staging: ti dspbridge: add driver documentation

Add a README with a general overview of TI's DSP Bridge driver,
a short explanations of how error codes are currently used,
and a CONTRIBUTORS file with all past & present contributors.

For additional information about TI's DSP Bridge,
check out http://omapzoom.org/gf/project/omapbridge/docman/?subdir=3

Note: if by any chance we forgot to mention any contributor,
please let us know and we will fix that.
Signed-off-by: NOmar Ramirez Luna <omar.ramirez@ti.com>
Signed-off-by: NKanigeri, Hari <h-kanigeri2@ti.com>
Signed-off-by: NAmeya Palande <ameya.palande@nokia.com>
Signed-off-by: NGuzman Lugo, Fernando <fernando.lugo@ti.com>
Signed-off-by: NHebbar, Shivananda <x0hebbar@ti.com>
Signed-off-by: NRamos Falcon, Ernesto <ernesto@ti.com>
Signed-off-by: NFelipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: NAnna, Suman <s-anna@ti.com>
Signed-off-by: NGupta, Ramesh <grgupta@ti.com>
Signed-off-by: NGomez Castellanos, Ivan <ivan.gomez@ti.com>
Signed-off-by: NAndy Shevchenko <ext-andriy.shevchenko@nokia.com>
Signed-off-by: NArmando Uribe De Leon <x0095078@ti.com>
Signed-off-by: NDeepak Chitriki <deepak.chitriki@ti.com>
Signed-off-by: NMenon, Nishanth <nm@ti.com>
Signed-off-by: NPhil Carmody <ext-phil.2.carmody@nokia.com>
Signed-off-by: NOhad Ben-Cohen <ohad@wizery.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/staging/tidspbridge/Documentation/CONTRIBUTORS

+TI DSP/Bridge Driver - Contributors File
+
+The DSP/Bridge project wish to thank all of its contributors, current bridge
+driver is the result of the work of all of them. If any name is accidentally
+omitted, let us know by sending a mail to omar.ramirez@ti.com or
+x095840@ti.com.
+
+Please keep the following list in alphabetical order.
+
+	Suman Anna
+	Sripal Bagadia
+	Felipe Balbi
+	Ohad Ben-Cohen
+	Phil Carmody
+	Deepak Chitriki
+	Felipe Contreras
+	Hiroshi Doyu
+	Seth Forshee
+	Ivan Gomez Castellanos
+	Mark Grosen
+	Ramesh Gupta G
+	Fernando Guzman Lugo
+	Axel Haslam
+	Janet Head
+	Shivananda Hebbar
+	Hari Kanigeri
+	Tony Lindgren
+	Antonio Luna
+	Hari Nagalla
+	Nishanth Menon
+	Ameya Palande
+	Vijay Pasam
+	Gilbert Pitney
+	Omar Ramirez Luna
+	Ernesto Ramos
+	Chris Ring
+	Larry Schiefer
+	Rebecca Schultz Zavin
+	Bhavin Shah
+	Andy Shevchenko
+	Jeff Taylor
+	Roman Tereshonkov
+	Armando Uribe de Leon
+	Nischal Varide
+	Wenbiao Wang
+
+
+
+The following list was taken from file Revision History, if you recognize your
+alias or did any contribution to the project please let us now, so we can
+proper credit your work.
+
+	ag
+	ap
+	cc
+	db
+	dh4
+	dr
+	hp
+	jg
+	kc
+	kln
+	kw
+	ge
+	gv
+	map
+	mf
+	mk
+	mr
+	nn
+	rajesh
+	rg
+	rr
+	rt
+	sb
+	sg
+	sh
+	sp
+	srid
+	swa
+	vp
+	ww

