[PATCH rtems-docs 1/2] user/bsps: Add imxrt

Tue Nov 17 17:41:06 UTC 2020

On Tue, Nov 17, 2020 at 4:09 AM Christian Mauderer
<christian.mauderer at embedded-brains.de> wrote:
>
> Update #4180
> ---
>  user/bsps/arm/imxrt.rst | 174 ++++++++++++++++++++++++++++++++++++++++
>  user/bsps/bsps-arm.rst  |   1 +
>  2 files changed, 175 insertions(+)
>  create mode 100644 user/bsps/arm/imxrt.rst
>
> diff --git a/user/bsps/arm/imxrt.rst b/user/bsps/arm/imxrt.rst
> new file mode 100644
> index 0000000..41c6bff
> --- /dev/null
> +++ b/user/bsps/arm/imxrt.rst
> @@ -0,0 +1,174 @@
> +.. SPDX-License-Identifier: CC-BY-SA-4.0
> +
> +.. Copyright (C) 2020 embedded brains GmbH
> +.. Copyright (C) 2020 Christian Mauderer
> +
> +imxrt (NXP i.MXRT)
> +==================
> +
> +This BSP offers only one variant, the `imxrt1052`. This variant supports the
> +i.MXRT 1052 processor on a IMXRT1050-EVKB (tested with rev A1). You can also
> +configure it to work with custom boards.
> +
> +Build Configuration Options
> +---------------------------
> +
> +Please see the documentation of the `IMXRT_*` and `BSP_*` configuration options
> +for that. You can generate a default set of options with::
one colon: I think?

> +
> +  ./waf bsp_defaults --rtems-bsps=arm/imxrt1052 > config.ini
> +
> +Boot Process
> +------------
> +
> +There are two possible boot processes supported:
> +
> +1) The ROM code loads a configuration from HyperFlash (connected to FlexSPI),
> +   does some initialization (based on device configuration data (DCD)) and then
> +   starts the application. This is the default case. `linkcmds.flexspi` is used
> +   for this case.
> +
> +2) Some custom bootloader does the basic initialization, loads the application
> +   to SDRAM and starts it from there. Select the `linkcmds.sdram` for this.
> +
> +For programming the HyperFlash in case 1, you can use the on board debugger
> +integrated into the IMXRT1050-EVKB. You can generate a flash image out of a
> +compiled RTEMS application with for example::
> +
> +  arm-rtems6-objcopy -O binary build/arm/imxrt1052/testsuites/samples/hello.exe hello.bin
> +
> +Then just copy the generated binary to the mass storage provided by the
> +debugger. Wait a bit till the mass storage vanishes and re-appears. After that,
> +reset the board and the newly programmed application will start.
> +
> +For debugging: Create a special application with a `while(true)` loop at end of
> +`bsp_start_hook_1`. Load that application into flash. Then remove the loop
> +again, build your BSP for SDRAM and use a debugger to load the application into
> +SDRAM after the BSP started from flash did the basic initialization.
> +
> +Flash Image
> +-----------
> +
> +For booting from a HyperFlash (or other storage connected to FlexSPI), the ROM
> +code of the i.MXRT first reads some special flash header information from a
> +fixed location of the connected flash device. This consists of the Image vector
> +table (IVT), Boot data and Device configuration data (DCD).
> +
> +In RTEMS, these flash headers are generated using some C-structures. If you use
> +a board other then the IMXRT1050-EVKB, they have to be adapted. To do that
s/then/than
s/they have/it has

