subsys/sd/sd.c - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 /*
  * Copyright 2022 NXP
  *
  * SPDX-License-Identifier: Apache-2.0
  */

 #include <zephyr/zephyr.h>
 #include <zephyr/drivers/sdhc.h>
 #include <zephyr/sd/sd.h>
 #include <zephyr/sd/sdmmc.h>
 #include <zephyr/sd/sd_spec.h>
 #include <zephyr/logging/log.h>
 #include <zephyr/sys/__assert.h>

 #include "sd_utils.h"
 #include "sdmmc_priv.h"


 LOG_MODULE_REGISTER(sd, CONFIG_SD_LOG_LEVEL);

 /* Idle all cards on bus. Can be used to clear errors on cards */
 static inline int sd_idle(struct sd_card *card)
 {
 	struct sdhc_command cmd = {0};

 	/* Reset card with CMD0 */
 	cmd.opcode = SD_GO_IDLE_STATE;
 	cmd.response_type = (SD_RSP_TYPE_NONE | SD_SPI_RSP_TYPE_R1);
 	cmd.timeout_ms = CONFIG_SD_CMD_TIMEOUT;
 	return sdhc_request(card->sdhc, &cmd, NULL);
 }

 /* Sends CMD8 during SD initialization */
 static int sd_send_interface_condition(struct sd_card *card)
 {
 	struct sdhc_command cmd = {0};
 	int ret;
 	uint32_t resp;

 	cmd.opcode = SD_SEND_IF_COND;
 	cmd.arg = SD_IF_COND_VHS_3V3 | SD_IF_COND_CHECK;
 	cmd.response_type = (SD_RSP_TYPE_R7 | SD_SPI_RSP_TYPE_R7);
 	cmd.timeout_ms = CONFIG_SD_CMD_TIMEOUT;
 	ret = sdhc_request(card->sdhc, &cmd, NULL);
 	if (ret) {
 		LOG_DBG("SD CMD8 failed with error %d", ret);
 		/* Retry */
 		return SD_RETRY;
 	}
 	if (card->host_props.is_spi) {
 		resp = cmd.response[1];
 	} else {
 		resp = cmd.response[0];
 	}
 	if ((resp & 0xFF) != SD_IF_COND_CHECK) {
 		LOG_INF("Legacy card detected, no CMD8 support");
 		/* Retry probe */
 		return SD_RETRY;
 	}
 	if ((resp & SD_IF_COND_VHS_MASK) != SD_IF_COND_VHS_3V3) {
 		/* Card does not support 3.3V */
 		return -ENOTSUP;
 	}
 	LOG_DBG("Found SDHC with CMD8 support");
 	card->flags |= SD_SDHC_FLAG;
 	return 0;
 }

 /* Sends CMD59 to enable CRC checking for SD card in SPI mode */
 static int sd_enable_crc(struct sd_card *card)
 {
 	struct sdhc_command cmd = {0};

 	/* CMD59 for CRC mode is only valid for SPI hosts */
 	__ASSERT_NO_MSG(card->host_props.is_spi);
 	cmd.opcode = SD_SPI_CRC_ON_OFF;
 	cmd.arg = 0x1; /* Enable CRC */
 	cmd.response_type = SD_SPI_RSP_TYPE_R1;
 	cmd.timeout_ms = CONFIG_SD_CMD_TIMEOUT;
 	return sdhc_request(card->sdhc, &cmd, NULL);
 }

 /*
  * Perform init required for both SD and SDIO cards.
  * This function performs the following portions of SD initialization
  * - CMD0 (SD reset)
  * - CMD8 (SD voltage check)
  */
 static int sd_common_init(struct sd_card *card)
 {
 	int ret;

 	/* Reset card with CMD0 */
 	ret = sd_idle(card);
 	if (ret) {
 		LOG_ERR("Card error on CMD0");
 		return ret;
 	}
 	/* Perform voltage check using SD CMD8 */
 	ret = sd_retry(sd_send_interface_condition, card, CONFIG_SD_RETRY_COUNT);
 	if (ret == -ETIMEDOUT) {
 		LOG_INF("Card does not support CMD8, assuming legacy card");
 		return sd_idle(card);
 	} else if (ret) {
 		LOG_ERR("Card error on CMD 8");
 		return ret;
 	}
 	if (card->host_props.is_spi &&
 		IS_ENABLED(CONFIG_SDHC_SUPPORTS_SPI_MODE)) {
 		/* Enable CRC for spi commands using CMD59 */
 		ret = sd_enable_crc(card);
 	}
 	return ret;
 }

 static int sd_init_io(struct sd_card *card)
 {
 	struct sdhc_io *bus_io = &card->bus_io;
 	int ret;

