290 строки
11 KiB
ReStructuredText
290 строки
11 KiB
ReStructuredText
===============================
|
|
Linux Gadget Serial Driver v2.0
|
|
===============================
|
|
|
|
11/20/2004
|
|
|
|
(updated 8-May-2008 for v2.3)
|
|
|
|
|
|
License and Disclaimer
|
|
----------------------
|
|
This program is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU General Public License as
|
|
published by the Free Software Foundation; either version 2 of
|
|
the License, or (at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public
|
|
License along with this program; if not, write to the Free
|
|
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
|
|
MA 02111-1307 USA.
|
|
|
|
This document and the gadget serial driver itself are
|
|
Copyright (C) 2004 by Al Borchers (alborchers@steinerpoint.com).
|
|
|
|
If you have questions, problems, or suggestions for this driver
|
|
please contact Al Borchers at alborchers@steinerpoint.com.
|
|
|
|
|
|
Prerequisites
|
|
-------------
|
|
Versions of the gadget serial driver are available for the
|
|
2.4 Linux kernels, but this document assumes you are using
|
|
version 2.3 or later of the gadget serial driver in a 2.6
|
|
Linux kernel.
|
|
|
|
This document assumes that you are familiar with Linux and
|
|
Windows and know how to configure and build Linux kernels, run
|
|
standard utilities, use minicom and HyperTerminal, and work with
|
|
USB and serial devices. It also assumes you configure the Linux
|
|
gadget and usb drivers as modules.
|
|
|
|
With version 2.3 of the driver, major and minor device nodes are
|
|
no longer statically defined. Your Linux based system should mount
|
|
sysfs in /sys, and use "mdev" (in Busybox) or "udev" to make the
|
|
/dev nodes matching the sysfs /sys/class/tty files.
|
|
|
|
|
|
|
|
Overview
|
|
--------
|
|
The gadget serial driver is a Linux USB gadget driver, a USB device
|
|
side driver. It runs on a Linux system that has USB device side
|
|
hardware; for example, a PDA, an embedded Linux system, or a PC
|
|
with a USB development card.
|
|
|
|
The gadget serial driver talks over USB to either a CDC ACM driver
|
|
or a generic USB serial driver running on a host PC::
|
|
|
|
Host
|
|
--------------------------------------
|
|
| Host-Side CDC ACM USB Host |
|
|
| Operating | or | Controller | USB
|
|
| System | Generic USB | Driver |--------
|
|
| (Linux or | Serial | and | |
|
|
| Windows) Driver USB Stack | |
|
|
-------------------------------------- |
|
|
|
|
|
|
|
|
|
|
|
Gadget |
|
|
-------------------------------------- |
|
|
| Gadget USB Periph. | |
|
|
| Device-Side | Gadget | Controller | |
|
|
| Linux | Serial | Driver |--------
|
|
| Operating | Driver | and |
|
|
| System USB Stack |
|
|
--------------------------------------
|
|
|
|
On the device-side Linux system, the gadget serial driver looks
|
|
like a serial device.
|
|
|
|
On the host-side system, the gadget serial device looks like a
|
|
CDC ACM compliant class device or a simple vendor specific device
|
|
with bulk in and bulk out endpoints, and it is treated similarly
|
|
to other serial devices.
|
|
|
|
The host side driver can potentially be any ACM compliant driver
|
|
or any driver that can talk to a device with a simple bulk in/out
|
|
interface. Gadget serial has been tested with the Linux ACM driver,
|
|
the Windows usbser.sys ACM driver, and the Linux USB generic serial
|
|
driver.
|
|
|
|
With the gadget serial driver and the host side ACM or generic
|
|
serial driver running, you should be able to communicate between
|
|
the host and the gadget side systems as if they were connected by a
|
|
serial cable.
|
|
|
|
The gadget serial driver only provides simple unreliable data
|
|
communication. It does not yet handle flow control or many other
|
|
features of normal serial devices.
|
|
|
|
|
|
Installing the Gadget Serial Driver
|
|
-----------------------------------
|
|
To use the gadget serial driver you must configure the Linux gadget
|
|
side kernel for "Support for USB Gadgets", for a "USB Peripheral
|
|
Controller" (for example, net2280), and for the "Serial Gadget"
|
|
driver. All this are listed under "USB Gadget Support" when
|
|
configuring the kernel. Then rebuild and install the kernel or
|
|
modules.
