Low-level SDIO/SD/MMC peripheral driver. More...

Detailed Description

Low-level SDIO/SD/MMC peripheral driver.

The low-level SDIO/SD/MMC peripheral driver interface as used by high-level SDIO/SD/MMC device API functions. It has to be implemented for a specific CPU.

Note: High-level functions such as sdmmc_read_blocks are provided by the SDIO/SD/MMC API and should be used instead. Directly calling these functions is not recommended.

Definition at line 956 of file sdmmc.h.

#include <sdmmc.h>

Data Fields
void(*	init )(sdmmc_dev_t *dev)
	Basic initialization of the given SDIO/SD/MMC device.

int(*	send_cmd )(sdmmc_dev_t dev, sdmmc_cmd_t cmd_idx, uint32_t arg, sdmmc_resp_t resp_type, uint32_t resp)
	Send command to SDIO/SD/MMC Card and optionally wait for response.

int(*	card_init )(sdmmc_dev_t *dev)
	Card Initialization and Identification.

int(*	set_bus_width )(sdmmc_dev_t *dev, sdmmc_bus_width_t width)
	Set data bus width.

int(*	set_clock_rate )(sdmmc_dev_t *dev, sdmmc_clock_rate_t rate)
	Set SD CLK signal rate.

int(*	enable_clock )(sdmmc_dev_t *dev, bool enable)
	Enable or disable the SD CLK signal.

int(*	xfer_prepare )(sdmmc_dev_t dev, sdmmc_xfer_desc_t xfer)
	Prepare a data transfer.

int(*	xfer_execute )(sdmmc_dev_t dev, sdmmc_xfer_desc_t xfer, const void data_wr, void data_rd, uint16_t *done)
	Execute the data transfer.

int(*	xfer_finish )(sdmmc_dev_t dev, sdmmc_xfer_desc_t xfer)
	Finish the data transfer.

Field Documentation

◆ card_init

int(* sdmmc_driver_t::card_init) (sdmmc_dev_t *dev)

Card Initialization and Identification.

Warning: Usually the standard procedure implemented by the high-level SDIO/SD/MMC device API function sdmmc_card_init is used for card initialization and identification (recommended). The low-level SDIO/SD/MMC peripheral driver should implement its own sdmmc_driver_t::card_init function only in very special cases, e.g. when special hardware handling is required. Therefore, this driver function should be set to NULL, that is the card initialization and identification function is not implemented by low-level SDIO/SD/MMC peripheral driver

See also: sdmmc_card_init

Precondition: dev must not be NULL.

Parameters

[in] dev SDIO/SD/MMC device to be used

Return values

0	on success
-ENODEV	if card is not present or not usable
-ENOTSUP	if card is not supported or can't operate under supplied voltage
-EFAULT	on card status error
-ETIMEDOUT	on card initialization and identification timeout
-EBADMSG	on CRC7 error
-EIO	on not further specified error incl. hardware errors

Definition at line 1060 of file sdmmc.h.

◆ enable_clock

int(* sdmmc_driver_t::enable_clock) (sdmmc_dev_t *dev, bool enable)

Enable or disable the SD CLK signal.

The function is used by the SDIO/SD/MMC device API functions to enable or disable the SD CLK signal if the SDIO/SD/MMC peripheral driver does not support the Auto CLK feature (periph_sdmmc_auto_clk). It can be left NULL if the SDIO/SD/MMC peripheral driver does not support enabling or disabling the SD CLK signal.

Parameters

[in]	dev	SDIO/SD/MMC device to be used
[in]	enable	enable SD CLK signal on true or disable the SD CLK signal on false

Return values

0	on success
-EIO	if the SD CLK signal could not be enabled or disabled

Definition at line 1156 of file sdmmc.h.

◆ init

void(* sdmmc_driver_t::init) (sdmmc_dev_t *dev)

Basic initialization of the given SDIO/SD/MMC device.

Low-level SDIO/SD/MMC peripheral driver function for basic initialization of the peripheral including pin configuration of used pins. It is called by sdmmc_init during the board initialization to prepare the SDIO/SD/MMC peripheral for further usage. Specific initialization parameters required for this initialization are defined in the board's periph_conf.h.

Errors like configuration parameter problems are not signaled by return values, but by using the assert().

See also: sdmmc_init

Precondition: dev must not be NULL.

Parameters

[in] dev SDIO/SD/MMC device to initialize

Definition at line 975 of file sdmmc.h.

◆ send_cmd

int(* sdmmc_driver_t::send_cmd) (sdmmc_dev_t *dev, sdmmc_cmd_t cmd_idx, uint32_t arg, sdmmc_resp_t resp_type, uint32_t *resp)

Send command to SDIO/SD/MMC Card and optionally wait for response.

