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doc: storage: update storage documentation for SD subsystem

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add section about SD subsystem to disk documentation, and document new
SDHC SPI bindings

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>
This commit is contained in:
Daniel DeGrasse 2022-04-06 21:55:33 -05:00 • committed by David Leach
commit e74d8457c4
1 changed files with 17 additions and 2 deletions
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19
doc/services/storage/disk/access.rst
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@ -23,6 +23,16 @@ Both standard and high-capacity SD cards are supported.
FAT filesystems are not power safe so the filesystem may become FAT filesystems are not power safe so the filesystem may become
corrupted if power is lost or if the card is removed. corrupted if power is lost or if the card is removed.
SD Memory Card subsystem
========================
Zephyr supports SD memory cards via the disk driver API, or via the SDMMC
subsystem. This subsystem can be used transparently via the disk driver API,
but also supports direct block level access to cards. The SDMMC subsystem
interacts with the :ref:`sd host controller api <sdhc_api>` to communicate
with attached SD cards.
SD Card support via SPI SD Card support via SPI
======================= =======================
@ -37,10 +47,15 @@ at 24 MHz once the SD card has been initialized:
cs-gpios = <&porta 27 GPIO_ACTIVE_LOW>; cs-gpios = <&porta 27 GPIO_ACTIVE_LOW>;
sdhc0: sdhc@0 { sdhc0: sdhc@0 {
compatible = "zephyr,mmc-spi-slot"; compatible = "zephyr,sdhc-spi-slot";
reg = <0>; reg = <0>;
status = "okay"; status = "okay";
label = "SDHC0"; label = "SDHC_0";
mmc {
compatible = "zephyr,sdmmc-disk";
status = "okay";
label = "SDMMC_0";
};
spi-max-frequency = <24000000>; spi-max-frequency = <24000000>;
}; };
}; };