source: rtems/c/src/lib/libbsp/powerpc/mbx8xx/README @ 39ee704e

This is a README file for the MBX860/MBX821 port of RTEMS 4.5.0

Please send any comments, improvements, or bug reports to:

Charles-Antoine Gauthier
charles.gauthier@nrc.ca

or

Darlene Stewart
Darlene.Stewart@nrc.ca
  
Software Engineering Group
Institute for Information Technology
National Research Council of Canada
Ottawa, ON, K1A 0R6
Canada  


Disclaimer
----------

The National Research Council of Canada is distributing this RTEMS
board support package for the Motorola MBX860 and MBX821 as free
software; you can redistribute it and/or modify it under terms of
the GNU General Public License as published by the Free Software
Foundation; either version 2, or (at your option) any later version.
This software 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 RTEMS; see file
COPYING. If not, write to the Free Software Foundation, 675 Mass Ave,
Cambridge, MA 02139, USA.

Under no circumstances will the National Research Council of Canada
nor Her Majesty the Queen in right of Canada assume any liablility
for the use this software, nor any responsibility for its quality or
its support.


Summary
-------

BSP NAME:           mbx8xx
BOARD:              Motorola MBX860 and MBX821 Embedded Controllers
BUS:                No backplane. On-board ISA, PCI, PC/104 and PCMCIA.
CPU FAMILY:         PowerPC
CPU:                PowerPC MPC860 or MPC821
COPROCESSORS:       Built-in Motorola QUICC
MODE:               32 bit mode

DEBUG MONITOR:      EPPC-Bug

PERIPHERALS
===========
TIMERS:             PIT / Timebase
  RESOLUTION:       1 microsecond / frequency = clock-speed / 16
SERIAL PORTS:       2 or 4 SCCs (SCC1 is hardwired for Ethernet)
                    2 SMC
                    1 SIO
REAL-TIME CLOCK:    Many. Look at documentation.
DMA:                Each SCC and SMC.
VIDEO:              None on-board. MPC821 has a built-in LCD panel driver.
SCSI:               None on-board.
NETWORKING:         Ethernet (10 Mbps) on SCC1
                   

DRIVER INFORMATION
==================
CLOCK DRIVER:       yes
CONSOLE DRIVER:     yes
SHMSUPP:            N/A
TIMER DRIVER:       yes
NETWORK DRIVER:     yes

NOTES
=====
On-chip resources:
        SCC1            network or console
        SCC2            serial port
        SMC1            gdb debug console/application console
        SMC2            application console
        CLK1            network
        CLK2            network
        CLK3
        CLK4
        CLK5
        CLK6
        CLK7
        CLK8
        BRG1            console
        BRG2            console
        BRG3            console
        BRG4            console
        RTC
        PIT             clock
        TB
        DEC
        SWT     
        *CS0            FLASH
        *CS1            DRAM bank (onboard)
        *CS2            DRAM bank 0 (1st half of DIMM)
        *CS3            DRAM bank 1 (2nd half of DIMM)
        *CS4            Battery-Backed SRAM
        *CS5            QSPAN PCI
        *CS6            QSPAN
        *CS7            Boot ROM
        UPMA
        UPMB
        IRQ0
        IRQ1
        IRQ2            
        IRQ3            
        IRQ4            
        IRQ5    
        IRQ6
        IRQ7
        IRQ_LVL0        
        IRQ_LVL1
        IRQ_LVL2
        IRQ_LVL3
        IRQ_LVL4
        IRQ_LVL5
        IRQ_LVL6
        IRQ_LVL7
        

Board description
-----------------
Clock rate:     50MHz Entry level boards, 40 MHz others.
Bus width:      8/32 bit Flash, 32 bit DRAM
FLASH:          2-4MB, 120ns
RAM:            4-16MB EDO, 60ns DRAM DIMM


Installation
------------

All MBX821/MBX860 ports share the same source code base. The MPC821 does
not have SCC3 and SCC4. Instead, it has an LCD panel driver. Otherwise,
the MBX821 and MBX860 boards are essentially identical. Entry level boards
do not have all connectors and peripheral devices present. This has no
impact on the source code base; it merely means that some functionality
is not available on these entry level boards. For the most part, the port
uses the standard build process for powerpc targets. However, you must
specify the EXACT model of MBX board that you are building for as the
argument to the RTEMS_BSP make variable. If you do not, the build process
will build for a MBX860-002. Look at rtems/make/custom/mbx8xx.cfg for the
specific list of boards supported and their corresponding names. An
example build command is:

        make RTEMS_BSP=mbx821_001 VARIANT=DEBUG

This will build the debug version of all RTEMS libraries, samples and tests
(if the latter are enabled).

