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>
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