Re: [Xen-devel] [PATCH 2/2] ns16550: Add compatible string for Raspberry Pi 4

[Andre Przywara <andre.przywara@xxxxxxx>]

On Wed, 24 Jul 2019 14:34:55 +0000
Stewart Hildebrand <Stewart.Hildebrand@xxxxxxxxxxxxxxx> wrote:

Hi,

I am afraid this is not enough. In your repo you hack the DT to contain
the reg-shift and io-width properties, but those are not part of the
"brcm,bcm2835-aux-uart" binding. Using 32-bit accesses is an integral
property of this UART, and since it is only *somewhat* compatible to an
8250 or DW UART, it cannot use that binding. So I had the following
additional hunk in:

@@ -1572,6 +1572,12 @@ static int __init ns16550_uart_dt_init(struct 
dt_device_node *dev,
     if ( uart->reg_width != 1 && uart->reg_width != 4 )
         return -EINVAL;
 
+    if ( dt_device_is_compatible(dev, "brcm,bcm2835-aux-uart") )
+    {
+        uart->reg_width = 4;
+        uart->reg_shift = 2;
+    }
+
     res = platform_get_irq(dev, 0);
     if ( ! res )
         return -EINVAL;

Feel free to use that snippet, that should work with the normal DT.

Cheers,
Andre.

> Signed-off-by: Stewart Hildebrand <stewart.hildebrand@xxxxxxxxxxxxxxx>
> ---
> xen/drivers/char/ns16550.c | 1 +
> 1 file changed, 1 insertion(+)
> 
> diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c
> index e518f2d790..c8d7c9b710 100644
> --- a/xen/drivers/char/ns16550.c
> +++ b/xen/drivers/char/ns16550.c
> @@ -1611,6 +1611,7 @@ static const struct dt_device_match ns16550_dt_match[] 
> __initconst =
>      DT_MATCH_COMPATIBLE("ns16550"),
>      DT_MATCH_COMPATIBLE("ns16550a"),
>      DT_MATCH_COMPATIBLE("snps,dw-apb-uart"),
> +    DT_MATCH_COMPATIBLE("brcm,bcm2835-aux-uart"),
>      { /* sentinel */ },
> };
> --
> 2.22.0


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