Description: PCI UART Linux 2.6 driver patches
==================================================
The Oxford Semiconductor serial device driver patches support the Oxford
Semiconductor family of PCI to Serial bridge devices and Local Bus to Serial
bridge devices. This includes the:
OX16PCI952
OX16PCI954
OX16PCI958
OXmPCI952
OXmPCI954
OXuPCI952
OXuPCI954
OX16C954B
OX16C950B
This set of patches includes the following:
oxford_pci_linux2.6_uart_8250
oxford_pci_linux2.6_uart_8250_pci
This README includes instructions for applying the patches, along with some
useful prerequisites and considerations for the user.
At the bottom of this README the user can also find details on how to use the
Oxford Semiconductor Card Bus to Serial and Compact Flash to Serial devices:
OXCF950
OXCB950
See section "Other Oxford Semiconductor Devices"
Prerequisites:-
===============
Before getting started with the Linux 2.6 serial device driver patches for the
Oxford Semiconductor family of devices there are a few prerequisites for users
to consider on their Linux 2.6 system.
Please note that the following README for the serial patches makes the
assumption that the user is working on a PC distribution of Linux such as
Red Hat, Suse or Fedora etc... The patch will be the same or similar for any
Linux 2.6 based system, however the following steps may change depending on the
users system.
The serial device driver patch will be applied to the source code for the Linux
OS. Hence the user will need the source code for their particular version of the
Linux kernel. There are two general options for acquiring the Linux kernel
source code, the user can either download the source for their particular
distributions kernel or the user can download the Linux communities "vanilla"
kernel from www.kernel.org. To rebuild the patched serial driver the user will
also need the kernel build tools relative to their Linux distribution. For more
information on the source code and the build tools for the users system one
should consult the documentation for their particular distribution.
In general, the kernel source code is copied to /usr/src/. As some distributions
may do this slightly differently, we will make the assumption in this document
that the root directory of the kernel source code is located at
/usr/src/linux-2.6
General Tips:-
==============
In general the Linux kernel pre-built with each Linux distribution will have the
serial driver built into the kernel, and not built as a kernel loadable module.
This means that regardless of whether the user would like to have the serial
driver for the Oxford UART device built into the kernel, or available as a
kernel loadable module the user will have to rebuild the full kernel.
To rebuild the kernel with the serial driver as a kernel loadable module, the
user should use a tool such as menuconfig to configure the kernels .config file.
- From the command line navigate to the root directory of the linux
kernel source:
~> cd /usr/src/linux-2.6
- Start "menuconfig" to configure the .config file:
~> make menuconfig
- Within the "menuconfig" utility:
- The first page is the "Linux Kernel Configuration" page. On this
page select the Device Drivers menu.
- From the "Device Drivers" menu one should select the "Character
Devices" menu.
- From the "Character Devices" menu, select "Serial Drivers".
- To build the serial drivers as part of the kernel confirm that
the entry for "8250/16550 and compatible serial support" is
selected as {*}.
- To build the serial drivers as a kernel loadable module confirm
that the entry for "8250/16550 and compatible serial support"
is selected as {M}.
- Once all changes have been made, exit back through the menus
and select "Yes" to save the new .config file. Now proceed to
build your kernel and modules.
Also, in general the Linux kernel pre-built with each Linux distribution will be
set to only enumerate 4 serial ports at runtime. As many of the Oxford devices
contain 4 and 8 UARTs this can prove to be a problem. As the user will need to
rebuild the kernel already, this is easily resolved.
- From the command line navigate to the root directory of the linux
kernel source:
~> cd /usr/src/linux-2.6
- Start "menuconfig" to configure the .config file:
~> make menuconfig
- Within the "menuconfig" utility:
- The first page is the "Linux Kernel Configuration" page. On this
page select the Device Drivers menu.
- From the "Device Drivers" menu one should select the "Character
Devices" menu.
- From the "Character Devices" menu, select "Serial Drivers".
- To adjust the number of serial ports enumerated at runtime,
select "Number of 8250/16550 serial ports to register at runtime"
and enter a suitable number (e.g. 20).
- Once all changes have been made, exit back through the menus
and select "Yes" to save the new .config file. Now proceed to
build your kernel and modules.
Building the Linux kernel from source code:-
============================================
Depending of the Linux distribution that the user has, and the build tools
provided, building the kernel can be done in different ways. For most systems,
including Red Hat, Suse and Fedora, the following steps are used to build the
Linux kernel from source code.
- Navigate to the root directory of the Linux kernel source code:
~> cd /usr/src/linux-2.6
- Build the kernel image:
~> make bzImage
- Build the modules specified in the .config file:
~> make modules
- Run the install scripts for the kernel loadable modules:
~> make modules_install
- Run the install scripts for the kernel
~> make install
For more information on building the Linux kernel from source code, the user
should refer to the documentation for their chosen distribution.
