tree 7c990888edf4043e58a6eafb3ce56246cebd01b8
parent bbafc36b1cca944f738e44d5efa3d2a41b7f43a6
author Michael Hope <mlhx@google.com> 1513891027 +0100
committer Anas Nashif <anas.nashif@intel.com> 1546205050 -0500

disk: add a SDHC card over SPI driver.

Features:

- Uses the SPI bus to communicate with the card
- Detects and safely rejects SDSC (<= 2 GiB) cards
- Uses the optional CRC support for data integrity
- Retries resumable errors like CRC failure or temporary IO failure
- Works well with ELMFAT
- When used on a device with a FIFO or DMA, achieves >= 310 KiB/s on a
  4 MHz bus

Tested on a mix of SanDisk, Samsung, 4V, and ADATA cards from 4 GiB to
32 GiB.

Signed-off-by: Michael Hope <mlhx@google.com>