 	/* SD clock should start gated */
 	bus_io->clock = 0;
 	/* SPI requires SDHC PUSH PULL, and open drain buses use more power */
 	bus_io->bus_mode = SDHC_BUSMODE_PUSHPULL;
 	bus_io->power_mode = SDHC_POWER_ON;
 	bus_io->bus_width = SDHC_BUS_WIDTH1BIT;
 	/* Cards start with legacy timing and 3.3V signalling at power on */
 	bus_io->timing = SDHC_TIMING_LEGACY;
 	bus_io->signal_voltage = SD_VOL_3_3_V;

 	/* Toggle power to card to reset it */
 	LOG_DBG("Resetting power to card");
 	bus_io->power_mode = SDHC_POWER_OFF;
 	ret = sdhc_set_io(card->sdhc, bus_io);
 	if (ret) {
 		LOG_ERR("Could not disable card power via SDHC");
 		return ret;
 	}
 	sd_delay(card->host_props.power_delay);
 	bus_io->power_mode = SDHC_POWER_ON;
 	ret = sdhc_set_io(card->sdhc, bus_io);
 	if (ret) {
 		LOG_ERR("Could not disable card power via SDHC");
 		return ret;
 	}
 	/* After reset or init, card voltage should be 3.3V */
 	card->card_voltage = SD_VOL_3_3_V;
 	/* Reset card flags */
 	card->flags = 0U;
 	/* Delay so card can power up */
 	sd_delay(card->host_props.power_delay);
 	/* Start bus clock */
 	bus_io->clock = SDMMC_CLOCK_400KHZ;
 	ret = sdhc_set_io(card->sdhc, bus_io);
 	if (ret) {
 		LOG_ERR("Could not start bus clock");
 		return ret;
 	}
 	return 0;
 }

 /*
  * Sends CMD5 to SD card, and uses response to determine if card
  * is SDIO or SDMMC card. Return 0 if SDIO card, positive value if not, or
  * negative errno on error
  */
 int sd_test_sdio(struct sd_card *card)
 {
 	struct sdhc_command cmd = {0};
 	int ret;

 	cmd.opcode = SDIO_SEND_OP_COND;
 	cmd.arg = 0;
 	cmd.response_type = (SD_RSP_TYPE_R4 | SD_SPI_RSP_TYPE_R4);
 	cmd.timeout_ms = CONFIG_SD_CMD_TIMEOUT;
 	ret = sdhc_request(card->sdhc, &cmd, NULL);
 	if (ret) {
 		/*
 		 * We are just probing card, and it is likely an SD.
 		 * return error
 		 */
 		card->type = CARD_SDMMC;
 		return SD_NOT_SDIO;
 	}
 	/* Check the number of I/O functions */
 	card->num_io = ((cmd.response[0] & SDIO_OCR_IO_NUMBER)
 			>> SDIO_OCR_IO_NUMBER_SHIFT);
 	if ((card->num_io == 0) | ((cmd.response[0] & SDIO_IO_OCR_MASK) == 0)) {
 		if (cmd.response[0] & SDIO_OCR_MEM_PRESENT_FLAG) {
 			/* Card is not an SDIO card. */
 			card->type = CARD_SDMMC;
 			return SD_NOT_SDIO;
 		}
 		/* Card is not a valid SD device. We do not support it */
 		return -ENOTSUP;
 	}
 	/* Since we got a valid OCR response,
 	 * we know this card is an SDIO card.
 	 */
 	card->type = CARD_SDIO;
 	return 0;
 }

 /*
  * Check SD card type
  * Uses SDIO OCR response to determine what type of card is present.
  */
 static int sd_check_card_type(struct sd_card *card)
 {
 	int ret;

