This patch adds the relevant documentations required for booting the new BSP. JTAG support is added for debugging. I have built the HTML docs and verified them. --- user/bsps/aarch64/raspberrypi4.rst | 92 ++++++++++++++++++++++++++++++ user/bsps/bsps-aarch64.rst | 1 + 2 files changed, 93 insertions(+) create mode 100644 user/bsps/aarch64/raspberrypi4.rst
diff --git a/user/bsps/aarch64/raspberrypi4.rst b/user/bsps/aarch64/raspberrypi4.rst new file mode 100644 index 0000000..94daacf --- /dev/null +++ b/user/bsps/aarch64/raspberrypi4.rst @@ -0,0 +1,92 @@ +.. SPDX-License-Identifier: CC-BY-SA-4.0 + +.. Copyright (C) 2022 Mohd Noor Aman + +.. _BSP_aarch64_Raspberrypi_4: + +Raspberry Pi 4B +=============== + +The 'raspberrypi4b' BSP currently supports only the LP64 ABI. Raspberry pi 4B +and Raspberry Pi 400 are supported. The default bootloader which is used by the +Raspbian OS or other OS can be used to boot the RTEMS. Currently, QEMU is not +supported. This BSP supports the GICv2 interrupt controller. + +Clock Driver +------------ + +The clock driver uses the `ARM Generic Timer`. + +Console Driver +-------------- + +The console driver supports the default Qemu emulated ARM PL011 PrimeCell UART +as well as the physical ARM PL011 PrimeCell UART in the raspberrypi hardware. +Only UART0 is supported as of now. + +Preparing to boot +------------------ + +Raspberry Pi uses a different mechanism to boot. First the GPU initializes, +loads the bootloader and then looks for the kernel img. By default the arm64 +mode looks for the ``kernel8.img``. Any other kernel can be loaded by adding +`kernel=<img_name>` to the ``config.txt``. + +The Firmware files are required in order to boot RTEMS. The latest firmware can +be downloaded from the `Raspberry Pi Firmware Repository +<https://github.com/raspberrypi/firmware/>`_. USB boot is supported. All the +files (Firmwares and kernel) must be place in the FAT32 partition only. Add +``arm_64bit=1`` in the config.txt file in order to boot the BSP in 64bit kernel +mode. + + +UART Setup +^^^^^^^^^^ + +Connect your serial device to the GPIO15 and GPIO14. Add the following to the +config.txt file in order to use the PL011 UART0. + +.. code-block:: none + + dtoverlay = disable-bt + enable_uart=1 + +Generating kernel image +^^^^^^^^^^^^^^^^^^^^^^^ + +The following steps show how to run ``hello.exe`` on the BSP. Other executables +can be processed in a similar way. + +To create the kernel image: + +.. code-block:: shell + + $ aarch64-rtems@rtems-ver-major@-objcopy -Obinary hello.exe kernel8.img + +Copy the kernel image to the SD card. + +JTAG Setup +---------- + +The Raspberry Pi 4 doesn't have dedicated JTAG pins. Instead, you must configure +the GPIO pins (GPIO22-GPIO27) to activate the JTAG functionality. The RPi 4 +documentation refers to this as Alt4 functions of those pins. Alt5 does exist +too, which goes from GPIO4, 5, 6, 12 and 13. you can check this out from +`pinout.xyz <https://pinout.xyz/pinout/jtag#>`_ or `eLinux +<https://elinux.org/RPi_BCM2835_GPIOs>`_ + +One more thing to note on JTAG with Raspberry pi 4B is that, by default, All the +GPIO pins are pulled down, according to the `BCM2711 documentation +<https://datasheets.raspberrypi.com/bcm2711/bcm2711-peripherals.pdf>`_. This +wasn't the case in the earlier models. So in order to let the data flow freely, +we will have to disable them. + +.. code-block:: none + + # Disable pull downs + gpio=22-27=np + + # Enable jtag pins (i.e. GPIO22-GPIO27) + enable_jtag_gpio=1 + + diff --git a/user/bsps/bsps-aarch64.rst b/user/bsps/bsps-aarch64.rst index 933370f..f3aa15c 100644 --- a/user/bsps/bsps-aarch64.rst +++ b/user/bsps/bsps-aarch64.rst @@ -9,3 +9,4 @@ aarch64 (AArch64) .. include:: aarch64/a72.rst .. include:: aarch64/xilinx-versal.rst .. include:: aarch64/xilinx-zynqmp.rst +.. include:: aarch64/raspberrypi4.rst \ No newline at end of file -- 2.34.1 _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