drivers/staging/tidspbridge/Documentation/README

+                        Linux DSP/BIOS Bridge release
+
+DSP/BIOS Bridge overview
+========================
+
+DSP/BIOS Bridge is designed for platforms that contain a GPP and one or more
+attached DSPs.  The GPP is considered the master or "host" processor, and the
+attached DSPs are processing resources that can be utilized by applications
+and drivers running on the GPP.
+
+The abstraction that DSP/BIOS Bridge supplies, is a direct link between a GPP
+program and a DSP task.  This communication link is partitioned into two
+types of sub-links:  messaging (short, fixed-length packets) and data
+streaming (multiple, large buffers).  Each sub-link operates independently,
+and features in-order delivery of data, meaning that messages are delivered
+in the order they were submitted to the message link, and stream buffers are
+delivered in the order they were submitted to the stream link.
+
+In addition, a GPP client can specify what inputs and outputs a DSP task
+uses. DSP tasks typically use message objects for passing control and status
+information and stream objects for efficient streaming of real-time data.
+
+GPP Software Architecture
+=========================
+
+A GPP application communicates with its associated DSP task running on the
+DSP subsystem using the DSP/BIOS Bridge API. For example, a GPP audio
+application can use the API to pass messages to a DSP task that is managing
+data flowing from analog-to-digital converters (ADCs) to digital-to-analog
+converters (DACs).
+
+From the perspective of the GPP OS, the DSP is treated as just another
+peripheral device.   Most high level GPP OS typically support a device driver
+model, whereby applications can safely access and share a hardware peripheral
+through standard driver interfaces.  Therefore, to allow multiple GPP
+applications to share access to the DSP, the GPP side of DSP/BIOS Bridge
+implements a device driver for the DSP.
+
+Since driver interfaces are not always standard across GPP OS, and to provide
+some level of interoperability of application code using DSP/BIOS Bridge
+between GPP OS, DSP/BIOS Bridge provides a standard library of APIs which
+wrap calls into the device driver.   So, rather than calling GPP OS specific
+driver interfaces, applications (and even other device drivers) can use the
+standard API library directly.
+
+DSP Software Architecture
+=========================
+
+For DSP/BIOS, DSP/BIOS Bridge adds a device-independent streaming I/O (STRM)
+interface, a messaging interface (NODE), and a Resource Manager (RM) Server.
+The RM Server runs as a task of DSP/BIOS and is subservient to commands
+and queries from the GPP.  It executes commands to start and stop DSP signal
+processing nodes in response to GPP programs making requests through the
+(GPP-side) API.
+
+DSP tasks started by the RM Server are similar to any other DSP task with two
+important differences:  they must follow a specific task model consisting of
+three C-callable functions (node create, execute, and delete), with specific
+sets of arguments, and they have a pre-defined task environment established
+by the RM Server.
+
+Tasks started by the RM Server communicate using the STRM and NODE interfaces
+and act as servers for their corresponding GPP clients, performing signal
+processing functions as requested by messages sent by their GPP client.
+Typically, a DSP task moves data from source devices to sink devices using
+device independent I/O streams, performing application-specific processing
+and transformations on the data while it is moved.  For example, an audio
+task might perform audio decompression (ADPCM, MPEG, CELP) on data received
+from a GPP audio driver and then send the decompressed linear samples to a
+digital-to-analog converter.

