Embedded Peripherals IP User Guide

ID 683130
Date 10/24/2025
Public
Document Table of Contents
1. Introduction 2. Avalon® -ST Serial Peripheral Interface Core 3. SPI Core 4. SPI Agent/JTAG to Avalon® Host Bridge Cores 5. Intel eSPI Agent Core 6. eSPI to LPC Bridge Core 7. Ethernet MDIO Core 8. Intel FPGA 16550 Compatible UART Core 9. UART Core 10. Lightweight UART Core 11. JTAG UART Core 12. Intel FPGA Avalon® Mailbox Core 13. Intel FPGA Avalon® Mutex Core 14. Intel FPGA Avalon® I2C (Host) Core 15. Intel FPGA I2C Agent to Avalon® -MM Host Bridge Core 16. EPCS/EPCQA Serial Flash Controller Core 17. Intel FPGA Serial Flash Controller Core 18. Intel FPGA Serial Flash Controller II Core 19. Intel FPGA Generic QUAD SPI Controller Core 20. Intel FPGA Generic QUAD SPI Controller II Core 21. Interval Timer Core 22. Intel FPGA Avalon FIFO Memory Core 23. On-Chip Memory (RAM and ROM) Intel FPGA IP 24. On-Chip Memory II (RAM or ROM) Intel FPGA IP 25. PIO Core 26. PLL Cores 27. DMA Controller Core 28. Modular Scatter-Gather DMA Core 29. Scatter-Gather DMA Controller Core 30. Video Sync Generator and Pixel Converter Cores 31. Intel FPGA Interrupt Latency Counter Core 32. Performance Counter Unit Core 33. Vectored Interrupt Controller Core 34. System ID Peripheral Core 35. Intel FPGA GMII to RGMII Converter Core 36. HPS GMII to RGMII Adapter IP 37. Intel FPGA MII to RMII Converter Core 38. HPS GMII to TSE 1000BASE-X/SGMII PCS Bridge Core IP 39. Intel FPGA HPS EMAC to Multi-rate PHY GMII Adapter Core 40. Intel FPGA MSI to GIC Generator Core 41. Cache Coherency Translator IP 42. Altera ACE5-Lite Cache Coherency Translator

27.4.1. HAL System Library Support

The Intel-provided driver implements a HAL DMA device driver that integrates into the HAL system library for Nios® II and Nios® V processors systems. HAL users should access the DMA controller via the familiar HAL API, rather than accessing the registers directly.

If your program uses the HAL device driver to access the DMA controller, accessing the device registers directly interferes with the correct behavior of the driver.

The HAL DMA driver provides both ends of the DMA process; the driver registers itself as both a receive channel (alt_dma_rxchan) and a transmit channel (alt_dma_txchan). The Nios® II Software Developer’s Handbook provides complete details of the HAL system library and the usage of DMA devices.

ioctl() Operations

ioctl() operation requests are defined for both the receive and transmit channels, which allows you to control the hardware-dependent aspects of the DMA controller. Two ioctl() functions are defined for the receiver driver and the transmitter driver: alt_dma_rxchan_ioctl() and alt_dma_txchan_ioctl(). The table below lists the available operations. These are valid for both the transmit and receive channels.

Table 313.  Operations for alt_dma_rxchan_ioctl() and alt_dma_txchan_ioctl()
Request Meaning
ALT_DMA_SET_MODE_8 Transfers data in units of 8 bits. The parameter arg is ignored.
ALT_DMA_SET_MODE_16 Transfers data in units of 16 bits. The parameter arg is ignored.
ALT_DMA_SET_MODE_32 Transfers data in units of 32 bits. The parameter arg is ignored.
ALT_DMA_SET_MODE_64 Transfers data in units of 64 bits. The parameter arg is ignored.
ALT_DMA_SET_MODE_128 Transfers data in units of 128 bits. The parameter arg is ignored.
ALT_DMA_RX_ONLY_ON (1) Sets a DMA receiver into streaming mode. In this case, data is read continuously from a single location. The parameter arg specifies the address to read from.
ALT_DMA_RX_ONLY_OFF (1) Turns off streaming mode for a receive channel. The parameter arg is ignored.
ALT_DMA_TX_ONLY_ON (1) Sets a DMA transmitter into streaming mode. In this case, data is written continuously to a single location. The parameter arg specifies the address to write to.
ALT_DMA_TX_ONLY_OFF (1) Turns off streaming mode for a transmit channel. The parameter arg is ignored.
Notes :
  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 Intel-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.