[U-Boot] [RFC] ns16550: Add support for AUX regs usage on some ARC SoCs

[Alexey Brodkin <Alexey.Brodkin@synopsys.com>]

Hi Tom,

On Thu, 2018-02-22 at 10:43 -0500, Tom Rini wrote:
> On Wed, Feb 21, 2018 at 03:26:05PM +0300, Alexey Brodkin wrote:

[snip]

> >  static inline void serial_out_shift(void *addr, int shift, int value)
> >  {
> > -#ifdef CONFIG_SYS_NS16550_PORT_MAPPED
> > +#ifdef CONFIG_ARCH_DFSS
> > +	write_aux_reg((int)addr, value);
> > +#elif defined(CONFIG_SYS_NS16550_PORT_MAPPED)
> >  	outb(value, (ulong)addr);
> >  #elif defined(CONFIG_SYS_NS16550_MEM32) && !defined(CONFIG_SYS_BIG_ENDIAN)
> >  	out_le32(addr, value);
> > @@ -70,7 +75,9 @@ static inline void serial_out_shift(void *addr, int shift, int value)
> >  
> >  static inline int serial_in_shift(void *addr, int shift)
> >  {
> > -#ifdef CONFIG_SYS_NS16550_PORT_MAPPED
> > +#ifdef CONFIG_ARCH_DFSS
> > +	return read_aux_reg((int)addr);
> > +#elif defined(CONFIG_SYS_NS16550_PORT_MAPPED)
> >  	return inb((ulong)addr);
> >  #elif defined(CONFIG_SYS_NS16550_MEM32) && !defined(CONFIG_SYS_BIG_ENDIAN)
> >  	return in_le32(addr);
> 
> As always, thanks for the detailed explanation.  Yes, I think that of
> the options, putting the details in read/write_aux_reg (and please make
> sure read/write_aux_reg have a good function comment too) is the best
> choice.  Thanks!

Frankly I didn't understand your comment well enough :)
Do you suggest to keep proposed implementation (i.e. modification of
serial_{in|out}_shift()) but add comments on what do we do and why or
you really meant something completely different?

-Alexey