SDHCI(4)               FreeBSD Kernel Interfaces Manual               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>

FreeBSD 15.1-STABLE-HBSD        October 3, 2025                       SDHCI(4)