CAM, FreeBSD, GSoC, mmccam, RTEMS, SDIO

Backporting MMCCAM/SDIO framework to FreeBSD head 642b174dadd

My phase 2, GSoC objectives includes Backporting the current(rev: d6756a3ac8 ) MMCCAM framework to FreeBSD head 642b174dadd and then importing it to RTEMS. This post mainly concerns with intricacies and workarounds during the backporting process. Backporting is a process that enables old kernels run a latest driver. MMCCAM framework is one such enhancement in the past few months that enables FreeBSD to talk to devices behind the SDIO bus. It’s a major architectural change, that enables further driver development for devices on SDIO bus. So, first step during backporting is to finalize the revisions from which driver will be imported(d6756a3ac8…

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CAM, FreeBSD, mmccam, SDIO, Software

Implementing a MMC/SD/SDIO stack using CAM framework(Part 2)

Hi, In the next part lets look at other files which makes up the SDIO stack within mmccam framework. Please have  a look at previous part for more info: mmc_sdio.c +void sdio_fill_mmcio_rw_direct(union ccb *ccb, uint8_t f, uint8_t wr, uint32_t adr, uint8_t *data) { + struct ccb_mmcio *mmcio; + + CAM_DEBUG(ccb->ccb_h.path, CAM_DEBUG_TRACE, + (“sdio_fill_mmcio(f=%d, wr=%d, adr=%02x, data=%02x)\n”, f, wr, adr, (data == NULL ? 0 : *data))); + mmcio = &ccb->mmcio; + + mmcio->cmd.opcode = SD_IO_RW_DIRECT; + mmcio->cmd.arg = SD_IO_RW_FUNC(f) | SD_IO_RW_ADR(adr); + if (wr) + mmcio->cmd.arg |= SD_IO_RW_WR | SD_IO_RW_RAW | SD_IO_RW_DAT(*data); + mmcio->cmd.flags = MMC_RSP_R5 | MMC_CMD_AC; +…

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Understanding SD, SDIO and MMC Interface

  TL;DR; MMC and SD-card have the same physical and electrical specifications but different software controls. They both are used as a storage device only. SDIO and SD-Combo cards, on the other hand, incorporate Input/Output functionality(like Bluetooth, Wifi, GPS, etc) without and with the storage facility respectively. So, a SD-Combo card can act as a wifi adapter along with a storage device. In this blog post, I will present a gist of the paper  (updated link). This is meant for anyone willing to understand how removable devices like sd card work and different protocols/functionalities they support. Secure Digital (SD)…

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