Linux pin Numbering / GPIO using Sysfs

Has anyone managed to get linux pin numbering for i96?
how to calculate the linux pin number of GPIO_A15?

I am trying to access gpio using sysfs to toggle Gpio by exporting the pin .Please help me as I am unable to find correct linux pin numbers for the board.

Detailed Problem :

As per the 2g_iot board linux pin numbering i found the correct pin number for physical pin 25(GPIO_B24) = 56 . when i export pin 56 using sysfs the gpio works fine, But all the Pins starting with ‘A’ i.e. GPIO_A(xx) do not work.

Physical pin 23 (GPIO_A15) = linux no 15 exporting pin 15 using sysfs the gpio does not work.

Thanks in advance

For GPIO_A calculation is correct, from SDK kernel source code sequence is:
GPIO_A -> 0…31
GPIO_B -> 32…63
GPIO_D -> 64…95 !!!
!!! GPIO_C -> 96…127 (in some kernel GPIO_C is excluded at all, because it comes from different CPU)
!!! GPO -> 128… if is GPIO_C , else 96…
But each pin (with some exceptions) have alternative functions, most selected by default, so GPIO function may not work.