[PATCH] user: Add xilinx-zynq BSP details

[Gedare Bloom]

Thanks for the doco. Just a few comments.

On Mon, Sep 7, 2020 at 9:30 PM <chrisj at rtems.org> wrote:
>
> From: Chris Johns <chrisj at rtems.org>
>
> ---
>  user/bsps/arm/xilinx-zynq.rst | 114 +++++++++++++++++++++++++++++++++-
>  1 file changed, 112 insertions(+), 2 deletions(-)
>
> diff --git a/user/bsps/arm/xilinx-zynq.rst b/user/bsps/arm/xilinx-zynq.rst
> index 909b23e..365c336 100644
> --- a/user/bsps/arm/xilinx-zynq.rst
> +++ b/user/bsps/arm/xilinx-zynq.rst
> @@ -1,8 +1,118 @@
>  .. SPDX-License-Identifier: CC-BY-SA-4.0
>
> -.. Copyright (C) 2019 TBD
> +.. Copyright (C) 2020 Chris Johns (chrisj at rtems.org)
>
>  xilinx-zynq
>  ===========
>
> -TODO.
> +This BSP supports the Xilinx Zynq range of devices. This family of
> +devices contain the same ARM hard IP and the different parts have
> +different sizes of programable logic.
programmable?
(Might be a UK/AU English thing, if so let me know :).)

> +
> +The BSP defaults may need to be adjusted using ``configure`` BSP
> +options to match the size of memory your board may have.
> +
> +Bootloader
> +----------
> +
> +The bootloader initialises the Zynq device. The Xilinx tool provide an
"tools provide" or "tool provides"

> +interface to configure the hardware. This is includes the buses,
delete 'is'

> +clocks, memory and UART board rate. The output of this is called
> +``ps7_init`` and it a C file. The Xilinx SDK builds a first stage boot
"it is a"

> +loader (FSBL) using this file.
> +
> +The U-Boot boot loader has it's own FSBL called ``MLO`` to initialise
no apostrophe: its

> +the hardware.
> +
> +Clocks
> +------
> +
> +An application can provide a function called:
> +
> +.. code-block:: none
> +
> +    uint32_t a9mpcore_clock_periphclk(void);
> +
> +to return the peripheral clock. Normally this is half the CPU
> +clock. This function is declared ``weak`` so you can override the
> +default behaviour by providing it in your application.
> +
> +Debugging with xilinx_zynq_a9_qemu
> +----------------------------------
> +
> +To debug an application add the QEMU options ``-s``. If you need to
> +debug an initialisation issue also add ``-S``. For example to debug a
> +networking application you could use:
> +
> +.. code-block:: none
> +
> +    qemu-system-arm -M xilinx-zynq-a9 -m 256M -no-reboot -serial \
> +        null -serial mon:stdio -nographic \
> +       -net nic,model=cadence_gem -net vde,id=vde0,sock=/tmp/vde1 \
> +       -kernel myapp.exe \
> +       -s -S
> +
> +Start GDB with the same executable QEMU is running and connect to the
> +QEMU GDB server:
> +
> +.. code-block:: none
> +
> +    (gdb) target remote :1234
> +
> +If your application is crashing set a breakpoint on the fatal error
> +handler:
> +
> +.. code-block:: none
> +
> +    (gdb) b bsp_fatal_extension
> +
> +Enter continue to run the application. Running QEMU loads the
> +executable and initialises the CPU. If the ``-S`` option is provided
> +the CPU is held in reset. Without the option the CPU runs starting
> +RTEMS. Either way you are connecting to set up target and all you need
"set up the"

> +to do is continue:
> +
> +.. code-block:: none
> +
> +    (gdb) c
> +
> +If you have a crash and the breakpoint on ``bsp_fatal_extension`` is
> +hit, load the following a GDB script:
delete 'a'

> +
> +.. code-block:: none
> +
> +    define arm-crash
> +     set $code = $arg0
> +     set $r0 = ((const rtems_exception_frame *) $code)->register_r0
> +     set $r1 = ((const rtems_exception_frame *) $code)->register_r1
> +     set $r2 = ((const rtems_exception_frame *) $code)->register_r2
> +     set $r3 = ((const rtems_exception_frame *) $code)->register_r3
> +     set $r4 = ((const rtems_exception_frame *) $code)->register_r4
> +     set $r5 = ((const rtems_exception_frame *) $code)->register_r5
> +     set $r6 = ((const rtems_exception_frame *) $code)->register_r6
> +     set $r7 = ((const rtems_exception_frame *) $code)->register_r7
> +     set $r8 = ((const rtems_exception_frame *) $code)->register_r8
> +     set $r9 = ((const rtems_exception_frame *) $code)->register_r9
> +     set $r10 = ((const rtems_exception_frame *) $code)->register_r10
> +     set $r11 = ((const rtems_exception_frame *) $code)->register_r11
> +     set $r12 = ((const rtems_exception_frame *) $code)->register_r12
> +     set $sp = ((const rtems_exception_frame *) $code)->register_sp
> +     set $lr = ((const rtems_exception_frame *) $code)->register_lr
> +     set $pc = ((const rtems_exception_frame *) $code)->register_pc
> +     set $cpsr = ((const rtems_exception_frame *) $code)->register_cpsr
> +   end
> +
> +Enter the command:
> +
> +.. code-block:: none
> +
> +    (gdb) arm-crash code
> +
> +
> +Enter ``bt`` to see the stack back trace.
> +
> +The script moves the context back to the crash location. You should be
> +able to view variables and inspect the stack.
> +
> +The fatal error handler runs inside an exception context that is not
> +the one than generated the exception.
s/than/that

> --
> 2.24.1
>
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