<dev/protocols/mmcdrv.h>

Block-device protocol shared by every SD/MMC driver ("/dev/mmc0").

One client at a time. Every request gets exactly one reply, sent once the transfer has finished. Requests and replies travel in the message buffer; block data goes through the buffer page from SD_CMD_GET_BUF.

#include <dev/protocols/mmcdrv.h>

Constants

Name	Value	Description
SD_CMD_GET_BUF	1	Get the transfer buffer. SdRequest {cmd}; replies SdReply and grants the driver-owned buffer page (PERM_MAP | PERM_WRITE | PERM_TXFR). Asking again grants the same buffer.
SD_CMD_READ	2	Read blocks. SdRequest {cmd, lba, count}; the data lands at buffer offset 0.
SD_CMD_WRITE	3	Write blocks. SdRequest {cmd, lba, count}; the data is taken from buffer offset 0.
SD_ERR_IO	ERR_IO	A block transfer failed: CRC error, timeout, or FIFO overrun or underrun.
SD_BLOCK_SIZE	512u	Bytes per block.
SD_BUF_SIZE	4096u	Size of the transfer buffer: one page, so at most 8 blocks per request.

Structures

SdRequest

A request, in the message buffer.

Field	Type	Description
cmd	uint32_t	An SD_CMD_* value.
lba	uint32_t	First block.
count	uint32_t	Number of blocks.

SdReply

A reply, in the message buffer; READ and WRITE fill in only status.

Field	Type	Description
status	Err	ZUZU_OK, or an error code.
buf_size	uint32_t	GET_BUF: size of the transfer buffer.
block_size	uint32_t	GET_BUF: bytes per block.
block_count	uint32_t	GET_BUF: blocks on the card, or 0 if unknown.