Merge tag 'usb-for-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/balbi/usb into usb-testing

Felipe writes:

usb: changes for v4.13 merge window

This time around we have a total of 57 non-merge commits. A list of
most important changes follows:

- Improvements to dwc3 tracing interface
- Initial dual-role support for dwc3
- Improvements to how we handle DMA resources in dwc3
- A new f_uac1 implementation which much more flexible
- Removal of AVR32 bits
- Improvements to f_mass_storage driver

4 files changed, 997 insertions, 0 deletions

diff --git a/Documentation/driver-api/usb/dwc3.rst b/Documentation/driver-api/usb/dwc3.rst
new file mode 100644
index 000000000000..c3dc84a50ce5
--- /dev/null
+++ b/Documentation/driver-api/usb/dwc3.rst
@@ -0,0 +1,712 @@
+===============================================================
+Synopsys DesignWare Core SuperSpeed USB 3.0 Controller
+===============================================================
+
+:Author: Felipe Balbi <felipe.balbi@linux.intel.com>
+:Date: April 2017
+
+Introduction
+============
+
+The *Synopsys DesignWare Core SuperSpeed USB 3.0 Controller*
+(hereinafter referred to as *DWC3*) is a USB SuperSpeed compliant
+controller which can be configured in one of 4 ways:
+
+	1. Peripheral-only configuration
+	2. Host-only configuration
+	3. Dual-Role configuration
+	4. Hub configuration
+
+Linux currently supports several versions of this controller. In all
+likelyhood, the version in your SoC is already supported. At the time
+of this writing, known tested versions range from 2.02a to 3.10a. As a
+rule of thumb, anything above 2.02a should work reliably well.
+
+Currently, we have many known users for this driver. In alphabetical
+order:
+
+	1. Cavium
+	2. Intel Corporation
+	3. Qualcomm
+	4. Rockchip
+	5. ST
+	6. Samsung
+	7. Texas Instruments
+	8. Xilinx
+
+Summary of Features
+======================
+
+For details about features supported by your version of DWC3, consult
+your IP team and/or *Synopsys DesignWare Core SuperSpeed USB 3.0
+Controller Databook*. Following is a list of features supported by the
+driver at the time of this writing:
+
+	1. Up to 16 bidirectional endpoints (including the control
+	   pipe - ep0)
+	2. Flexible endpoint configuration
+	3. Simultaneous IN and OUT transfer support
+	4. Scatter-list support
+	5. Up to 256 TRBs [#trb]_ per endpoint
+	6. Support for all transfer types (*Control*, *Bulk*,
+	   *Interrupt*, and *Isochronous*)
+	7. SuperSpeed Bulk Streams
+	8. Link Power Management
+	9. Trace Events for debugging
+	10. DebugFS [#debugfs]_ interface
+
+These features have all been exercised with many of the **in-tree**
+gadget drivers. We have verified both *ConfigFS* [#configfs]_ and
+legacy gadget drivers.
+
+Driver Design
+==============
+
+The DWC3 driver sits on the *drivers/usb/dwc3/* directory. All files
+related to this driver are in this one directory. This makes it easy
+for new-comers to read the code and understand how it behaves.
+
+Because of DWC3's configuration flexibility, the driver is a little
+complex in some places but it should be rather straightforward to
+understand.
+
+The biggest part of the driver refers to the Gadget API.
+
+Known Limitations
+===================
+
+Like any other HW, DWC3 has its own set of limitations. To avoid
+constant questions about such problems, we decided to document them
+here and have a single location to where we could point users.
+
+OUT Transfer Size Requirements
+---------------------------------
+
+According to Synopsys Databook, all OUT transfer TRBs [#trb]_ must
+have their *size* field set to a value which is integer divisible by
+the endpoint's *wMaxPacketSize*. This means that *e.g.* in order to
+receive a Mass Storage *CBW* [#cbw]_, req->length must either be set
+to a value that's divisible by *wMaxPacketSize* (1024 on SuperSpeed,
+512 on HighSpeed, etc), or DWC3 driver must add a Chained TRB pointing
+to a throw-away buffer for the remaining length. Without this, OUT
+transfers will **NOT** start.
