57.13.1.6.1.2 Host Read Mode

f SPCK max = 1 SPI 0 or  SPI 3 + t valid

tvalid is the client time response to output data after detecting an SPCK edge.

For a nonvolatile memory with tvalid (or tv) = 5 ns, fSPCKmax = 57 MHz at VDDIO = 3.3V.