The Software Engineering Group of the Institute for Information Technology
only owns an MBX821-001 and MBX86-002. The only provided config files are
mbx821_001.cfg and mbx860_002.cfg. A SPECIFIC CONFIG FILE IS REQUIRED. Use
one of the provided files as a template to create a specific config file for
another model.
 
We rely on EPPC-BUG to download to the targets. We use the "PLH" command.
We enabled a TFTP deamon on our development host.


Port Description
Console driver
---------------

This BSP includes an termios-capable asynchronous serial line driver that
supports SMC1, SMC2, SCC2, and SCC3 and SCC4 if present. The RTEMS console is
selected in rtems/make/custom/mbx8xx.cfg with the CONSOLE_MINOR variable, or
in NVRAM if that option is enabled in the rtems/make/custom/mbx8xx.cfg file.
We normally run with the RTEMS application console on SMC2. SMC1 is used by
the debugger.

Support is provided for five different modes of operation:

  1. polled I/O done by EPPC-Bug with termios support,
  2. polled I/O done by EPPC-Bug without termios support,
  3. polled I/O done by the supplied device driver with termios support,
  4. polled I/O done by the supplied device driver without termios support,
  5. interrupt-driven I/O done by the supplied device driver with termios
     support.
     
If NVRAM_CONFIGURE is set to 1 in rtems/make/custom/mbx8xx.cfg, the mode of
operation of the driver is determined at boot time from the values stored
in the user area in NVRAM. See the Configuration Parameters section below for
instructions on setting up NVRAM. Otherwise, the mode of operation of the
serial driver is determined at build time in part by the value of the
UARTS_IO_MODE constant in rtems/make/custom/mbx8xx.cfg. Edit the file to select
the type of I/O desired before building RTEMS. The choices are:

  0 - polled I/O done by the supplied device driver,
  1 - interrupt-driven I/O done by the supplied device driver,
  2 - polled I/O done by EPPC-Bug.
  
Also, if NVRAM_CONFIGURE is not set to 1 in rtems/make/custom/mbx8xx.cfg, set
the value of UARTS_USE_TERMIOS to select whether termios should be used to
perform buffering and input/output processing. Without termios support, input
processing is limited to the substitution of LF for a received CR, and output
processing is limited to the transmission of a CR following the transmission of
a LF. The choices for UARTS_USE_TERMIOS are:

  0 - do not use termios
  1 - use termios

In most real-time applications, the driver should be configured to use
termios and interrupt-driven I/O. Special requirements may dictate otherwise.

Polled I/O must be used when running the timing tests. It must also be used
to run some other tests and some samples, such as the cdtest. Some tests
change the interrupt mask and will hang interrupt-driven I/O indefinitely.
Others, such as cdtest, perform console output from the static constructors
before the console is opened, causing the test to hang. Still other tests
produce output that is supposed to be in some specific order. For these
tests, termios should not be used, as termios buffers output and the
transmission of the buffers occur at somewhat unpredictable times.

The real solution is to fix the tests so that they work with interrupt-driven
I/O and termios.


printk() and debug output
-----------------------

The implementation of printk() in RTEMS is mostly independent of most system
services. The printk() function can therefore be used to print messages to a
debug console, particularly when debugging startup code or device drivers,
i.e. code that runs before the console driver is opened or that runs with
interrupts disabled.

Support is provided to send printk output to any port. Specify the desired
port at build time in rtems/make/custom/mbx8xx.cfg by setting the value
of PRINTK_MINOR to one of SMC1_MINOR, SMC2_MINOR, SCC2_MINOR, SCC3_MINOR,
or SCC4_MINOR. Alternatively, if NVRAM_CONFIGURE is set to 1 in
rtems/make/custom/mbx8xx.cfg, the printk port is selected based on data that
is stored in the user area in NVRAM. See the Configuration Parameters section
below for instructions on setting up NVRAM. 

Select the type of output desired for printk() by setting the value of
PRINTK_IO_MODE in rtems/make/custom/mbx8xx.cfg. The choices are:

  0 - polled I/O done by the supplied device driver,
  1 - polled I/O done by the supplied device driver,
  2 - polled I/O done by EPPC-Bug.
  
printk() does not use termios.

