Is it possible to program the PS FCLK_CLK clock through software while system on the fly?

[d4223738]

Hi,

I use the PS FCLK_CLK0 to clock the PL peripherals.

Is it possible to program the PS FCLK_CLK clock through software while system on the fly?

Best wishes,

Lei

[hbucher · Accepted solution]

@d4223738

I dont think so. At least I have never done it. But what do I know? 

Some options though: 

1. You can connect FCLK_CLKN to Clocking Wizard, which exposes an AXI LITE interface that you can use to dynamically reconfigure the clock output

See page 38 here

https://www.xilinx.com/support/documentation/ip_documentation/clk_wiz/v5_1/pg065-clk-wiz.pdf

2. Some boards (zc702, zc706) have a programmable clock (eg SI570) that you can program using the i2c protocol.

3. In verilog, here is something for you (look but dont do ok?):

https://forums.xilinx.com/t5/Welcome-Join/MUX-for-clock-selection-in-Spartan-6/td-p/327539

4. I also found this 3rd party solution: 

https://www.xilinx.com/products/intellectual-property/1-4zb9tn.html

Hope this helps

[hpoetzl]

@d4223738

Yes, it is definitely possible to change the FCLK from the PS side.

The Linux kernel even provides a driver for this, so you can simply do something like this:

echo fclk0 >/sys/devices/soc0/amba/f8007000.devcfg/fclk_export
echo 100000000 >/sys/class/fclk/fclk0/set_rate

Hope this helps,

Herbert