Function led_write_channels 

pub unsafe extern "C" fn led_write_channels(
    dev: *const device,
    start_channel: u32,
    num_channels: u32,
    buf: *const u8,
) -> i32

@brief Write/update a strip of LED channels

This optional routine writes a strip of LED channels to the given array of levels. Therefore it can be used to configure several LEDs at the same time.

Calling this function after led_blink() won’t affect blinking.

@param dev LED device @param start_channel Absolute number (i.e. not relative to a LED) of the first channel to update. @param num_channels The number of channels to write/update. @param buf array of values to configure the channels with. num_channels entries must be provided. @return 0 on success, negative on error