design issue

[frantony]

gpio-sqwave (at least version edf17a0) combines several functionalities into one driver:

• direct gpio controller registers access;
• direct system controller timer registers access;
• system controller timer interrupt handler.

These design features make gpio-sqware driver very AR9331-dependent, lead to DoS and hardware access conflicts.

In modern linux kernel there are architecture independend subsystems for gpio-sqwave portable realization:

• abstract descriptor-based gpio interface (please see this AR9331-related example);
• high-resolution timer interface (e.g. see usage examples in pps_gen_parport driver and in pcsp driver); (note that MIPS32 cores have very precise CP0 timer and ATH79 systems use CEVT_R4K clock events).