+
+Note that as of this writing, this won't be a problem because DWC3 is
+fully capable of appending a chained TRB for the remaining length and
+completely hide this detail from the gadget driver. It's still worth
+mentioning because this seems to be the largest source of queries
+about DWC3 and *non-working transfers*.
+
+TRB Ring Size Limitation
+-------------------------
+
+We, currently, have a hard limit of 256 TRBs [#trb]_ per endpoint,
+with the last TRB being a Link TRB [#link_trb]_ pointing back to the
+first. This limit is arbitrary but it has the benefit of adding up to
+exactly 4096 bytes, or 1 Page.
+
+DWC3 driver will try its best to cope with more than 255 requests and,
+for the most part, it should work normally. However this is not
+something that has been exercised very frequently. If you experience
+any problems, see section **Reporting Bugs** below.
+
+Reporting Bugs
+================
+
+Whenever you encounter a problem with DWC3, first and foremost you
+should make sure that:
+
+	1. You're running latest tag from `Linus' tree`_
+	2. You can reproduce the error without any out-of-tree changes
+	   to DWC3
+	3. You have checked that it's not a fault on the host machine
+
+After all these are verified, then here's how to capture enough
+information so we can be of any help to you.
+
+Required Information
+---------------------
+
+DWC3 relies exclusively on Trace Events for debugging. Everything is
+exposed there, with some extra bits being exposed to DebugFS
+[#debugfs]_.
+
+In order to capture DWC3's Trace Events you should run the following
+commands **before** plugging the USB cable to a host machine:
+
+.. code-block:: sh
+
+		 # mkdir -p /d
+		 # mkdir -p /t
+		 # mount -t debugfs none /d
+		 # mount -t tracefs none /t
+		 # echo 81920 > /t/buffer_size_kb
+		 # echo 1 > /t/events/dwc3/enable
+
+After this is done, you can connect your USB cable and reproduce the
+problem. As soon as the fault is reproduced, make a copy of files
+``trace`` and ``regdump``, like so:
+
+.. code-block:: sh
+
+		# cp /t/trace /root/trace.txt
+		# cat /d/*dwc3*/regdump > /root/regdump.txt
+
+Make sure to compress ``trace.txt`` and ``regdump.txt`` in a tarball
+and email it to `me`_ with `linux-usb`_ in Cc. If you want to be extra
+sure that I'll help you, write your subject line in the following
+format:
+
+	**[BUG REPORT] usb: dwc3: Bug while doing XYZ**
+
+On the email body, make sure to detail what you doing, which gadget
+driver you were using, how to reproduce the problem, what SoC you're
+using, which OS (and its version) was running on the Host machine.
+
+With all this information, we should be able to understand what's
+going on and be helpful to you.
+
+Debugging
+===========
+
+First and foremost a disclaimer::
+
+  DISCLAIMER: The information available on DebugFS and/or TraceFS can
+  change at any time at any Major Linux Kernel Release. If writing
+  scripts, do **NOT** assume information to be available in the
+  current format.
+
+With that out of the way, let's carry on.
+
+If you're willing to debug your own problem, you deserve a round of
+applause :-)
+
+Anyway, there isn't much to say here other than Trace Events will be
+really helpful in figuring out issues with DWC3. Also, access to
+Synopsys Databook will be **really** valuable in this case.
+
+A USB Sniffer can be helpful at times but it's not entirely required,
+there's a lot that can be understood without looking at the wire.
+
+Feel free to email `me`_ and Cc `linux-usb`_ if you need any help.
+
+``DebugFS``
+-------------
+
+``DebugFS`` is very good for gathering snapshots of what's going on
+with DWC3 and/or any endpoint.
