Custom board using the Zynq 7020. I'm upgrading from ISE to Vivado 2018.3. I am trying to enable and use the PS SPI0 but when I read the registers for this device they all read 0. With the ISE image I read values from these registers, for example if I read the XSPIPS_CR_FFSET register at address 0xE0006000 with my ISE image I read the reset value of 0x20000. However with my Vivado/Petalinux 2018.3 image I read all 0's from this and all spi0 device registers.
I have the device enabled in Vivado and it seems that the device is enabled on my Linux image (status = okay), but I read no data from the device registers. Below I'm using the busybox utility devmem to read the device register, in my code I mmap and dev/mem and have the same results.
I dont' have much experience with Linux drivers/dts, etc... so I'm hoping someone can point me in the right direction to troubleshoot.
Looks like it might be an issue with dev/mem. If I get to the u-boot prompt and use the md (memory display) command I can see that register 0xe0006000 has the expected value of 0x20000, but if I then boot to linux and use devmem I read all 0's.