Low-level SDIO/SD/MMC peripheral driver function to send command cmd_idx with argument arg to the SDIO/SD/MMC card. resp_type specifies the type of the response expected.

Warning: This function must not be used for application specific commands. The high-level SDIO/SD/MMC device API function sdmmc_send_acmd is used instead.

To ensure that the sdmmc_send_acmd function is used for application specific commands, the function must fail if the command cmd_idx is an application specific command (ACMDx). Use

assert((cmd_idx & SDMMC_ACMD_PREFIX) == 0);

assert

#define assert(cond)

abort the program if assertion is false

Definition assert.h:137

SDMMC_ACMD_PREFIX

#define SDMMC_ACMD_PREFIX

Application specific command index prefix (Bit is 7 used)

Definition sdmmc.h:186

in the implementation of this function for that purpose.

The response has to be stored word-wise in host byte order in the buffer provided by resp as follows:

resp_type = SDMMC_NO_R (No Response): resp can be NULL
resp_tpye = SDMMC_R2 (Long Response): resp = { R[127:96], R[95:64], R[63:32], R[31:0] }
resp_type = anything else (Short Response): resp = { R[39:8] }

The buffer provided by resp can be NULL if the response is not needed. However, the low-level SDIO/SD/MMC peripheral driver must receive the expected response, but does not store it in resp in that case.

Note: R3 does not use CRC7 in CRC field but a fixed value of 0b111111. The driver must check the CRC field for this response.

See also: sdmmc_send_cmd and sdmmc_send_acmd

Precondition: dev must not be NULL.

Parameters

[in]	dev	SDIO/SD/MMC device to be used
[in]	cmd_idx	Command index
[in]	arg	Command argument
[in]	resp_type	Type of response expected
[out]	resp	Buffer of 32-bit words to store the response if needed, otherwise NULL

Return values

0	on success
-ENODEV	if card is not present or not usable
-ENOTSUP	if card does not support the command or is in wrong state
-EFAULT	on card status error
-ETIMEDOUT	on timeout condition
-EBADMSG	on CRC7 error in response
-EIO	on not further specified error incl. hardware errors

Definition at line 1031 of file sdmmc.h.

◆ set_bus_width

int(* sdmmc_driver_t::set_bus_width) (sdmmc_dev_t *dev, sdmmc_bus_width_t width)

Set data bus width.

Set the data bus width used by the SDIO/SD/MMC peripheral. The function is called by the high-level SDIO/SD/MMC device function sdmmc_card_init at the end of the card initialization and identification procedure to change the data bus width used by the SDIO/SD/MMC peripheral. The data bus width of the card has been already changed at that time by sending the ACMD6 (SET_BUS_WIDTH) command.

Supported data bus width depend on

the card type,
the mode in which the card operates and
the SDIO/SD/MMC peripheral.

In identification mode, always 1-bit data bus width is used. When switching from the identification mode to the data transfer mode, the data bus width is changed. In data transfer mode, the data bus width depends on the type of the used card:

MMCs V3.x support 4-bit data bus width
MMCs V4.x support 8-bit data bus width
SD Memory Cards support 4-bit data bus width
SDIO Cards support 4-bit data bus width
Embedded SDIO devices support 8-bit data bus width

The data bus width width is the minimum of the data bus width supported by the identified card and the data bus width sdmmc_dev_t::bus_width configured for the SDIO/SD/MMC peripheral. The low-level SDIO/SD/MMC peripheral driver is responsible for correctly setting sdmmc_dev_t::bus_width in the sdmmc_driver_t::init function.

Note: The set_bus_width function must not change sdmmc_dev_t::bus_width because it is the configured data bus width which may be larger than the supported data bus width of the identified card.

Precondition: dev must not be NULL.

Parameters

[in]	dev	SDIO/SD/MMC device to be used
[in]	width	Data bus width to be set

Return values

0	on success
-ENOTSUP	if SDIO/SD/MMC peripheral does not support the width
-EIO	on not further specified error incl. hardware errors

Definition at line 1111 of file sdmmc.h.

◆ set_clock_rate

int(* sdmmc_driver_t::set_clock_rate) (sdmmc_dev_t *dev, sdmmc_clock_rate_t rate)

Set SD CLK signal rate.

Set the SD CLK rate used by the SDIO/SD/MMC peripheral. The clock frequency in identification mode f_OD is fixed and is 400 kHz. The actual clock frequency in data transfer mode f_PP depends on the SDIO/SD/MMC device and the card used.

