Add helper routines for PCI device drivers to read, write, and modify

PCI-Express capability registers (that is, PCI config registers in the
standard PCI config space belonging to the PCI-Express capability
register set).

Note that all of the current PCI-e registers are either 16 or 32-bits,
so only widths of 2 or 4 bytes are supported.

Reviewed by:	imp
MFC after:	1 week
Sponsored by:	Chelsio
Differential Revision:	https://reviews.freebsd.org/D4088

2 files changed, 63 insertions, 3 deletions

diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile
index 516d6c3..5ae857e 100644
--- a/share/man/man9/Makefile
+++ b/share/man/man9/Makefile
@@ -1290,7 +1290,10 @@ MLINKS+=pci.9 pci_alloc_msi.9 \
 	pci.9 pci_save_state.9 \
 	pci.9 pci_set_powerstate.9 \
 	pci.9 pci_set_max_read_req.9 \
-	pci.9 pci_write_config.9
+	pci.9 pci_write_config.9 \
+	pci.9 pcie_adjust_config.9 \
+	pci.9 pcie_read_config.9 \
+	pci.9 pcie_write_config.9 \
 MLINKS+=pci_iov_schema.9 pci_iov_schema_alloc_node.9 \
 	pci_iov_schema.9 pci_iov_schema_add_bool.9 \
 	pci_iov_schema.9 pci_iov_schema_add_string.9 \
diff --git a/share/man/man9/pci.9 b/share/man/man9/pci.9
index 5d98e9c..2321638 100644
--- a/share/man/man9/pci.9
+++ b/share/man/man9/pci.9
@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd July 8, 2015
+.Dd November 5, 2015
 .Dt PCI 9
 .Os
 .Sh NAME
@@ -58,7 +58,10 @@
 .Nm pci_save_state ,
 .Nm pci_set_max_read_req ,
 .Nm pci_set_powerstate ,
-.Nm pci_write_config
+.Nm pci_write_config ,
+.Nm pcie_adjust_config ,
+.Nm pcie_read_config ,
+.Nm pcie_write_config
 .Nd PCI bus interface
 .Sh SYNOPSIS
 .In sys/bus.h
@@ -118,6 +121,18 @@
 .Fn pci_set_powerstate "device_t dev" "int state"
 .Ft void
 .Fn pci_write_config "device_t dev" "int reg" "uint32_t val" "int width"
+.Ft uint32_t
+.Fo pcie_adjust_config
+.Fa "device_t dev"
+.Fa "int reg"
+.Fa "uint32_t mask"
+.Fa "uint32_t val"
+.Fa "int width"
+.Fc
+.Ft uint32_t
+.Fn pcie_read_config "device_t dev" "int reg" "int width"
+.Ft void
+.Fn pcie_write_config "device_t dev" "int reg" "uint32_t val" "int width"
 .In dev/pci/pci_iov.h
 .Ft int
 .Fn pci_iov_attach "device_t dev" "nvlist_t *pf_schema" "nvlist_t *vf_schema"
@@ -159,6 +174,48 @@ with
 .Fa width
 specifying the size of the access.
 .Pp
+The
+.Fn pcie_adjust_config
+function is used to modify the value of a register in the PCI-express
+capability register set of device
+.Fa dev .
+The offset
+.Fa reg
+specifies a relative offset in the register set with
+.Fa width
+specifying the size of the access.
+The new value of the register is computed by modifying bits set in
+.Fa mask
+to the value in
+.Fa val .
+Any bits not specified in
+.Fa mask
+are preserved.
+The previous value of the register is returned.
+.Pp
+The
+.Fn pcie_read_config
+function is used to read the value of a register in the PCI-express
+capability register set of device
+.Fa dev .
+The offset
+.Fa reg
+specifies a relative offset in the register set with
+.Fa width
+specifying the size of the access.
+.Pp
+The
+.Fn pcie_write_config
+function is used to write the value
+.Fa val
+to a register in the PCI-express capability register set of device
+.Fa dev .
+The offset
+.Fa reg
+specifies a relative offset in the register set with
+.Fa width
+specifying the size of the access.
+.Pp
 .Em NOTE :
 Device drivers should only use these functions for functionality that
 is not available via another