linux-kernel - [PATCH v3 0/4] bus: fsl-mc: enhance Management Complex userspace support

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Date:   Tue, 20 Nov 2018 15:39:43 +0000
From:   Ioana Ciornei <ioana.ciornei@....com>
To:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Laurentiu Tudor <laurentiu.tudor@....com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev-owner@...r.kernel.org" <netdev-owner@...r.kernel.org>,
        Ioana Ciocoi Radulescu <ruxandra.radulescu@....com>,
        Horia Geanta <horia.geanta@....com>,
        Leo Li <leoyang.li@....com>,
        Ioana Ciornei <ioana.ciornei@....com>
Subject: [PATCH v3 0/4] bus: fsl-mc: enhance Management Complex userspace
 support

This patch set adds userspace support in the fsl-mc bus along with a rescan
attribute to the root DPRC container.  Also, the patches here depend on one
other patch submitted but not yet accepted:
 - https://lkml.org/lkml/2018/11/15/776

An earlier discussion on this functionality can be found here:
https://lkml.org/lkml/2018/3/23/941

The FSL_MC_SEND_MC_COMMAND ioctl acts as a direct passthrough to the Management
Complex (or MC) by passing fixed-length command/response pairs. Keeping in mind
that the MC manages DPAA2 hardware resources and provides and object-based
abstraction for sofware drivers, the proposed ioctl interface enables userspace
tools to do the following:
 - create and destroy DPAA2 objects
 - manage the DPRC container that objects live in (by moving objects between
   containers)
 - establish connections between different objects as needed

The ioctl interface is intended for dynamic usecases where DPAA2 objects need
to be created on demand or destroyed so that the underlying hardware resources
can be further repurposed. In static usecases, depending on the requirements, a
firmware configuration file can be used to describe the needed DPAA2 objects,
their attributes or any link between them.

Some examples of device drivers that probe on said DPAA2 objects are listed
below:
 - https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/soc/fsl/dpio
 - https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/tree/drivers/net/ethernet/freescale/dpaa2
 - https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git/tree/drivers/crypto/caam/

Having a low-level ioctl interface where the command is passed through to the
MC without any intervention from the fsl-mc bus reduces the complexity added in
the kernel while also making the command structure, in turn the ioctl, very
stable.

Changes in v2:
   - use root dprc MC portal by default
   - create the uapi misc device from the root dprc probe function
   - remove the rescan dev_attr on the remove path

Changes in v3:
   - use dev_ instead of pr_
   - remove dynamic_instance_count and uapi_created variables
   - do not assign true to a u32
   - return the actual error code (the decision to defer is for the caller)

Ioana Ciornei (4):
  bus: fsl-mc: move fsl_mc_command struct in a uapi header
  bus: fsl-mc: add fsl-mc userspace support
  bus: fsl-mc: add root dprc rescan attribute
  bus: fsl-mc: add bus rescan attribute

 Documentation/ABI/stable/sysfs-bus-fsl-mc |  19 ++++
 Documentation/ioctl/ioctl-number.txt      |   1 +
 MAINTAINERS                               |   2 +
 drivers/bus/fsl-mc/Kconfig                |   7 ++
 drivers/bus/fsl-mc/Makefile               |   3 +
 drivers/bus/fsl-mc/dprc-driver.c          |  54 +++++++++-
 drivers/bus/fsl-mc/fsl-mc-bus.c           |  41 ++++++++
 drivers/bus/fsl-mc/fsl-mc-private.h       |  41 ++++++++
 drivers/bus/fsl-mc/fsl-mc-uapi.c          | 168 ++++++++++++++++++++++++++++++
 include/linux/fsl/mc.h                    |   8 +-
 include/uapi/linux/fsl_mc.h               |  34 ++++++
 11 files changed, 368 insertions(+), 10 deletions(-)
 create mode 100644 Documentation/ABI/stable/sysfs-bus-fsl-mc
 create mode 100644 drivers/bus/fsl-mc/fsl-mc-uapi.c
 create mode 100644 include/uapi/linux/fsl_mc.h

-- 
1.9.1