[PATCH 00/10] drivers: PL011: add ARM SBSA Generic UART support

[Graeme Gregory]

On Fri, Jan 16, 2015 at 05:22:56PM +0000, Andre Przywara wrote:
> The ARM Server Base System Architecture[1] document describes a
> generic UART which is a subset of the PL011 UART.
> It lacks DMA support, baud rate control and modem status line
> control, among other things.
> The idea is to move the UART initialization and setup into the
> firmware (which does this job today already) and let the kernel just
> use the UART for sending and receiving characters.
> 
> This patchset integrates support for this UART subset into the
> existing PL011 driver - basically by refactoring some
> functions and providing a new uart_ops structure for it. It also has
> a separate probe function to be not dependent on AMBA/PrimeCell.
> It provides a device tree binding, but can easily be adapted to other
> device configuration systems.
> Beside the obvious effect of code sharing reusing most of the PL011
> code has the advantage of not introducing another serial device
> prefix, so it can go with ttyAMA, which seems to be pretty common.
> 
> This series relies on Dave's recent PL011 fix[2], which gets rid of
> the loopback trick to get the UART going. There is a repo at [3]
> (branch sbsa-uart/v1), which has this patch already integrated.
> 
> Patch 1/10 contains a bug fix which applies to the PL011 part also,
> it should be considered regardless of the rest of the series.
> Patch 2-7 refactor some PL011 functions by splitting them up into
> smaller pieces, so that most of the code can be reused later by the
> SBSA part.
> Patch 8 and 9 introduce two new properties for the vendor structure,
> this is for SBSA functionality which cannot be controlled by
> separate uart_ops members only.
> Patch 10 then finally drops in the SBSA specific code, by providing
> a new uart_ops, vendor struct and probe function for it. Also the new
> device tree binding is documented.
> 
> For testing you should be able to take any hardware which has a PL011
> and change the DT to use a "arm,sbsa-uart" compatible string.
> Of course testing with a real SBSA Generic UART is welcomed!
> 
I have tested this series on Juno where it seems to work and also on FVP
model where there are some issues.

On the FVP when we enter usespace a couple of 32 character strings are
printed then nothing else. 32 Characters is a suspicious number.

This occurs with both OE based FS from linaro and debian ubstable FS.

My FVP is version 5602

Graeme

> Cheers,
> Andre
> 
> [1] ARM-DEN-0029 Server Base System Architecture, available (click-
>     thru...) from http://infocenter.arm.com
> [2] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-January/315248.html
> [3] http://www.linux-arm.org/git?p=linux-ap.git
>     git://linux-arm.org/linux-ap.git
> 
> Andre Przywara (10):
>   drivers: PL011: avoid potential unregister_driver call
>   drivers: PL011: refactor pl011_startup()
>   drivers: PL011: refactor pl011_shutdown()
>   drivers: PL011: refactor pl011_set_termios()
>   drivers: PL011: refactor pl011_probe()
>   drivers: PL011: replace UART_MIS reading with _RIS & _IMSC
>   drivers: PL011: move cts_event workaround into separate function
>   drivers: PL011: allow avoiding UART enabling/disabling
>   drivers: PL011: allow to supply fixed option string
>   drivers: PL011: add support for the ARM SBSA generic UART
> 
>  .../devicetree/bindings/serial/arm_sbsa_uart.txt   |    9 +
>  drivers/tty/serial/amba-pl011.c                    |  510 ++++++++++++++------
>  2 files changed, 381 insertions(+), 138 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/serial/arm_sbsa_uart.txt
> 
> -- 
> 1.7.9.5
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel