•
writel(value, address);
2.
readl
to read from HPS register
•
readl(address);
For example:
5.4.1.7. Check HPS PLL Lock Status in Preloader
•
Read HPS PLL Status Register in
clock_manager.c
and print out in
spl.c
— Define global variable in
clock_manager.c
and “extern variable” in
spl.c
— Unable to printout value in
clock_manager.c
as the UART has not been
initialized yet
5.4.2. Access HPS SDRAM via the FPGA-to-SDRAM Interface
The HPS bridges can be enabled from the Preloader (SPL/MPL) or U-Boot and in some
cases from Linux.
Note:
Preloaders (SPL) and U-Boot generated from SoC EDS 13.1 and later contain extra
functionality and built in functions to safely enable the HPS bridges.
To enable the HPS FPGA-to-SDRAM bridge from the Preloader or U-Boot, follow the
appropriate steps.
5. Embedded Software Design Guidelines for SoC FPGAs
AN-796 | 2018.06.18
AN 796: Cyclone V and Arria V SoC Device Design Guidelines
67