[PATCH v4] doc/raspberrypi: Added instructions for raspberrypi

[G. S. Niteesh]

Can someone take a look at this, It has been unnoticed for quite a while.

Thank you,
Niteesh

On Sat, Jan 25, 2020 at 10:49 PM G S Niteesh <gsnb.gn at gmail.com> wrote:

> Added instructions to run examples on raspberrypi.
> ---
>  user/bsps/arm/raspberrypi.rst | 111 +++++++++++++++++++++++++++++++++-
>  1 file changed, 110 insertions(+), 1 deletion(-)
>
> diff --git a/user/bsps/arm/raspberrypi.rst b/user/bsps/arm/raspberrypi.rst
> index 4ef75bd..72889a5 100644
> --- a/user/bsps/arm/raspberrypi.rst
> +++ b/user/bsps/arm/raspberrypi.rst
> @@ -5,4 +5,113 @@
>  raspberrypi
>  ===========
>
> -TODO.
> +This BSP supports `Raspberry Pi 1` and `Raspberry Pi 2` currently.
> +The support for `Raspberry Pi 3` is work under progress.
> +The default bootloader on the Raspberry Pi which is used to boot Raspbian
> +or other OS can be also used to boot RTEMS. U-boot can also be used.
> +
> +Setup SD card
> +----------------
> +
> +The Raspberry Pis have an unconventional booting mechanism. The GPU
> +boots first, initializes itself, runs the bootloader and starts the CPU.
> +The bootloader looks for a kernel image, by default the kernel images must
> +have a name of the form ``kernel*.img`` but this can be changed by adding
> +`kernel=<img_name>` to ``config.txt``.
> +
> +You must provide the required files for the GPU to proceed. These files
> +can be downloaded from
> +`the Raspberry Pi Firmware Repository <
> https://github.com/raspberrypi/firmware/tree/master/boot>`_.
> +You can remove the ``kernel*.img`` files if you want too, but don't touch
> +the other files.
> +
> +Copy these files in to a SD card with FAT filesystem.
> +
> +Kernel image
> +------------
> +
> +The following steps show how to run ``hello.exe`` on a Raspberry Pi 2.
> +The same instructions can be applied to Raspberry Pi 1 also.
> +Other executables can be processed in a similar way.
> +
> +To create the kernel image:
> +
> +.. code-block:: none
> +
> +     $ arm-rtems5-objcopy -Obinary hello.exe kernel.img
> +
> +Copy the kernel image to the SD card.
> +
> +Make sure you have these lines below, in your ``config.txt``.
> +
> +.. code-block:: none
> +
> +     enable-uart=1
> +     kernel_address=0x200000
> +     kernel=kernel.img
> +
> +Testing using QEMU
> +------------------
> +
> +QEMU can be built using RSB. Navigate to ``<SOURCE_BUILDER_DIR>/rtems``
> +and run this command.
> +
> +.. code-block:: none
> +
> +     $ ../source-builder/sb-set-builder --prefix=<TOOLCHAIN_DIR>
> devel/qemu4.bset
> +
> +**Note**: Replace ``<SOURCE_BUILDER_DIR>`` and ``<TOOLCHAIN_DIR>`` with
> the
> +correct path of the directories. For example, if you used quick-start
> section
> +as your reference, these two will be ``$HOME/quick-start/src/rsb`` and
> +``$HOME/quick-start/rtems/5`` respectively,
> +
> +QEMU along with GDB can be used for debugging, but it only supports
> +Raspberry Pi 2 and the emulation is also incomplete. So some of the
> +features might not work as expected.
> +
> +Make sure your version of QEMU is newer than v2.6, because older ones
> don't
> +support Raspberry Pis.
> +
> +.. code-block:: none
> +
> +     $ qemu-system-arm -M raspi2 -m 1G -kernel hello.exe -serial
> mon:stdio -nographic -S -s
> +
> +This starts QEMU and creates a socket at port ``localhost:1234`` for GDB
> to
> +connect.
> +
> +The Device Tree Blob (DTB) is needed to load the device tree while
> starting up
> +the kernel. The BSP uses information from this file to initialize the
> drivers.
> +
> +Make sure you pass in the correct DTB file. There are currently two
> version of
> +DTB for the Raspberry Pi 2 ``bcm2709-rpi-2-b.dtb`` and
> ``bcm2710-rpi-2-b.dtb``.
> +The ``bcm2709-rpi-2-b.dtb`` is for Raspberry Pi 2 Model B and
> +``bcm2710-rpi-2-b.dtb`` is for Raspberry Pi 2 Model B v1.2
> +
> +We need to pass in the DTB file to GDB before running the example.
> +
> +In a new terminal, run GDB using
> +
> +.. code-block:: none
> +
> +     $ arm-rtems5-gdb hello.exe
> +
> +This will open GDB and will load the symbol table from hello.exe. Issue
> the
> +following commands in the GDB prompt.
> +
> +.. code-block:: none
> +
> +     (gdb) tar remote:1234
> +     (gdb) load
> +     (gdb) restore bcm2709-rpi-2-b.dtb binary 0x2ef00000
> +     (gdb) set $r2 = 0x2ef00000
> +
> +This will connect GDB to QEMU and will load the DTB file and the
> application.
> +
> +.. code-block:: none
> +
> +     (gdb) continue
> +
> +The ``continue`` command will run the executable.
> +
> +**Note**: Add ``set scheduler-locking on`` in GDB if you have any issues
> +running the examples.
> --
> 2.17.1
>
>
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