esp-idf/components/sdmmc/sdmmc_cmd.c

/*
 * Copyright (c) 2006 Uwe Stuehler <uwe@openbsd.org>
 * Adaptations to ESP-IDF Copyright (c) 2016 Espressif Systems (Shanghai) PTE LTD
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <string.h>
#include "esp_log.h"
#include "esp_heap_caps.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/sdmmc_defs.h"
#include "driver/sdmmc_types.h"
#include "sdmmc_cmd.h"
#include "sys/param.h"
#include "soc/soc_memory_layout.h"

#define SDMMC_GO_IDLE_DELAY_MS              20
#define SDMMC_IO_SEND_OP_COND_DELAY_MS      10

/* These delay values are mostly useful for cases when CD pin is not used, and
 * the card is removed. In this case, SDMMC peripheral may not always return
 * CMD_DONE / DATA_DONE interrupts after signaling the error. These timeouts work
 * as a safety net in such cases.
 */
#define SDMMC_DEFAULT_CMD_TIMEOUT_MS  1000   // Max timeout of ordinary commands
#define SDMMC_WRITE_CMD_TIMEOUT_MS    5000   // Max timeout of write commands

/* Maximum retry/error count for SEND_OP_COND (CMD1).
 * These are somewhat arbitrary, values originate from OpenBSD driver.
 */
#define SDMMC_SEND_OP_COND_MAX_RETRIES  100
#define SDMMC_SEND_OP_COND_MAX_ERRORS   3

static const char* TAG = "sdmmc_cmd";

static esp_err_t sdmmc_send_cmd(sdmmc_card_t* card, sdmmc_command_t* cmd);
static esp_err_t sdmmc_send_app_cmd(sdmmc_card_t* card, sdmmc_command_t* cmd);
static esp_err_t sdmmc_send_cmd_go_idle_state(sdmmc_card_t* card);
static esp_err_t sdmmc_send_cmd_send_if_cond(sdmmc_card_t* card, uint32_t ocr);
static esp_err_t sdmmc_send_cmd_send_op_cond(sdmmc_card_t* card, uint32_t ocr, uint32_t *ocrp);
static esp_err_t sdmmc_send_cmd_read_ocr(sdmmc_card_t *card, uint32_t *ocrp);
static esp_err_t sdmmc_send_cmd_send_cid(sdmmc_card_t *card, sdmmc_cid_t *out_cid);
static esp_err_t sdmmc_decode_cid(sdmmc_response_t resp, sdmmc_cid_t* out_cid);
static esp_err_t sddmc_send_cmd_all_send_cid(sdmmc_card_t* card, sdmmc_cid_t* out_cid);
static esp_err_t sdmmc_send_cmd_set_relative_addr(sdmmc_card_t* card, uint16_t* out_rca);
static esp_err_t sdmmc_send_cmd_set_blocklen(sdmmc_card_t* card, sdmmc_csd_t* csd);
static esp_err_t sdmmc_send_cmd_switch_func(sdmmc_card_t* card,
        uint32_t mode, uint32_t group, uint32_t function,
        sdmmc_switch_func_rsp_t* resp);
static esp_err_t sdmmc_enable_hs_mode(sdmmc_card_t* card);
static esp_err_t sdmmc_enable_hs_mode_and_check(sdmmc_card_t* card);
static esp_err_t sdmmc_io_enable_hs_mode(sdmmc_card_t* card);
static esp_err_t sdmmc_decode_csd(sdmmc_response_t response, sdmmc_csd_t* out_csd);
static esp_err_t sdmmc_send_cmd_send_csd(sdmmc_card_t* card, sdmmc_csd_t* out_csd);
static esp_err_t sdmmc_send_cmd_select_card(sdmmc_card_t* card, uint32_t rca);
static esp_err_t sdmmc_decode_scr(uint32_t *raw_scr, sdmmc_scr_t* out_scr);
static esp_err_t sdmmc_send_cmd_send_scr(sdmmc_card_t* card, sdmmc_scr_t *out_scr);
static esp_err_t sdmmc_send_cmd_set_bus_width(sdmmc_card_t* card, int width);
static esp_err_t sdmmc_send_cmd_send_status(sdmmc_card_t* card, uint32_t* out_status);
static esp_err_t sdmmc_send_cmd_crc_on_off(sdmmc_card_t* card, bool crc_enable);
static uint32_t  get_host_ocr(float voltage);
static void flip_byte_order(uint32_t* response, size_t size);
static esp_err_t sdmmc_write_sectors_dma(sdmmc_card_t* card, const void* src,
        size_t start_block, size_t block_count);
static esp_err_t sdmmc_read_sectors_dma(sdmmc_card_t* card, void* dst,
        size_t start_block, size_t block_count);
static esp_err_t sdmmc_io_send_op_cond(sdmmc_card_t* card, uint32_t ocr, uint32_t *ocrp);
static esp_err_t sdmmc_io_rw_direct(sdmmc_card_t* card, int function,
        uint32_t reg, uint32_t arg, uint8_t *byte);
static esp_err_t sdmmc_io_rw_extended(sdmmc_card_t* card, int function,
        uint32_t reg, int arg, void *data, size_t size);
static void sdmmc_fix_host_flags(sdmmc_card_t* card);

static bool host_is_spi(const sdmmc_card_t* card)
{
    return (card->host.flags & SDMMC_HOST_FLAG_SPI) != 0;
}

esp_err_t sdmmc_card_init(const sdmmc_host_t* config, sdmmc_card_t* card)
{
    esp_err_t err;
    memset(card, 0, sizeof(*card));
    memcpy(&card->host, config, sizeof(*config));
    const bool is_spi = host_is_spi(card);

    if (!is_spi) {
        // Check if host flags are compatible with slot configuration.
        sdmmc_fix_host_flags(card);
    }
    
    /* ----------- standard initialization process starts here ---------- */

    /* Reset SDIO (CMD52, RES) before re-initializing IO (CMD5). */
    uint8_t sdio_reset = CCCR_CTL_RES;
    err = sdmmc_io_rw_direct(card, 0, SD_IO_CCCR_CTL, SD_ARG_CMD52_WRITE, &sdio_reset);
    if (err == ESP_ERR_TIMEOUT || (is_spi && err == ESP_ERR_NOT_SUPPORTED)) {
        /* Non-IO cards are allowed to time out (in SD mode) or
         * return "invalid command" error (in SPI mode).
         */
    } else if (err == ESP_ERR_NOT_FOUND) {
        ESP_LOGD(TAG, "%s: card not present", __func__);
        return err;
    } else if (err != ESP_OK) {
        ESP_LOGE(TAG, "%s: sdio_reset: unexpected return: 0x%x", __func__, err );
        return err;
    }

    /* GO_IDLE_STATE (CMD0) command resets the card */
    err = sdmmc_send_cmd_go_idle_state(card);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "%s: go_idle_state (1) returned 0x%x", __func__, err);
        return err;
    }
    vTaskDelay(SDMMC_GO_IDLE_DELAY_MS / portTICK_PERIOD_MS);

