Visible to Intel only — GUID: uxa1655798451429
Ixiasoft
Visible to Intel only — GUID: uxa1655798451429
Ixiasoft
8.6. Accessing Hardware
All components provide a directory that defines the device hardware and software. For example, each component provided in the Quartus® Prime software has its own directory in the <Intel Quartus Prime installation>/ip/altera/ directory. Many components provide a header file that defines their hardware interface. The header file is named <component name>_regs.h, included in the inc subdirectory for the specific component. For example, the Intel-provided JTAG UART component defines its hardware interface in the file <Intel Quartus Primeinstallation>/ip/altera/sopc_builder_ip/altera_avalon_jtag_uart/inc/altera_avalon_jtag_uart_regs.h.
The _regs.h header file defines the following access macros for the component:
- Register access macros that provide either or both a read or write macro for each register in the component that supports the operation. The macros are:
- IORD_ <component name>_<register name> (<component base address>)
- IOWR_ <component name>_<register name> (<component base address>, <data>)
For example, altera_avalon_jtag_uart_regs.h defines the following macros:
- IORD_ALTERA_AVALON_JTAG_UART_DATA()
- IOWR_ALTERA_AVALON_JTAG_UART_DATA()
- IORD_ALTERA_AVALON_JTAG_UART_CONTROL()
- IOWR_ALTERA_AVALON_JTAG_UART_CONTROL()
- Register address macros that return the physical address for each register in a component. The address register returned is the component’s base address + the specified register offset value. These macros are named IOADDR_<component name>_<register name> (<component base address>).
For example, altera_avalon_jtag_uart_regs.h defines the following macros:
- IOADDR_ALTERA_AVALON_JTAG_UART_DATA()
- IOADDR_ALTERA_AVALON_JTAG_UART_CONTROL()
Use these macros only as parameters to a function that requires the specific address of a data source or destination. For example, a routine that reads a stream of data from a particular source register in a component might require the physical address of the register as a parameter.
- Bit-field masks and offsets that provide access to individual bit-fields in a register. These macros have the following names:
- <component name>_<register name>_<name of field>_MSK—A bit-mask of the field
- <component name>_<register name>_<name of field>_OFST—The bit offset of the start of the field
For example, ALTERA_AVALON_UART_STATUS_PE_MSK and ALTERA_AVALON_UART_STATUS_PE_OFST access the pe field of the status register.
Access a device’s registers only with the macros defined in the _regs.h file. You must use the register access functions to ensure that the processor bypasses the data cache(if present) when reading and or writing the device. Do not use hard-coded constants, because they make your software susceptible to changes in the underlying hardware.
If you are writing the driver for a completely new hardware device, you must prepare the _regs.h header file.
For more information about a complete example of the _regs.h file, refer to the component directory for any of the Intel-supplied components, such as <Intel Quartus Prime installation>/ip/sopc_builder_ip/altera_avalon_jtag_uart/inc.