Re: [PATCH 1/2] serial: support register interface with 16-bit stride for console

[Peter Hurley <peter@hurleysoftware.com>]

On 10/19/2015 01:40 AM, Masahiro Yamada wrote:
> Currently, 8-bit (MMIO) and 32-bit (MMIO32) strides are supported for
> the 8250 console, but 16-bit (MMIO16) stride is not.  The 8250 UART
> device on my board has 16-bit stride (reg-shift = <1>) and I am eager
> to use earlycon with it.
> 
> Refer to arch/arm/boot/dts/uniphier-support-card.dtsi:
> 
>         serialsc: uart@000b0000 {
>                 compatible = "ns16550a";
>                 reg = <0x000b0000 0x20>;
>                 clock-frequency = <12288000>;
>                 reg-shift = <1>;
>         };
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
> 
>  Documentation/kernel-parameters.txt  |  9 +++++----
>  drivers/tty/serial/8250/8250_early.c |  5 +++++
>  drivers/tty/serial/8250/8250_port.c  | 20 ++++++++++++++++++++
>  drivers/tty/serial/earlycon.c        | 15 +++++++++++----
>  drivers/tty/serial/serial_core.c     |  9 +++++++--
>  include/linux/serial_core.h          |  1 +
>  include/uapi/linux/serial.h          |  9 +++++----
>  7 files changed, 54 insertions(+), 14 deletions(-)
> 

[...]

> diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h
> index 25331f9..1d20d9c 100644
> --- a/include/uapi/linux/serial.h
> +++ b/include/uapi/linux/serial.h
> @@ -65,10 +65,11 @@ struct serial_struct {
>  #define SERIAL_IO_PORT	0
>  #define SERIAL_IO_HUB6	1
>  #define SERIAL_IO_MEM	2
> -#define SERIAL_IO_MEM32	  3
> -#define SERIAL_IO_AU	  4
> -#define SERIAL_IO_TSI	  5
> -#define SERIAL_IO_MEM32BE 6
> +#define SERIAL_IO_MEM16	3
> +#define SERIAL_IO_MEM32	  4
> +#define SERIAL_IO_AU	  5
> +#define SERIAL_IO_TSI	  6
> +#define SERIAL_IO_MEM32BE 7

The existing values cannot be re-defined since they're userspace visible.

Regards,
Peter Hurley


>  #define UART_CLEAR_FIFO		0x01
>  #define UART_USE_FIFO		0x02
>