sdspi VS qspiflash

I have built a lot of open-source C++ tooling for design verification. You can find a lot of my C++ models posted on my Github. Example C++ models include: UART, SPI/DSPI/QSPI Flash, SD-Card (SPI-based interface), VGA Video, Ethernet MDIO, PS/2 mouse, OLED display, SDRAM and more. (I've even simulated PLLs using C++ models ...) I have also written extensively about doing so at ZipCPU.com.

You mean ... sort of like I did in this project? I implemented an SPI based controller, where the controller took care of all the bit-banging for you, but the CPU still needed to issue the commands as appropriate for the protocol?

How about an SD card controller? I know I have a SPI based SD card controller, but the SDIO isn't that much harder. If you look hard enough you can find open source SDIO controllers.

There are also open source versions of many of the pieces you will need. I now use an open source crossbar interconnect for most of my designs. I use AutoFPGA to connect all the pieces together. I mentioned my flash controller above, but I also have a SD Card controller I've used quite successfully. I've also posted a UART to Wishbone bridge and discussed network debugging, both of which I use routinely with the ZipCPU. If for no other reason, these components allow me to load or update software on my CPU even after it's been placed into an FPGA. Of course, many of those components are tied to a Wishbone bus infrastructure. You may find you need a bridge of some type to connect different buses structures together--memory naturally tends to operate at one width and clock, video at another, and your CPU at another, so it helps at times to have a universal bus adapter kit handy.

I have built a lot of open-source C++ tooling for design verification. You can find a lot of my C++ models posted on my Github. Example C++ models include: UART, SPI/DSPI/QSPI Flash, SD-Card (SPI-based interface), VGA Video, Ethernet MDIO, PS/2 mouse, OLED display, SDRAM and more. (I've even simulated PLLs using C++ models ...) I have also written extensively about doing so at ZipCPU.com.

I have published, on GitHub, a C++ SPI (and Dual SPI, Quad SPI, etc.) model that I use extensively with Verilator. It's held nicely against all of the flash devices I've had to work with when using Xilinx chips, with a bit of an exception for Micron's delay between the Quad SPI address and any returned data. I also wrote an article about how to design, and then formally verify an SPI flash controller. Feel free to check them out and see if they'll work for you.

Since I don't use the Xilinx IP, I've found myself doing this often on any board bringup. You can find my flash IP here, and the software I use to get the flash ID here.

Here's the flash controller repo I use. There's a flash controller in there for SPI, Dual SPI, and Quad SPI. The Dual and Quad SPI controllers need a device specific startup script to get them into the right mode. This script should be fairly well explained by the comments. You should find at least one of these controllers that works for you. More recent versions of the controller have a Wishbone arbiter within them -- they're just not checked in the repo yet. (DSPI, QSPI). This makes it so the design fully supports two two Wishbone ports: a config port by which you can send any value and the memory mapped read port. (You can't use both at the same time.)