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Merge tag 'char-misc-4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

Browse Source 
Pull char/misc driver updates from Greg KH:
 "Here is the "big" char and misc driver patches for 4.18-rc1.

  It's not a lot of stuff here, but there are some highlights:

   - coreboot driver updates

   - soundwire driver updates

   - android binder updates

   - fpga big sync, mostly documentation

   - lots of minor driver updates

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'char-misc-4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (81 commits)
  vmw_balloon: fixing double free when batching mode is off
  MAINTAINERS: Add driver-api/fpga path
  fpga: clarify that unregister functions also free
  documentation: fpga: move fpga-region.txt to driver-api
  documentation: fpga: add bridge document to driver-api
  documentation: fpga: move fpga-mgr.txt to driver-api
  Documentation: fpga: move fpga overview to driver-api
  fpga: region: kernel-doc fixes
  fpga: bridge: kernel-doc fixes
  fpga: mgr: kernel-doc fixes
  fpga: use SPDX
  fpga: region: change api, add fpga_region_create/free
  fpga: bridge: change api, don't use drvdata
  fpga: manager: change api, don't use drvdata
  fpga: region: don't use drvdata in common fpga code
  Drivers: hv: vmbus: Removed an unnecessary cast from void *
  ver_linux: Drop redundant calls to system() to test if file is readable
  ver_linux: Move stderr redirection from function parameter to function body
  misc: IBM Virtual Management Channel Driver (VMC)
  rpmsg: Correct support for MODULE_DEVICE_TABLE()
  ...
This commit is contained in:
Linus Torvalds
2018-06-05 16:20:22 -07:00
parent 07c4dd3435 b23220fe05
commit abf7dba7c4
132 changed files with 8983 additions and 1236 deletions
Download Patch File Download Diff File Expand all files Collapse all files

49
Documentation/driver-api/fpga/fpga-bridge.rst Normal file
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FPGA Bridge
===========
API to implement a new FPGA bridge
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. kernel-doc:: include/linux/fpga/fpga-bridge.h
:functions: fpga_bridge
.. kernel-doc:: include/linux/fpga/fpga-bridge.h
:functions: fpga_bridge_ops
.. kernel-doc:: drivers/fpga/fpga-bridge.c
:functions: fpga_bridge_create
.. kernel-doc:: drivers/fpga/fpga-bridge.c
:functions: fpga_bridge_free
.. kernel-doc:: drivers/fpga/fpga-bridge.c
:functions: fpga_bridge_register
.. kernel-doc:: drivers/fpga/fpga-bridge.c
:functions: fpga_bridge_unregister
API to control an FPGA bridge
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
You probably won't need these directly. FPGA regions should handle this.
.. kernel-doc:: drivers/fpga/fpga-bridge.c
:functions: of_fpga_bridge_get
.. kernel-doc:: drivers/fpga/fpga-bridge.c
:functions: fpga_bridge_get
.. kernel-doc:: drivers/fpga/fpga-bridge.c
:functions: fpga_bridge_put
.. kernel-doc:: drivers/fpga/fpga-bridge.c
:functions: fpga_bridge_get_to_list
.. kernel-doc:: drivers/fpga/fpga-bridge.c
:functions: of_fpga_bridge_get_to_list
.. kernel-doc:: drivers/fpga/fpga-bridge.c
:functions: fpga_bridge_enable
.. kernel-doc:: drivers/fpga/fpga-bridge.c
:functions: fpga_bridge_disable