    /* SEND_IF_COND (CMD8) command is used to identify SDHC/SDXC cards.
     * SD v1 and non-SD cards will not respond to this command.
     */
    uint32_t host_ocr = get_host_ocr(config->io_voltage);
    err = sdmmc_send_cmd_send_if_cond(card, host_ocr);
    if (err == ESP_OK) {
        ESP_LOGD(TAG, "SDHC/SDXC card");
        host_ocr |= SD_OCR_SDHC_CAP;
    } else if (err == ESP_ERR_TIMEOUT) {
        ESP_LOGD(TAG, "CMD8 timeout; not an SD v2.00 card");
    } else if (is_spi && err == ESP_ERR_NOT_SUPPORTED) {
        ESP_LOGD(TAG, "CMD8 rejected; not an SD v2.00 card");
    } else {
        ESP_LOGE(TAG, "%s: send_if_cond (1) returned 0x%x", __func__, err);
        return err;
    }

    /* IO_SEND_OP_COND(CMD5), Determine if the card is an IO card.
     * Non-IO cards will not respond to this command.
     */ 
    err = sdmmc_io_send_op_cond(card, 0, &card->ocr);
    if (err != ESP_OK) {
        ESP_LOGD(TAG, "%s: io_send_op_cond (1) returned 0x%x; not IO card", __func__, err);
        card->is_sdio = 0;
        card->is_mem = 1;
    } else {
        card->is_sdio = 1;

        if (card->ocr & SD_IO_OCR_MEM_PRESENT) {
            ESP_LOGD(TAG, "%s: IO-only card", __func__);
            card->is_mem = 0;
        }
        card->num_io_functions = SD_IO_OCR_NUM_FUNCTIONS(card->ocr);
        ESP_LOGD(TAG, "%s: number of IO functions: %d", __func__, card->num_io_functions);
        if (card->num_io_functions == 0) {
            card->is_sdio = 0;
        }
        host_ocr &= card->ocr;
        err = sdmmc_io_send_op_cond(card, host_ocr, &card->ocr);
        if (err != ESP_OK) {
            ESP_LOGE(TAG, "%s: sdmmc_io_send_op_cond (1) returned 0x%x", __func__, err);
            return err;
        }
        sdmmc_io_enable_int(card);
    }

    if (card->is_mem) {
        /* In SPI mode, READ_OCR (CMD58) command is used to figure out which voltage
         * ranges the card can support. This step is skipped since 1.8V isn't
         * supported on the ESP32.
         */

        /* In SD mode, CRC checks of data transfers are mandatory and performed
         * by the hardware. In SPI mode, CRC16 of data transfers is optional and
         * needs to be enabled.
         */
        if (is_spi) {
            err = sdmmc_send_cmd_crc_on_off(card, true);
            if (err != ESP_OK) {
                ESP_LOGE(TAG, "%s: sdmmc_send_cmd_crc_on_off returned 0x%x", __func__, err);
                return err;
            }
        }

        /* Send SEND_OP_COND (ACMD41) command to the card until it becomes ready. */
        err = sdmmc_send_cmd_send_op_cond(card, host_ocr, &card->ocr);
        if (err != ESP_OK) {
            ESP_LOGE(TAG, "%s: send_op_cond (1) returned 0x%x", __func__, err);
            return err;
        }
        if (is_spi) {
            err = sdmmc_send_cmd_read_ocr(card, &card->ocr);
            if (err != ESP_OK) {
                ESP_LOGE(TAG, "%s: read_ocr returned 0x%x", __func__, err);
                return err;
            }
        }
        ESP_LOGD(TAG, "host_ocr=0x%x card_ocr=0x%x", host_ocr, card->ocr);

        /* Clear all voltage bits in host's OCR which the card doesn't support.
         * Don't touch CCS bit because in SPI mode cards don't report CCS in ACMD41
         * response.
         */
        host_ocr &= (card->ocr | (~SD_OCR_VOL_MASK));
        ESP_LOGD(TAG, "sdmmc_card_init: host_ocr=%08x, card_ocr=%08x", host_ocr, card->ocr);
    }

    /* Read and decode the contents of CID register */
    if (!is_spi) {
        if (card->is_mem) {
            err = sddmc_send_cmd_all_send_cid(card, &card->cid);
            if (err != ESP_OK) {
                ESP_LOGE(TAG, "%s: all_send_cid returned 0x%x", __func__, err);
                return err;
            }
        }
        err = sdmmc_send_cmd_set_relative_addr(card, &card->rca);
        if (err != ESP_OK) {
            ESP_LOGE(TAG, "%s: set_relative_addr returned 0x%x", __func__, err);
            return err;
        }
    } else {
        err = sdmmc_send_cmd_send_cid(card, &card->cid);
        if (err != ESP_OK) {
            ESP_LOGE(TAG, "%s: send_cid returned 0x%x", __func__, err);
            return err;
        }
    }
    if (card->is_mem) {
        /* Get and decode the contents of CSD register. Determine card capacity. */
        err = sdmmc_send_cmd_send_csd(card, &card->csd);
        if (err != ESP_OK) {
            ESP_LOGE(TAG, "%s: send_csd (1) returned 0x%x", __func__, err);
            return err;
        }
        const size_t max_sdsc_capacity = UINT32_MAX / card->csd.sector_size + 1;
        if (!(card->ocr & SD_OCR_SDHC_CAP) &&
             card->csd.capacity > max_sdsc_capacity) {
            ESP_LOGW(TAG, "%s: SDSC card reports capacity=%u. Limiting to %u.",
                    __func__, card->csd.capacity, max_sdsc_capacity);
            card->csd.capacity = max_sdsc_capacity;
        }
    }
    /* ----------- standard initialization process ends here ----------- */

    /* Switch the card from stand-by mode to data transfer mode (not needed if
     * SPI interface is used). This is needed to issue SET_BLOCKLEN and
     * SEND_SCR commands.
     */
    if (!is_spi) {
        err = sdmmc_send_cmd_select_card(card, card->rca);
        if (err != ESP_OK) {
            ESP_LOGE(TAG, "%s: select_card returned 0x%x", __func__, err);
            return err;
        }
    }

    if (card->is_mem) {
        /* SDSC cards support configurable data block lengths.
         * We don't use this feature and set the block length to 512 bytes,
         * same as the block length for SDHC cards.
         */
        if ((card->ocr & SD_OCR_SDHC_CAP) == 0) {
            err = sdmmc_send_cmd_set_blocklen(card, &card->csd);
            if (err != ESP_OK) {
                ESP_LOGE(TAG, "%s: set_blocklen returned 0x%x", __func__, err);
                return err;
            }
        }
        /* Get the contents of SCR register: bus width and the version of SD spec
         * supported by the card.
         * In SD mode, this is the first command which uses D0 line. Errors at
         * this step usually indicate connection issue or lack of pull-up resistor.
         */
        err = sdmmc_send_cmd_send_scr(card, &card->scr);
        if (err != ESP_OK) {
            ESP_LOGE(TAG, "%s: send_scr (1) returned 0x%x", __func__, err);
            return err;
        }
    }