|
|
|
|
Then you must load the gadget serial driver. To load it as an
|
|
ACM device (recommended for interoperability), do this::
|
|
|
|
modprobe g_serial
|
|
|
|
To load it as a vendor specific bulk in/out device, do this::
|
|
|
|
modprobe g_serial use_acm=0
|
|
|
|
This will also automatically load the underlying gadget peripheral
|
|
controller driver. This must be done each time you reboot the gadget
|
|
side Linux system. You can add this to the start up scripts, if
|
|
desired.
|
|
|
|
Your system should use mdev (from busybox) or udev to make the
|
|
device nodes. After this gadget driver has been set up you should
|
|
then see a /dev/ttyGS0 node::
|
|
|
|
# ls -l /dev/ttyGS0 | cat
|
|
crw-rw---- 1 root root 253, 0 May 8 14:10 /dev/ttyGS0
|
|
#
|
|
|
|
Note that the major number (253, above) is system-specific. If
|
|
you need to create /dev nodes by hand, the right numbers to use
|
|
will be in the /sys/class/tty/ttyGS0/dev file.
|
|
|
|
When you link this gadget driver early, perhaps even statically,
|
|
you may want to set up an /etc/inittab entry to run "getty" on it.
|
|
The /dev/ttyGS0 line should work like most any other serial port.
|
|
|
|
|
|
If gadget serial is loaded as an ACM device you will want to use
|
|
either the Windows or Linux ACM driver on the host side. If gadget
|
|
serial is loaded as a bulk in/out device, you will want to use the
|
|
Linux generic serial driver on the host side. Follow the appropriate
|
|
instructions below to install the host side driver.
|
|
|
|
|
|
Installing the Windows Host ACM Driver
|
|
--------------------------------------
|
|
To use the Windows ACM driver you must have the "linux-cdc-acm.inf"
|
|
file (provided along this document) which supports all recent versions
|
|
of Windows.
|
|
|
|
When the gadget serial driver is loaded and the USB device connected
|
|
to the Windows host with a USB cable, Windows should recognize the
|
|
gadget serial device and ask for a driver. Tell Windows to find the
|
|
driver in the folder that contains the "linux-cdc-acm.inf" file.
|
|
|
|
For example, on Windows XP, when the gadget serial device is first
|
|
plugged in, the "Found New Hardware Wizard" starts up. Select
|
|
"Install from a list or specific location (Advanced)", then on the
|
|
next screen select "Include this location in the search" and enter the
|
|
path or browse to the folder containing the "linux-cdc-acm.inf" file.
|
|
Windows will complain that the Gadget Serial driver has not passed
|
|
Windows Logo testing, but select "Continue anyway" and finish the
|
|
driver installation.
|
|
|
|
On Windows XP, in the "Device Manager" (under "Control Panel",
|
|
"System", "Hardware") expand the "Ports (COM & LPT)" entry and you
|
|
should see "Gadget Serial" listed as the driver for one of the COM
|
|
ports.
|
|
|
|
To uninstall the Windows XP driver for "Gadget Serial", right click
|
|
on the "Gadget Serial" entry in the "Device Manager" and select
|
|
"Uninstall".
|
|
|
|
|
|
Installing the Linux Host ACM Driver
|
|
------------------------------------
|
|
To use the Linux ACM driver you must configure the Linux host side
|
|
kernel for "Support for Host-side USB" and for "USB Modem (CDC ACM)
|
|
support".
|
|
|
|
Once the gadget serial driver is loaded and the USB device connected
|
|
to the Linux host with a USB cable, the host system should recognize
|
|
the gadget serial device. For example, the command::
|
|
|
|
cat /sys/kernel/debug/usb/devices
|
|
|
|
should show something like this:::
|
|
|
|
T: Bus=01 Lev=01 Prnt=01 Port=01 Cnt=02 Dev#= 5 Spd=480 MxCh= 0
|
|
D: Ver= 2.00 Cls=02(comm.) Sub=00 Prot=00 MxPS=64 #Cfgs= 1
|
|
P: Vendor=0525 ProdID=a4a7 Rev= 2.01
|
|
S: Manufacturer=Linux 2.6.8.1 with net2280
|
|
S: Product=Gadget Serial
|
|
S: SerialNumber=0
|
|
C:* #Ifs= 2 Cfg#= 2 Atr=c0 MxPwr= 2mA
|
|
I: If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=02 Prot=01 Driver=acm
|
|
E: Ad=83(I) Atr=03(Int.) MxPS= 8 Ivl=32ms
|
|
I: If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=acm
|
|
E: Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
|
|
E: Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
|
|
|
|
If the host side Linux system is configured properly, the ACM driver
|
|
should be loaded automatically. The command "lsmod" should show the
|
|
"acm" module is loaded.