If the printk() port is opened by RTEMS, then PRINK_IO_MODE mode must have
the same value as UARTS_IO_MODE, otherwise the I/O functions will be in
conflict. Interrupt-driven printk() output did not work, although we think
that it should have. It would have been of dubious value anyways. If
interrupt-driven I/O is selected (value of 1), the driver defaults to using
polled I/O through the RTEMS driver.

IMPORTANT: Polled I/O through the RTEMS driver requires that the driver be
initialized. Consequently, to debug startup code using printk prior to the
initialization of the serial driver, use mode 2: polled I/O through EPPC-Bug,
and read the next section.


EPPC-Bug and I/O
----------------

IMPORTANT: When using EPPC-Bug 1.1 for polled I/O, only the SMC1 port is
usable. This is a deficiency of the firmware which may be fixed in later
revision. When using this monitor with UARTS_IO_MODE set to 2, CONSOLE_MINOR
must be set to SMC1_MINOR. Similarly, if PRINTK_IO_MODE set to 2,
PRINTK_MINOR must be set to SMC1_MINOR. When UARTS_IO_MODE is set to 2,
only SMC1 is usable.

Be warned that when EPPC-Bug does I/O through a serial port, all interrupts
get turned off in the SIMASK register! This is a definite bug in release 1.1
of the firmware. It may have been fixed in later releases. EPPB-Bug does
I/O through its debug port whenever it is given control, e.g. after a
breakpoint is hit, not just when it is used to perform polled I/O on behalf
of RTEMS applications. In particular, in our configuration, we have gdb
communication with EPPC-Bug through SMC1.

To solve this problem, whenever the BSP manipulates the SIMASK, it makes a
copy of the written value in a global variable called 'simask_copy'. That
value must be restored by GDB before execution resumes. The following commands
placed in the .gdbinit file takes care of this:

# GDB Initialization file for EPPC-Bug.

define hook-stepi
set language c
set *(int *)0xFA200014=simask_copy
set language auto
end

define hook-step
set language c
set *(int *)0xFA200014=simask_copy
set language auto
end

define hook-continue
set language c
set *(int *)0xFA200014=simask_copy
set language auto
end

define hook-nexti
set language c
set *(int *)0xFA200014=simask_copy
set language auto
end

define hook-next
set language c
set *(int *)0xFA200014=simask_copy
set language auto
end

define hook-finish
set language c
set *(int *)0xFA200014=simask_copy
set language auto
end

IMPORTANT: When using EPPC-Bug on SMC1, either for debugging or for polled I/O,
EPPCBUG_SMC1 must be defined in rtems/make/custom/mbx8xx.cfg, or the eppc_bug
field set to non-zero in NVRAM. Defining this constant prevents the device
driver from re-initializing SMC1. It also causes the network driver, the clock
driver, and the asynchronous serial line driver to maintain simask_copy for use
by gdb.

Polled I/O through EPPC-Bug is pretty funky... If your are old enough, it might
bring back fond memories of the days of 300 baud modems. If not, you can
experience for yourself what the state of the art used to be.


Floating-point
--------------

The MPC860 and MPC821 do not have floating-point units. All code should
get compiled with the appropriate -mcpu flag. The nof variants of the gcc
runtime libraries should be used for linking.


Configuration Parameters
------------------------

If NVRAM_CONFIGURE is set in rtems/make/custom/mbx8xx.cfg, certain
configuration parameters will be read from the first 31 bytes of the  NVRAM
User Area, which starts at 0xFA001000. The user is responsible for writing
the appropriate values in NVRAM (via EPPC-Bug). The paramaters
that are configurable and their default settings are described below. 
                
  Cache Mode (0xFA001000 - 1 byte)
    Set the following bits in the byte to control the caches:
      bit 0
        0 - data cache disable
        1 - data cache enable
      bit 1
        0 - instruction cache disable
        1 - instruction cache enable
    If enabled, all of RAM except for the last 512 KB will be cached using
    copyback mode. The last 512 KB of RAMis for the use of EPPC-Bug.
    