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FPGA Manager
============
Overview
--------
The FPGA manager core exports a set of functions for programming an FPGA with
an image. The API is manufacturer agnostic. All manufacturer specifics are
hidden away in a low level driver which registers a set of ops with the core.
The FPGA image data itself is very manufacturer specific, but for our purposes
it's just binary data. The FPGA manager core won't parse it.
The FPGA image to be programmed can be in a scatter gather list, a single
contiguous buffer, or a firmware file. Because allocating contiguous kernel
memory for the buffer should be avoided, users are encouraged to use a scatter
gather list instead if possible.
The particulars for programming the image are presented in a structure (struct
fpga_image_info). This struct contains parameters such as pointers to the
FPGA image as well as image-specific particulars such as whether the image was
built for full or partial reconfiguration.
How to support a new FPGA device
--------------------------------
To add another FPGA manager, write a driver that implements a set of ops. The
probe function calls fpga_mgr_register(), such as::
static const struct fpga_manager_ops socfpga_fpga_ops = {
.write_init = socfpga_fpga_ops_configure_init,
.write = socfpga_fpga_ops_configure_write,
.write_complete = socfpga_fpga_ops_configure_complete,
.state = socfpga_fpga_ops_state,
};
static int socfpga_fpga_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct socfpga_fpga_priv *priv;
struct fpga_manager *mgr;
int ret;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
/*
* do ioremaps, get interrupts, etc. and save
* them in priv
*/
mgr = fpga_mgr_create(dev, "Altera SOCFPGA FPGA Manager",
&socfpga_fpga_ops, priv);
if (!mgr)
return -ENOMEM;
platform_set_drvdata(pdev, mgr);
ret = fpga_mgr_register(mgr);
if (ret)
fpga_mgr_free(mgr);
return ret;
}
static int socfpga_fpga_remove(struct platform_device *pdev)
{
struct fpga_manager *mgr = platform_get_drvdata(pdev);
fpga_mgr_unregister(mgr);
return 0;
}
The ops will implement whatever device specific register writes are needed to
do the programming sequence for this particular FPGA. These ops return 0 for
success or negative error codes otherwise.
The programming sequence is::
1. .write_init
2. .write or .write_sg (may be called once or multiple times)
3. .write_complete
The .write_init function will prepare the FPGA to receive the image data. The
buffer passed into .write_init will be atmost .initial_header_size bytes long,
if the whole bitstream is not immediately available then the core code will
buffer up at least this much before starting.
The .write function writes a buffer to the FPGA. The buffer may be contain the
whole FPGA image or may be a smaller chunk of an FPGA image. In the latter
case, this function is called multiple times for successive chunks. This interface
is suitable for drivers which use PIO.
The .write_sg version behaves the same as .write except the input is a sg_table
scatter list. This interface is suitable for drivers which use DMA.
The .write_complete function is called after all the image has been written
to put the FPGA into operating mode.
The ops include a .state function which will read the hardware FPGA manager and
return a code of type enum fpga_mgr_states. It doesn't result in a change in
hardware state.
How to write an image buffer to a supported FPGA
------------------------------------------------
Some sample code::
#include <linux/fpga/fpga-mgr.h>
struct fpga_manager *mgr;
struct fpga_image_info *info;
int ret;
/*
* Get a reference to FPGA manager. The manager is not locked, so you can
* hold onto this reference without it preventing programming.
*
* This example uses the device node of the manager. Alternatively, use
* fpga_mgr_get(dev) instead if you have the device.
*/
mgr = of_fpga_mgr_get(mgr_node);
/* struct with information about the FPGA image to program. */
info = fpga_image_info_alloc(dev);
/* flags indicates whether to do full or partial reconfiguration */
info->flags = FPGA_MGR_PARTIAL_RECONFIG;
/*
* At this point, indicate where the image is. This is pseudo-code; you're
* going to use one of these three.
*/
if (image is in a scatter gather table) {
info->sgt = [your scatter gather table]
} else if (image is in a buffer) {
info->buf = [your image buffer]
info->count = [image buffer size]
} else if (image is in a firmware file) {
info->firmware_name = devm_kstrdup(dev, firmware_name, GFP_KERNEL);
}
/* Get exclusive control of FPGA manager */
ret = fpga_mgr_lock(mgr);
/* Load the buffer to the FPGA */
ret = fpga_mgr_buf_load(mgr, &info, buf, count);
/* Release the FPGA manager */
fpga_mgr_unlock(mgr);
fpga_mgr_put(mgr);
/* Deallocate the image info if you're done with it */
fpga_image_info_free(info);
API for implementing a new FPGA Manager driver
----------------------------------------------
.. kernel-doc:: include/linux/fpga/fpga-mgr.h
:functions: fpga_manager
.. kernel-doc:: include/linux/fpga/fpga-mgr.h
:functions: fpga_manager_ops
.. kernel-doc:: drivers/fpga/fpga-mgr.c
:functions: fpga_mgr_create
.. kernel-doc:: drivers/fpga/fpga-mgr.c
:functions: fpga_mgr_free
.. kernel-doc:: drivers/fpga/fpga-mgr.c
:functions: fpga_mgr_register
.. kernel-doc:: drivers/fpga/fpga-mgr.c
:functions: fpga_mgr_unregister
API for programming a FPGA
--------------------------
.. kernel-doc:: include/linux/fpga/fpga-mgr.h
:functions: fpga_image_info
.. kernel-doc:: include/linux/fpga/fpga-mgr.h
:functions: fpga_mgr_states
.. kernel-doc:: drivers/fpga/fpga-mgr.c
:functions: fpga_image_info_alloc
.. kernel-doc:: drivers/fpga/fpga-mgr.c
:functions: fpga_image_info_free
.. kernel-doc:: drivers/fpga/fpga-mgr.c
:functions: of_fpga_mgr_get
.. kernel-doc:: drivers/fpga/fpga-mgr.c
:functions: fpga_mgr_get
.. kernel-doc:: drivers/fpga/fpga-mgr.c
:functions: fpga_mgr_put
.. kernel-doc:: drivers/fpga/fpga-mgr.c
:functions: fpga_mgr_lock
.. kernel-doc:: drivers/fpga/fpga-mgr.c
:functions: fpga_mgr_unlock
.. kernel-doc:: include/linux/fpga/fpga-mgr.h
:functions: fpga_mgr_states
Note - use :c:func:`fpga_region_program_fpga()` instead of :c:func:`fpga_mgr_load()`
.. kernel-doc:: drivers/fpga/fpga-mgr.c
:functions: fpga_mgr_load