Note that the steps above will not work for a debian based system such as
Ubuntu, and the user should look to their distribution's documentation for
guidance.
How to apply the serial device driver patch:-
=============================================
If the user plans on building the serial driver as part of the Linux kernel
(i.e. not as a kernel loadable module) then you will have to apply the patch to
the serial driver code within the Linux source code directory.
If the user would like to build the serial driver as a kernel loadable module
then the user can take a copy of the serial device driver source code from
within the Linux kernel source code, copy this driver source to a working
directory such as one's home directory, and then patch this copy of the driver.
The advantage of working on a copy is that the user will still have a clean copy
of the kernel source just in case.
The Linux serial device driver is located at:
~> /usr/src/linux-2.6/drivers/serial
To apply the patch:
- Paste the oxford_pci_linux2.6_uart_8250 and oxford_pci_linux2.6_uart_8250_pci
patch files into the serial folder.
- Open a terminal and navigate to the serial folder.
- To apply the patches, enter the following commands:
~> patch -p0 < oxford_pci_linux2.6_uart_8250
~> patch -p0 < oxford_pci_linux2.6_uart_8250_pci
The oxford_pci_linux2.6_uart_8250 patch will modify the file "8250.c". It adds
the enhanced features capabilities flag for the C950/C954 UART.
The oxford_pci_linux2.6_uart_8250_pci patch will add code to the file
"8250_pci.c". It is a simple patch that basically adds baud_base and base
address information for the Oxford devices that are not already supported by
the generic Linux kernel.
Because the "8250_pci.c" and "8250.c" files can be updated at any time by the
Linux community, the patch may fail. If this happens the user is encouraged to
take a look at the contents of the patch and try adding this manually.
To build the patched serial device driver into the kernel the user will now
simply have to follow the usual build steps as described above.
To build the patched serial driver as a kernel loadable module:-
================================================================
Kernel loadable modules can be dynamically loaded and unloaded from the running
Linux kernel. This can be very advantageous depending on the user needs.
To build the patched serial driver as a kernel loadable module, the user must
have first satisfied the above prerequisite of configuring the kernel's .config
file to build the serial driver as a kernel loadable module. To then build the
module:
- Navigate to the serial device driver directory. I.e. if a copy of the serial
device driver has been copied to /home/user/ and then patched as above:
~> cd /home/user/serial/
- To build the patched serial device driver enter the following command:
~> make -C /usr/src/linux-2.6 M=$PWD modules
This will generate the serial driver kernel loadable modules (.ko files) in
/home/user/serial. The serial driver for the Oxford devices will be "8250.ko",
and the module "8250_pci.ko" performs the binding of the driver to the Oxford
device.
To load the kernel loadable modules:
- Insert the serial device driver module (from /home/usr/serial):
~> insmod 8250.ko
- Insert the serial PCI module:
~> insmod 8250_pci.ko
Note that often the serial device driver module will already be loaded at
startup, in which case the vanilla 8250.ko and 8250_pci.ko modules will need
to be removed (see below) before the above insmod commands will work.
To see the debug output from the Linux kernel, the user can open another
terminal and enter:
~> tail -f /var/log/messages
To see a list of the kernel loadable modules currently loaded on the system:
~> lsmod
To unload the modules:
~> rmmod 8250_pci.ko
~> rmmod 8250.ko
Other Oxford Semiconductor Devices:-
====================================
The OXCF950 does not require any patches to the Linux serial device driver. To
see full details on how to enable the OXCF950 on a Linux system see the
following web page:
http://www.tldp.org/HOWTO/PCMCIA-HOWTO.html
From this document, chapter "PCMCIA serial and modem devices":
"If you configure your kernel to load the basic Linux serial port driver as a
module, you must edit /etc/pcmcia/config to indicate that this module must be
loaded. Edit the serial device entry to read:
device "serial_cs"
class "serial" module "misc/serial", "serial_cs"
"
Also, the user should edit /etc/pcmcia/serial.opts (more details on the above
web page):
#Symbolic link to dialout device
LINK = "/dev/ttyS1"
#Options for "setserial"
SERIAL_OPTS = "baud_base XXXX"
where XXXX = {115200 x 1.8432/crystal_frequency}
The OXCB950 can be driven by the generic Linux serial device driver, however
the user will first need to enable PCI hotplug in their kernel configuration.
Download Driver Pack
After your driver has been downloaded, follow these simple steps to install it.
Expand the archive file (if the download file is in zip or rar format).
If the expanded file has an .exe extension, double click it and follow the installation instructions.
Otherwise, open Device Manager by right-clicking the Start menu and selecting Device Manager.
Find the device and model you want to update in the device list.
Double-click on it to open the Properties dialog box.
From the Properties dialog box, select the Driver tab.
Click the Update Driver button, then follow the instructions.
Very important: You must reboot your system to ensure that any driver updates have taken effect.
For more help, visit our Driver Support section for step-by-step videos on how to install drivers for every file type.