drivers/staging/tidspbridge/Documentation/error-codes

+			DSP/Bridge Error Code Guide
+
+
+Success code is always taken as 0, except for one case where a success status
+different than 0 can be possible, this is when enumerating a series of dsp
+objects, if the enumeration doesn't have any more objects it is considered as a
+successful case. In this case a positive ENODATA is returned (TODO: Change to
+avoid this case).
+
+Error codes are returned as a negative 1, if an specific code is expected, it
+can be propagated to user space by reading errno symbol defined in errno.h, for
+specific details on the implementation a copy of the standard used should be
+read first.
+
+The error codes used by this driver are:
+
+[EPERM]
+    General driver failure.
+
+    According to the use case the following might apply:
+    - Device is in 'sleep/suspend' mode due to DPM.
+    - User cannot mark end of stream on an input channel.
+    - Requested operation is invalid for the node type.
+    - Invalid alignment for the node messaging buffer.
+    - The specified direction is invalid for the stream.
+    - Invalid stream mode.
+
+[ENOENT]
+    The specified object or file was not found.
+
+[ESRCH]
+    A shared memory buffer contained in a message or stream could not be mapped
+    to the GPP client process's virtual space.
+
+[EIO]
+    Driver interface I/O error.
+
+    or:
+    - Unable to plug channel ISR for configured IRQ.
+    - No free I/O request packets are available.
+
+[ENXIO]
+    Unable to find a named section in DSP executable or a non-existent memory
+    segment identifier was specified.
+
+[EBADF]
+    General error for file handling:
+
+    - Unable to open file.
+    - Unable to read file.
+    - An error occurred while parsing the DSP executable file.
+
+[ENOMEM]
+    A memory allocation failure occurred.
+
+[EACCES]
+    - Unable to read content of DCD data section; this is typically caused by
+    improperly configured nodes.
+    - Unable to decode DCD data section content; this is typically caused by
+    changes to DSP/BIOS Bridge data structures.
+    - Unable to get pointer to DCD data section; this is typically caused by
+    improperly configured UUIDs.
+    - Unable to load file containing DCD data section; this is typically
+    caused by a missing COFF file.
+    - The specified COFF file does not contain a valid node registration
+    section.
+
+[EFAULT]
+    Invalid pointer or handler.
+
+[EEXIST]
+    Attempted to create a channel manager  when one already exists.
+
+[EINVAL]
+    Invalid argument.
+
+[ESPIPE]
+    Symbol not found in the COFF file.  DSPNode_Create will return this if
+    the iAlg function table for an xDAIS socket is not found in the COFF file.
+    In this case, force the symbol to be linked into the COFF file.
+    DSPNode_Create, DSPNode_Execute, and DSPNode_Delete will return this if
+    the create, execute, or delete phase function, respectively, could not be
+    found in the COFF file.
+
+    - No symbol table is loaded/found for this board.
+    - Unable to initialize the ZL COFF parsing module.
+
+[EPIPE]
+    I/O is currently pending.
+
+    - End of stream was already requested on this output channel.
+
+[EDOM]
+    A parameter is specified outside its valid range.
+
+[ENOSYS]
+    The indicated operation is not supported.
+
+[EIDRM]
+    During enumeration a change in the number or properties of the objects
+    has occurred.
+
+[ECHRNG]
+    Attempt to created channel manager with too many channels or channel ID out
+    of range.
+
+[EBADR]
+    The state of the specified object is incorrect for the requested operation.
+
+    - Invalid segment ID.
+
+[ENODATA]
+    Unable to retrieve resource information from the registry.
+
+    - No more registry values.
+
+[ETIME]
+    A timeout occurred before the requested operation could complete.
+
+[ENOSR]
+    A stream has been issued the maximum number of buffers allowed in the
+    stream at once; buffers must be reclaimed from the stream before any more
+    can be issued.
+
+    - No free channels are available.
+
+[EILSEQ]
+    Error occurred in a dynamic loader library function.
+
+[EISCONN]
+    The Specified Connection already exists.
+
+[ENOTCONN]
+    Nodes not connected.
+
+[ETIMEDOUT]
+    Timeout occurred waiting for a response from the hardware.
+
+    - Wait for flush operation on an output channel timed out.
+
+[ECONNREFUSED]
+    No more connections can be made for this node.
+
+[EALREADY]
+    Channel is already in use.
+
+[EREMOTEIO]
+    dwTimeOut parameter was CHNL_IOCNOWAIT, yet no I/O completions were
+    queued.
+
+[ECANCELED]
+    I/O has been cancelled on this channel.
+
+[ENOKEY]
+    Invalid subkey parameter.
+
+    - UUID not found in registry.