coreboot-mirror
/
chrome-ec
mirror of https://review.coreboot.org/chrome-ec.git
1
0
Fork 0
Code Issues Releases Wiki Activity

USB Serial: Add README and update CCD docs 

The README points the reader back to the docs directory where the
CCD documentation lives.  I've added information about the install
script, and about how the raiden module identifies a CCD serial
console.

Signed-off-by: Anton Staaf <robotboy@chromium.org>

BRANCH=None
BUG=None
TEST=make buildall -j

Change-Id: I8714dffcad0b8c30f46529a8f2d670b5d432cda6
Reviewed-on: https://chromium-review.googlesource.com/352787
Commit-Ready: Anton Staaf <robotboy@chromium.org>
Tested-by: Anton Staaf <robotboy@chromium.org>
Reviewed-by: Anton Staaf <robotboy@chromium.org>
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
This commit is contained in:
Anton Staaf 2016-06-13 11:17:27 -07:00 committed by chrome-bot
parent 0201aa1620
commit 3a382417d1
2 changed files with 22 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
docs/case_closed_debugging.md
View File

@ -29,11 +29,13 @@ ChromiumOS SDK.
### Udev rules file
There is a udev rules file, `extra/usb_serial/51-google-serial.rules` that
should be installed in `/etc/udev/rules.d/` and udev should be told to reread
its rules.
its rules. This rules file can be installed using the
`extra/usb_serial/install` script.
### Kernel module
A trivial Linux kernel module that identifies case closed debug capable USB
interfaces can be found in `extra/usb_serial`.
interfaces can be found in `extra/usb_serial`. This module is also built and
installed using the `extra/usb_serial/install` script.
### ChromiumOS chroot
This is really only a requirement for using flashrom. If you only need access
@ -70,16 +72,21 @@ running kernel. It just adds an entry into the `usbserial` module's driver
table that causes `usbserial` to recognize any case closed debugging serial
console as a simple USB serial device. This addition has already made its way
into the upstream kernel (v3.19), so eventually this module can be removed.
The `Makefile` in the `extra/usb_serial` directory will build the kernel module
against the current running kernel, and `insmod raiden.ko` will install it.
If installation fails due to missing dependencies you need to
`modprobe usbserial` first.
The `extra/usb_serial/install` script will build and install the kernel module
as well as install the udev rules file.
An alternative to using this module is to install `usbserial` with
`modprobe usbserial vendor=<VID> product=<PID>`. The disadvantage of this method
is that it only works for an exact VID:PID match, and the module above does a
more detailed match of the USB descriptors to find interfaces that export the
Google simple serial vendor specific subclass.
If for some reason you can't or don't want to use the kernel module the install
script provides a --fallback option that will install a udev rules file and
helper script instead that will add each new CCD capable device that is
attached to the host to the list of devices that usbserial will handle. The
disadvantage of this method is that it will generate `/dev/ttyUSB*` entries for
any USB interface on the device that has an IN/OUT pair of bulk endpoints.
This results in extra `/dev/ttyUSB*` entries that should not be used because
they are actually I2C or SPI bridges.
The raiden module solves this by identifying a CCD serial port by the subclass
and protocol numbers of the USB device interface. This means that there does
not need to be a list of CCD capable device IDs anywhere.
Use
---

4
extra/usb_serial/README.md Normal file
View File

@ -0,0 +1,4 @@
Case Closed Debugging Serial Consoles over USB
==============================================
Please see the documentation in `../docs/case_closed_debugging.md`.