Re: [Xen-devel] [PATCH V2 2/2] xen: arm: implement early prink for 8250 uart

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2013-07-03 at 07:38 -0600, Bamvor Jian Zhang wrote:
> Hi, Ian
> 
> >>>Wrote "Ian Campbell <Ian.Campbell@xxxxxxxxxx>"> On Tue
> > On Tue, 2013-07-02 at 21:11 +0800, Bamvor Jian Zhang wrote:
> > > diff --git a/xen/arch/arm/arm32/debug-8250.inc 
> > > b/xen/arch/arm/arm32/debug-8250.inc
> > > new file mode 100644
> > > index 0000000..c11357d
> > > --- /dev/null
> > > +++ b/xen/arch/arm/arm32/debug-8250.inc
> > > @@ -0,0 +1,48 @@
> > > +/*
> > > + * xen/arch/arm/arm32/debug-8250.inc
> > > + *
> > > + * 8250 specific debug code
> > > + *
> > > + * Bamvor Jian Zhang <bjzhang@xxxxxxxx>
> > > + * Copyright (c) 2013 SUSE
> > > + *
> > > + * This program is free software; you can redistribute it and/or modify
> > > + * it under the terms of the GNU General Public License as published by
> > > + * the Free Software Foundation; either version 2 of the License, or
> > > + * (at your option) any later version.
> > > + *
> > > + * This program is distributed in the hope that it will be useful,
> > > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > > + * GNU General Public License for more details.
> > > + */
> > > +
> > > +
> > > +#define UART_TX           (0x00<<2)    /* Out: Transmit buffer */
> > > +#define UART_LSR          (0x05<<2)    /* In:  Line Status Register */
> > 
> > Is the shift 2 on Baozi's platform too? Perhaps this could be a #define
> > provided in the same style as EARLY_UART_BASE_ADDRESS or via some other
> > means?
> > 
> > The definitions themselves duplicate those in
> > xen/drivers/char/ns16550.c, perhaps we could refactor those into a
> > suitable header?
> yes. it should be. meanwhile considering the shift bit and other things. 
> i am not sure how to merge the headers until i got the ns16550 actual used by
> arm SOC. 

I think move the definitions as is from ns16550.c but add a UART_
prefix. Leave the shift in this code.

Eventually ns16550 will need to learn about shifts (and perhaps io vs
memory mapped io).

Ian.


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