+
+On DWC3's ``DebugFS`` directory, you will find the following files and
+directories:
+
+``ep[0..15]{in,out}/``
+``link_state``
+``regdump``
+``testmode``
+
+``link_state``
+``````````````
+
+When read, ``link_state`` will print out one of ``U0``, ``U1``,
+``U2``, ``U3``, ``SS.Disabled``, ``RX.Detect``, ``SS.Inactive``,
+``Polling``, ``Recovery``, ``Hot Reset``, ``Compliance``,
+``Loopback``, ``Reset``, ``Resume`` or ``UNKNOWN link state``.
+
+This file can also be written to in order to force link to one of the
+states above.
+
+``regdump``
+`````````````
+
+File name is self-explanatory. When read, ``regdump`` will print out a
+register dump of DWC3. Note that this file can be grepped to find the
+information you want.
+
+``testmode``
+``````````````
+
+When read, ``testmode`` will print out a name of one of the specified
+USB 2.0 Testmodes (``test_j``, ``test_k``, ``test_se0_nak``,
+``test_packet``, ``test_force_enable``) or the string ``no test`` in
+case no tests are currently being executed.
+
+In order to start any of these test modes, the same strings can be
+written to the file and DWC3 will enter the requested test mode.
+
+
+``ep[0..15]{in,out}``
+``````````````````````
+
+For each endpoint we expose one directory following the naming
+convention ``ep$num$dir`` *(ep0in, ep0out, ep1in, ...)*. Inside each
+of these directories you will find the following files:
+
+``descriptor_fetch_queue``
+``event_queue``
+``rx_fifo_queue``
+``rx_info_queue``
+``rx_request_queue``
+``transfer_type``
+``trb_ring``
+``tx_fifo_queue``
+``tx_request_queue``
+
+With access to Synopsys Databook, you can decode the information on
+them.
+
+``transfer_type``
+~~~~~~~~~~~~~~~~~~
+
+When read, ``transfer_type`` will print out one of ``control``,
+``bulk``, ``interrupt`` or ``isochronous`` depending on what the
+endpoint descriptor says. If the endpoint hasn't been enabled yet, it
+will print ``--``.
+
+``trb_ring``
+~~~~~~~~~~~~~
+
+When read, ``trb_ring`` will print out details about all TRBs on the
+ring. It will also tell you where our enqueue and dequeue pointers are
+located in the ring:
+
+.. code-block:: sh
+   
+		buffer_addr,size,type,ioc,isp_imi,csp,chn,lst,hwo
+		000000002c754000,481,normal,1,0,1,0,0,0         
+		000000002c75c000,481,normal,1,0,1,0,0,0         
+		000000002c780000,481,normal,1,0,1,0,0,0         
+		000000002c788000,481,normal,1,0,1,0,0,0         
+		000000002c78c000,481,normal,1,0,1,0,0,0         
+		000000002c754000,481,normal,1,0,1,0,0,0         
+		000000002c75c000,481,normal,1,0,1,0,0,0         
+		000000002c784000,481,normal,1,0,1,0,0,0         
+		000000002c788000,481,normal,1,0,1,0,0,0         
+		000000002c78c000,481,normal,1,0,1,0,0,0         
+		000000002c790000,481,normal,1,0,1,0,0,0         
+		000000002c758000,481,normal,1,0,1,0,0,0         
+		000000002c780000,481,normal,1,0,1,0,0,0         
+		000000002c788000,481,normal,1,0,1,0,0,0         
+		000000002c790000,481,normal,1,0,1,0,0,0         
+		000000002c758000,481,normal,1,0,1,0,0,0         
+		000000002c780000,481,normal,1,0,1,0,0,0         
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+		000000002c78c000,481,normal,1,0,1,0,0,0         
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+		000000002c758000,481,normal,1,0,1,0,0,0         
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+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		0000000000000000,0,UNKNOWN,0,0,0,0,0,0         
+		00000000381ab000,0,link,0,0,0,0,0,1
+
+
+Trace Events
+-------------
+
+DWC3 also provides several trace events which help us gathering
+information about the behavior of the driver during runtime.
