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  1. 10 3月, 2020 22 次提交
  3. 09 3月, 2020 18 次提交
    • D
      Merge branch 'net-introduce-Qualcomm-IPA-driver' · fbd43602
      由 David S. Miller 提交于 
      Alex Elder says:

====================
net: introduce Qualcomm IPA driver (UPDATED)

This series presents the driver for the Qualcomm IP Accelerator (IPA).

This is version 2 of this updated series.  It includes the following
small changes since the previous version:
  - Now based on net-next instead of v5.6-rc
  - Config option now named CONFIG_QCOM_IPA
  - Some minor cleanup in the GSI code
  - Small change to replenish logic
  - No longer depends on remoteproc bug fixes
What follows is the basically same explanation as was posted previously.

					-Alex

I have posted earlier versions of this code previously, but it has
undergone quite a bit of development since the last time, so rather
than calling it "version 3" I'm just treating it as a new series
(indicating it's been updated in this message).  The fast/data path
is the same as before.  But the driver now (nearly) supports a
second platform, its transaction handling has been generalized
and improved, and modem activities are now handled in a more
unified way.

This series is available (based on net-next in branch "ipa_updated-v2"
in this git repository:
  https://git.linaro.org/people/alex.elder/linux.git

The branch depends on other one other small patch that I sent out
for review earlier.
  https://lore.kernel.org/lkml/20200306042302.17602-1-elder@linaro.org/

I want to address some of the discussion that arose last time.

First, there was the WWAN discussion.  Here's the history:
  - This was last posted nine months ago.
  - Reviewers at that time favored developing a new WWAN subsystem that
    would be used for managing devices like this.  And the suggestion
    was to not accept this driver until that could be developed.
  - Along the way, Apple acquired much of Intel's modem business.
    And as a result, the generic framework became less pressing.
  - I did participate in the WWAN subsystem design however, and
    although it went dormant for a while it's been resurrected:
      https://lore.kernel.org/netdev/20200225100053.16385-1-johannes@sipsolutions.net/
  - Unfortunately the proposed WWAN design was not an easy fit
    with Qualcomm's integrated modem interfaces.  Given that
    rmnet is a supported link type for in the upstream "iproute2"
    package (more on this below), I have opted not to integrate
    with any WWAN subsystem.

So in summary, this driver does not integrate with a generic WWAN
framework.  And I'd like it to be accepted upstream despite that.

Next, Arnd Bergmann had some concerns about flow control.  (Note:
some of my discussions with Arnd about this were offline.) The
overall architecture here also involves the "rmnet" driver:
  drivers/net/ethernet/qualcomm/rmnet

The rmnet driver presents a network device for use.  It connects
with another network device presented, by the IPA driver.  The
rmnet driver wraps (and unwraps) packets transferred to (and from)
the IPA driver with QMAP headers.

   ---------------
   | rmnet_data0 |    <-- "real" netdev
   ---------------
          ||       }- QMAP spoken here
   --------------
   | rmnet_ipa0 |     <-- also netdev, transporting QMAP packets
   --------------
          ||
   --------------
  ( IPA hardware )
   --------------

Arnd's concern was that the rmnet_data0 network device does not
have the benefit of information about the state of the underlying
IPA hardware in order to be effective in controlling TX flow.
The feared result is over-buffering of TX packets (bufferbloat).
I began working on some simple experiments to see whether (or how
much) his concern was warranted.  But it turned out that completing
these experiments was much more work than had been hoped.

The rmnet driver is present in the upstream kernel.  There is also
support for the rmnet link type in the upstream "ip" user space
command in the "iproute2" package.  Changing the layering of rmnet
over IPA likely involves deprecating the rmnet driver and its
support in "iproute2".  I would really rather not go down that
path.

There is precedent for this sort of layering of network devices
(L2TP, VLAN).  And any architecture like this would suffer the
issues Arnd mentioned; the problem is not limited to rmnet and IPA.
I do think this is a problem worth solving, but the prudent thing
to do might be to try to solve it more generally.

So to summarize on this issue, this driver does not attempt to
change the way the rmnet and IPA drivers work together.  And even
though I think Arnd's concerns warrant more investigation, I'd like
this driver to to be accepted upstream without any change to this
architecture.

