[RFC PATCH v2 vfio 7/7] vfio/pds: Add Kconfig and documentation

[Brett Creeley <brett.creeley@amd.com>]

Add Kconfig entries and pds_vfio.rst. Also, add an entry in the
MAINTAINERS file for this new driver.

It's not clear where documentation for vendor specific VFIO
drivers should live, so just re-use the current Pensando
ethernet location.

Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
---
 .../device_drivers/ethernet/index.rst         |  1 +
 .../ethernet/pensando/pds_vfio.rst            | 88 +++++++++++++++++++
 MAINTAINERS                                   |  7 ++
 drivers/vfio/pci/Kconfig                      |  2 +
 drivers/vfio/pci/pds/Kconfig                  | 17 ++++
 5 files changed, 115 insertions(+)
 create mode 100644 Documentation/networking/device_drivers/ethernet/pensando/pds_vfio.rst
 create mode 100644 drivers/vfio/pci/pds/Kconfig

diff --git a/Documentation/networking/device_drivers/ethernet/index.rst b/Documentation/networking/device_drivers/ethernet/index.rst
index 5196905582c5..0242bbc3bb2a 100644
--- a/Documentation/networking/device_drivers/ethernet/index.rst
+++ b/Documentation/networking/device_drivers/ethernet/index.rst
@@ -44,6 +44,7 @@ Contents:
    neterion/s2io
    netronome/nfp
    pensando/ionic
+   pensando/pds_vfio
    smsc/smc9
    stmicro/stmmac
    ti/cpsw
diff --git a/Documentation/networking/device_drivers/ethernet/pensando/pds_vfio.rst b/Documentation/networking/device_drivers/ethernet/pensando/pds_vfio.rst
new file mode 100644
index 000000000000..adc144a4a7b8
--- /dev/null
+++ b/Documentation/networking/device_drivers/ethernet/pensando/pds_vfio.rst
@@ -0,0 +1,88 @@
+.. SPDX-License-Identifier: GPL-2.0+
+.. note: can be edited and viewed with /usr/bin/formiko-vim
+
+==========================================================
+PCI VFIO driver for the Pensando(R) DSC adapter family
+==========================================================
+
+Pensando Linux VFIO PCI Device Driver
+Copyright(c) 2022 Pensando Systems, Inc
+
+Overview
+========
+
+The ``pds_vfio`` driver is both a PCI and auxiliary bus driver. The
+PCI driver supports Live Migration capable NVMe Virtual Function (VF)
+devices and the auxiliary driver is used to communicate with the
+``pds_core`` driver and hardware.
+
+Using the device
+================
+
+The pds_vfio device is enabled via multiple configuration steps and
+depends on the ``pds_core`` driver to create and enable SR-IOV Virtual
+Function devices.
+
+Shown below are the steps to bind the driver to a VF and also to the
+associated auxiliary device created by the ``pds_core`` driver. This
+example assumes the pds_core and pds_vfio modules are already
+loaded.
+
+.. code-block:: bash
+  :name: example-setup-script
+
+  #!/bin/bash
+
+  PF_BUS="0000:60"
+  PF_BDF="0000:60:00.0"
+  VF_BDF="0000:60:00.1"
+
+  # Enable live migration VF auxiliary device(s)
+  devlink dev param set pci/$PF_BDF name enable_migration value true cmode runtime
+
+  # Prevent nvme driver from probing the NVMe VF device
+  echo 0 > /sys/class/pci_bus/$PF_BUS/device/$PF_BDF/sriov_drivers_autoprobe
+
+  # Create single VF for NVMe Live Migration via VFIO
+  echo 1 > /sys/bus/pci/drivers/pds_core/$PF_BDF/sriov_numvfs
+
+  # Allow the VF to be bound to the pds_vfio driver
+  echo "pds_vfio" > /sys/class/pci_bus/$PF_BUS/device/$VF_BDF/driver_override
+
+  # Bind the VF to the pds_vfio driver
+  echo "$VF_BDF" > /sys/bus/pci/drivers/pds_vfio/bind
+
+After performing the steps above the pds_vfio driver's PCI probe should
+have been called, the pds_vfio driver's auxiliary probe should have
+been called, and a file in /dev/vfio/<iommu_group> should have been created.
+There will also be an entry in /sys/bus/auxiliary/device/pds_core.LM.<nn>
+for the VF's auxiliary device and the associated driver registered by the
+pds_vfio module will be at /sys/bus/auxiliary/drivers/pds_vfio.LM.
+
+
+Enabling the driver
+===================
+
+The driver is enabled via the standard kernel configuration system,
+using the make command::
+
+  make oldconfig/menuconfig/etc.
+
+The driver is located in the menu structure at:
+
+  -> Device Drivers
+    -> VFIO Non-Privileged userspace driver framework
+      -> VFIO support for PDS PCI devices
+
+Support
+=======
+
+For general Linux networking support, please use the netdev mailing
+list, which is monitored by Pensando personnel::
+
+  netdev@vger.kernel.org
+
+For more specific support needs, please use the Pensando driver support
+email::
+
+  drivers@pensando.io
diff --git a/MAINTAINERS b/MAINTAINERS
index 50d7442e7f43..ba2d139ccee9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21623,6 +21623,13 @@ S:	Maintained
 P:	Documentation/driver-api/vfio-pci-device-specific-driver-acceptance.rst
 F:	drivers/vfio/pci/*/
 
+VFIO PDS PCI DRIVER
+M:	Brett Creeley <brett.creeley@amd.com>
+L:	kvm@vger.kernel.org
+S:	Maintained
+F:	Documentation/networking/device_drivers/ethernet/pensando/pds_vfio.rst
+F:	drivers/vfio/pci/pds/
+
 VFIO PLATFORM DRIVER
 M:	Eric Auger <eric.auger@redhat.com>
 L:	kvm@vger.kernel.org
diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
index f9d0c908e738..2c3831dd60ef 100644
--- a/drivers/vfio/pci/Kconfig
+++ b/drivers/vfio/pci/Kconfig
@@ -59,4 +59,6 @@ source "drivers/vfio/pci/mlx5/Kconfig"
 
 source "drivers/vfio/pci/hisilicon/Kconfig"
 
+source "drivers/vfio/pci/pds/Kconfig"
+
 endif
diff --git a/drivers/vfio/pci/pds/Kconfig b/drivers/vfio/pci/pds/Kconfig
new file mode 100644
index 000000000000..d9bc9734c3cf
--- /dev/null
+++ b/drivers/vfio/pci/pds/Kconfig
@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: GPL-2.0
+config PDS_VFIO_PCI
+	tristate "VFIO support for PDS PCI devices"
+	depends on PDS_CORE
+	depends on VFIO_PCI_CORE
+	help
+	  This provides generic PCI support for PDS devices using the VFIO
+	  framework.
+
+	  More specific information on this driver can be
+	  found in
+	  <file:Documentation/networking/device_drivers/ethernet/pensando/pds_vfio.rst>.
+
+	  To compile this driver as a module, choose M here. The module
+	  will be called pds_vfio.
+
+	  If you don't know what to do here, say N.
-- 
2.17.1