Specifications

Available from ISR
See description.
Include
<sys/alt_dma.h>
Description
The alt_dma_rxchan_ioctl() function performs DMA I/O operations on the DMA receive channel,
dma. The I/O operations are device specific. For example, some DMA drivers support options to control
the width of the transfer operations. The input argument, req, is an enumeration of the requested
operation; arg is an additional argument for the request. The interpretation of arg is request dependent.
Whether a call to alt_dma_rxchan_ioctl() is thread-safe, or can be called from an ISR, is device
dependent. In general it safest to assume that it is not thread-safe.
Do not call the alt_dma_rxchan_ioctl() function while DMA transfers are pending, or unpredictable
behavior could result.
For device-specific information about the Altera DMA controller core, refer to the "DMA Controller
Core" chapter in the Embedded Peripherals IP User Guide.
Return
A negative return value indicates failure. The interpretation of nonnegative return values is request
specific.
Table 14-1: Generic Requests DMA Might Support
Request Meaning
ALT_DMA_SET_MODE_8 Transfer data in units of 8 bits. The value of arg is ignored.
ALT_DMA_SET_MODE_16 Transfer data in units of 16 bits. The value of arg is ignored.
ALT_DMA_SET_MODE_32 Transfer data in units of 32 bits. The value of arg is ignored.
ALT_DMA_SET_MODE_64 Transfer data in units of 64 bits. The value of arg is ignored.
ALT_DMA_SET_MODE_128 Transfer data in units of 128 bits. The value of arg is ignored.
ALT_DMA_GET_MODE Return the transfer width. The value of arg is ignored.
ALT_DMA_TX_ONLY_ON The ALT_DMA_TX_ONLY_ON request causes a DMA channel to operate in
a mode in which only the transmitter is under software control. The
other side writes continuously from a single location. The address to
which to write is the argument to this request.
ALT_DMA_TX_ONLY_OFF Return to the default mode, in which both the receive and transmit
sides of the DMA can be under software control.
ALT_DMA_RX_ONLY_ON The ALT_DMA_RX_ONLY_ON request causes a DMA channel to operate in
a mode in which only the receiver is under software control. The other
side reads continuously from a single location. The address to read is
the argument to this request.
NII5V2
2015.05.14
alt_dma_rxchan_ioctl()
14-25
HAL API Reference
Altera Corporation
Send Feedback