 	/* Test if the card response to CMD5 (only SDIO cards will) */
 	/* Note that CMD5 can take many retries */
 	ret = sd_test_sdio(card);
 	if ((ret == SD_NOT_SDIO) && card->type == CARD_SDMMC) {
 		LOG_INF("Detected SD card");
 		return 0;
 	} else if ((ret == 0) && card->type == CARD_SDIO) {
 		LOG_INF("Detected SDIO card");
 		return 0;
 	}
 	LOG_ERR("No usable card type was found");
 	return -ENOTSUP;
 }


 /*
  * Performs init flow described in section 3.6 of SD specification.
  */
 static int sd_command_init(struct sd_card *card)
 {
 	int ret;
 	/*
 	 * We must wait 74 clock cycles, per SD spec, to use card after power
 	 * on. At 400000KHz, this is a  185us delay. Wait 1ms to be safe.
 	 */
 	sd_delay(1);
 	/*
 	 * Start card initialization and identification
 	 * flow described in section 3.6 of SD specification
 	 */
 	ret = sd_common_init(card);
 	if (ret) {
 		return ret;
 	}
 	/* Use CMD5 to determine card type */
 	ret = sd_check_card_type(card);
 	if (ret) {
 		LOG_ERR("Unusable card");
 		return -ENOTSUP;
 	}
 	if (card->type == CARD_SDMMC) {
 		/*
 		 * Reset the card first- CMD5 sent to see if it is SDIO card
 		 * may have left it in error state
 		 */
 		ret = sd_common_init(card);
 		if (ret) {
 			LOG_ERR("Init after CMD5 failed");
 			return ret;
 		}
 		/* Perform memory card initialization */
 		ret = sdmmc_card_init(card);
 	} else if (card->type == CARD_SDIO) {
 		LOG_ERR("SDIO cards not currently supported");
 		return -ENOTSUP;
 	}
 	if (ret) {
 		LOG_ERR("Card init failed");
 		return ret;
 	}
 	return 0;
 }

 /* Initializes SD/SDIO card */
 int sd_init(const struct device *sdhc_dev, struct sd_card *card)
 {
 	int ret;

 	if (!sdhc_dev) {
 		return -ENODEV;
 	}
 	card->sdhc = sdhc_dev;
 	ret = sdhc_get_host_props(card->sdhc, &card->host_props);
 	if (ret) {
 		LOG_ERR("SD host controller returned invalid properties");
 		return ret;
 	}

 	/* init and lock card mutex */
 	ret = k_mutex_init(&card->lock);
 	if (ret) {
 		LOG_DBG("Could not init card mutex");
 		return ret;
 	}
 	ret = k_mutex_lock(&card->lock, K_MSEC(CONFIG_SD_INIT_TIMEOUT));
 	if (ret) {
 		LOG_ERR("Timeout while trying to acquire card mutex");
 		return ret;
 	}

 	/* Initialize SDHC IO with defaults */
 	ret = sd_init_io(card);
 	if (ret) {
 		k_mutex_unlock(&card->lock);
 		return ret;
 	}

 	/*
 	 * SD protocol is stateful, so we must account for the possibility
 	 * that the card is in a bad state. The return code SD_RESTART
 	 * indicates that the initialization left the card in a bad state.
 	 * In this case the subsystem takes the following steps:
 	 * - set card status to error
 	 * - re init host I/O (will also toggle power to the SD card)
 	 * - retry initialization once more
 	 * If initialization then fails, the sd_init routine will assume the
 	 * card is inaccessible
 	 */
 	ret = sd_command_init(card);
 	if (ret == SD_RESTART) {
 		/* Reset I/O, and retry sd initialization once more */
 		card->status = CARD_ERROR;
 		/* Reset I/O to default */
 		ret = sd_init_io(card);
 		if (ret) {
 			LOG_ERR("Failed to reset SDHC I/O");
 			k_mutex_unlock(&card->lock);
 			return ret;
 		}
 		ret = sd_command_init(card);
 		if (ret) {
 			LOG_ERR("Failed to init SD card after I/O reset");
 			k_mutex_unlock(&card->lock);
 			return ret;
 		}
 	} else if (ret != 0) {
 		/* Initialization failed */
 		k_mutex_unlock(&card->lock);
 		card->status = CARD_ERROR;
 		return ret;
 	}
 	/* Card initialization succeeded. */
 	card->status = CARD_INITIALIZED;
 	/* Unlock card mutex */
 	ret = k_mutex_unlock(&card->lock);
 	if (ret) {
 		LOG_DBG("Could not unlock card mutex");
 		return ret;
 	}
 	return ret;
 }

