So you are interested in the MGSL_* set of ioctls, right?
AFAICS, they are all compatible, with the exception of
MGSL_IOCGPARAMS and MGSL_IOCSPARAMS.
Fortunately, these two have different ioctl numbers on
64 bit, so you can define a new
#define MGSL_IOCSPARAMS32 _IOR(MGSL_MAGIC_IOC,0,struct _MGSL_PARAMS32)
#define MGSL_IOCGPARAMS32 _IOR(MGSL_MAGIC_IOC,1,struct _MGSL_PARAMS32)
and handle both versions in the ioctl function.
Yes, that would be the right solution. I've started this
some time ago, but never finished it:
Currently the tty file ops do not include that and
tty_io.c does not register a compat_ioctl(), instead
relying on compat_ioctl.h and compat_ioctl.c
Just adding the hook in tty_io.c should be trivial, please do that.
If you like, you can also move the vt ioctls in order to reduce
the size of fs/compat_ioctl.c.