+
+In order to use these events, you must enable ``CONFIG_FTRACE`` in
+your kernel config.
+
+For details about how enable DWC3 events, see section **Reporting
+Bugs**.
+
+The following subsections will give details about each Event Class and
+each Event defined by DWC3.
+
+MMIO
+```````
+
+It is sometimes useful to look at every MMIO access when looking for
+bugs. Because of that, DWC3 offers two Trace Events (one for
+dwc3_readl() and one for dwc3_writel()). ``TP_printk`` follows::
+
+  TP_printk("addr %p value %08x", __entry->base + __entry->offset,
+  		__entry->value)
+
+Interrupt Events
+````````````````
+
+Every IRQ event can be logged and decoded into a human readable
+string. Because every event will be different, we don't give an
+example other than the ``TP_printk`` format used::
+
+  TP_printk("event (%08x): %s", __entry->event,
+  		dwc3_decode_event(__entry->event, __entry->ep0state))
+
+Control Request
+`````````````````
+
+Every USB Control Request can be logged to the trace buffer. The
+output format is::
+
+  TP_printk("%s", dwc3_decode_ctrl(__entry->bRequestType,
+  				__entry->bRequest, __entry->wValue,
+  				__entry->wIndex, __entry->wLength)
+  )
+
+Note that Standard Control Requests will be decoded into
+human-readable strings with their respective arguments. Class and
+Vendor requests will be printed out a sequence of 8 bytes in hex
+format.
+
+Lifetime of a ``struct usb_request``
+```````````````````````````````````````
+
+The entire lifetime of a ``struct usb_request`` can be tracked on the
+trace buffer. We have one event for each of allocation, free,
+queueing, dequeueing, and giveback. Output format is::
+
+  TP_printk("%s: req %p length %u/%u %s%s%s ==> %d",
+  	__get_str(name), __entry->req, __entry->actual, __entry->length,
+  	__entry->zero ? "Z" : "z",
+  	__entry->short_not_ok ? "S" : "s",
+  	__entry->no_interrupt ? "i" : "I",
+  	__entry->status
+  )
+
+Generic Commands
+````````````````````
+
+We can log and decode every Generic Command with its completion
+code. Format is::
+
+  TP_printk("cmd '%s' [%x] param %08x --> status: %s",
+  	dwc3_gadget_generic_cmd_string(__entry->cmd),
+  	__entry->cmd, __entry->param,
+  	dwc3_gadget_generic_cmd_status_string(__entry->status)
+  )
+
+Endpoint Commands
+````````````````````
+
+Endpoints commands can also be logged together with completion
+code. Format is::
+
+  TP_printk("%s: cmd '%s' [%d] params %08x %08x %08x --> status: %s",
+  	__get_str(name), dwc3_gadget_ep_cmd_string(__entry->cmd),
+  	__entry->cmd, __entry->param0,
+  	__entry->param1, __entry->param2,
+  	dwc3_ep_cmd_status_string(__entry->cmd_status)
+  )
+
+Lifetime of a ``TRB``
+``````````````````````
+
+A ``TRB`` Lifetime is simple. We are either preparing a ``TRB`` or
+completing it. With these two events, we can see how a ``TRB`` changes
+over time. Format is::
+
+  TP_printk("%s: %d/%d trb %p buf %08x%08x size %s%d ctrl %08x (%c%c%c%c:%c%c:%s)",
+  	__get_str(name), __entry->queued, __entry->allocated,
+  	__entry->trb, __entry->bph, __entry->bpl,
+  	({char *s;
+  	int pcm = ((__entry->size >> 24) & 3) + 1;
+  	switch (__entry->type) {
+  	case USB_ENDPOINT_XFER_INT:
+  	case USB_ENDPOINT_XFER_ISOC:
+  		switch (pcm) {
+  		case 1:
+  			s = "1x ";
