefined. If pc was
already destroyed, results are undefined.
pci_conf_read(pc, tag, reg)
Read from register reg in PCI configuration space. The argument
tag is the PCI tag for the current device attached to PCI
chipset pc.
pci_conf_write(pc, tag, reg, val)
Write to register reg in PCI configuration space. The argument
tag is the PCI tag for the current device attached to PCI
chipset pc.
pci_conf_print(pc, tag, func)
Print out most of the registers in the PCI configuration for the
device. The argument tag is the PCI tag for the current device
attached to PCI chipset pc. The argument func is a function
called by pci_conf_print() to print the device-dependent regis‐
ters. This function is only useful for driver development and
is usually wrapped in pre-processor declarations.
pci_conf_capture(pc, tag, pcs)
Capture PCI configuration space into structure pcs. The argu‐
ment tag is the PCI tag for the current device attached to the
PCI chipset pc.
pci_conf_restore(pc, tag, pcs)
Restores PCI configuration space from structure pcs. The argu‐
ment tag is the PCI tag for the current device attached to the
PCI chipset pc.
pci_find_device(pa, func)
Find a device using a match function on all probed busses. The
argument func is called by pci_find_device() to match a device.
The argument pa is filled in if the device is matched.
pci_find_device() returns 1 if the device is matched, and zero
otherwise. This function is specifically for use by kernel mod‐
ules and its use otherwise is strongly discouraged.
pci_get_capability(pc, tag, capid, offsetp, valuep)
Parse the device capability list in configuration space looking
for capability capid. If offsetp is not NULL, the register off‐
set in configuration space is returned in offsetp. If valuep is
not NULL, the value of the capability is returned in valuep.
The argument tag is the PCI tag for the current device attached
to PCI chipset pc. This function returns 1 if the capability
was found. If the capability was not found, it returns zero,
and offsetp and valuep remain unchanged.
pci_mapreg_type(pc, tag, reg)
Interrogates the Base Address Register (BAR) in configuration
space specified by reg and returns the default (or current) map‐
ping type. Valid returns values are:
PCI_MAPREG_TYPE_IO
The mapping is to I/O address space.
PCI_MAPREG_TYPE_MEM
The mapping is to memory address space.
PCI_MAPREG_TYPE_MEM | PCI_MAPREG_MEM_TYPE_64BIT
The mapping is to 64-bit memory address space.
PCI_MAPREG_TYPE_ROM
The mapping is to ROM. Note that in the current imple‐
mentation, PCI_MAPREG_TYPE_ROM has the same numeric
value as PCI_MAPREG_TYPE_MEM.
The argument tag is the PCI tag for the current device attached
to PCI chipset pc.
pci_mapreg_map(pa, reg, type, busflags, tagp, handlep, basep, sizep)
Maps the register windows for the device into kernel virtual
address space. This function is generally only called during
the driver attach step and takes a pointer to the struct
pci_attach_args in pa. The physical address of the mapping is
in the Base Address Register (BAR) in configuration space speci‐
fied by reg. Valid values for the type of mapping type are:
PCI_MAPREG_TYPE_IO
The mapping should be to I/O address space.
PCI_MAPREG_TYPE_MEM
The mapping should be to memory address space.
PCI_MAPREG_TYPE_ROM
The mapping is to access ROM. This type of mapping is
only permitted when the value for reg is
PCI_MAPREG_ROM.
The argument busflags are bus-space flags passed to
bus_space_map() to perform the mapping (see bus_space(9)). The
bus-space tag and handle for the mapped register window are
returned in tagp and handlep respectively. The bus-address and
size of the mapping are returned in basep and sizep respec‐
tively. If any of tagp, handlep, basep, or sizep are NULL then
pci_mapreg_map() does not define their return value. This func‐
tion returns zero on success and non-zero on error.
pci_mapreg_info(pc, tag, reg, type, basep, sizep, flagsp)
Performs the same operations as pci_mapreg_map() but doesn't
actually map the register window into kernel virtual address
space. Returns the bus-address, size and bus flags in basep,
sizep and flagsp respectively. These return values can be used
by bus_space_map() to actually map the register window into ker‐
nel virtual address space. This function is useful for setting
up the registers in configuration space and deferring the map‐
ping to a later time, such as in a bus-independent attachment
routine. pci_mapreg_info returns zero on success and non-zero
on failure.
pci_find_rom(pa, bst, bsh, code, handlep, sizep)
Locates a suitable ROM image within a PCI expansion ROM previ‐
ously mapped with pci_mapreg_map() and creates a subregion for
it with bus_space_subregion(). The bst and bsh arguments are
the bus tag and handle obtained with the prior call to
pci_mapreg_map(). Valid values for the image type code are:
PCI_ROM_CODE_TYPE_X86
Find a ROM image containing i386 executable code for
use by PC BIOS.
PCI_ROM_CODE_TYPE_OFW
Find a ROM image containing Forth code for use by Open
Firmware.
PCI_ROM_CODE_TYPE_HPPA
Find a ROM image containing HP PA/RISC executable code.
The created subregion will cover the entire selected ROM image,
including header data. The handle to this subregion is returned
in handlep. The size of the image (and the corresponding subre‐
gion) is returned in sizep. This function can only be used with
expansion ROMs located at the PCI_MAPREG_ROM base address regis‐
ter (BAR).
pci_intr_map(pa, ih)
See pci_intr(9).
pci_intr_string(pc, ih)
See pci_intr(9).
pci_intr_evcnt(pc, ih)
See pci_intr(9).
pci_intr_establish(pc, ih, level, handler, arg)
See pci_intr(9).
pci_intr_disestablish(pc, ih)
See pci_intr(9).
pci_set_powerstate(pc, tag, newstate)
Set power state of the device to newstate. Valid values for
newstate are:
PCI_PMCSR_STATE_D0
PCI_PMCSR_STATE_D1
PCI_PMCSR_STATE_D2
PCI_PMCSR_STATE_D3
pci_get_powerstate(pc, tag, state)
Get current power state of the device.
pci_vpd_read(pc, tag, offset, count, data)
Read count 32-bit words of Vital Product Data for the device
starting at offset offset into the buffer pointed to by data.
Returns 0 on success or non-zero if the device has no Vital
Product Data capability or if reading the Vital Product Data
fails.
pci_vpd_write(pc, tag, offset, count, data)
Write count 32-bit words of Vital Product Data for the device
starting at offset offset from the buffer pointed to by data.
Returns 0 on success or non-zero if the device has no Vital
Product Data capability of if writing the Vital Product Data
fails.
pci_make_tag(pc, bus, device, function)
Create a new PCI tag for the PCI device specified by the tuple
⟨bus, device, function⟩. This function is not useful to the
usual PCI device driver. It is generally used by drivers of
multi-function devices when attaching other PCI device drivers
to each function.
pci_decompose_tag(pc, tag, busp, devicep, fnp)
Decompose the PCI tag tag generated by pci_make_tag() into its
⟨bus, device, function⟩ tuple.
pci_findvendor(id)
Return the string of the vendor name for the device specified by
id.
pci_devinfo(id, class, show, cp, len)
Returns the description string from the in-kernel PCI database
for the device described by id and class. The description
string is returned in cp; the size of that storage is given in
len. The argument show specifies whether the PCI subsystem
should report the string to the console.
pci_aprint_devinfo(pa, naive)
Print device information to the console and system log, using
the aprint_normal(9) and aprint_naive(9) functions. For the
device information, the “pci_devinfo” function above is used, or
the naive argument in the “AB_QUIET” case. This function is
intended to be used early in device attach.
PCI_VENDOR(id)
Return the PCI vendor id for device id.
PCI_PRODUCT(id)
Return the PCI product id for device id.
PCI_REVISION(id)
Return the PCI product revision for device id.
AUTOCONFIGURATION
During autoconfiguration, a PCI driver will receive a pointer to struct
pci_attach_args describing the device attaches to the PCI bus. Drivers
match the device using the pa_id member using PCI_VENDOR().
PCI_PRODUCT() and PCI_REVISION().
During the driver attach step, drivers can read the device configuration
space using pci_conf_read(). The meaning attached to registers in the
PCI configuration space are device-dependent, but will usually contain
physical addresses of the device register windows. Device options can
also be stored into the PCI configuration space using pci_conf_write().
For example, the driver can request support for bus-mastering DMA by
writing the option to the PCI configuration space.
Device capabilities can be queried using pci_get_capability(), and
returns device-specific information which can be found in the PCI config‐
uration space to alter device operation.
After reading the physical addresses of the device register windows from
configuration space, these windows must be mapped into kernel virtual
address space using pci_mapreg_map(). Device registers can now be
accessed using the standard bus-space API (see bus_space(9)).
Details of using PCI interrupts is described in pci_intr(9).
DMA SUPPORT
The PCI bus supports bus-mastering operations from any device on the bus.
The DMA facilities are accessed through the standard bus_dma(9) inter‐
face. To support DMA transfers from the device to the host, it is neces‐
sary to enable bus-mastering in the PCI configuration space for the
device.
During system shutdown, it is necessary to abort any DMA transfers in
progress by registering a shutdown hook (see pmf(9)).
CODE REFERENCES
The PCI subsystem itself is implemented within the files
sys/dev/pci/pci.c, sys/dev/pci/pci_subr.c, sys/dev/pci/pci_map.c,
sys/dev/pci/pci_quirks.c, and sys/dev/pci/pciconf.c. Machine-dependent
portions are implemented within the file
sys/arch/<arch>/pci/pci_machdep.c.
The database of known devices exists within the file
sys/dev/pci/pcidevs_data.h and is generated automatically from the file
sys/dev/pci/pcidevs. New vendor and product identifiers should be added
to this file. The database can be regenerated using the Makefile
sys/dev/pci/Makefile.pcidevs.
SEE ALSOpci(4), autoconf(9), bus_dma(9), bus_space(9), driver(9),
pci_configure_bus(9), pci_intr(9), pmf(9)HISTORY
The machine-independent PCI subsystem appeared in NetBSD 1.2.
BSD January 30, 2012 BSD
