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

[Tom Rini]

On Thu, Feb 22, 2018 at 04:07:39PM +0000, Alexey Brodkin wrote:
> 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?

I'm fine with what you have above, in the driver.  I missed that
read_aux_reg already exists, sorry.  So I guess a detailed commit
message will have to be enough documentation for future reviewers of the
code.  Or, we'll see what comes out of Simon's comments.

-- 
Tom
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