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FPGA Region
===========
Overview
--------
This document is meant to be an brief overview of the FPGA region API usage. A
more conceptual look at regions can be found in the Device Tree binding
document [#f1]_.
For the purposes of this API document, let's just say that a region associates
an FPGA Manager and a bridge (or bridges) with a reprogrammable region of an
FPGA or the whole FPGA. The API provides a way to register a region and to
program a region.
Currently the only layer above fpga-region.c in the kernel is the Device Tree
support (of-fpga-region.c) described in [#f1]_. The DT support layer uses regions
to program the FPGA and then DT to handle enumeration. The common region code
is intended to be used by other schemes that have other ways of accomplishing
enumeration after programming.
An fpga-region can be set up to know the following things:
* which FPGA manager to use to do the programming
* which bridges to disable before programming and enable afterwards.
Additional info needed to program the FPGA image is passed in the struct
fpga_image_info including:
* pointers to the image as either a scatter-gather buffer, a contiguous
buffer, or the name of firmware file
* flags indicating specifics such as whether the image if for partial
reconfiguration.
How to program a FPGA using a region
------------------------------------
First, allocate the info struct::
info = fpga_image_info_alloc(dev);
if (!info)
return -ENOMEM;
Set flags as needed, i.e.::
info->flags |= FPGA_MGR_PARTIAL_RECONFIG;
Point to your FPGA image, such as::
info->sgt = &sgt;
Add info to region and do the programming::
region->info = info;
ret = fpga_region_program_fpga(region);
:c:func:`fpga_region_program_fpga()` operates on info passed in the
fpga_image_info (region->info). This function will attempt to:
* lock the region's mutex
* lock the region's FPGA manager
* build a list of FPGA bridges if a method has been specified to do so
* disable the bridges
* program the FPGA
* re-enable the bridges
* release the locks
Then you will want to enumerate whatever hardware has appeared in the FPGA.
How to add a new FPGA region
----------------------------
An example of usage can be seen in the probe function of [#f2]_.
.. [#f1] ../devicetree/bindings/fpga/fpga-region.txt
.. [#f2] ../../drivers/fpga/of-fpga-region.c
API to program a FGPA
---------------------
.. kernel-doc:: drivers/fpga/fpga-region.c
:functions: fpga_region_program_fpga
API to add a new FPGA region
----------------------------
.. kernel-doc:: include/linux/fpga/fpga-region.h
:functions: fpga_region
.. kernel-doc:: drivers/fpga/fpga-region.c
:functions: fpga_region_create
.. kernel-doc:: drivers/fpga/fpga-region.c
:functions: fpga_region_free
.. kernel-doc:: drivers/fpga/fpga-region.c
:functions: fpga_region_register
.. kernel-doc:: drivers/fpga/fpga-region.c
:functions: fpga_region_unregister

