I am going to design a project which uses SPI interface, which has 4 signals: SS* SCLK MISO MOSI. To my knowledge,
SS*, SCLK and MOSI are input singal and MISO is output signals. I have two questions:

1)
I am told the SPI is 25MHz. Is 25MHz too high for this SPI interface? What's the normal frequency range for SPI.

2)
In order to generate the digital output signal (MISO), I need clock signal. Is it possible to directly use SCLK to generate
this digital output signal (MISO)

Thank you!

You should use sclk as clock reference in transmition and reception.