+  			break;
+  		case 2:
+  			s = "2x ";
+  			break;
+  		case 3:
+  			s = "3x ";
+  			break;
+  		}
+  	default:
+  		s = "";
+  	} s; }),
+  	DWC3_TRB_SIZE_LENGTH(__entry->size), __entry->ctrl,
+  	__entry->ctrl & DWC3_TRB_CTRL_HWO ? 'H' : 'h',
+  	__entry->ctrl & DWC3_TRB_CTRL_LST ? 'L' : 'l',
+  	__entry->ctrl & DWC3_TRB_CTRL_CHN ? 'C' : 'c',
+  	__entry->ctrl & DWC3_TRB_CTRL_CSP ? 'S' : 's',
+  	__entry->ctrl & DWC3_TRB_CTRL_ISP_IMI ? 'S' : 's',
+  	__entry->ctrl & DWC3_TRB_CTRL_IOC ? 'C' : 'c',
+      dwc3_trb_type_string(DWC3_TRBCTL_TYPE(__entry->ctrl))
+  )  
+
+Lifetime of an Endpoint
+```````````````````````
+
+And endpoint's lifetime is summarized with enable and disable
+operations, both of which can be traced. Format is::
+
+  TP_printk("%s: mps %d/%d streams %d burst %d ring %d/%d flags %c:%c%c%c%c%c:%c:%c",
+  	__get_str(name), __entry->maxpacket,
+  	__entry->maxpacket_limit, __entry->max_streams,
+  	__entry->maxburst, __entry->trb_enqueue,
+  	__entry->trb_dequeue,
+  	__entry->flags & DWC3_EP_ENABLED ? 'E' : 'e',
+  	__entry->flags & DWC3_EP_STALL ? 'S' : 's',
+  	__entry->flags & DWC3_EP_WEDGE ? 'W' : 'w',
+  	__entry->flags & DWC3_EP_BUSY ? 'B' : 'b',
+  	__entry->flags & DWC3_EP_PENDING_REQUEST ? 'P' : 'p',
+  	__entry->flags & DWC3_EP_MISSED_ISOC ? 'M' : 'm',
+  	__entry->flags & DWC3_EP_END_TRANSFER_PENDING ? 'E' : 'e',
+  	__entry->direction ? '<' : '>'
+  )
+
+
+Structures, Methods and Definitions
+====================================
+
+.. kernel-doc:: drivers/usb/dwc3/core.h
+   :doc: main data structures
+   :internal:
+
+.. kernel-doc:: drivers/usb/dwc3/gadget.h
+   :doc: gadget-only helpers
+   :internal:
+
+.. kernel-doc:: drivers/usb/dwc3/gadget.c
+   :doc: gadget-side implementation
+   :internal:
+
+.. kernel-doc:: drivers/usb/dwc3/core.c
+   :doc: core driver (probe, PM, etc)
+   :internal:
+   
+.. [#trb] Transfer Request Block
+.. [#link_trb] Transfer Request Block pointing to another Transfer
+	       Request Block.
+.. [#debugfs] The Debug File System
+.. [#configfs] The Config File System
+.. [#cbw] Command Block Wrapper
+.. _Linus' tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
+.. _me: felipe.balbi@linux.intel.com
+.. _linux-usb: linux-usb@vger.kernel.org
diff --git a/Documentation/driver-api/usb/index.rst b/Documentation/driver-api/usb/index.rst
index 1bf64edc8c8a..8fe995a1ec94 100644
--- a/Documentation/driver-api/usb/index.rst
+++ b/Documentation/driver-api/usb/index.rst
@@ -16,7 +16,10 @@ Linux USB API
    persist
    error-codes
    writing_usb_driver
+   dwc3
    writing_musb_glue_layer
+   typec
+   usb3-debug-port
 
 .. only::  subproject and html
 
diff --git a/Documentation/driver-api/usb/typec.rst b/Documentation/driver-api/usb/typec.rst
new file mode 100644
index 000000000000..8a7249f2ff04
--- /dev/null
+++ b/Documentation/driver-api/usb/typec.rst
@@ -0,0 +1,182 @@
+
+USB Type-C connector class
+==========================
+
+Introduction
+------------
+
+The typec class is meant for describing the USB Type-C ports in a system to the
+user space in unified fashion. The class is designed to provide nothing else
+except the user space interface implementation in hope that it can be utilized
+on as many platforms as possible.
