[PATCH v3] lib: utils/serial: Update Shakti UART based on latest implementation

[Prasanna Thandabani]

Yes Anup,

That's right. The current UART is being used everywhere, and we have
realised the gap in OpenSBI V1.1 release ( realised that we didn't
update the OpenSBI Repo). Hence the patch.

Please let me know if more information would help.

Thanks
Prasanna
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On Fri, Jul 8, 2022 at 11:19 PM Anup Patel <anup at brainfault.org> wrote:
>
> On Fri, Jul 8, 2022 at 11:11 PM Jessica Clarke <jrtc27 at jrtc27.com> wrote:
> >
> > On 8 Jul 2022, at 12:52, Anup Patel <apatel at ventanamicro.com> wrote:
> > >
> > > From: Prasanna T <ptprasanna at gmail.com>
> > >
> > > The age old version of Shakti UART was upgraded long back, but we missed
> > > updating the driver in OpenSBI. The old version of UART is not supported
> > > anymore, hence removed the inline comment which is also outdated now.
> >
> > This part of the description is referencing a comment that was
> > *introduced* by an earlier version of this patch; there is no comment
> > in the source being removed and so this part of the commit message is
> > inaccurate.
> >
> > I’m also rather concerned about reusing an existing compatible string
> > for an incompatible device, it seems like even if you’re dropping
> > support for an old UART the new one should have its own compatible with
> > the version suffix bumped. They have versions in them for a reason.
>
> My understanding is that they (Shakti folks) never used the old version
> of UART on any actual silicon. It seems they are already using the newer
> UART everywhere and they just forgot to change the code here.
>
> @Prasanna Thandabani Is the above understanding correct ?
>
> Regards,
> Anup
>
> >
> > Jess
> >
> > > Signed-off-by: Prasanna T <ptprasanna at gmail.com>
> > > Signed-off-by: Anup Patel <apatel at ventanamicro.com>
> > > ---
> > > Changes since v2:
> > > - Updated patch subject and description
> > > - Minor fix in shakti_uart_getc()
> > > ---
> > > lib/utils/serial/shakti-uart.c | 6 +++---
> > > 1 file changed, 3 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/lib/utils/serial/shakti-uart.c b/lib/utils/serial/shakti-uart.c
> > > index 5f2fe75..3556935 100644
> > > --- a/lib/utils/serial/shakti-uart.c
> > > +++ b/lib/utils/serial/shakti-uart.c
> > > @@ -19,21 +19,21 @@
> > > #define REG_RX_THRES  0x20
> > >
> > > #define UART_TX_FULL  0x2
> > > +#define UART_RX_NOT_EMPTY 0x4
> > > #define UART_RX_FULL  0x8
> > >
> > > static volatile char *uart_base;
> > >
> > > static void shakti_uart_putc(char ch)
> > > {
> > > -     while((readw(uart_base + REG_STATUS) & UART_TX_FULL))
> > > +     while ((readb(uart_base + REG_STATUS) & UART_TX_FULL))
> > >               ;
> > >       writeb(ch, uart_base + REG_TX);
> > > }
> > >
> > > static int shakti_uart_getc(void)
> > > {
> > > -     u16 status = readw(uart_base + REG_STATUS);
> > > -     if (status & UART_RX_FULL)
> > > +     if (readb(uart_base + REG_STATUS) & UART_RX_NOT_EMPTY)
> > >               return readb(uart_base + REG_RX);
> > >       return -1;
> > > }
> > > --
> > > 2.34.1
> > >
> > >
> > > --
> > > opensbi mailing list
> > > opensbi at lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/opensbi
> >