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==============
FPGA Subsystem
==============
:Author: Alan Tull
.. toctree::
:maxdepth: 2
intro
fpga-mgr
fpga-bridge
fpga-region

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Introduction
============
The FPGA subsystem supports reprogramming FPGAs dynamically under
Linux. Some of the core intentions of the FPGA subsystems are:
* The FPGA subsystem is vendor agnostic.
* The FPGA subsystem separates upper layers (userspace interfaces and
enumeration) from lower layers that know how to program a specific
FPGA.
* Code should not be shared between upper and lower layers. This
should go without saying. If that seems necessary, there's probably
framework functionality that that can be added that will benefit
other users. Write the linux-fpga mailing list and maintainers and
seek out a solution that expands the framework for broad reuse.
* Generally, when adding code, think of the future. Plan for re-use.
The framework in the kernel is divided into:
FPGA Manager
------------
If you are adding a new FPGA or a new method of programming a FPGA,
this is the subsystem for you. Low level FPGA manager drivers contain
the knowledge of how to program a specific device. This subsystem
includes the framework in fpga-mgr.c and the low level drivers that
are registered with it.
FPGA Bridge
-----------
FPGA Bridges prevent spurious signals from going out of a FPGA or a
region of a FPGA during programming. They are disabled before
programming begins and re-enabled afterwards. An FPGA bridge may be
actual hard hardware that gates a bus to a cpu or a soft ("freeze")
bridge in FPGA fabric that surrounds a partial reconfiguration region
of an FPGA. This subsystem includes fpga-bridge.c and the low level
drivers that are registered with it.
FPGA Region
-----------
If you are adding a new interface to the FPGA framework, add it on top
of a FPGA region to allow the most reuse of your interface.
The FPGA Region framework (fpga-region.c) associates managers and
bridges as reconfigurable regions. A region may refer to the whole
FPGA in full reconfiguration or to a partial reconfiguration region.
The Device Tree FPGA Region support (of-fpga-region.c) handles
reprogramming FPGAs when device tree overlays are applied.

1
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@@ -51,6 +51,7 @@ available subsections can be seen below.
dmaengine/index
slimbus
soundwire/index
fpga/index
.. only:: subproject and html