The function is called by the high-level SDIO/SD/MMC device API function sdmmc_card_init at the end of the card identification procedure with rate set to any of the clock rates defined in sdmmc_clock_rate_t. The low-level SDIO/SD/MMC peripheral is responsible to set the clock rate to the highest value it supports for the identified card type.

Precondition: dev must not be NULL.

Parameters

[in]	dev	SDIO/SD/MMC device to be used
[in]	rate	Clock rate to be set

Return values

0	on success
-ENOTSUP	if SDIO/SD/MMC peripheral does not support the clock rate
-EIO	on not further specified error incl. hardware errors

Definition at line 1137 of file sdmmc.h.

◆ xfer_execute

int(* sdmmc_driver_t::xfer_execute) (sdmmc_dev_t *dev, sdmmc_xfer_desc_t *xfer, const void *data_wr, void *data_rd, uint16_t *done)

Execute the data transfer.

Low-level SDIO/SD/MMC peripheral driver function to transfer the data (read or write) by the SDIO/SD/MMC peripheral.

It is called by the high-level SDIO/SD/MMC device API function sdmmc_xfer after it sent the block-oriented, stream or byte/multi-byte command to start the transfer from or to the card.

The function returns the number of transferred blocks in done. Most SDIO/SD/MMC peripherals use a block or byte counter when transferring data, which can be used for this purpose.

Note: If the SDIO/SD/MMC peripheral does not allow to determine the number of transferred blocks, the function must return 0 in done in case of an error or sdmmc_xfer_desc_t::block_num on success.

See also: sdmmc_xfer

Precondition: dev and xfer must not be NULL.
data_rd must not be NULL for read transfers and
data_wr must not be NULL for write transfers.

Parameters

[in]	dev	SDIO/SD/MMC device to be used
[in]	xfer	Transfer descriptor of type sdmmc_xfer_desc_t
[in]	data_wr	Buffer with data to write in write transfers, NULL otherwise
[out]	data_rd	Buffer for data to read in read transfers, NULL otherwise
[out]	done	Number of blocks transferred, can be `NULL`

Return values

0	on success
-ENODEV	if card is not present or not usable
-ENOTSUP	if card does not support a used command or is in wrong state
-EBUSY	if card is busy
-EFAULT	on card status error
-ETIMEDOUT	on timeout condition
-EINVAL	on invalid transfer parameters
-EBADMSG	on CRC7 error in data
-ENOMEM	on RX FIFO overflow or TX FIFO underrun error
-EIO	on not further specified error incl. hardware errors

Definition at line 1226 of file sdmmc.h.

◆ xfer_finish

int(* sdmmc_driver_t::xfer_finish) (sdmmc_dev_t *dev, sdmmc_xfer_desc_t *xfer)

Finish the data transfer.

Low-level SDIO/SD/MMC peripheral driver function to terminate a data transfer (read or write) in the SDIO/SD/MMC peripheral.

It is called by the high-level SDIO/SD/MMC device API function sdmmc_xfer after the data transfer has been executed and the stop command (CMD12) has been sent if necessary.

See also: sdmmc_xfer

Precondition: dev and xfer must not be NULL.

Parameters

[in]	dev	SDIO/SD/MMC device to be used
[in]	xfer	Transfer descriptor of type sdmmc_xfer_desc_t

Return values

0	on success
-EIO	on not further specified error incl. hardware errors

Definition at line 1249 of file sdmmc.h.

◆ xfer_prepare

int(* sdmmc_driver_t::xfer_prepare) (sdmmc_dev_t *dev, sdmmc_xfer_desc_t *xfer)

Prepare a data transfer.

Low-level SDIO/SD/MMC peripheral driver function to prepare a data transfer (read or write) in the SDIO/SD/MMC peripheral.

It is called by the high-level SDIO/SD/MMC device API function sdmmc_xfer before it sends a block-oriented, stream or byte/multi-byte command to the card to start the transfer from or to the card.

A typical activity of this function is the configuration of the DMA transfer.

See also: sdmmc_xfer

Precondition: dev and xfer must not be NULL.

Parameters

[in]	dev	SDIO/SD/MMC device to be used
[in]	xfer	Transfer descriptor of type sdmmc_xfer_desc_t

Return values

0	on success
-EINVAL	on invalid transfer parameters
-EIO	on not further specified error incl. hardware errors

Definition at line 1183 of file sdmmc.h.

The documentation for this struct was generated from the following file:

drivers/include/sdmmc/sdmmc.h

Detailed Description

Data Fields

Field Documentation

◆ card_init

◆ enable_clock

◆ init

◆ send_cmd

◆ set_bus_width

◆ set_clock_rate

◆ xfer_execute

◆ xfer_finish

◆ xfer_prepare