New patch sent with new changes. On Fri, 7 Oct 2022 at 10:30, Mohd Noor Aman <nooraman5...@gmail.com> wrote:
> 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 | 111 +++++++++++++++++++++++++++++ > user/bsps/bsps-aarch64.rst | 1 + > 2 files changed, 112 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..b36d47b > --- /dev/null > +++ b/user/bsps/aarch64/raspberrypi4.rst > @@ -0,0 +1,111 @@ > +.. 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. ILP32 is not > +supported. Raspberry pi 4B all variants and Raspberry Pi 400 are > supported. The > +default bootloader which is used by the Raspbian OS or other OS can be > used to > +boot RTEMS. SMP is currently not supported. > + > +Raspberry Pi 4B has 2 types of interrupt controller, GIC-400 (GICv2) and > ARM > +legacy generic controller. Both are supported. By default, raspberrypi 4B > uses > +ARM legacy generic controller. Set ``enable_gic=1`` in the ``config.txt`` > file > +to enable GIC. > + > +Clock Driver > +------------ > + > +The clock driver uses the `ARM Generic Timer`. > + > +Console Driver > +-------------- > + > +Raspberry pi 4B has 2 types of UARTs, ARM PL011 and Mini-uart. The PL011 > is a > +capable, broadly 16550-compatible UART, while the mini UART has a reduced > +feature set. 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. Mini-uart is not supported. > + > +Preparing to boot > +------------------ > + > +Raspberry Pi uses a different mechanism to boot when compared with any > ARM SoC. > +First the GPU initializes, loads the bootloader (Raspberry pi firmware) > and then > +looks for the kernel img. This whole process is done by the GPU > (VideoCore IV) > +till the kernel is loaded. More information can be found on the > `Raspberry pi > +documentation page > +< > https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#boot-sequence > >`_. > +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`` file. > + > +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 and thus disabling the > +default Mini-uart. > + > +.. code-block:: none > + > + # if user wants to enable GIC, uncomment the next line > + # enable_gic=1 > + arm_64bit=1 > + dtoverlay = disable-bt > + enable_uart=1 > + > +.. note:: > + The Raspberry Pi 4B and 400 have an additional four PL011 UARTs. They > are not > + supported. > + > +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 > -- > 2.38.0 > >
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