CONTENT:
dma.h
dma1.c
dma2.s
WHAT ARE THESE FILES:
These files contain MPC8240 (Kahlua) DMA controller
driver routines. The driver routines are not
written for any specific operating system.
They serves the purpose of code sample, and
jump-start for using the MPC8240 DMA controller.
For the reason of correctness of C language
syntax, these files are compiled by Metaware
C compiler and assembler.
ENDIAN NOTATION:
The algorithm is designed for big-endian mode,
software is responsible for byte swapping.
USAGE:
1. The host system that is running on MPC8240
or using MPC8240 as I/O device shall link
the files listed here. The memory location
of driver routines shall take into account of
that driver routines need to run in supervisor
mode and they process DMA controller interrupt.
2. The host system is responsible for configuring
the MPC8240 including Embedded Utilities Memory
Block. Since the DMA controller on MPC8240 can
be accessed by either local 603e core or the host
that MPC8240 serves as I/O processor through host
PCI configuration, it is important that the local
processor uses EUMBBAR to access its local DMA
controller while the PCI master uses I/O
processor's PCSRBAR to access the DMA controller
on I/O device.
To qualify whether is EUMBBAR or PCSRBAR, one
additional parameter is requied from the host
system, LOCAL or REMOTE so that the base value
can be correctly interpreted.
3. If the host system is also using the EPIC unit
on MPC8240, the system can register the
DMA_ISR with the EPIC including other
desired resources.
If the host system does not using the EPIC unit
on MPC8240, DMA_ISR function can be called for
each desired time interval.
In both cases, the host system is free to
provide its own interrupt service routine.
4. To start a direct mode DMA transaction,
use DMA_Bld_Curr with the start parameter
set to 1.
To start a chaining mode DMA transaction,
the application shall build descriptors
in memory first, next, use DMA_Bld_Desp
with the start parameter set to 1.
5. DMA_Start function clears, then sets the CS
bit of DMA mode register.
DMA_Halt function clears the CS bit of DMA
mode register.
These functions can be used to start and
halt the DMA transaction.
If the chaining descriptors has been
modified since the last time a DMA
transaction started, use DMA_Chn_Cnt
function to let DMA controller process
the modified descriptor chain without
stopping or disturbing the current DMA
transaction.
It is the host system's responsibility of
setting up the correct DMA transfer mode
and pass the correct memory address parameters.
6. It is the host system's responsibility of
queueing the DMA I/O request. The host
system can call the DMA_ISR with its own
desired interrupt service subroutines to
handle each individual interrupt and queued
DMA I/O requests.
7. The DMA driver routines contains a set
of utilities, Set and Get, for host system
to query and modify the desired DMA registers.