    if (card->is_mem) {
        /* If the host has been initialized with 4-bit bus support, and the card
         * supports 4-bit bus, switch to 4-bit bus now.
         */
        if ((card->host.flags & SDMMC_HOST_FLAG_4BIT) &&
            (card->scr.bus_width & SCR_SD_BUS_WIDTHS_4BIT)) {
            ESP_LOGD(TAG, "switching to 4-bit bus mode");
            err = sdmmc_send_cmd_set_bus_width(card, 4);
            if (err != ESP_OK) {
                ESP_LOGE(TAG, "set_bus_width failed");
                return err;
            }
            err = (*config->set_bus_width)(config->slot, 4);
            if (err != ESP_OK) {
                ESP_LOGE(TAG, "slot->set_bus_width failed");
                return err;
            }
        }

        /* Wait for the card to be ready for data transfers */
        uint32_t status = 0;
        while (!is_spi && !(status & MMC_R1_READY_FOR_DATA)) {
            // TODO: add some timeout here
            uint32_t count = 0;
            err = sdmmc_send_cmd_send_status(card, &status);
            if (err != ESP_OK) {
                return err;
            }
            if (++count % 16 == 0) {
                ESP_LOGV(TAG, "waiting for card to become ready (%d)", count);
            }
        }
    } else {
        /* IO card */
        if (config->flags & SDMMC_HOST_FLAG_4BIT) {
            uint8_t card_cap = 0;
            err = sdmmc_io_rw_direct(card, 0, SD_IO_CCCR_CARD_CAP,
                    SD_ARG_CMD52_READ, &card_cap);
            if (err != ESP_OK) {
                ESP_LOGE(TAG, "%s: sdmmc_io_rw_direct (read SD_IO_CCCR_CARD_CAP) returned 0x%0x", __func__, err);
                return err;
            }
            ESP_LOGD(TAG, "IO card capabilities byte: %02x", card_cap);
            if (!(card_cap & CCCR_CARD_CAP_LSC) ||
                    (card_cap & CCCR_CARD_CAP_4BLS)) {
                // This card supports 4-bit bus mode
                uint8_t bus_width = CCCR_BUS_WIDTH_4;
                err = sdmmc_io_rw_direct(card, 0, SD_IO_CCCR_BUS_WIDTH,
                                    SD_ARG_CMD52_WRITE, &bus_width);
                if (err != ESP_OK) {
                    ESP_LOGE(TAG, "%s: sdmmc_io_rw_direct (write SD_IO_CCCR_BUS_WIDTH) returned 0x%0x", __func__, err);
                    return err;
                }
                err = (*config->set_bus_width)(config->slot, 4);
                if (err != ESP_OK) {
                    ESP_LOGE(TAG, "slot->set_bus_width failed");
                    return err;
                }                
            }
        }
    }
    /* So far initialization has been done using 400kHz clock. Determine the
     * clock rate which both host and the card support, and switch to it.
     */
    bool freq_switched = false;
    if (config->max_freq_khz >= SDMMC_FREQ_HIGHSPEED &&
            !is_spi /* SPI doesn't support >26MHz in some cases */) {
        if (card->is_mem) {
            err = sdmmc_enable_hs_mode_and_check(card);
        } else {
            err = sdmmc_io_enable_hs_mode(card);
        }

        if (err == ESP_ERR_NOT_SUPPORTED) {
            ESP_LOGD(TAG, "%s: host supports HS mode, but card doesn't", __func__);
        } else if (err != ESP_OK) {
            return err;
        } else {
            ESP_LOGD(TAG, "%s: switching host to HS mode", __func__);
            /* ESP_OK, HS mode has been enabled on the card side.
             * Switch the host to HS mode.
             */
            err = (*config->set_card_clk)(config->slot, SDMMC_FREQ_HIGHSPEED);
            if (err != ESP_OK) {
                ESP_LOGE(TAG, "failed to switch peripheral to HS bus mode");
                return err;
            }
            freq_switched = true;
        }
    }
    /* All SD cards must support default speed mode (25MHz).
     * config->max_freq_khz may be used to limit the clock frequency.
     */
    if (!freq_switched &&
        config->max_freq_khz >= SDMMC_FREQ_DEFAULT) {
        ESP_LOGD(TAG, "switching to DS bus mode");
        err = (*config->set_card_clk)(config->slot, SDMMC_FREQ_DEFAULT);
        if (err != ESP_OK) {
            ESP_LOGE(TAG, "failed to switch peripheral to HS bus mode");
            return err;
        }
        freq_switched = true;
    }
    /* If frequency switch has been performed, read SCR register one more time
     * and compare the result with the previous one. Use this simple check as
     * an indicator of potential signal integrity issues.
     */
    if (freq_switched) {
        if (card->is_mem) {
            sdmmc_scr_t scr_tmp;
            err = sdmmc_send_cmd_send_scr(card, &scr_tmp);
            if (err != ESP_OK) {
                ESP_LOGE(TAG, "%s: send_scr (2) returned 0x%x", __func__, err);
                return err;
            }
            if (memcmp(&card->scr, &scr_tmp, sizeof(scr_tmp)) != 0) {
                ESP_LOGE(TAG, "got corrupted data after increasing clock frequency");
                return ESP_ERR_INVALID_RESPONSE;
            }
        } else {
            /* TODO: For IO cards, read some data to see if frequency switch
             * was successful.
             */
        }
    }
    return ESP_OK;
}

void sdmmc_card_print_info(FILE* stream, const sdmmc_card_t* card)
{
    fprintf(stream, "Name: %s\n", card->cid.name);
    fprintf(stream, "Type: %s\n", (card->ocr & SD_OCR_SDHC_CAP)?"SDHC/SDXC":"SDSC");
    fprintf(stream, "Speed: %s\n", (card->csd.tr_speed > 25000000)?"high speed":"default speed");
    fprintf(stream, "Size: %lluMB\n", ((uint64_t) card->csd.capacity) * card->csd.sector_size / (1024 * 1024));
    fprintf(stream, "CSD: ver=%d, sector_size=%d, capacity=%d read_bl_len=%d\n",
            card->csd.csd_ver,
            card->csd.sector_size, card->csd.capacity, card->csd.read_block_len);
    fprintf(stream, "SCR: sd_spec=%d, bus_width=%d\n", card->scr.sd_spec, card->scr.bus_width);
}

static void sdmmc_fix_host_flags(sdmmc_card_t* card)
{
    const uint32_t width_1bit = SDMMC_HOST_FLAG_1BIT;
    const uint32_t width_4bit = SDMMC_HOST_FLAG_4BIT;
    const uint32_t width_8bit = SDMMC_HOST_FLAG_8BIT;
    const uint32_t width_mask = width_1bit | width_4bit | width_8bit;