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========================
SoundWire Error Handling
========================
The SoundWire PHY was designed with care and errors on the bus are going to
be very unlikely, and if they happen it should be limited to single bit
errors. Examples of this design can be found in the synchronization
mechanism (sync loss after two errors) and short CRCs used for the Bulk
Register Access.
The errors can be detected with multiple mechanisms:
1. Bus clash or parity errors: This mechanism relies on low-level detectors
that are independent of the payload and usages, and they cover both control
and audio data. The current implementation only logs such errors.
Improvements could be invalidating an entire programming sequence and
restarting from a known position. In the case of such errors outside of a
control/command sequence, there is no concealment or recovery for audio
data enabled by the SoundWire protocol, the location of the error will also
impact its audibility (most-significant bits will be more impacted in PCM),
and after a number of such errors are detected the bus might be reset. Note
that bus clashes due to programming errors (two streams using the same bit
slots) or electrical issues during the transmit/receive transition cannot
be distinguished, although a recurring bus clash when audio is enabled is a
indication of a bus allocation issue. The interrupt mechanism can also help
identify Slaves which detected a Bus Clash or a Parity Error, but they may
not be responsible for the errors so resetting them individually is not a
viable recovery strategy.
2. Command status: Each command is associated with a status, which only
covers transmission of the data between devices. The ACK status indicates
that the command was received and will be executed by the end of the
current frame. A NAK indicates that the command was in error and will not
be applied. In case of a bad programming (command sent to non-existent
Slave or to a non-implemented register) or electrical issue, no response
signals the command was ignored. Some Master implementations allow for a
command to be retransmitted several times. If the retransmission fails,
backtracking and restarting the entire programming sequence might be a
solution. Alternatively some implementations might directly issue a bus
reset and re-enumerate all devices.
3. Timeouts: In a number of cases such as ChannelPrepare or
ClockStopPrepare, the bus driver is supposed to poll a register field until
it transitions to a NotFinished value of zero. The MIPI SoundWire spec 1.1
does not define timeouts but the MIPI SoundWire DisCo document adds
recommendation on timeouts. If such configurations do not complete, the
driver will return a -ETIMEOUT. Such timeouts are symptoms of a faulty
Slave device and are likely impossible to recover from.
Errors during global reconfiguration sequences are extremely difficult to
handle:
1. BankSwitch: An error during the last command issuing a BankSwitch is
difficult to backtrack from. Retransmitting the Bank Switch command may be
possible in a single segment setup, but this can lead to synchronization
problems when enabling multiple bus segments (a command with side effects
such as frame reconfiguration would be handled at different times). A global
hard-reset might be the best solution.
Note that SoundWire does not provide a mechanism to detect illegal values
written in valid registers. In a number of cases the standard even mentions
that the Slave might behave in implementation-defined ways. The bus
implementation does not provide a recovery mechanism for such errors, Slave
or Master driver implementers are responsible for writing valid values in
valid registers and implement additional range checking if needed.

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@@ -6,6 +6,9 @@ SoundWire Documentation
:maxdepth: 1
summary
stream
error_handling
locking
.. only:: subproject

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=================
SoundWire Locking
=================
This document explains locking mechanism of the SoundWire Bus. Bus uses
following locks in order to avoid race conditions in Bus operations on
shared resources.
- Bus lock
- Message lock
Bus lock
========
SoundWire Bus lock is a mutex and is part of Bus data structure
(sdw_bus) which is used for every Bus instance. This lock is used to
serialize each of the following operations(s) within SoundWire Bus instance.
- Addition and removal of Slave(s), changing Slave status.
- Prepare, Enable, Disable and De-prepare stream operations.
- Access of Stream data structure.
Message lock
============
SoundWire message transfer lock. This mutex is part of
Bus data structure (sdw_bus). This lock is used to serialize the message
transfers (read/write) within a SoundWire Bus instance.
Below examples show how locks are acquired.
Example 1
---------
Message transfer.
1. For every message transfer
a. Acquire Message lock.
b. Transfer message (Read/Write) to Slave1 or broadcast message on
Bus in case of bank switch.
c. Release Message lock ::
+----------+ +---------+
| | | |
| Bus | | Master |
| | | Driver |
| | | |
+----+-----+ +----+----+
| |
| bus->ops->xfer_msg() |
<-------------------------------+ a. Acquire Message lock
| | b. Transfer message
| |
+-------------------------------> c. Release Message lock
| return success/error | d. Return success/error
| |
+ +
Example 2
---------
Prepare operation.
1. Acquire lock for Bus instance associated with Master 1.
2. For every message transfer in Prepare operation
a. Acquire Message lock.
b. Transfer message (Read/Write) to Slave1 or broadcast message on
Bus in case of bank switch.
c. Release Message lock.
3. Release lock for Bus instance associated with Master 1 ::
+----------+ +---------+
| | | |
| Bus | | Master |
| | | Driver |
| | | |
+----+-----+ +----+----+
| |
| sdw_prepare_stream() |
<-------------------------------+ 1. Acquire bus lock
| | 2. Perform stream prepare
| |
| |
| bus->ops->xfer_msg() |
<-------------------------------+ a. Acquire Message lock
| | b. Transfer message
| |
+-------------------------------> c. Release Message lock
| return success/error | d. Return success/error
| |
| |
| return success/error | 3. Release bus lock
+-------------------------------> 4. Return success/error
| |
+ +