> +re-define the following variables in your application (you only need the ones
> +that need different values):
> +
> +.. code-block:: c
> +
> +  #include <bsp/flash-headers.h>
> +  const uint8_t imxrt_dcd_data[] =
> +      { /* Your DCD data here */ };
> +  const ivt imxrt_image_vector_table =
> +      { /* Your IVT here */ };
> +  const BOOT_DATA_T imxrt_boot_data =
> +      { /* Your boot data here */ };
> +  const flexspi_nor_config_t imxrt_flexspi_config =
> +      { /* Your FlexSPI config here */ };
> +
> +You can find the default definitions in `bsps/arm/imxrt/start/flash-*.c`. Take a
> +look at the `i.MX RT1050 Processor Reference Manual, Rev. 4, 12/2019` chapter
> +`9.7 Program image` for details about the contents.
> +
> +FDT
> +---
> +
> +The BSP used a FDT based initialization. The FDT is linked into the application.
> +You can find the default FDT used in the BSP in
> +`bsps/arm/imxrt/dts/imxrt1050-evkb.dts`. To use your own FDT compile it and
> +convert it into a C file with (replace `YOUR.dts` and simmilar with your FDT
> +source names)::
> +
> +  sh> export BSP_DIR="${RTEMS_SRC_DIR}/bsps/arm/imxrt/"
> +  sh> arm-rtems6-cpp -P -x assembler-with-cpp \
> +          -I "${BSP_DIR}/include/" \
> +          -include "YOUR.dts" /dev/null | \
> +      dtc -@ -O dtb -o "YOUR.dtb" -b 0 -p 1024
> +  sh> rtems-bin2c -C -N imxrt_dtb "YOUR.dtb" "YOUR.c"
> +
> +Make sure that your new c file is compiled and linked into the application.
> +
> +Clock Driver
> +------------
> +
> +The clock driver uses the generic `ARMv7-M Clock`.
> +
> +IOMUX
> +-----
> +
> +The i.MXRT IOMUXC is initialized based on the FDT. For that, the `pinctrl-0`
> +fields of all devices with a status of `ok` or `okay` will be parsed.
> +
> +Console Driver
> +--------------
> +
> +LPUART drivers are registered based on the FDT. The special `rtems,path`
> +attribute defines where the device file for the console is created.
> +
> +The `stdout-path` in the `chosen` node determines which LPUART is used for the
> +console.
> +
> +I2C Driver
> +----------
> +
> +I2C drivers are registered based on the FDT. The special `rtems,path` attribute
> +defines where the device file for the I2C bus is created.
> +
> +Limitations:
> +
> +* Only basic I2C is implemented. This is mostly a driver limitation and not a
> +  hardware one.
> +
> +SPI Driver
> +----------
> +
> +SPI drivers are registered based on the FDT. The special `rtems,path` attribute
> +defines where the device file for the SPI bus is created.
> +
> +Note that the SPI-pins on the evaluation board are shared with the SD card.
> +Populate R278, R279, R280, R281 on the IMXRT1050-EVKB (Rev A) to use the SPI
> +pins on the Arduino connector.
> +
> +Limitations:
> +
> +* Only a basic SPI driver is implemented. This is mostly a driver limitation and
> +  not a hardware one.
> +
> +Network Interface Driver
> +------------------------
> +
> +The network interface driver is provided by the `libbsd`. It is initialized
We probably need a libbsd (or update of the networking) manual soon.

> +according to the device tree.
> +
> +Note on the hardware: The i.MXRT1050 EVKB maybe has a wrong termination of the
> +RXP, RXN, TXP and TXN lines. The resistors R126 through R129 maybe shouldn't be
> +populated because the used KSZ8081RNB already has an internal termination.
> +Ethernet does work on short distance anyway. But keep it in mind in case you
> +have problems. Source:
> +https://community.nxp.com/t5/i-MX-RT/Error-in-IMXRT1050-EVKB-and-1060-schematic-ethernet/m-p/835540#M1587
> +
> +NXP SDK files
> +-------------
> +
> +A lot of peripherals are currently not yet supported by RTEMS drivers. The NXP
> +SDK offers drivers for these. For convenience, the BSP compiles the drivers from
> +the SDK. But please note that they are not tested and maybe won't work out of
> +the box. Everything that works with interrupts most likely needs some special
> +treatment.
> +
> +Caveats
> +-------
> +
> +The clock configuration support is quite rudimentary. The same is true for
> +SDRAM. It mostly relies on the DCD and on a static clock configuration that is
> +taken from the NXP SDK example projects.
> +
> +The MPU settings are currently quite permissive. Some stronger rules might could
> +improve the security.
I'd prefer we avoid statements regarding security here. Just delete
the last sentence.

> +
> +There is no power management support.
> diff --git a/user/bsps/bsps-arm.rst b/user/bsps/bsps-arm.rst
> index 295ed82..a63dd5f 100644
> --- a/user/bsps/bsps-arm.rst
> +++ b/user/bsps/bsps-arm.rst
> @@ -14,6 +14,7 @@ arm (ARM)
>  .. include:: arm/edb7312.rst
>  .. include:: arm/gumstix.rst
>  .. include:: arm/imx.rst
> +.. include:: arm/imxrt.rst
>  .. include:: arm/lm3s69xx.rst
>  .. include:: arm/lpc176x.rst
>  .. include:: arm/imx.rst
> --
> 2.26.2
>
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