    int slot_bit_width = card->host.get_bus_width(card->host.slot);
    if (slot_bit_width == 1 &&
            (card->host.flags & (width_4bit | width_8bit))) {
        ESP_LOGW(TAG, "host slot is configured in 1-bit mode");
        card->host.flags &= ~width_mask;
        card->host.flags |= ~(width_1bit);
    } else if (slot_bit_width == 4 && (card->host.flags & width_8bit)){
        ESP_LOGW(TAG, "host slot is configured in 4-bit mode");
        card->host.flags &= ~width_mask;
        card->host.flags |= width_4bit;
    }
}

static esp_err_t sdmmc_send_cmd(sdmmc_card_t* card, sdmmc_command_t* cmd)
{
    if (card->host.command_timeout_ms != 0) {
        cmd->timeout_ms = card->host.command_timeout_ms;
    } else if (cmd->timeout_ms == 0) {
        cmd->timeout_ms = SDMMC_DEFAULT_CMD_TIMEOUT_MS;
    }

    int slot = card->host.slot;
    ESP_LOGV(TAG, "sending cmd slot=%d op=%d arg=%x flags=%x data=%p blklen=%d datalen=%d timeout=%d",
            slot, cmd->opcode, cmd->arg, cmd->flags, cmd->data, cmd->blklen, cmd->datalen, cmd->timeout_ms);
    esp_err_t err = (*card->host.do_transaction)(slot, cmd);
    if (err != 0) {
        ESP_LOGD(TAG, "cmd=%d, sdmmc_req_run returned 0x%x", cmd->opcode, err);
        return err;
    }
    int state = MMC_R1_CURRENT_STATE(cmd->response);
    ESP_LOGV(TAG, "cmd response %08x %08x %08x %08x err=0x%x state=%d",
               cmd->response[0],
               cmd->response[1],
               cmd->response[2],
               cmd->response[3],
               cmd->error,
               state);
    return cmd->error;
}

static esp_err_t sdmmc_send_app_cmd(sdmmc_card_t* card, sdmmc_command_t* cmd)
{
    sdmmc_command_t app_cmd = {
        .opcode = MMC_APP_CMD,
        .flags = SCF_CMD_AC | SCF_RSP_R1,
        .arg = MMC_ARG_RCA(card->rca),
    };
    esp_err_t err = sdmmc_send_cmd(card, &app_cmd);
    if (err != ESP_OK) {
        return err;
    }
    // Check APP_CMD status bit (only in SD mode)
    if (!host_is_spi(card) && !(MMC_R1(app_cmd.response) & MMC_R1_APP_CMD)) {
        ESP_LOGW(TAG, "card doesn't support APP_CMD");
        return ESP_ERR_NOT_SUPPORTED;
    }
    return sdmmc_send_cmd(card, cmd);
}


static esp_err_t sdmmc_send_cmd_go_idle_state(sdmmc_card_t* card)
{
    sdmmc_command_t cmd = {
        .opcode = MMC_GO_IDLE_STATE,
        .flags = SCF_CMD_BC | SCF_RSP_R0,
    };
    esp_err_t err = sdmmc_send_cmd(card, &cmd);
    if (host_is_spi(card)) {
        /* To enter SPI mode, CMD0 needs to be sent twice (see figure 4-1 in
         * SD Simplified spec v4.10). Some cards enter SD mode on first CMD0,
         * so don't expect the above command to succeed.
         * SCF_RSP_R1 flag below tells the lower layer to expect correct R1
         * response (in SPI mode).
         */
        (void) err;
        vTaskDelay(SDMMC_GO_IDLE_DELAY_MS / portTICK_PERIOD_MS);

        cmd.flags |= SCF_RSP_R1;
        err = sdmmc_send_cmd(card, &cmd);
    }
    return err;
}


static esp_err_t sdmmc_send_cmd_send_if_cond(sdmmc_card_t* card, uint32_t ocr)
{
    const uint8_t pattern = 0xaa; /* any pattern will do here */
    sdmmc_command_t cmd = {
        .opcode = SD_SEND_IF_COND,
        .arg = (((ocr & SD_OCR_VOL_MASK) != 0) << 8) | pattern,
        .flags = SCF_CMD_BCR | SCF_RSP_R7,
    };
    esp_err_t err = sdmmc_send_cmd(card, &cmd);
    if (err != ESP_OK) {
        return err;
    }
    uint8_t response = cmd.response[0] & 0xff;
    if (response != pattern) {
        ESP_LOGD(TAG, "%s: received=0x%x expected=0x%x", __func__, response, pattern);
        return ESP_ERR_INVALID_RESPONSE;
    }
    return ESP_OK;
}

static esp_err_t sdmmc_send_cmd_send_op_cond(sdmmc_card_t* card, uint32_t ocr, uint32_t *ocrp)
{
    sdmmc_command_t cmd = {
            .arg = ocr,
            .flags = SCF_CMD_BCR | SCF_RSP_R3,
            .opcode = SD_APP_OP_COND
    };
    int nretries = SDMMC_SEND_OP_COND_MAX_RETRIES;
    int err_cnt = SDMMC_SEND_OP_COND_MAX_ERRORS;
    for (; nretries != 0; --nretries)  {
        esp_err_t err = sdmmc_send_app_cmd(card, &cmd);
        if (err != ESP_OK) {
            if (--err_cnt == 0) {
                ESP_LOGD(TAG, "%s: sdmmc_send_app_cmd err=0x%x", __func__, err);
                return err;
            } else {
                ESP_LOGV(TAG, "%s: ignoring err=0x%x", __func__, err);
                continue;
            }
        }
        // In SD protocol, card sets MEM_READY bit in OCR when it is ready.
        // In SPI protocol, card clears IDLE_STATE bit in R1 response.
        if (!host_is_spi(card)) {
            if ((MMC_R3(cmd.response) & MMC_OCR_MEM_READY) ||
                ocr == 0) {
                break;
            }
        } else {
            if ((SD_SPI_R1(cmd.response) & SD_SPI_R1_IDLE_STATE) == 0) {
                break;
            }
        }
        vTaskDelay(10 / portTICK_PERIOD_MS);
    }
    if (nretries == 0) {
        return ESP_ERR_TIMEOUT;
    }
    if (ocrp) {
        *ocrp = MMC_R3(cmd.response);
    }
    return ESP_OK;
}

static esp_err_t sdmmc_send_cmd_read_ocr(sdmmc_card_t *card, uint32_t *ocrp)
{
    assert(ocrp);
    sdmmc_command_t cmd = {
        .opcode = SD_READ_OCR,
        .flags = SCF_CMD_BCR | SCF_RSP_R2
    };
    esp_err_t err = sdmmc_send_cmd(card, &cmd);
    if (err != ESP_OK) {
        return err;
    }
    *ocrp = SD_SPI_R3(cmd.response);
    return ESP_OK;
}