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=========================
Audio Stream in SoundWire
=========================
An audio stream is a logical or virtual connection created between
(1) System memory buffer(s) and Codec(s)
(2) DSP memory buffer(s) and Codec(s)
(3) FIFO(s) and Codec(s)
(4) Codec(s) and Codec(s)
which is typically driven by a DMA(s) channel through the data link. An
audio stream contains one or more channels of data. All channels within
stream must have same sample rate and same sample size.
Assume a stream with two channels (Left & Right) is opened using SoundWire
interface. Below are some ways a stream can be represented in SoundWire.
Stream Sample in memory (System memory, DSP memory or FIFOs) ::
-------------------------
| L | R | L | R | L | R |
-------------------------
Example 1: Stereo Stream with L and R channels is rendered from Master to
Slave. Both Master and Slave is using single port. ::
+---------------+ Clock Signal +---------------+
| Master +----------------------------------+ Slave |
| Interface | | Interface |
| | | 1 |
| | Data Signal | |
| L + R +----------------------------------+ L + R |
| (Data) | Data Direction | (Data) |
+---------------+ +-----------------------> +---------------+
Example 2: Stereo Stream with L and R channels is captured from Slave to
Master. Both Master and Slave is using single port. ::
+---------------+ Clock Signal +---------------+
| Master +----------------------------------+ Slave |
| Interface | | Interface |
| | | 1 |
| | Data Signal | |
| L + R +----------------------------------+ L + R |
| (Data) | Data Direction | (Data) |
+---------------+ <-----------------------+ +---------------+
Example 3: Stereo Stream with L and R channels is rendered by Master. Each
of the L and R channel is received by two different Slaves. Master and both
Slaves are using single port. ::
+---------------+ Clock Signal +---------------+
| Master +---------+------------------------+ Slave |
| Interface | | | Interface |
| | | | 1 |
| | | Data Signal | |
| L + R +---+------------------------------+ L |
| (Data) | | | Data Direction | (Data) |
+---------------+ | | +-------------> +---------------+
| |
| |
| | +---------------+
| +----------------------> | Slave |
| | Interface |
| | 2 |
| | |
+----------------------------> | R |
| (Data) |
+---------------+
Example 4: Stereo Stream with L and R channel is rendered by two different
Ports of the Master and is received by only single Port of the Slave
interface. ::
+--------------------+
| |
| +--------------+ +----------------+
| | || | |
| | Data Port || L Channel | |
| | 1 |------------+ | |
| | L Channel || | +-----+----+ |
| | (Data) || | L + R Channel || Data | |
| Master +----------+ | +---+---------> || Port | |
| Interface | | || 1 | |
| +--------------+ | || | |
| | || | +----------+ |
| | Data Port |------------+ | |
| | 2 || R Channel | Slave |
| | R Channel || | Interface |
| | (Data) || | 1 |
| +--------------+ Clock Signal | L + R |
| +---------------------------> | (Data) |
+--------------------+ | |
+----------------+
SoundWire Stream Management flow
================================
Stream definitions
------------------
(1) Current stream: This is classified as the stream on which operation has
to be performed like prepare, enable, disable, de-prepare etc.
(2) Active stream: This is classified as the stream which is already active
on Bus other than current stream. There can be multiple active streams
on the Bus.
SoundWire Bus manages stream operations for each stream getting
rendered/captured on the SoundWire Bus. This section explains Bus operations
done for each of the stream allocated/released on Bus. Following are the
stream states maintained by the Bus for each of the audio stream.
SoundWire stream states
-----------------------
Below shows the SoundWire stream states and state transition diagram. ::
+-----------+ +------------+ +----------+ +----------+
| ALLOCATED +---->| CONFIGURED +---->| PREPARED +---->| ENABLED |
| STATE | | STATE | | STATE | | STATE |
+-----------+ +------------+ +----------+ +----+-----+
^
|
|
v
+----------+ +------------+ +----+-----+
