RE: [PATCH v4 2/2] misc: Add iop driver for Sunplus SP7021

[Tony Huang 黃懷厚]

Dear Arnd:
> 
> > 3.So you ask me to control IOP(8051) through file_operations, not
> > through DEVICE_ATTR
> 
> No, neither of them. Use the appropriate drivers/*/ subsystems for any
> functionality that has an existing subsystem. If there is something that the iop
> does that does not yet have a subsystem, that requires a more thorough design
> discussion for creating a new user interface, ideally in a hardware-independent
> way. You should not start with that until all the normal features (rtc, wakeup,
> suspend, gpio, ...) are supported.
> 

IOP(8051) has 12 bytes Mailbox registers, which can be read and written by IOP(8051) and System, used to exchange information with the system, faster than shared memory.

Thanks