esp_err_t sdmmc_decode_cid(sdmmc_response_t resp, sdmmc_cid_t* out_cid)
{
    out_cid->mfg_id = SD_CID_MID(resp);
    out_cid->oem_id = SD_CID_OID(resp);
    SD_CID_PNM_CPY(resp, out_cid->name);
    out_cid->revision = SD_CID_REV(resp);
    out_cid->serial = SD_CID_PSN(resp);
    out_cid->date = SD_CID_MDT(resp);
    return ESP_OK;
}

static esp_err_t sddmc_send_cmd_all_send_cid(sdmmc_card_t* card, sdmmc_cid_t* out_cid)
{
    assert(out_cid);
    sdmmc_command_t cmd = {
            .opcode = MMC_ALL_SEND_CID,
            .flags = SCF_CMD_BCR | SCF_RSP_R2
    };
    esp_err_t err = sdmmc_send_cmd(card, &cmd);
    if (err != ESP_OK) {
        return err;
    }
    return sdmmc_decode_cid(cmd.response, out_cid);
}

static esp_err_t sdmmc_send_cmd_send_cid(sdmmc_card_t *card, sdmmc_cid_t *out_cid)
{
    assert(out_cid);
    assert(host_is_spi(card) && "SEND_CID should only be used in SPI mode");
    sdmmc_response_t buf;
    sdmmc_command_t cmd = {
        .opcode = MMC_SEND_CID,
        .flags = SCF_CMD_READ | SCF_CMD_ADTC,
        .arg = 0,
        .data = &buf[0],
        .datalen = sizeof(buf)
    };
    esp_err_t err = sdmmc_send_cmd(card, &cmd);
    if (err != ESP_OK) {
        return err;
    }
    flip_byte_order(buf, sizeof(buf));
    return sdmmc_decode_cid(buf, out_cid);
}


static esp_err_t sdmmc_send_cmd_set_relative_addr(sdmmc_card_t* card, uint16_t* out_rca)
{
    assert(out_rca);
    sdmmc_command_t cmd = {
            .opcode = SD_SEND_RELATIVE_ADDR,
            .flags = SCF_CMD_BCR | SCF_RSP_R6
    };

    esp_err_t err = sdmmc_send_cmd(card, &cmd);
    if (err != ESP_OK) {
        return err;
    }
    *out_rca = SD_R6_RCA(cmd.response);
    return ESP_OK;
}


static esp_err_t sdmmc_send_cmd_set_blocklen(sdmmc_card_t* card, sdmmc_csd_t* csd)
{
    sdmmc_command_t cmd = {
            .opcode = MMC_SET_BLOCKLEN,
            .arg = csd->sector_size,
            .flags = SCF_CMD_AC | SCF_RSP_R1
    };
    return sdmmc_send_cmd(card, &cmd);
}

static esp_err_t sdmmc_decode_csd(sdmmc_response_t response, sdmmc_csd_t* out_csd)
{
    out_csd->csd_ver = SD_CSD_CSDVER(response);
    switch (out_csd->csd_ver) {
    case SD_CSD_CSDVER_2_0:
        out_csd->capacity = SD_CSD_V2_CAPACITY(response);
        out_csd->read_block_len = SD_CSD_V2_BL_LEN;
        break;
    case SD_CSD_CSDVER_1_0:
        out_csd->capacity = SD_CSD_CAPACITY(response);
        out_csd->read_block_len = SD_CSD_READ_BL_LEN(response);
        break;
    default:
        ESP_LOGE(TAG, "unknown SD CSD structure version 0x%x", out_csd->csd_ver);
        return ESP_ERR_NOT_SUPPORTED;
    }
    out_csd->card_command_class = SD_CSD_CCC(response);
    int read_bl_size = 1 << out_csd->read_block_len;
    out_csd->sector_size = MIN(read_bl_size, 512);
    if (out_csd->sector_size < read_bl_size) {
        out_csd->capacity *= read_bl_size / out_csd->sector_size;
    }
    int speed = SD_CSD_SPEED(response);
    if (speed == SD_CSD_SPEED_50_MHZ) {
        out_csd->tr_speed = 50000000;
    } else {
        out_csd->tr_speed = 25000000;
    }
    return ESP_OK;
}

static esp_err_t sdmmc_send_cmd_send_csd(sdmmc_card_t* card, sdmmc_csd_t* out_csd)
{
    /* The trick with SEND_CSD is that in SPI mode, it acts as a data read
     * command, while in SD mode it is an AC command with R2 response.
     */
    sdmmc_response_t spi_buf;
    const bool is_spi = host_is_spi(card);
    sdmmc_command_t cmd = {
            .opcode = MMC_SEND_CSD,
            .arg = is_spi ? 0 : MMC_ARG_RCA(card->rca),
            .flags = is_spi ? (SCF_CMD_READ | SCF_CMD_ADTC | SCF_RSP_R1) :
                    (SCF_CMD_AC | SCF_RSP_R2),
            .data = is_spi ? &spi_buf[0] : 0,
            .datalen = is_spi ? sizeof(spi_buf) : 0,
    };
    esp_err_t err = sdmmc_send_cmd(card, &cmd);
    if (err != ESP_OK) {
        return err;
    }
    uint32_t* ptr = cmd.response;
    if (is_spi) {
        flip_byte_order(spi_buf,  sizeof(spi_buf));
        ptr = spi_buf;
    }
    return sdmmc_decode_csd(ptr, out_csd);
}

static esp_err_t sdmmc_send_cmd_select_card(sdmmc_card_t* card, uint32_t rca)
{
    /* Don't expect to see a response when de-selecting a card */
    uint32_t response = (rca == 0) ? 0 : SCF_RSP_R1;
    sdmmc_command_t cmd = {
            .opcode = MMC_SELECT_CARD,
            .arg = MMC_ARG_RCA(rca),
            .flags = SCF_CMD_AC | response
    };
    return sdmmc_send_cmd(card, &cmd);
}

static esp_err_t sdmmc_decode_scr(uint32_t *raw_scr, sdmmc_scr_t* out_scr)
{
    sdmmc_response_t resp = {0xabababab, 0xabababab, 0x12345678, 0x09abcdef};
    resp[1] = __builtin_bswap32(raw_scr[0]);
    resp[0] = __builtin_bswap32(raw_scr[1]);
    int ver = SCR_STRUCTURE(resp);
    if (ver != 0) {
        return ESP_ERR_NOT_SUPPORTED;
    }
    out_scr->sd_spec = SCR_SD_SPEC(resp);
    out_scr->bus_width = SCR_SD_BUS_WIDTHS(resp);
    return ESP_OK;
}

