Comtrol eCos - Manual (Page 741)

Example Host-side Device Driver
Name
Example Host-side Device Driver — Provide host-side support for the eCos USB-ethernet package
Description
The USB-ethernet package is supplied with a single host-side device driver. This driver has been developed against
the Linux kernel 2.2.16-22, as shipped with Red Hat 7. The driver is provided as is and should not be considered
production quality: for example it only checks for a bogus vendor id
0x4242 rather than an official vendor id
supplied by the USB Implementers Forum (http://www.usb.org/). Also, if the peripheral involves multiple config-
urations or multiple interfaces, it will fail to detect this. However, the driver can be used for simple testing and
as the basis of a full device driver. Details of the protocol used between host and peripheral can be found in the
Communication Protocol section.
The host-side device driver can be found in the host subdirectory of the USB-ethernet package, specifically the
file ecos_usbeth.c , and comes with a Makefile . Both files may need to be modified for specific applications.
For example, the vendor id table ecos_usbeth_implementations may need to be updated for the specific USB
peripheral being built. The Makefile assumes that the Linux kernel sources reside in /usr/src/linux , and
that the kernel has already been configured and built. Assuming this is the case, the device driver can be built
simply by invoking make with no additional arguments. This will result in a dynamically loadable kernel module,
ecos_usbeth.o , in the current directory.
Note: As normal for Linux kernel builds, the generated files such as ecos_usbeth.o live in the same directory
as the source tree. This is very different from eCos where the source tree (or component repository) is kept
separate from any builds. There may be problems if the component repository is kept read-only or if it is put
under source code control. Any such problems can be avoided by making a copy of the
host subdirectory and
building that copy.
Loading the kernel module into the current system requires root privileges. If the generic USB support is also a
loadable module and has not been loaded already, this must happen first:
# insmod usb-uhci
Using /lib/modules/2.2.16-22/usb/usb-uhci.o
Depending on the host hardware, the uhci or usb-ohci modules may be more appropriate. Loading the generic
USB module will typically result in a number of messages to the logfile /var/log/messages , giving details of
the specific host-side hardware that has been detected plus any hubs. The next step is to load the USB-ethernet
module:
# insmod ecos_usbeth.o
This should result in a number of additional diagnostics in the logfile:
Apr 1 18:01:08 grumpy kernel: eCos USB-ethernet device driver
Apr 1 18:01:08 grumpy kernel: usb.c: registered new driver ecos_usbeth
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