CAM, GSoC, mmccam, RTEMS, SDIO

RTEMS SDIO driver: Current progress

Hi, this post mainly concerns with the current progress of SDIO driver’s implementation on RTEMS. In a nutshell, driver is able to detect, initialize the type of card. However, the part concerned with registering the partitions of the card as RTEMS disks is still buggy. So, I’ll discuss some of the bugs which were previously resolved and the ones that are still left. Starting with a very short introduction of how MMCCAM driver is being interfaced with SDHCI driver: Part 1: Interfacing Complete interfacing task is done mainly via these two files: nexus_devices.h #ifdef RTEMS_BSD_MODULE_MMCCAM SYSINIT_MODULE_REFERENCE(cam); SYSINIT_MODULE_REFERENCE(mmcprobe); SYSINIT_MODULE_REFERENCE(sdda); #endif /*…

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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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Benchmark, Bonnie++, FIO, FreeBSD, GSoC, IOZONE, RTEMS, Software

Comparing IO benchmarks: FIO, IOZONE and BONNIE++

IO benchmarks refer to the computerized test for measuring various properties of an IO device under multiple conditions. Various features include Read/Write speed, IOPS, seek time, etc and various conditions refer to random/sequential reads/writes, block size used by the filesystem, buffer cache size, etc. There are multiple IO benchmarks available online, but the top 3 opensource IO benchmarks, in my view, include FIO, IOZONE, and BONNIE++. There are several pros and cons for each of them, which we will be discussing in this blog post. Fio (Documentation, Repository) FIO is an I/O tool meant to be used both for benchmark and…

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Benchmark, CAM, File system, FreeBSD, GSoC, mmccam, SDIO

microSD Card benchmarking on BeagleBone Black

Hi all, I have been recently involved in benchmarking two different device drivers of FreeBSD ,namely SDHCI and the SDIO driver to compare their relative performance under different circumstances. Here, I will summarize my results, possible conclusions and the benchmarking procedure. Before moving towards benchmarking, i’d prefer going through this article. It really good and provides a great overview of how data is transferred to disk, different APIs available. This will surely help you selecting options for the benchmark. Benchmarking procedure I initially experimented with different benchmarks like iorate, iozone, fio, bonnie++ etc but the one i really liked was…

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ARM, CAM, FreeBSD, mmccam, SDIO, Software

Building FreeBSD’s SDIO driver for BeagleBone Black

Hi all, This post mainly concern with building FreeBSD’s SDIO driver for BeagleBone Black by cross compiling it on AMD platform. I had few unresolved issues with the master branch of current FreeBSD tree. So, for this i used another unofficial branch: https://github.com/kibab/freebsd/tree/mmcam-new . It does have the required KERNCONF file with stable SDIO driver. A lot of steps below are similar to the one given on: https://forums.freebsd.org/threads/cross-compiling-beaglebone-on-amd64.64718/#post-384835  with slight but inevitable changes. Procedure:  Before proceeding you need to first install git. sudo pkg update -f sudo pkg install git  Setup project directory by mkdir /BBB  Clone the repository to…

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FreeBSD, GSoC, Software

Setting up FreeBSD environment on virtualbox

Hi all, In this post we will review the procedure of setting up the FreeBSD environment on VirtualBox along with setting up Internet on the guest OS(this was pretty tricky!).BTW, my host OS is Ubuntu 14.04 So, I am assuming you have already installed VirtualBox as per your host OS and has downloaded the FreeBSD amd64 iso image(If not you can do it from here and extract it appropriately to get a .iso file. Installing FreeBSD on VirtualBox Installing FreeBSD on virtual box is pretty straight forward, just insert use the downloaded iso to boot up the VM with default…

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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: http://uditagarwal.in/index.php/2018/03/19/implementing-a-mmc-sd-sdio-stack-using-cam-framework/ 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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CAM, FreeBSD, Hardware, mmccam, SDIO, Software

Detailed SDIO protocol Implementation

Reference: Wikipedia, https://www.sdcard.org/developers/overview/sdio/sdio_spec/Simplified_SDIO_Card_Spec.pdf  SDIO cards are intended to provide high-speed data Input/Output on our regular sd card slot. SDIO cards are compatible with any sd card slot and will not cause any physical damage to the host if it’s not compatible with SDIO. When SDIO is plugged in an SDIO compatible host, in its early stage it is in low power mode and consumes very little current. The host identifies the SDIO card, it’s power requirement, it’s I/O capabilities, etc. If the host finds that the power requirement is manageable and there is a driver for the I/O functionality card…

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CAM, FreeBSD, mmccam

Implementing a MMC/SD/SDIO stack using CAM framework(Part 1)

In this blog post we will have a detailed look at all the files added/changed while implementing the MMC/SD/SDIO stack via CAM framework. We will basically discuss the commit  https://github.com/freebsd/freebsd/commit/a87c7a85be3e3727b6b08b19741b4282f942400d which aims at adding MMC/SD/SDIO stack to FreeBSD’s already existing CAM framework. So, lets start one by one with each file: mmc.h #ifndef CAM_MMC_H #define CAM_MMC_H #include <dev/mmc/mmcreg.h> /* * This structure describes an MMC/SD card */ struct mmc_params { u_int8_t model[40]; /* Card model */ /* Card OCR */ uint32_t card_ocr; /* OCR of the IO portion of the card */ uint32_t io_ocr; /* Card CID — raw and…

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CAM, FreeBSD

Understanding FreeBSD’s CAM Framework

This blog post presents a gist of Free BSD’s doc on CAM(here) and chapter 14 of the book FreeBSD device driver- A guide for intrepid. It gives an introduction to the CAM(Common access method), it’s applications, it’s working and it’s organization in FreeBSD. It is written to get myself a really good understanding of mmccam stack which is nothing but SDHC/SDIO protocols wired within the CAM framework. COMMON ACCESS METHOD CAM is a method for separating HBA adapters from storage adapters and is primarily used for SCSI. By separating these drivers it reduces the complexity of both the drivers.Furthermore, this…

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