Altera Embedded Peripherals IP - Manual (Page 237)

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Table 23-2 :
1. These macro names changed in version 1.1 of the Nios II Embedded Design Suite (EDS). The
old names (
ALT_DMA_TX_STREAM_ON
,
ALT_DMA_TX_STREAM_OFF
,
ALT_DMA_RX_STREAM_ON
, and
ALT_DMA_RX_STREAM_OFF)
are still valid, but new designs should use the new names.
Limitations
Currently the Altera-provided drivers do not support 64-bit and 128-bit DMA transactions.
This function is not thread safe. If you want to access the DMA controller from more than one thread
then you should use a semaphore or mutex to ensure that only one thread is executing within this
function at any time.
Software Files
The DMA controller is accompanied by the following software files. These files define the low-level
interface to the hardware. Application developers should not modify these files.
•
altera_avalon_dma_regs.h —This file defines the core’s register map, providing symbolic constants to
access the low-level hardware. The symbols in this file are used only by device driver functions.
• altera_avalon_dma.h , altera_avalon_dma.c —These files implement the DMA controller’s device driver for
the HAL system library.
Register Map
Programmers using the HAL API never access the DMA controller hardware directly via its registers. In
general, the register map is only useful to programmers writing a device driver.
The Altera-provided HAL device driver accesses the device registers directly. If you are writing a device
driver, and the HAL driver is active for the same device, your driver will conflict and fail to operate.
Device drivers control and communicate with the hardware through five memory-mapped 32-bit
registers.
Table 23-3: DMA Controller Register Map
Offset Register Name Read/Write 31 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0
status
(1) RW (2)
LE
N
WE
OP
RE
OP
BU
SY
D
O
N
E
1
readaddress
RW Read master start address
2
writeaddress
RW Write master start address
3
length
RW DMA transaction length (in bytes)
4 — — Reserved (3)
5 — — Reserved (3)
23-6 Software Files
UG-01085
2014.24.07
Altera Corporation DMA Controller Core
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