|
|
|
|
|
|
Installing the Linux Host Generic USB Serial Driver
|
|
---------------------------------------------------
|
|
To use the Linux generic USB serial driver you must configure the
|
|
Linux host side kernel for "Support for Host-side USB", for "USB
|
|
Serial Converter support", and for the "USB Generic Serial Driver".
|
|
|
|
Once the gadget serial driver is loaded and the USB device connected
|
|
to the Linux host with a USB cable, the host system should recognize
|
|
the gadget serial device. For example, the command::
|
|
|
|
cat /sys/kernel/debug/usb/devices
|
|
|
|
should show something like this:::
|
|
|
|
T: Bus=01 Lev=01 Prnt=01 Port=01 Cnt=02 Dev#= 6 Spd=480 MxCh= 0
|
|
D: Ver= 2.00 Cls=ff(vend.) Sub=00 Prot=00 MxPS=64 #Cfgs= 1
|
|
P: Vendor=0525 ProdID=a4a6 Rev= 2.01
|
|
S: Manufacturer=Linux 2.6.8.1 with net2280
|
|
S: Product=Gadget Serial
|
|
S: SerialNumber=0
|
|
C:* #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr= 2mA
|
|
I: If#= 0 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=serial
|
|
E: Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
|
|
E: Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
|
|
|
|
You must load the usbserial driver and explicitly set its parameters
|
|
to configure it to recognize the gadget serial device, like this::
|
|
|
|
echo 0x0525 0xA4A6 >/sys/bus/usb-serial/drivers/generic/new_id
|
|
|
|
The legacy way is to use module parameters::
|
|
|
|
modprobe usbserial vendor=0x0525 product=0xA4A6
|
|
|
|
If everything is working, usbserial will print a message in the
|
|
system log saying something like "Gadget Serial converter now
|
|
attached to ttyUSB0".
|
|
|
|
|
|
Testing with Minicom or HyperTerminal
|
|
-------------------------------------
|
|
Once the gadget serial driver and the host driver are both installed,
|
|
and a USB cable connects the gadget device to the host, you should
|
|
be able to communicate over USB between the gadget and host systems.
|
|
You can use minicom or HyperTerminal to try this out.
|
|
|
|
On the gadget side run "minicom -s" to configure a new minicom
|
|
session. Under "Serial port setup" set "/dev/ttygserial" as the
|
|
"Serial Device". Set baud rate, data bits, parity, and stop bits,
|
|
to 9600, 8, none, and 1--these settings mostly do not matter.
|
|
Under "Modem and dialing" erase all the modem and dialing strings.
|
|
|
|
On a Linux host running the ACM driver, configure minicom similarly
|
|
but use "/dev/ttyACM0" as the "Serial Device". (If you have other
|
|
ACM devices connected, change the device name appropriately.)
|
|
|
|
On a Linux host running the USB generic serial driver, configure
|
|
minicom similarly, but use "/dev/ttyUSB0" as the "Serial Device".
|
|
(If you have other USB serial devices connected, change the device
|
|
name appropriately.)
|
|
|
|
On a Windows host configure a new HyperTerminal session to use the
|
|
COM port assigned to Gadget Serial. The "Port Settings" will be
|
|
set automatically when HyperTerminal connects to the gadget serial
|
|
device, so you can leave them set to the default values--these
|
|
settings mostly do not matter.
|
|
|
|
With minicom configured and running on the gadget side and with
|
|
minicom or HyperTerminal configured and running on the host side,
|
|
you should be able to send data back and forth between the gadget
|
|
side and host side systems. Anything you type on the terminal
|
|
window on the gadget side should appear in the terminal window on
|
|
the host side and vice versa.
|