PWM

Maverick_by_

I try to use PWM, using this link:
https://wiki.t-firefly.com/en/iCore-3568JQ/driver_pwm.html
1) There is NO kernel/arch/arm64/boot/dts/rockchip/rk3399-firefly-demo.dtsi in my /rockchip/ folder.
And i can't add the PWM DTS configuration in the DTS source file
pwm_demo: pwm_demo {
        status = "disabled";
        compatible = "firefly,rk356x-pwm";
        pwms = <&pwm1 0 10000 1>;   //pwm1WM number   0 10000WM period in nanoseconds  1:polarity
        duty_ns = <5000>;   //pwm duty cycle activation time, unit ns
    };
Is documentation wrong?
2) I don't understand what to do with this C++ code:
struct pwm_device * pwm1 = NULL;pwm0 = pwm_request(1, “firefly-pwm”);pwm_config(pwm0, 500000, 1000000);pwm_enable(pwm0);

This is kernel driver source code, necessary to rebuild kernel and write firmware to SOM, why should i change it ? I need to change PWM parameters dinamically.How can i control it ?