+
+The platforms are expected to register every USB Type-C port they have with the
+class. In a normal case the registration will be done by a USB Type-C or PD PHY
+driver, but it may be a driver for firmware interface such as UCSI, driver for
+USB PD controller or even driver for Thunderbolt3 controller. This document
+considers the component registering the USB Type-C ports with the class as "port
+driver".
+
+On top of showing the capabilities, the class also offer user space control over
+the roles and alternate modes of ports, partners and cable plugs when the port
+driver is capable of supporting those features.
+
+The class provides an API for the port drivers described in this document. The
+attributes are described in Documentation/ABI/testing/sysfs-class-typec.
+
+User space interface
+--------------------
+Every port will be presented as its own device under /sys/class/typec/. The
+first port will be named "port0", the second "port1" and so on.
+
+When connected, the partner will be presented also as its own device under
+/sys/class/typec/. The parent of the partner device will always be the port it
+is attached to. The partner attached to port "port0" will be named
+"port0-partner". Full path to the device would be
+/sys/class/typec/port0/port0-partner/.
+
+The cable and the two plugs on it may also be optionally presented as their own
+devices under /sys/class/typec/. The cable attached to the port "port0" port
+will be named port0-cable and the plug on the SOP Prime end (see USB Power
+Delivery Specification ch. 2.4) will be named "port0-plug0" and on the SOP
+Double Prime end "port0-plug1". The parent of a cable will always be the port,
+and the parent of the cable plugs will always be the cable.
+
+If the port, partner or cable plug supports Alternate Modes, every supported
+Alternate Mode SVID will have their own device describing them. Note that the
+Alternate Mode devices will not be attached to the typec class. The parent of an
+alternate mode will be the device that supports it, so for example an alternate
+mode of port0-partner will be presented under /sys/class/typec/port0-partner/.
+Every mode that is supported will have its own group under the Alternate Mode
+device named "mode<index>", for example /sys/class/typec/port0/<alternate
+mode>/mode1/. The requests for entering/exiting a mode can be done with "active"
+attribute file in that group.
+
+Driver API
+----------
+
+Registering the ports
+~~~~~~~~~~~~~~~~~~~~~
+
+The port drivers will describe every Type-C port they control with struct
+typec_capability data structure, and register them with the following API:
+
+.. kernel-doc:: drivers/usb/typec/typec.c
+   :functions: typec_register_port typec_unregister_port
+
+When registering the ports, the prefer_role member in struct typec_capability
+deserves special notice. If the port that is being registered does not have
+initial role preference, which means the port does not execute Try.SNK or
+Try.SRC by default, the member must have value TYPEC_NO_PREFERRED_ROLE.
+Otherwise if the port executes Try.SNK by default, the member must have value
+TYPEC_DEVICE, and with Try.SRC the value must be TYPEC_HOST.
+
+Registering Partners
+~~~~~~~~~~~~~~~~~~~~
+
+After successful connection of a partner, the port driver needs to register the
+partner with the class. Details about the partner need to be described in struct
+typec_partner_desc. The class copies the details of the partner during
+registration. The class offers the following API for registering/unregistering
+partners.
+
+.. kernel-doc:: drivers/usb/typec/typec.c
+   :functions: typec_register_partner typec_unregister_partner
+
+The class will provide a handle to struct typec_partner if the registration was
+successful, or NULL.