 /* Return true if card is present, false otherwise */
 bool sd_is_card_present(const struct device *sdhc_dev)
 {
 	if (!sdhc_dev) {
 		return false;
 	}
 	return sdhc_card_present(sdhc_dev) == 1;
 }
	/*
	* Copyright 2022 NXP
	*
	* SPDX-License-Identifier: Apache-2.0
	*/

	#include <zephyr/zephyr.h>
	#include <zephyr/drivers/sdhc.h>
	#include <zephyr/sd/sd.h>
	#include <zephyr/sd/sdmmc.h>
	#include <zephyr/sd/sd_spec.h>
	#include <zephyr/logging/log.h>
	#include <zephyr/sys/__assert.h>

	#include "sd_utils.h"
	#include "sdmmc_priv.h"


	LOG_MODULE_REGISTER(sd, CONFIG_SD_LOG_LEVEL);

	/* Idle all cards on bus. Can be used to clear errors on cards */
	static inline int sd_idle(struct sd_card *card)
	{
	struct sdhc_command cmd = {0};

	/* Reset card with CMD0 */
	cmd.opcode = SD_GO_IDLE_STATE;
	cmd.response_type = (SD_RSP_TYPE_NONE \| SD_SPI_RSP_TYPE_R1);
	cmd.timeout_ms = CONFIG_SD_CMD_TIMEOUT;
	return sdhc_request(card->sdhc, &cmd, NULL);
	}

	/* Sends CMD8 during SD initialization */
	static int sd_send_interface_condition(struct sd_card *card)
	{
	struct sdhc_command cmd = {0};
	int ret;
	uint32_t resp;

	cmd.opcode = SD_SEND_IF_COND;
	cmd.arg = SD_IF_COND_VHS_3V3 \| SD_IF_COND_CHECK;
	cmd.response_type = (SD_RSP_TYPE_R7 \| SD_SPI_RSP_TYPE_R7);
	cmd.timeout_ms = CONFIG_SD_CMD_TIMEOUT;
	ret = sdhc_request(card->sdhc, &cmd, NULL);
	if (ret) {
	LOG_DBG("SD CMD8 failed with error %d", ret);
	/* Retry */
	return SD_RETRY;
	}
	if (card->host_props.is_spi) {
	resp = cmd.response[1];
	} else {
	resp = cmd.response[0];
	}
	if ((resp & 0xFF) != SD_IF_COND_CHECK) {
	LOG_INF("Legacy card detected, no CMD8 support");
	/* Retry probe */
	return SD_RETRY;
	}
	if ((resp & SD_IF_COND_VHS_MASK) != SD_IF_COND_VHS_3V3) {
	/* Card does not support 3.3V */
	return -ENOTSUP;
	}
	LOG_DBG("Found SDHC with CMD8 support");
	card->flags \|= SD_SDHC_FLAG;
	return 0;
	}

	/* Sends CMD59 to enable CRC checking for SD card in SPI mode */
	static int sd_enable_crc(struct sd_card *card)
	{
	struct sdhc_command cmd = {0};

	/* CMD59 for CRC mode is only valid for SPI hosts */
	__ASSERT_NO_MSG(card->host_props.is_spi);
	cmd.opcode = SD_SPI_CRC_ON_OFF;
	cmd.arg = 0x1; /* Enable CRC */
	cmd.response_type = SD_SPI_RSP_TYPE_R1;
	cmd.timeout_ms = CONFIG_SD_CMD_TIMEOUT;
	return sdhc_request(card->sdhc, &cmd, NULL);
	}

	/*
	* Perform init required for both SD and SDIO cards.
	* This function performs the following portions of SD initialization
	* - CMD0 (SD reset)
	* - CMD8 (SD voltage check)
	*/
	static int sd_common_init(struct sd_card *card)
	{
	int ret;