Finally, a more technical description for the series, and some
acknowledgements to some people who contributed to it.

The IPA is a component present in some Qualcomm SoCs that allows
network functions such as aggregation, filtering, routing, and NAT
to be performed without active involvement of the main application
processor (AP).

In this initial patch series these advanced features are not
implemented.  The IPA driver simply provides a network interface
that makes the modem's LTE network available in Linux.  This initial
series supports only the Qualcomm SDM845 SoC.  The Qualcomm SC7180
SoC is partially supported, and support for other platforms will
follow.

This code is derived from a driver developed by Qualcomm.  A version
of the original source can be seen here:
  https://source.codeaurora.org/quic/la/kernel/msm-4.9/tree
in the "drivers/platform/msm/ipa" directory.  Many were involved in
developing this, but the following individuals deserve explicit
acknowledgement for their substantial contributions:

    Abhishek Choubey
    Ady Abraham
    Chaitanya Pratapa
    David Arinzon
    Ghanim Fodi
    Gidon Studinski
    Ravi Gummadidala
    Shihuan Liu
    Skylar Chang
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      fbd43602
    • A
      arm64: dts: sdm845: add IPA information · 9cc5ae12
      由 Alex Elder 提交于 
      Add IPA-related nodes and definitions to "sdm845.dtsi".
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      9cc5ae12
    • A
      MAINTAINERS: add entry for the Qualcomm IPA driver · aa302745
      由 Alex Elder 提交于 
      Add an entry in the MAINTAINERS file for the Qualcomm IPA driver
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      aa302745
    • A
      soc: qcom: ipa: support build of IPA code · 08120d23
      由 Alex Elder 提交于 
      Add build and Kconfig support for the Qualcomm IPA driver.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      08120d23
    • A
      soc: qcom: ipa: AP/modem communications · 530f9216
      由 Alex Elder 提交于 
      This patch implements two forms of out-of-band communication between
the AP and modem.

  - QMI is a mechanism that allows clients running on the AP
    interact with services running on the modem (and vice-versa).
    The AP IPA driver uses QMI to communicate with the corresponding
    IPA driver resident on the modem, to agree on parameters used
    with the IPA hardware and to ensure both sides are ready before
    entering operational mode.

  - SMP2P is a more primitive mechanism available for the modem and
    AP to communicate with each other.  It provides a means for either
    the AP or modem to interrupt the other, and furthermore, to provide
    32 bits worth of information.  The IPA driver uses SMP2P to tell
    the modem what the state of the IPA clock was in the event of a
    crash.  This allows the modem to safely access the IPA hardware
    (or avoid doing so) when a crash occurs, for example, to access
    information within the IPA hardware.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      530f9216
    • A
      soc: qcom: ipa: modem and microcontroller · a646d6ec
      由 Alex Elder 提交于 
      This patch includes code implementing the modem functionality.
There are several communication paths between the AP and modem,
separate from the main data path provided by IPA.  SMP2P provides
primitive messaging and interrupt capability, and QMI allows more
complex out-of-band messaging to occur between entities on the AP
and modem.  (SMP2P and QMI support are added by the next patch.)
Management of these (plus the network device implementing the data
path) is done by code within "ipa_modem.c".

Sort of unrelated, this patch also includes the code supporting the
microcontroller CPU present on the IPA.  The microcontroller can be
used to implement special handling of packets, but at this time we
don't support that.  Still, it is a component that needs to be
initialized, and in the event of a crash we need to do some
synchronization between the AP and the microcontroller.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      a646d6ec
    • A
      soc: qcom: ipa: immediate commands · 731c46ed
      由 Alex Elder 提交于 
      One TX endpoint (per EE) is used for issuing immediate commands to
the IPA.  These commands request activites beyond simple data
transfers to be done by the IPA hardware.  For example, the IPA is
able to manage routing packets among endpoints, and immediate commands
are used to configure tables used for that routing.