+
+If the partner is USB Power Delivery capable, and the port driver is able to
+show the result of Discover Identity command, the partner descriptor structure
+should include handle to struct usb_pd_identity instance. The class will then
+create a sysfs directory for the identity under the partner device. The result
+of Discover Identity command can then be reported with the following API:
+
+.. kernel-doc:: drivers/usb/typec/typec.c
+   :functions: typec_partner_set_identity
+
+Registering Cables
+~~~~~~~~~~~~~~~~~~
+
+After successful connection of a cable that supports USB Power Delivery
+Structured VDM "Discover Identity", the port driver needs to register the cable
+and one or two plugs, depending if there is CC Double Prime controller present
+in the cable or not. So a cable capable of SOP Prime communication, but not SOP
+Double Prime communication, should only have one plug registered. For more
+information about SOP communication, please read chapter about it from the
+latest USB Power Delivery specification.
+
+The plugs are represented as their own devices. The cable is registered first,
+followed by registration of the cable plugs. The cable will be the parent device
+for the plugs. Details about the cable need to be described in struct
+typec_cable_desc and about a plug in struct typec_plug_desc. The class copies
+the details during registration. The class offers the following API for
+registering/unregistering cables and their plugs:
+
+.. kernel-doc:: drivers/usb/typec/typec.c
+   :functions: typec_register_cable typec_unregister_cable typec_register_plug typec_unregister_plug
+
+The class will provide a handle to struct typec_cable and struct typec_plug if
+the registration is successful, or NULL if it isn't.
+
+If the cable is USB Power Delivery capable, and the port driver is able to show
+the result of Discover Identity command, the cable descriptor structure should
+include handle to struct usb_pd_identity instance. The class will then create a
+sysfs directory for the identity under the cable device. The result of Discover
+Identity command can then be reported with the following API:
+
+.. kernel-doc:: drivers/usb/typec/typec.c
+   :functions: typec_cable_set_identity
+
+Notifications
+~~~~~~~~~~~~~
+
+When the partner has executed a role change, or when the default roles change
+during connection of a partner or cable, the port driver must use the following
+APIs to report it to the class:
+
+.. kernel-doc:: drivers/usb/typec/typec.c
+   :functions: typec_set_data_role typec_set_pwr_role typec_set_vconn_role typec_set_pwr_opmode
+
+Alternate Modes
+~~~~~~~~~~~~~~~
+
+USB Type-C ports, partners and cable plugs may support Alternate Modes. Each
+Alternate Mode will have identifier called SVID, which is either a Standard ID
+given by USB-IF or vendor ID, and each supported SVID can have 1 - 6 modes. The
+class provides struct typec_mode_desc for describing individual mode of a SVID,
+and struct typec_altmode_desc which is a container for all the supported modes.
+
+Ports that support Alternate Modes need to register each SVID they support with
+the following API:
+
+.. kernel-doc:: drivers/usb/typec/typec.c
+   :functions: typec_port_register_altmode
+
+If a partner or cable plug provides a list of SVIDs as response to USB Power
+Delivery Structured VDM Discover SVIDs message, each SVID needs to be
+registered.
+
+API for the partners:
+
+.. kernel-doc:: drivers/usb/typec/typec.c
+   :functions: typec_partner_register_altmode
+
+API for the Cable Plugs:
+
+.. kernel-doc:: drivers/usb/typec/typec.c
+   :functions: typec_plug_register_altmode
+
+So ports, partners and cable plugs will register the alternate modes with their
+own functions, but the registration will always return a handle to struct
+typec_altmode on success, or NULL. The unregistration will happen with the same
+function:
+
+.. kernel-doc:: drivers/usb/typec/typec.c
+   :functions: typec_unregister_altmode
+
+If a partner or cable plug enters or exits a mode, the port driver needs to
+notify the class with the following API:
+
+.. kernel-doc:: drivers/usb/typec/typec.c
+   :functions: typec_altmode_update_active
diff --git a/Documentation/driver-api/usb/usb3-debug-port.rst b/Documentation/driver-api/usb/usb3-debug-port.rst
new file mode 100644
index 000000000000..feb1a36a65b7
--- /dev/null
+++ b/Documentation/driver-api/usb/usb3-debug-port.rst
@@ -0,0 +1,100 @@
+===============
+USB3 debug port
+===============
+
+:Author: Lu Baolu <baolu.lu@linux.intel.com>
+:Date: March 2017
+
+GENERAL
+=======
+
+This is a HOWTO for using the USB3 debug port on x86 systems.