static esp_err_t sdmmc_send_cmd_send_scr(sdmmc_card_t* card, sdmmc_scr_t *out_scr)
{
    size_t datalen = 8;
    uint32_t* buf = (uint32_t*) heap_caps_malloc(datalen, MALLOC_CAP_DMA);
    if (buf == NULL) {
        return ESP_ERR_NO_MEM;
    }
    sdmmc_command_t cmd = {
            .data = buf,
            .datalen = datalen,
            .blklen = datalen,
            .flags = SCF_CMD_ADTC | SCF_CMD_READ | SCF_RSP_R1,
            .opcode = SD_APP_SEND_SCR
    };
    esp_err_t err = sdmmc_send_app_cmd(card, &cmd);
    if (err == ESP_OK) {
        err = sdmmc_decode_scr(buf, out_scr);
    }
    free(buf);
    return err;
}

static esp_err_t sdmmc_send_cmd_set_bus_width(sdmmc_card_t* card, int width)
{
    sdmmc_command_t cmd = {
            .opcode = SD_APP_SET_BUS_WIDTH,
            .flags = SCF_RSP_R1 | SCF_CMD_AC,
            .arg = (width == 4) ? SD_ARG_BUS_WIDTH_4 : SD_ARG_BUS_WIDTH_1
    };

    return sdmmc_send_app_cmd(card, &cmd);
}

static esp_err_t sdmmc_send_cmd_crc_on_off(sdmmc_card_t* card, bool crc_enable)
{
    assert(host_is_spi(card) && "CRC_ON_OFF can only be used in SPI mode");
    sdmmc_command_t cmd = {
            .opcode = SD_CRC_ON_OFF,
            .arg = crc_enable ? 1 : 0,
            .flags = SCF_CMD_AC | SCF_RSP_R1
    };
    return sdmmc_send_cmd(card, &cmd);
}

static uint32_t get_host_ocr(float voltage)
{
    // TODO: report exact voltage to the card
    // For now tell that the host has 2.8-3.6V voltage range
    (void) voltage;
    return SD_OCR_VOL_MASK;
}

static void flip_byte_order(uint32_t* response, size_t size)
{
    assert(size % (2 * sizeof(uint32_t)) == 0);
    const size_t n_words = size / sizeof(uint32_t);
    for (int i = 0; i < n_words / 2; ++i) {
        uint32_t left = __builtin_bswap32(response[i]);
        uint32_t right = __builtin_bswap32(response[n_words - i - 1]);
        response[i] = right;
        response[n_words - i - 1] = left;
    }
}

static esp_err_t sdmmc_send_cmd_send_status(sdmmc_card_t* card, uint32_t* out_status)
{
    sdmmc_command_t cmd = {
            .opcode = MMC_SEND_STATUS,
            .arg = MMC_ARG_RCA(card->rca),
            .flags = SCF_CMD_AC | SCF_RSP_R1
    };
    esp_err_t err = sdmmc_send_cmd(card, &cmd);
    if (err != ESP_OK) {
        return err;
    }
    if (out_status) {
        *out_status = MMC_R1(cmd.response);
    }
    return ESP_OK;
}

esp_err_t sdmmc_write_sectors(sdmmc_card_t* card, const void* src,
        size_t start_block, size_t block_count)
{
    esp_err_t err = ESP_OK;
    size_t block_size = card->csd.sector_size;
    if (esp_ptr_dma_capable(src) && (intptr_t)src % 4 == 0) {
        err = sdmmc_write_sectors_dma(card, src, start_block, block_count);
    } else {
        // SDMMC peripheral needs DMA-capable buffers. Split the write into
        // separate single block writes, if needed, and allocate a temporary
        // DMA-capable buffer.
        void* tmp_buf = heap_caps_malloc(block_size, MALLOC_CAP_DMA);
        if (tmp_buf == NULL) {
            return ESP_ERR_NO_MEM;
        }
        const uint8_t* cur_src = (const uint8_t*) src;
        for (size_t i = 0; i < block_count; ++i) {
            memcpy(tmp_buf, cur_src, block_size);
            cur_src += block_size;
            err = sdmmc_write_sectors_dma(card, tmp_buf, start_block + i, 1);
            if (err != ESP_OK) {
                ESP_LOGD(TAG, "%s: error 0x%x writing block %d+%d",
                        __func__, err, start_block, i);
                break;
            }
        }
        free(tmp_buf);
    }
    return err;
}

static esp_err_t sdmmc_write_sectors_dma(sdmmc_card_t* card, const void* src,
        size_t start_block, size_t block_count)
{
    if (start_block + block_count > card->csd.capacity) {
        return ESP_ERR_INVALID_SIZE;
    }
    size_t block_size = card->csd.sector_size;
    sdmmc_command_t cmd = {
            .flags = SCF_CMD_ADTC | SCF_RSP_R1,
            .blklen = block_size,
            .data = (void*) src,
            .datalen = block_count * block_size,
            .timeout_ms = SDMMC_WRITE_CMD_TIMEOUT_MS
    };
    if (block_count == 1) {
        cmd.opcode = MMC_WRITE_BLOCK_SINGLE;
    } else {
        cmd.opcode = MMC_WRITE_BLOCK_MULTIPLE;
    }
    if (card->ocr & SD_OCR_SDHC_CAP) {
        cmd.arg = start_block;
    } else {
        cmd.arg = start_block * block_size;
    }
    esp_err_t err = sdmmc_send_cmd(card, &cmd);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "%s: sdmmc_send_cmd returned 0x%x", __func__, err);
        return err;
    }
    uint32_t status = 0;
    size_t count = 0;
    while (!host_is_spi(card) && !(status & MMC_R1_READY_FOR_DATA)) {
        // TODO: add some timeout here
        err = sdmmc_send_cmd_send_status(card, &status);
        if (err != ESP_OK) {
            return err;
        }
        if (++count % 10 == 0) {
            ESP_LOGV(TAG, "waiting for card to become ready (%d)", count);
        }
    }
    return ESP_OK;
}

esp_err_t sdmmc_read_sectors(sdmmc_card_t* card, void* dst,
        size_t start_block, size_t block_count)
{
    esp_err_t err = ESP_OK;
    size_t block_size = card->csd.sector_size;
    if (esp_ptr_dma_capable(dst) && (intptr_t)dst % 4 == 0) {
        err = sdmmc_read_sectors_dma(card, dst, start_block, block_count);
    } else {
        // SDMMC peripheral needs DMA-capable buffers. Split the read into
        // separate single block reads, if needed, and allocate a temporary
        // DMA-capable buffer.
        void* tmp_buf = heap_caps_malloc(block_size, MALLOC_CAP_DMA);
        if (tmp_buf == NULL) {
            return ESP_ERR_NO_MEM;
        }
        uint8_t* cur_dst = (uint8_t*) dst;
        for (size_t i = 0; i < block_count; ++i) {
            err = sdmmc_read_sectors_dma(card, tmp_buf, start_block + i, 1);
            if (err != ESP_OK) {
                ESP_LOGD(TAG, "%s: error 0x%x writing block %d+%d",
                        __func__, err, start_block, i);
                break;
            }
            memcpy(cur_dst, tmp_buf, block_size);
            cur_dst += block_size;
        }
        free(tmp_buf);
    }
    return err;
}

