>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 < [email protected]> 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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