Immediate commands are built on top of GSI transactions.  They are
different from normal transfers (in that they use a special endpoint,
and their "payload" is interpreted differently), so separate functions
are used to issue immediate command transactions.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      731c46ed
    • A
      soc: qcom: ipa: filter and routing tables · 2b9feef2
      由 Alex Elder 提交于 
      This patch contains code implementing filter and routing tables for
the IPA.  A filter table allows rules to be used for filtering
packets that depart the AP at an endpoint.  A filter table entry
contains the address of a set of rules to apply for each endpoint
that supports filtering.

A routing table allows packets to be routed to an endpoint based
on packet metadata.  It is also a table whose entries each contain
the address of a set of routing rules to apply.

Neither filtering nor routing is supported by the current driver.
All table entries refer to rules that mean "no filtering" and "no
routing."
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      2b9feef2
    • A
      soc: qcom: ipa: IPA endpoints · 84f9bd12
      由 Alex Elder 提交于 
      This patch includes the code implementing an IPA endpoint.  This is
the primary abstraction implemented by the IPA.  An endpoint is one
end of a network connection between two entities physically
connected to the IPA.  Specifically, the AP and the modem implement
endpoints, and an (AP endpoint, modem endpoint) pair implements the
transfer of network data in one direction between the AP and modem.

Endpoints are built on top of GSI channels, but IPA endpoints
represent the higher-level functionality that the IPA provides.
Data can be sent through a GSI channel, but it is the IPA endpoint
that represents what is on the "other end" to receive that data.
Other functionality, including aggregation, checksum offload and
(at some future date) IP routing and filtering are all associated
with the IPA endpoint.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      84f9bd12
    • A
      soc: qcom: ipa: GSI transactions · 9dd441e4
      由 Alex Elder 提交于 
      This patch implements GSI transactions.  A GSI transaction is a
structure that represents a single request (consisting of one or
more TREs) sent to the GSI hardware.  The last TRE in a transaction
includes a flag requesting that the GSI interrupt the AP to notify
that it has completed.

TREs are executed and completed strictly in order.  For this reason,
the completion of a single TRE implies that all previous TREs (in
particular all of those "earlier" in a transaction) have completed.

Whenever there is a need to send a request (a set of TREs) to the
IPA, a GSI transaction is allocated, specifying the number of TREs
that will be required.  Details of the request (e.g. transfer offsets
and length) are represented by in a Linux scatterlist array that is
incorporated in the transaction structure.

Once all commands (TREs) are added to a transaction it is committed.
When the hardware signals that the request has completed, a callback
function allows for cleanup or followup activity to be performed
before the transaction is freed.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      9dd441e4
    • A
      soc: qcom: ipa: IPA interface to GSI · c3f398b1
      由 Alex Elder 提交于 
      This patch provides interface functions supplied by the IPA layer
that are called from the GSI layer.  One function is called when a
GSI transaction has completed.  The others allow the GSI layer to
inform the IPA layer when the hardware has been told it has new TREs
to execute, and when the hardware has indicated transactions have
completed.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      c3f398b1
    • A
      soc: qcom: ipa: the generic software interface · 650d1603
      由 Alex Elder 提交于 
      This patch includes "gsi.c", which implements the generic software
interface (GSI) for IPA.  The generic software interface abstracts
channels, which provide a means of transferring data either from the
AP to the IPA, or from the IPA to the AP.  A ring buffer of "transfer
elements" (TREs) is used to describe data transfers to perform.  The
AP writes a doorbell register associated with a channel to let it know
it has added new entries (for an AP->IPA channel) or has finished
processing entries (for an IPA->AP channel).

Each channel also has an event ring buffer, used by the IPA to
communicate information about events related to a channel (for
example, the completion of TREs).  The IPA writes its own doorbell
register, which triggers an interrupt on the AP, to signal that
new event information has arrived.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      650d1603
    • A
      soc: qcom: ipa: GSI headers · ca48b27b
      由 Alex Elder 提交于 
      The Generic Software Interface is a layer of the IPA driver that
abstracts the underlying hardware.  The next patch includes the
main code for GSI (including some additional documentation).  This
patch just includes three GSI header files.

  - "gsi.h" is the top-level GSI header file.  This structure is
    is embedded within the IPA structure.  The main abstraction
    implemented by the GSI code is the channel, and this header
    exposes several operations that can be performed on a GSI channel.