static esp_err_t sdmmc_read_sectors_dma(sdmmc_card_t* card, void* dst,
        size_t start_block, size_t block_count)
{
    if (start_block + block_count > card->csd.capacity) {
        return ESP_ERR_INVALID_SIZE;
    }
    size_t block_size = card->csd.sector_size;
    sdmmc_command_t cmd = {
            .flags = SCF_CMD_ADTC | SCF_CMD_READ | SCF_RSP_R1,
            .blklen = block_size,
            .data = (void*) dst,
            .datalen = block_count * block_size
    };
    if (block_count == 1) {
        cmd.opcode = MMC_READ_BLOCK_SINGLE;
    } else {
        cmd.opcode = MMC_READ_BLOCK_MULTIPLE;
    }
    if (card->ocr & SD_OCR_SDHC_CAP) {
        cmd.arg = start_block;
    } else {
        cmd.arg = start_block * block_size;
    }
    esp_err_t err = sdmmc_send_cmd(card, &cmd);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "%s: sdmmc_send_cmd returned 0x%x", __func__, err);
        return err;
    }
    uint32_t status = 0;
    size_t count = 0;
    while (!host_is_spi(card) && !(status & MMC_R1_READY_FOR_DATA)) {
        // TODO: add some timeout here
        err = sdmmc_send_cmd_send_status(card, &status);
        if (err != ESP_OK) {
            return err;
        }
        if (++count % 10 == 0) {
            ESP_LOGV(TAG, "waiting for card to become ready (%d)", count);
        }
    }
    return ESP_OK;
}

static esp_err_t sdmmc_send_cmd_switch_func(sdmmc_card_t* card,
        uint32_t mode, uint32_t group, uint32_t function,
        sdmmc_switch_func_rsp_t* resp)
{
    if (card->scr.sd_spec < SCR_SD_SPEC_VER_1_10 ||
        ((card->csd.card_command_class & SD_CSD_CCC_SWITCH) == 0)) {
            return ESP_ERR_NOT_SUPPORTED;
    }

    if (group == 0 ||
        group > SD_SFUNC_GROUP_MAX ||
        function > SD_SFUNC_FUNC_MAX) {
        return ESP_ERR_INVALID_ARG;
    }

    if (mode > 1) {
        return ESP_ERR_INVALID_ARG;
    }

    uint32_t group_shift = (group - 1) << 2;
    /* all functions which should not be affected are set to 0xf (no change) */
    uint32_t other_func_mask = (0x00ffffff & ~(0xf << group_shift));
    uint32_t func_val = (function << group_shift) | other_func_mask;

    sdmmc_command_t cmd = {
            .opcode = MMC_SWITCH,
            .flags = SCF_CMD_ADTC | SCF_CMD_READ | SCF_RSP_R1,
            .blklen = sizeof(sdmmc_switch_func_rsp_t),
            .data = resp->data,
            .datalen = sizeof(sdmmc_switch_func_rsp_t),
            .arg = (!!mode << 31) | func_val
    };

    esp_err_t err = sdmmc_send_cmd(card, &cmd);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "%s: sdmmc_send_cmd returned 0x%x", __func__, err);
        return err;
    }
    flip_byte_order(resp->data, sizeof(sdmmc_switch_func_rsp_t));
    uint32_t resp_ver = SD_SFUNC_VER(resp->data);
    if (resp_ver == 0) {
        /* busy response is never sent */
    } else if (resp_ver == 1) {
        if (SD_SFUNC_BUSY(resp->data, group) & (1 << function)) {
            ESP_LOGD(TAG, "%s: response indicates function %d:%d is busy",
                    __func__, group, function);
            return ESP_ERR_INVALID_STATE;
        }
    } else {
        ESP_LOGD(TAG, "%s: got an invalid version of SWITCH_FUNC response: 0x%02x",
                __func__, resp_ver);
        return ESP_ERR_INVALID_RESPONSE;
    }
    return ESP_OK;
}

static esp_err_t sdmmc_enable_hs_mode(sdmmc_card_t* card)
{
    /* This will determine if the card supports SWITCH_FUNC command,
     * and high speed mode. If the cards supports both, this will enable
     * high speed mode at the card side.
     */
    if (card->scr.sd_spec < SCR_SD_SPEC_VER_1_10 ||
        ((card->csd.card_command_class & SD_CSD_CCC_SWITCH) == 0)) {
            return ESP_ERR_NOT_SUPPORTED;
    }
    sdmmc_switch_func_rsp_t* response = (sdmmc_switch_func_rsp_t*)
            heap_caps_malloc(sizeof(*response), MALLOC_CAP_DMA);
    if (response == NULL) {
        return ESP_ERR_NO_MEM;
    }

    esp_err_t err = sdmmc_send_cmd_switch_func(card, 0, SD_ACCESS_MODE, 0, response);
    if (err != ESP_OK) {
        ESP_LOGD(TAG, "%s: sdmmc_send_cmd_switch_func (1) returned 0x%x", __func__, err);
        goto out;
    }
    uint32_t supported_mask = SD_SFUNC_SUPPORTED(response->data, 1);
    if ((supported_mask & BIT(SD_ACCESS_MODE_SDR25)) == 0) {
        err = ESP_ERR_NOT_SUPPORTED;
        goto out;
    }
    err = sdmmc_send_cmd_switch_func(card, 1, SD_ACCESS_MODE, SD_ACCESS_MODE_SDR25, response);
    if (err != ESP_OK) {
        ESP_LOGD(TAG, "%s: sdmmc_send_cmd_switch_func (2) returned 0x%x", __func__, err);
        goto out;
    }

out:
    free(response);
    return err;
}

static esp_err_t sdmmc_enable_hs_mode_and_check(sdmmc_card_t* card)
{
    /* Try to enabled HS mode */
    esp_err_t err = sdmmc_enable_hs_mode(card);
    if (err != ESP_OK) {
        return err;
    }
    /* HS mode has been enabled on the card.
     * Read CSD again, it should now indicate that the card supports
     * 50MHz clock.
     * Since SEND_CSD is allowed only in standby mode, and the card is
     * currently in data transfer more, deselect the card first, then
     * get the CSD, then select the card again.
     */
    err = sdmmc_send_cmd_select_card(card, 0);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "%s: select_card (2) returned 0x%x", __func__, err);
        return err;
    }
    err = sdmmc_send_cmd_send_csd(card, &card->csd);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "%s: send_csd (2) returned 0x%x", __func__, err);
        return err;
    }
    err = sdmmc_send_cmd_select_card(card, card->rca);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "%s: select_card (3) returned 0x%x", __func__, err);
        return err;
    }

    if (card->csd.tr_speed != 50000000) {
        ESP_LOGW(TAG, "unexpected: after enabling HS mode, tr_speed=%d", card->csd.tr_speed);
        return ESP_ERR_NOT_SUPPORTED;
    }

    return ESP_OK;
}

static esp_err_t sdmmc_io_enable_hs_mode(sdmmc_card_t* card)
{
    /* For IO cards, do write + read operation on "High Speed" register,
     * setting EHS bit. If both EHS and SHS read back as set, then HS mode
     * has been enabled.
     */
    uint8_t val = CCCR_HIGHSPEED_ENABLE;
    esp_err_t err = sdmmc_io_rw_direct(card, 0, SD_IO_CCCR_HIGHSPEED,
            SD_ARG_CMD52_WRITE | SD_ARG_CMD52_EXCHANGE, &val);
    if (err != ESP_OK) {
        ESP_LOGD(TAG, "%s: sdmmc_io_rw_direct returned 0x%x", __func__, err);
        return err;
    }