	/* Reset card with CMD0 */
	ret = sd_idle(card);
	if (ret) {
	LOG_ERR("Card error on CMD0");
	return ret;
	}
	/* Perform voltage check using SD CMD8 */
	ret = sd_retry(sd_send_interface_condition, card, CONFIG_SD_RETRY_COUNT);
	if (ret == -ETIMEDOUT) {
	LOG_INF("Card does not support CMD8, assuming legacy card");
	return sd_idle(card);
	} else if (ret) {
	LOG_ERR("Card error on CMD 8");
	return ret;
	}
	if (card->host_props.is_spi &&
	IS_ENABLED(CONFIG_SDHC_SUPPORTS_SPI_MODE)) {
	/* Enable CRC for spi commands using CMD59 */
	ret = sd_enable_crc(card);
	}
	return ret;
	}

	static int sd_init_io(struct sd_card *card)
	{
	struct sdhc_io *bus_io = &card->bus_io;
	int ret;

	/* SD clock should start gated */
	bus_io->clock = 0;
	/* SPI requires SDHC PUSH PULL, and open drain buses use more power */
	bus_io->bus_mode = SDHC_BUSMODE_PUSHPULL;
	bus_io->power_mode = SDHC_POWER_ON;
	bus_io->bus_width = SDHC_BUS_WIDTH1BIT;
	/* Cards start with legacy timing and 3.3V signalling at power on */
	bus_io->timing = SDHC_TIMING_LEGACY;
	bus_io->signal_voltage = SD_VOL_3_3_V;

	/* Toggle power to card to reset it */
	LOG_DBG("Resetting power to card");
	bus_io->power_mode = SDHC_POWER_OFF;
	ret = sdhc_set_io(card->sdhc, bus_io);
	if (ret) {
	LOG_ERR("Could not disable card power via SDHC");
	return ret;
	}
	sd_delay(card->host_props.power_delay);
	bus_io->power_mode = SDHC_POWER_ON;
	ret = sdhc_set_io(card->sdhc, bus_io);
	if (ret) {
	LOG_ERR("Could not disable card power via SDHC");
	return ret;
	}
	/* After reset or init, card voltage should be 3.3V */
	card->card_voltage = SD_VOL_3_3_V;
	/* Reset card flags */
	card->flags = 0U;
	/* Delay so card can power up */
	sd_delay(card->host_props.power_delay);
	/* Start bus clock */
	bus_io->clock = SDMMC_CLOCK_400KHZ;
	ret = sdhc_set_io(card->sdhc, bus_io);
	if (ret) {
	LOG_ERR("Could not start bus clock");
	return ret;
	}
	return 0;
	}

	/*
	* Sends CMD5 to SD card, and uses response to determine if card
	* is SDIO or SDMMC card. Return 0 if SDIO card, positive value if not, or
	* negative errno on error
	*/
	int sd_test_sdio(struct sd_card *card)
	{
	struct sdhc_command cmd = {0};
	int ret;

	cmd.opcode = SDIO_SEND_OP_COND;
	cmd.arg = 0;
	cmd.response_type = (SD_RSP_TYPE_R4 \| SD_SPI_RSP_TYPE_R4);
	cmd.timeout_ms = CONFIG_SD_CMD_TIMEOUT;
	ret = sdhc_request(card->sdhc, &cmd, NULL);
	if (ret) {
	/*
	* We are just probing card, and it is likely an SD.
	* return error
	*/
	card->type = CARD_SDMMC;
	return SD_NOT_SDIO;
	}
	/* Check the number of I/O functions */
	card->num_io = ((cmd.response[0] & SDIO_OCR_IO_NUMBER)
	>> SDIO_OCR_IO_NUMBER_SHIFT);
	if ((card->num_io == 0) \| ((cmd.response[0] & SDIO_IO_OCR_MASK) == 0)) {
	if (cmd.response[0] & SDIO_OCR_MEM_PRESENT_FLAG) {
	/* Card is not an SDIO card. */
	card->type = CARD_SDMMC;
	return SD_NOT_SDIO;
	}
	/* Card is not a valid SD device. We do not support it */
	return -ENOTSUP;
	}
	/* Since we got a valid OCR response,
	* we know this card is an SDIO card.
	*/
	card->type = CARD_SDIO;
	return 0;
	}

	/*
	* Check SD card type
	* Uses SDIO OCR response to determine what type of card is present.
	*/
	static int sd_check_card_type(struct sd_card *card)
	{
	int ret;

