Re: [Xen-devel] [PATCH V3 5/5] xen/arm: Add early printk support for SCIFA compatible UARTs

[Oleksandr <olekstysh@xxxxxxxxx>]

On 14.04.19 20:56, Julien Grall wrote:
> Hi Oleksandr,
Hi Julien


> On 4/8/19 11:14 AM, Oleksandr Tyshchenko wrote:
> > From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> >
> > This patch makes possible to use existing early prink code
> > for Renesas "Stout" board based on R-Car H2 SoC (SCIFA).
> >
> > The "EARLY_PRINTK_VERSION" for that board should be 'A':
> > CONFIG_EARLY_PRINTK=scif,0xe6c40000,A
> >
> > Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> > CC: Julien Grall <julien.grall@xxxxxxx>
> >
> > ---
> >      Changes in v3:
> >          - It was decided not to introduce new debug-scifa.inc
> >            for handling SCIFA interface, but to extend existing
> >            debug-scif.inc for handling both interfaces.
> >            This patch is a result of splitting an initial patch
> >            "xen/arm: Add SCIFA UART support for early printk"
> >            and only adds a support.
> > ---
> >   xen/arch/arm/arm32/debug-scif.inc | 9 ++++++---
> >   1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/xen/arch/arm/arm32/debug-scif.inc 
> > b/xen/arch/arm/arm32/debug-scif.inc
> > index a8d2eae..94a18ea 100644
> > --- a/xen/arch/arm/arm32/debug-scif.inc
> > +++ b/xen/arch/arm/arm32/debug-scif.inc
> > @@ -1,7 +1,7 @@
> >   /*
> >    * xen/arch/arm/arm32/debug-scif.inc
> >    *
> > - * SCIF specific debug code
> > + * SCIF(A) specific debug code
> >    *
> >    * Oleksandr Tyshchenko <oleksandr.tyshchenko@xxxxxxxxxxxxxxx>
> >    * Copyright (C) 2014, Globallogic.
> > @@ -22,10 +22,13 @@
> >   #ifdef EARLY_PRINTK_VERSION_NONE
> >   #define STATUS_REG    SCIF_SCFSR
> >   #define TX_FIFO_REG   SCIF_SCFTDR
> > +#elif EARLY_PRINTK_VERSION_A
> > +#define STATUS_REG    SCIFA_SCASSR
> > +#define TX_FIFO_REG   SCIFA_SCAFTDR
> >   #endif
> >     /*
> > - * SCIF UART wait UART to be ready to transmit
> > + * SCIF(A) UART wait UART to be ready to transmit
> When SCIFB will be introduced, we will have to modify this comment 
> again. As we are only dealing with any version of SCIC in this file, 
> could we just rework the comment to avoid mentioning the UART name?
I think, yes. What about using SCIF(X)? Shall I update 
scif-uart.c/scif-uart.h which has SCIF(A) string?

> >    * rb: register which contains the UART base address
> >    * rc: scratch register
> >    */
> > @@ -37,7 +40,7 @@
> >   .endm
> >     /*
> > - * SCIF UART transmit character
> > + * SCIF(A) UART transmit character
> Same here.
>
> >    * rb: register which contains the UART base address
> >    * rt: register which contains the character to transmit
> >    */
> Cheers,
--
Regards,

Oleksandr Tyshchenko


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