| RELEASED |<----------+ DEPREPARED |<-------+ DISABLED |
| STATE | | STATE | | STATE |
+----------+ +------------+ +----------+
NOTE: State transition between prepare and deprepare is supported in Spec
but not in the software (subsystem)
NOTE2: Stream state transition checks need to be handled by caller
framework, for example ALSA/ASoC. No checks for stream transition exist in
SoundWire subsystem.
Stream State Operations
-----------------------
Below section explains the operations done by the Bus on Master(s) and
Slave(s) as part of stream state transitions.
SDW_STREAM_ALLOCATED
~~~~~~~~~~~~~~~~~~~~
Allocation state for stream. This is the entry state
of the stream. Operations performed before entering in this state:
(1) A stream runtime is allocated for the stream. This stream
runtime is used as a reference for all the operations performed
on the stream.
(2) The resources required for holding stream runtime information are
allocated and initialized. This holds all stream related information
such as stream type (PCM/PDM) and parameters, Master and Slave
interface associated with the stream, stream state etc.
After all above operations are successful, stream state is set to
``SDW_STREAM_ALLOCATED``.
Bus implements below API for allocate a stream which needs to be called once
per stream. From ASoC DPCM framework, this stream state maybe linked to
.startup() operation.
.. code-block:: c
int sdw_alloc_stream(char * stream_name);
SDW_STREAM_CONFIGURED
~~~~~~~~~~~~~~~~~~~~~
Configuration state of stream. Operations performed before entering in
this state:
(1) The resources allocated for stream information in SDW_STREAM_ALLOCATED
state are updated here. This includes stream parameters, Master(s)
and Slave(s) runtime information associated with current stream.
(2) All the Master(s) and Slave(s) associated with current stream provide
the port information to Bus which includes port numbers allocated by
Master(s) and Slave(s) for current stream and their channel mask.
After all above operations are successful, stream state is set to
``SDW_STREAM_CONFIGURED``.
Bus implements below APIs for CONFIG state which needs to be called by
the respective Master(s) and Slave(s) associated with stream. These APIs can
only be invoked once by respective Master(s) and Slave(s). From ASoC DPCM
framework, this stream state is linked to .hw_params() operation.
.. code-block:: c
int sdw_stream_add_master(struct sdw_bus * bus,
struct sdw_stream_config * stream_config,
struct sdw_ports_config * ports_config,
struct sdw_stream_runtime * stream);
int sdw_stream_add_slave(struct sdw_slave * slave,
struct sdw_stream_config * stream_config,
struct sdw_ports_config * ports_config,
struct sdw_stream_runtime * stream);
SDW_STREAM_PREPARED
~~~~~~~~~~~~~~~~~~~
Prepare state of stream. Operations performed before entering in this state:
(1) Bus parameters such as bandwidth, frame shape, clock frequency,
are computed based on current stream as well as already active
stream(s) on Bus. Re-computation is required to accommodate current
stream on the Bus.
(2) Transport and port parameters of all Master(s) and Slave(s) port(s) are
computed for the current as well as already active stream based on frame
shape and clock frequency computed in step 1.
(3) Computed Bus and transport parameters are programmed in Master(s) and
Slave(s) registers. The banked registers programming is done on the
alternate bank (bank currently unused). Port(s) are enabled for the
already active stream(s) on the alternate bank (bank currently unused).
This is done in order to not disrupt already active stream(s).
(4) Once all the values are programmed, Bus initiates switch to alternate
bank where all new values programmed gets into effect.
(5) Ports of Master(s) and Slave(s) for current stream are prepared by
programming PrepareCtrl register.
After all above operations are successful, stream state is set to
``SDW_STREAM_PREPARED``.
Bus implements below API for PREPARE state which needs to be called once per
stream. From ASoC DPCM framework, this stream state is linked to
.prepare() operation.
.. code-block:: c
int sdw_prepare_stream(struct sdw_stream_runtime * stream);
