Raspberry Pi SD card support

[Gedare Bloom]

The license looked fine to me.

On Thu, Apr 3, 2014 at 10:06 PM, Alan Cudmore <alan.cudmore at gmail.com> wrote:
> From my limited research, it looks like the emmc controller in the Raspberry
> Pi BCM2835 may be the way to go.
> It looks like it is a high level controller for the SD/MMC card slot on the
> Pi.
>
> Since this is a custom controller, I don't think there would be an existing
> driver in RTEMS.
>
> It seems that this emmc controller in the Pi may handle different types of
> cards, and at a higher level than just using the SPI bus to access the card.
> ( This is based on some searches of conversations on the raspberry pi forums
> , not my experience )
>
> You would have to write a driver for this emmc controller and provide the
> interface to libblock for the file system interface on RTEMS. The code you
> have linked above for rpi-boot looks like it has a permissive license, so it
> *may* be possible to use this code in the RTEMS driver. There is some other
> potentially useful code in there too.
>
> I'll have to try the serial bootloader, I am also close to ordering an
> inexpensive JTAG adapter to try loading and debugging through JTAG. uboot is
> another possibility, using a TFTP server.
>
> Alan
>
>
>
>
> On Wed, Apr 2, 2014 at 12:02 PM, Andre Marques
> <andre.lousa.marques at gmail.com> wrote:
>>
>> Hello,
>>
>> I'm intending to work in the SD card support for the Raspberry Pi BSP,
>> using the SD mode instead of the SPI mode.
>>
>> The references I have gathered so far for this are as follows:
>>
>> The Raspberry Pi SOC guide: Broadcom BCM2835 Peripherals Guide (Chapter 5
>> - EMMC)
>>
>> The simplified SD standard -
>> https://www.sdcard.org/downloads/pls/simplified_specs/
>>
>> And the following github code -
>> https://github.com/jncronin/rpi-boot/blob/master/emmc.c
>>
>> There is also the libchip/i2c/spi-sd-card libi2c driver, which can also be
>> a reference (even though it uses SPI).
>>
>> Now, the questions:
>>
>> Should I use the Generic Disk Device driver, as the
>> libchip/i2c/spi-sd-card ?
>>
>> Is there any driver using the SD mode for sd card access, or using an emmc
>> interface currently in the RTEMS code base? I haven't found any.
>>
>> On a side note, I managed to send RTEMS applications to the RPi though the
>> UART interface using the xmodem protocol.
>>
>> For that I used the following bootloader
>>
>> https://github.com/dwelch67/raspberrypi/tree/master/bootloader05
>>
>> It takes me 2 minutes to send 1 MB of data to the RPi, but this could be
>> improved if it used 1024 byte block transfer instead of the default of 128.
>> The bootloader loads the transfered program to memory and runs it. Then the
>> RPi must be rebooted so a new program can be sent.
>>
>> It may not be the best way, but only requires an usb-to-uart cable, and
>> avoids the current SD card "dance" to run programs on the Pi.
>>
>> Thank you for your time.
>>
>> --André Marques
>>
>>
>
>
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