[PATCH rtems-docs] user/bsps: Add STM32H7 SDMMC driver

[Gedare Bloom]

doc looks good

On Thu, Mar 25, 2021 at 2:36 AM Christian Mauderer
<christian.mauderer at embedded-brains.de> wrote:
>
> ---
>  user/bsps/arm/stm32h7.rst | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>
> diff --git a/user/bsps/arm/stm32h7.rst b/user/bsps/arm/stm32h7.rst
> index 3eee511..483d029 100644
> --- a/user/bsps/arm/stm32h7.rst
> +++ b/user/bsps/arm/stm32h7.rst
> @@ -31,3 +31,29 @@ USB Host Driver
>  ---------------
>
>  The USB host driver ``dwc_otg`` is provided by the ``libbsd``.
> +
> +SD/MMC Driver
> +-------------
> +
> +The SDMMC driver ``st_sdmmc`` is provided by the ``libbsd``.
> +
> +The default initialization is done for the STM32H743I-EVAL 2 board.
> +
> +To use different pins, you can create a ``HAL_SD_MspInit()`` function in your
> +application that overwrites the default one defined in ``RTEMS``. If you don't
> +have direction lines like on the evaluation board, you can just skip
> +initializing these pins.
> +
> +If you want to use a different number of data lines, another polarity for the
> +data direction pins, a different voltage or similar, you have to redefine
> +``st_sdmmc_get_config()`` (normally provided by ``libbsd``) in your application.
> +
> +Known limitations:
> +
> +* Currently 1.8V signaling is not implemented. Therefore higher speeds like used
> +  for UHS cards are not available. All cards fall back to High Speed transfers.
> +* The driver uses the IDMA only. MDMA is currently not implemented. For SDMMC1
> +  that means that the memory buffers can only come from AXI SRAM, QSPI memory,
> +  Flash or the FMC (SDRAM, ...). The internal SRAM1, SRAM2, SRAM3 and SRAM4 is
> +  not supported. SDMMC2 should not have that limitation. See ST AN5200 "Getting
> +  started with STM32H7 Series SDMMC host controller" for more details.
> --
> 2.26.2
>
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