SDW_STREAM_ENABLED
~~~~~~~~~~~~~~~~~~
Enable state of stream. The data port(s) are enabled upon entering this state.
Operations performed before entering in this state:
(1) All the values computed in SDW_STREAM_PREPARED state are programmed
in alternate bank (bank currently unused). It includes programming of
already active stream(s) as well.
(2) All the Master(s) and Slave(s) port(s) for the current stream are
enabled on alternate bank (bank currently unused) by programming
ChannelEn register.
(3) Once all the values are programmed, Bus initiates switch to alternate
bank where all new values programmed gets into effect and port(s)
associated with current stream are enabled.
After all above operations are successful, stream state is set to
``SDW_STREAM_ENABLED``.
Bus implements below API for ENABLE state which needs to be called once per
stream. From ASoC DPCM framework, this stream state is linked to
.trigger() start operation.
.. code-block:: c
int sdw_enable_stream(struct sdw_stream_runtime * stream);
SDW_STREAM_DISABLED
~~~~~~~~~~~~~~~~~~~
Disable state of stream. The data port(s) are disabled upon exiting this state.
Operations performed before entering in this state:
(1) All the Master(s) and Slave(s) port(s) for the current stream are
disabled on alternate bank (bank currently unused) by programming
ChannelEn register.
(2) All the current configuration of Bus and active stream(s) are programmed
into alternate bank (bank currently unused).
(3) Once all the values are programmed, Bus initiates switch to alternate
bank where all new values programmed gets into effect and port(s) associated
with current stream are disabled.
After all above operations are successful, stream state is set to
``SDW_STREAM_DISABLED``.
Bus implements below API for DISABLED state which needs to be called once
per stream. From ASoC DPCM framework, this stream state is linked to
.trigger() stop operation.
.. code-block:: c
int sdw_disable_stream(struct sdw_stream_runtime * stream);
SDW_STREAM_DEPREPARED
~~~~~~~~~~~~~~~~~~~~~
De-prepare state of stream. Operations performed before entering in this
state:
(1) All the port(s) of Master(s) and Slave(s) for current stream are
de-prepared by programming PrepareCtrl register.
(2) The payload bandwidth of current stream is reduced from the total
bandwidth requirement of bus and new parameters calculated and
applied by performing bank switch etc.
After all above operations are successful, stream state is set to
``SDW_STREAM_DEPREPARED``.
Bus implements below API for DEPREPARED state which needs to be called once
per stream. From ASoC DPCM framework, this stream state is linked to
.trigger() stop operation.
.. code-block:: c
int sdw_deprepare_stream(struct sdw_stream_runtime * stream);
SDW_STREAM_RELEASED
~~~~~~~~~~~~~~~~~~~
Release state of stream. Operations performed before entering in this state:
(1) Release port resources for all Master(s) and Slave(s) port(s)
associated with current stream.
(2) Release Master(s) and Slave(s) runtime resources associated with
current stream.
(3) Release stream runtime resources associated with current stream.
After all above operations are successful, stream state is set to
``SDW_STREAM_RELEASED``.
Bus implements below APIs for RELEASE state which needs to be called by
all the Master(s) and Slave(s) associated with stream. From ASoC DPCM
framework, this stream state is linked to .hw_free() operation.
.. code-block:: c
int sdw_stream_remove_master(struct sdw_bus * bus,
struct sdw_stream_runtime * stream);
int sdw_stream_remove_slave(struct sdw_slave * slave,
struct sdw_stream_runtime * stream);
The .shutdown() ASoC DPCM operation calls below Bus API to release
stream assigned as part of ALLOCATED state.
In .shutdown() the data structure maintaining stream state are freed up.
.. code-block:: c
void sdw_release_stream(struct sdw_stream_runtime * stream);
Not Supported
=============
1. A single port with multiple channels supported cannot be used between two
streams or across stream. For example a port with 4 channels cannot be used
to handle 2 independent stereo streams even though it's possible in theory
in SoundWire.