e.MMC/SD/SDIO driver stack

The golden blocks represent the whole e.MMC/SD/SDIO driver stack. Block driver is located in /drivers/mmc/block, protocol bus driver (e.MMC/SD/SDIO) is located in /drivers/mmc/core, and host controller driver can be found at /drivers/mmc/host.

In MFLD platform, SDIO device driver is developed by Comms teams who own Comms devices (TI Wifi device).

The current Linux driver consists of the following kernel driver stack:

Ÿ  Host controller driver (sdhci): Driver for the standard e.MMC/SD/SDIO host controllers. Registers itself with the PCI bus subsystem, so that when sdhci is loaded and the host controller is present in the PCI bus the host controller will be probed, configured and initialized.  sdhci calls routines in mmc_core.

Ÿ  Protocol driver (mmc_core): implements the SD, MMC and SDIO protocols.  Properly detects and initializes SD, MMC or SDIO devices in the MMC bus.  Defines functions to read and write data to and from devices, so that higher level layers don’t have to issue MMC commands directly.

Ÿ  Block driver (mmc_block): abstracts an SD or e.MMC/MMC card as a standard Linux block kernel device, that is, as a random-access disk. Once the block device is available to the user (e.g. via /dev/mmc0), the user can partition the device (e.g. using fdisk), format with a file system (e.g. mkfs.ext3) or access the device with the ‘mount’ command.  mmc_block also calls routines in mmc_core.