SDHCI(4)

NAME
sdhci - PCI SD Host Controller bridge driver

SYNOPSIS
To compile this driver into the kernel, place the following lines in your kernel configuration file:

device mmc
device mmcsd
device sdhci

Alternatively, to load the driver as a module at boot time, place the following lines in loader.conf(5):

    mmc_load="YES"
    mmcsd_load="YES"
    sdhci_load="YES"

DESCRIPTION
The sdhci driver supports PCI devices with class 8 and subclass 5 according to SD Host Controller Specification. Driver supports up to six high speed 4bit MMC/SD slots per controller. Driver attaches mmc bus to the respective slot on card insertion and detaches it on card removing.

HARDWARE
The sdhci driver supports the SD Host Controller Specification. When attaching via the PCI bus, the controller is automatically configured. Many SoC chips provide a SDHCI controller directly mapped to I/O memory. For those, the controller may be configured using fdt(4) or acpi(4) methods, supplied by your board's vendor.

Unlike most other drivers that support a generic standard, sdhci requires a large number of quirks to cope with hardware bugs, proprietary registers and poorly specified power management. While many chipsets from Intel, Xilinx, Rockchip, Frescale, Ricoh, and TI have these entries, suboptimal performance may result when using some controllers. Quirks and custom configuration are most often required when the device is configured via fdt(4) or acpi(4).

SEE ALSO
mmc(4), mmcsd(4) SD Specifications, Part 2, SD Host Controller, Simplified Specification.

AUTHORS
Alexander Motin <mav@FreeBSD.org>