I am using the interesting AD-FMCOMMS1-EBZ board together with custom HDL & Zynq Linux. I have been able to tame I2C via PS7 hw i2c and Linux /dev/i2c-0 (an advice to others: only serial number query works @400kHz, but for the real functionality you need to set 100kHz in device tree!).
All the SPI devices respond well to Linux userspace code, and at least AD9523-1 got programmed exactly according to the docs.
However: the board is still incredibly hot (I am used to lots of electronics' heat, but this amount is really scary). Since I need now only an AD9523-1 and AD9643, I have issued power-down commands to all the devices. However, there are 3 chips, that can not be powered-down using SPI, but only using PIC GPIO pins.
* My question is: how to control these pins via I2C?
The "i2c_to_spi_bridge" wiki page lists a SPI_XCOMM_CMD_GPIO_SET (0x05) command, but without any further information about how to use it and how are the pins assigned. Can anybody tell me, how many bytes the command accepts, and how are the pins assigned? I prefer not to investigate by trial and error this time.