Re: [Xen-devel] [PATCH V2 3/3] xen/arm: Add SCIFA UART support for early printk

[Oleksandr <olekstysh@xxxxxxxxx>]

On 19.02.19 12:09, Julien Grall wrote:
> Hi Oleksandr,
Hi Julien


> > > Actually, the main difference for the "early printk" support is in 
> > > two reg offsets:
> > > +#define SCIFA_SCASSR   0x14    /* Serial status register */
> > > +#define SCIFA_SCAFTDR  0x20    /* Transmit FIFO data register */
> > >
> > > +#define SCIF_SCFSR             0x10    /* Serial status register */
> > > +#define SCIF_SCFTDR            0x0c    /* Transmit FIFO data 
> > > register */
> > >
> > > I am not mistaken, we will have to introduce two options to cover 
> > > this case, as the offsets are not correlated with each other, no?
> You don't need two options. For instance, you can only introduce an 
> option SCIF_VERSION that would be 0 for SCIF and 61 (ascii 'a') for 
> SCIFA.
> Then in the code, you can use SCIF_VERSION to decides which sets of 
> macros you are using.
I think I understand the idea. Will try.


--
Regards,

Oleksandr Tyshchenko


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