	/* Test if the card response to CMD5 (only SDIO cards will) */
	/* Note that CMD5 can take many retries */
	ret = sd_test_sdio(card);
	if ((ret == SD_NOT_SDIO) && card->type == CARD_SDMMC) {
	LOG_INF("Detected SD card");
	return 0;
	} else if ((ret == 0) && card->type == CARD_SDIO) {
	LOG_INF("Detected SDIO card");
	return 0;
	}
	LOG_ERR("No usable card type was found");
	return -ENOTSUP;
	}


	/*
	* Performs init flow described in section 3.6 of SD specification.
	*/
	static int sd_command_init(struct sd_card *card)
	{
	int ret;
	/*
	* We must wait 74 clock cycles, per SD spec, to use card after power
	* on. At 400000KHz, this is a 185us delay. Wait 1ms to be safe.
	*/
	sd_delay(1);
	/*
	* Start card initialization and identification
	* flow described in section 3.6 of SD specification
	*/
	ret = sd_common_init(card);
	if (ret) {
	return ret;
	}
	/* Use CMD5 to determine card type */
	ret = sd_check_card_type(card);
	if (ret) {
	LOG_ERR("Unusable card");
	return -ENOTSUP;
	}
	if (card->type == CARD_SDMMC) {
	/*
	* Reset the card first- CMD5 sent to see if it is SDIO card
	* may have left it in error state
	*/
	ret = sd_common_init(card);
	if (ret) {
	LOG_ERR("Init after CMD5 failed");
	return ret;
	}
	/* Perform memory card initialization */
	ret = sdmmc_card_init(card);
	} else if (card->type == CARD_SDIO) {
	LOG_ERR("SDIO cards not currently supported");
	return -ENOTSUP;
	}
	if (ret) {
	LOG_ERR("Card init failed");
	return ret;
	}
	return 0;
	}

	/* Initializes SD/SDIO card */
	int sd_init(const struct device sdhc_dev, struct sd_card card)
	{
	int ret;

	if (!sdhc_dev) {
	return -ENODEV;
	}
	card->sdhc = sdhc_dev;
	ret = sdhc_get_host_props(card->sdhc, &card->host_props);
	if (ret) {
	LOG_ERR("SD host controller returned invalid properties");
	return ret;
	}

	/* init and lock card mutex */
	ret = k_mutex_init(&card->lock);
	if (ret) {
	LOG_DBG("Could not init card mutex");
	return ret;
	}
	ret = k_mutex_lock(&card->lock, K_MSEC(CONFIG_SD_INIT_TIMEOUT));
	if (ret) {
	LOG_ERR("Timeout while trying to acquire card mutex");
	return ret;
	}

	/* Initialize SDHC IO with defaults */
	ret = sd_init_io(card);
	if (ret) {
	k_mutex_unlock(&card->lock);
	return ret;
	}

	/*
	* SD protocol is stateful, so we must account for the possibility
	* that the card is in a bad state. The return code SD_RESTART
	* indicates that the initialization left the card in a bad state.
	* In this case the subsystem takes the following steps:
	* - set card status to error
	* - re init host I/O (will also toggle power to the SD card)
	* - retry initialization once more
	* If initialization then fails, the sd_init routine will assume the
	* card is inaccessible
	*/
	ret = sd_command_init(card);
	if (ret == SD_RESTART) {
	/* Reset I/O, and retry sd initialization once more */
	card->status = CARD_ERROR;
	/* Reset I/O to default */
	ret = sd_init_io(card);
	if (ret) {
	LOG_ERR("Failed to reset SDHC I/O");
	k_mutex_unlock(&card->lock);
	return ret;
	}
	ret = sd_command_init(card);
	if (ret) {
	LOG_ERR("Failed to init SD card after I/O reset");
	k_mutex_unlock(&card->lock);
	return ret;
	}
	} else if (ret != 0) {
	/* Initialization failed */
	k_mutex_unlock(&card->lock);
	card->status = CARD_ERROR;
	return ret;
	}
	/* Card initialization succeeded. */
	card->status = CARD_INITIALIZED;
	/* Unlock card mutex */
	ret = k_mutex_unlock(&card->lock);
	if (ret) {
	LOG_DBG("Could not unlock card mutex");
	return ret;
	}
	return ret;
	}

	/* Return true if card is present, false otherwise */
	bool sd_is_card_present(const struct device *sdhc_dev)
	{
	if (!sdhc_dev) {
	return false;
	}
	return sdhc_card_present(sdhc_dev) == 1;
	}