  - "gsi_private.h" exposes some definitions that are intended to be
    private, used only by the main GSI code and the GSI transaction
    code (defined in an upcoming patch).

  - Like "ipa_reg.h", "gsi_reg.h" defines the offsets of the 32-bit
    registers used by the GSI layer, along with masks that define the
    position and width of fields less than 32 bits located within
    these registers.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      ca48b27b
    • A
      soc: qcom: ipa: clocking, interrupts, and memory · ba764c4d
      由 Alex Elder 提交于 
      This patch incorporates three source files (and their headers).  They're
grouped into one patch mainly for the purpose of making the number and
size of patches in this series somewhat reasonable.

  - "ipa_clock.c" and "ipa_clock.h" implement clocking for the IPA device.
    The IPA has a single core clock managed by the common clock framework.
    In addition, the IPA has three buses whose bandwidth is managed by the
    Linux interconnect framework.  At this time the core clock and all
    three buses are either on or off; we don't yet do any more fine-grained
    management than that.  The core clock and interconnects are enabled
    and disabled as a unit, using a unified clock-like abstraction,
    ipa_clock_get()/ipa_clock_put().

  - "ipa_interrupt.c" and "ipa_interrupt.h" implement IPA interrupts.
    There are two hardware IRQs used by the IPA driver (the other is
    the GSI interrupt, described in a separate patch).  Several types
    of interrupt are handled by the IPA IRQ handler; these are not part
    of data/fast path.

  - The IPA has a region of local memory that is accessible by the AP
    (and modem).  Within that region are areas with certain defined
    purposes.  "ipa_mem.c" and "ipa_mem.h" define those regions, and
    implement their initialization.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      ba764c4d
    • A
      soc: qcom: ipa: configuration data · 1ed7d0c0
      由 Alex Elder 提交于 
      This patch defines configuration data that is used to specify some
of the details of IPA hardware supported by the driver.  It is built
as Device Tree match data, discovered at boot time.  The driver
supports the Qualcomm SDM845 SoC.  Data for the Qualcomm SC7180 is
also defined here, but it is not yet completely supported.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      1ed7d0c0
    • A
      soc: qcom: ipa: main code · cdf2e941
      由 Alex Elder 提交于 
      This patch includes three source files that represent some basic "main
program" code for the IPA driver.  They are:
  - "ipa.h" defines the top-level IPA structure which represents an IPA
     device throughout the code.
  - "ipa_main.c" contains the platform driver probe function, along with
    some general code used during initialization.
  - "ipa_reg.h" defines the offsets of the 32-bit registers used for the
    IPA device, along with masks that define the position and width of
    fields within these registers.
  - "version.h" defines some symbolic IPA version numbers.

Each file includes some documentation that provides a little more
overview of how the code is organized and used.
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      cdf2e941
    • A
      dt-bindings: soc: qcom: add IPA bindings · fc39c40a
      由 Alex Elder 提交于 
      Add the binding definitions for the "qcom,ipa" device tree node.
Signed-off-by: NAlex Elder <elder@linaro.org>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      fc39c40a
    • A
      remoteproc: add IPA notification to q6v5 driver · d7f5f3c8
      由 Alex Elder 提交于 
      Set up a subdev in the q6v5 modem remoteproc driver that generates
event notifications for the IPA driver to use for initialization and
recovery following a modem shutdown or crash.

A pair of new functions provides a way for the IPA driver to register
and deregister a notification callback function that will be called
whenever modem events (about to boot, running, about to shut down,
etc.) occur.  A void pointer value (provided by the IPA driver at
registration time) and an event type are supplied to the callback
function.

One event, MODEM_REMOVING, is signaled whenever the q6v5 driver is
about to remove the notification subdevice.  It requires the IPA
driver de-register its callback.

This sub-device is only used by the modem subsystem (MSS) driver,
so the code that adds the new subdev and allows registration and
deregistration of the notifier is found in "qcom_q6v6_mss.c".
Signed-off-by: NAlex Elder <elder@linaro.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      d7f5f3c8