https://gist.github.com/eggman/40612fdeb6d081a9a7d1a63ddef647f1
https://patchwork.kernel.org/patch/9192525/
u-boot/drivers/mmc/bcm2835_sdhost.c

SDHOST is at 0x7e202000, appears to be a broadcom custom controller, and has "better performance" compared to SDHCI