  Console driver I/O mode (0xFA001001 - 1 byte)
    Set the following bits in the byte to set the desired I/O mode
    for the rtems ports:
      bit 0
        0 - do not use termios
        1 - use termios
      bit 2 & 1
        00 - polled I/O through RTEMS driver
        01 - interrupt-driven I/O
        10 - polled I/O through EPPC-Bug
    Set the following bits in the byte to set the desired I/O mode
    for printk:
      bit 5 & 4
        00 - polled I/O through RTEMS driver
        01 - polled I/O through RTEMS driver
        10 - polled I/O through EPPC-Bug

  Console driver ports (0xFA001002 - 1 byte)
    Set the following bits in the byte to select the console and printk ports:
    bit 2, 1  & 0 select the RTEMS console port
        000 - /dev/tty0, SMC1
        001 - /dev/tty1, SMC2
        011 - /dev/tty2, SCC2
        100 - /dev/tty3, SCC3
        101 - /dev/tty4, SCC4
    bit 6, 5 & 4 select the RTEMS printk port
        000 - /dev/tty0, SMC1
        001 - /dev/tty1, SMC2
        011 - /dev/tty2, SCC2
        100 - /dev/tty3, SCC3
        101 - /dev/tty4, SCC4
  If the printk port is the same as some other port that will be opened by an
  RTEMS application, then the driver must use polled I/O, or the printk port
  must not be used.

  EPPC-Bug in use on SMC1 (0xFA001003 - 1 byte)
    Set to non-zero to indicate that EPPC-Bug is using SMC1. This will prevent
    the SMC1 port from being re-initialized.

  IP Address (0xFA001004 - 4 bytes)
    Write the hexadecimal representation of the IP address of the board in this
    location, e.g. 192.168.1.2 = 0xC0A80102

  Netmask (0xFA001008 - 4 bytes)
    Write the hexadecimal representation of the netmask in this location
    for example, 255.255.255.0 = 0xFFFFFF00

  Ethernet Address (0xFA00100C - 6 bytes)
    Write the Ethernet address of the board in this location

  Processor ID (0xFA001012 - 2 bytes)
    Reserved for future use
                
  RMA start (0xFA001014 - 4 bytes)
    Reserved for future use
                
  VMA start (0xFA001018 - 4 bytes)
    Reserved for future use
                
  RamSize (0xFA00101C - 4 bytes)
    Reserved for future use


Miscellaneous
-------------

All development was based on the eth_comm port.


Host System
-----------

The port was developed on Pentiums II and III running RedHat Linux 6.0 and
6.1. The following tools were used:

    - GNU gcc snapshot dated 20000214 configured for powerpc-rtems;
    - GNU binutils 2.10 configured for powerpc-rtems;

Gcc 2.95.2 also worked. Gcc 2.95.1 will not compile the console driver with
-O4 or -O3. Compile it manually with -O2.


Known Problems
--------------

The cdtest will not run with interrupt-driven I/O. The reason is that the
constructors for the static objects are called at boot time when the
interrupts are still disabled. The output buffer fills up, but never empties,
and the application goes into an infinite loop waiting for buffer space. This
should have been documented in the rtems/c/src/tests/PROBLEMS file. The moral
of this story is: do not do I/O from the constructors or destructors of static
objects.

When using interrupt-driven I/O, psx08 fails with an internal assertion error.


What is new
----------

All known problems with use of the caches on the MBX860-002 and MBX821-001
have been resolved.

Configuration of the console and network is now possible at boot time through
NVRAM parameters.


Thanks
------

- to Jay Monkman (jmonkman@frasca.com) of Frasca International, Inc.
  for his eth_comm port.
  
- to On-Line Applications Research Corporation (OAR) for developing
  RTEMS and making it available on a Technology Transfer basis;

- to the FSF and to Cygnus Support for great free software;


Test Configuration
------------------

Board:                MBX821-001, MBX860-002
CPU:                  Motorola MPC821, MPC860
Clock Speed:          50 MHz, 40 MHz
RAM:                  4 MBytes of 32-bit DRAM
Cache Configuration:  Instruction cache on; data cache on, copyback mode.
Times Reported in:    clock ticks: TMBCLK = system clock / 16.
Timer Source:         Timebase clock
GCC Flags:            -O4 -fno-keep-inline-functions -mcpu=(821/860) 
Console:              Operates in polled mode on SMC2. No I/O through EPPC-Bug.    


Test Results
------------

Single processor tests:  All tests passed, except the following ones:
  
  - cpuuse and malloctest did not work.
  
  - The stackchk test got an access fault exception before the RTEMS stack
    checker had had a chance to detect the corrupted stack.
                         
                         
Multi-processort tests:  not applicable.


Timing tests:
        See the times-mbx821 and times-mbx860 files for the results of the
        timing tests.


Network tests:
       Worked.