lkml.org 
[lkml]   [2016]   [Aug]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Subject[RFC PATCH 0/3] UART slave device bus
    Date
    Currently, devices attached via a UART are not well supported in the
    kernel. The problem is the device support is done in tty line disciplines,
    various platform drivers to handle some sideband, and in userspace with
    utilities such as hciattach.

    There have been several attempts to improve support, but they suffer from
    still being tied into the tty layer and/or abusing the platform bus. This
    is a prototype to show creating a proper UART bus for UART devices. It is
    tied into the serial core (really struct uart_port) below the tty layer
    in order to use existing serial drivers.

    This is functional with minimal testing using the loopback driver and
    pl011 (w/o DMA) UART under QEMU (modified to add a DT node for the slave
    device). It still needs lots of work and polish.

    TODOs:
    - Figure out the port locking. mutex plus spinlock plus refcounting? I'm
    hoping all that complexity is from the tty layer and not needed here.
    - Split out the controller for uart_ports into separate driver. Do we see
    a need for controller drivers that are not standard serial drivers?
    - Implement/test the removal paths
    - Fix the receive callbacks for more than character at a time (i.e. DMA)
    - Need better receive buffering than just a simple circular buffer or
    perhaps a different receive interface (e.g. direct to client buffer)?
    - Test with other UART drivers
    - Convert a real driver/line discipline over to UART bus.

    Before I spend more time on this, I'm looking mainly for feedback on the
    general direction and structure (the interface with the existing serial
    drivers in particular).

    Rob


    Rob Herring (3):
    uart bus: Introduce new bus for UART slave devices
    tty: serial_core: make tty_struct optional
    tty: serial_core: add uart controller registration

    drivers/Kconfig | 2 +
    drivers/Makefile | 1 +
    drivers/tty/serial/serial_core.c | 11 +-
    drivers/tty/tty_buffer.c | 2 +
    drivers/uart/Kconfig | 17 ++
    drivers/uart/Makefile | 3 +
    drivers/uart/core.c | 458 +++++++++++++++++++++++++++++++++++++++
    drivers/uart/loopback.c | 72 ++++++
    include/linux/serial_core.h | 3 +-
    include/linux/uart_device.h | 163 ++++++++++++++
    10 files changed, 730 insertions(+), 2 deletions(-)
    create mode 100644 drivers/uart/Kconfig
    create mode 100644 drivers/uart/Makefile
    create mode 100644 drivers/uart/core.c
    create mode 100644 drivers/uart/loopback.c
    create mode 100644 include/linux/uart_device.h

    --
    2.9.2

    \
     
     \ /
      Last update: 2016-09-17 09:57    [W:5.814 / U:0.012 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site