pci: Add is_pci_device helper function

This returns true if a given device is a PCI device (child of a PCI
bus).

Reviewed by:	bz, kib
Sponsored by:	Chelsio Communications
Differential Revision:	https://reviews.freebsd.org/D56996

share/man/man9/Makefile

@@ -1803,7 +1803,8 @@ MLINKS+=osd.9 osd_call.9 \
 	osd.9 osd_set_reserved.9
 MLINKS+=panic.9 vpanic.9 \
 	panic.9 KERNEL_PANICKED.9
-MLINKS+=pci.9 pci_alloc_msi.9 \
+MLINKS+=pci.9 is_pci_device.9 \
+	pci.9 pci_alloc_msi.9 \
 	pci.9 pci_alloc_msix.9 \
 	pci.9 pci_clear_pme.9 \
 	pci.9 pci_disable_busmaster.9 \

share/man/man9/pci.9

@@ -23,11 +23,12 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd March 27, 2025
+.Dd May 18, 2026
 .Dt PCI 9
 .Os
 .Sh NAME
 .Nm pci ,
+.Nm is_pci_device ,
 .Nm pci_alloc_msi ,
 .Nm pci_alloc_msix ,
 .Nm pci_clear_pme ,
@@ -80,6 +81,8 @@
 .In sys/bus.h
 .In dev/pci/pcireg.h
 .In dev/pci/pcivar.h
+.Ft bool
+.Fn is_pci_device "device_t dev"
 .Ft int
 .Fn pci_alloc_msi "device_t dev" "int *count"
 .Ft int
@@ -202,6 +205,12 @@ device information,
 device configuration,
 and
 message signaled interrupts.
+.Pp
+The
+.Fn is_pci_device
+function can be used to determine if
+.Fa dev
+is a PCI device.
 .Ss Raw Configuration Access
 The
 .Fn pci_read_config

sys/dev/pci/pci.c

@@ -6993,6 +6993,17 @@ pci_print_faulted_dev(void)
 	}
 }
 
+bool
+is_pci_device(device_t dev)
+{
+	devclass_t pci_class;
+
+	if (device_get_parent(dev) == NULL)
+		return (false);
+	pci_class = devclass_find("pci");
+	return (device_get_devclass(device_get_parent(dev)) == pci_class);
+}
+
 #ifdef DDB
 DB_SHOW_COMMAND_FLAGS(pcierr, pci_print_faulted_dev_db, DB_CMD_MEMSAFE)
 {

sys/dev/pci/pcivar.h

@@ -676,6 +676,7 @@ pci_child_added(device_t dev)
     return (PCI_CHILD_ADDED(device_get_parent(dev), dev));
 }
 
+bool	is_pci_device(device_t dev);
 device_t pci_find_bsf(uint8_t, uint8_t, uint8_t);
 device_t pci_find_dbsf(uint32_t, uint8_t, uint8_t, uint8_t);
 device_t pci_find_device(uint16_t, uint16_t);