+
+Before using any kernel debugging functionality based on USB3
+debug port, you need to::
+
+	1) check whether any USB3 debug port is available in
+	   your system;
+	2) check which port is used for debugging purposes;
+	3) have a USB 3.0 super-speed A-to-A debugging cable.
+
+INTRODUCTION
+============
+
+The xHCI debug capability (DbC) is an optional but standalone
+functionality provided by the xHCI host controller. The xHCI
+specification describes DbC in the section 7.6.
+
+When DbC is initialized and enabled, it will present a debug
+device through the debug port (normally the first USB3
+super-speed port). The debug device is fully compliant with
+the USB framework and provides the equivalent of a very high
+performance full-duplex serial link between the debug target
+(the system under debugging) and a debug host.
+
+EARLY PRINTK
+============
+
+DbC has been designed to log early printk messages. One use for
+this feature is kernel debugging. For example, when your machine
+crashes very early before the regular console code is initialized.
+Other uses include simpler, lockless logging instead of a full-
+blown printk console driver and klogd.
+
+On the debug target system, you need to customize a debugging
+kernel with CONFIG_EARLY_PRINTK_USB_XDBC enabled. And, add below
+kernel boot parameter::
+
+	"earlyprintk=xdbc"
+
+If there are multiple xHCI controllers in your system, you can
+append a host contoller index to this kernel parameter. This
+index starts from 0.
+
+Current design doesn't support DbC runtime suspend/resume. As
+the result, you'd better disable runtime power management for
+USB subsystem by adding below kernel boot parameter::
+
+	"usbcore.autosuspend=-1"
+
+Before starting the debug target, you should connect the debug
+port to a USB port (root port or port of any external hub) on
+the debug host. The cable used to connect these two ports
+should be a USB 3.0 super-speed A-to-A debugging cable.
+
+During early boot of the debug target, DbC will be detected and
+initialized. After initialization, the debug host should be able
+to enumerate the debug device in debug target. The debug host
+will then bind the debug device with the usb_debug driver module
+and create the /dev/ttyUSB device.
+
+If the debug device enumeration goes smoothly, you should be able
+to see below kernel messages on the debug host::
+
+	# tail -f /var/log/kern.log
+	[ 1815.983374] usb 4-3: new SuperSpeed USB device number 4 using xhci_hcd
+	[ 1815.999595] usb 4-3: LPM exit latency is zeroed, disabling LPM.
+	[ 1815.999899] usb 4-3: New USB device found, idVendor=1d6b, idProduct=0004
+	[ 1815.999902] usb 4-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
+	[ 1815.999903] usb 4-3: Product: Remote GDB
+	[ 1815.999904] usb 4-3: Manufacturer: Linux
+	[ 1815.999905] usb 4-3: SerialNumber: 0001
+	[ 1816.000240] usb_debug 4-3:1.0: xhci_dbc converter detected
+	[ 1816.000360] usb 4-3: xhci_dbc converter now attached to ttyUSB0
+
+You can use any communication program, for example minicom, to
+read and view the messages. Below simple bash scripts can help
+you to check the sanity of the setup.
+
+.. code-block:: sh
+
+	===== start of bash scripts =============
+	#!/bin/bash
+
+	while true ; do
+		while [ ! -d /sys/class/tty/ttyUSB0 ] ; do
+			:
+		done
+	cat /dev/ttyUSB0
+	done
+	===== end of bash scripts ===============