    ESP_LOGD(TAG, "%s: CCCR_HIGHSPEED=0x%02x", __func__, val);
    const uint8_t hs_mask = CCCR_HIGHSPEED_ENABLE | CCCR_HIGHSPEED_SUPPORT;
    if ((val & hs_mask) != hs_mask) {
        return ESP_ERR_NOT_SUPPORTED;
    }
    return ESP_OK;
}


static esp_err_t sdmmc_io_send_op_cond(sdmmc_card_t* card, uint32_t ocr, uint32_t *ocrp)
{
    esp_err_t err = ESP_OK;
    sdmmc_command_t cmd = {
        .flags = SCF_CMD_BCR | SCF_RSP_R4,
        .arg = ocr,
        .opcode = SD_IO_SEND_OP_COND
    };
    for (size_t i = 0; i < 100; i++) {
        err = sdmmc_send_cmd(card, &cmd);
        if (err != ESP_OK) {
            break;
        }
        if ((MMC_R4(cmd.response) & SD_IO_OCR_MEM_READY) ||
            ocr == 0) {
            break;
        }
        err = ESP_ERR_TIMEOUT;
        vTaskDelay(SDMMC_IO_SEND_OP_COND_DELAY_MS / portTICK_PERIOD_MS);
    }
    if (err == ESP_OK && ocrp != NULL)
        *ocrp = MMC_R4(cmd.response);

    return err;
}

static esp_err_t sdmmc_io_rw_direct(sdmmc_card_t* card, int func,
        uint32_t reg, uint32_t arg, uint8_t *byte)
{
    esp_err_t err;
    sdmmc_command_t cmd = {
        .flags = SCF_CMD_AC | SCF_RSP_R5,
        .arg = 0,
        .opcode = SD_IO_RW_DIRECT
    };

    arg |= (func & SD_ARG_CMD52_FUNC_MASK) << SD_ARG_CMD52_FUNC_SHIFT;
    arg |= (reg & SD_ARG_CMD52_REG_MASK) << SD_ARG_CMD52_REG_SHIFT;
    arg |= (*byte & SD_ARG_CMD52_DATA_MASK) << SD_ARG_CMD52_DATA_SHIFT;
    cmd.arg = arg;

    err = sdmmc_send_cmd(card, &cmd);
    if (err != ESP_OK) {
        ESP_LOGV(TAG, "%s: sdmmc_send_cmd returned 0x%x", __func__, err);
        return err;
    }

    *byte = SD_R5_DATA(cmd.response);

    return ESP_OK;
}


esp_err_t sdmmc_io_read_byte(sdmmc_card_t* card, uint32_t function,
        uint32_t addr, uint8_t *out_byte)
{
    esp_err_t ret = sdmmc_io_rw_direct(card, function, addr, SD_ARG_CMD52_READ, out_byte);
    if (ret != ESP_OK) {
        ESP_LOGE(TAG, "%s: sdmmc_io_rw_direct (read 0x%x) returned 0x%x", __func__, addr, ret);
    }
    return ret;
}

esp_err_t sdmmc_io_write_byte(sdmmc_card_t* card, uint32_t function,
        uint32_t addr, uint8_t in_byte, uint8_t* out_byte)
{
    uint8_t tmp_byte = in_byte;
    esp_err_t ret = sdmmc_io_rw_direct(card, function, addr,
            SD_ARG_CMD52_WRITE | SD_ARG_CMD52_EXCHANGE, &tmp_byte);
    if (ret != ESP_OK) {
        ESP_LOGE(TAG, "%s: sdmmc_io_rw_direct (write 0x%x) returned 0x%x", __func__, addr, ret);
        return ret;
    }
    if (out_byte != NULL) {
        *out_byte = tmp_byte;
    }
    return ESP_OK;
}

static esp_err_t sdmmc_io_rw_extended(sdmmc_card_t* card, int func,
    uint32_t reg, int arg, void *datap, size_t datalen)
{
    esp_err_t err;
    const size_t max_byte_transfer_size = 512;
    sdmmc_command_t cmd = {
        .flags = SCF_CMD_AC | SCF_RSP_R5,
        .arg = 0,
        .opcode = SD_IO_RW_EXTENDED,
        .data = datap,
        .datalen = datalen,
        .blklen = max_byte_transfer_size /* TODO: read max block size from CIS */
    };

    uint32_t count; /* number of bytes or blocks, depending on transfer mode */
    if (arg & SD_ARG_CMD53_BLOCK_MODE) {
        if (cmd.datalen % cmd.blklen != 0) {
            return ESP_ERR_INVALID_SIZE;
        }
        count = cmd.datalen / cmd.blklen;
    } else {
        if (datalen > max_byte_transfer_size) {
            /* TODO: split into multiple operations? */
            return ESP_ERR_INVALID_SIZE;
        }
        if (datalen == max_byte_transfer_size) {
            count = 0;  // See 5.3.1 SDIO simplifed spec
        } else {
            count = datalen;
        }
        cmd.blklen = datalen;
    }

    arg |= (func & SD_ARG_CMD53_FUNC_MASK) << SD_ARG_CMD53_FUNC_SHIFT;
    arg |= (reg & SD_ARG_CMD53_REG_MASK) << SD_ARG_CMD53_REG_SHIFT;
    arg |= (count & SD_ARG_CMD53_LENGTH_MASK) << SD_ARG_CMD53_LENGTH_SHIFT;
    cmd.arg = arg;

    if ((arg & SD_ARG_CMD53_WRITE) == 0) {
        cmd.flags |= SCF_CMD_READ;
    }

    err = sdmmc_send_cmd(card, &cmd);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "%s: sdmmc_send_cmd returned 0x%x", __func__, err);
        return err;
    }

    return ESP_OK;
}

esp_err_t sdmmc_io_read_bytes(sdmmc_card_t* card, uint32_t function,
        uint32_t addr, void* dst, size_t size)
{
    /* host quirk: SDIO transfer with length not divisible by 4 bytes
     * has to be split into two transfers: one with aligned length,
     * the other one for the remaining 1-3 bytes.
     */
    uint8_t *pc_dst = dst;
    while (size > 0) {
        size_t size_aligned = size & (~3);
        size_t will_transfer = size_aligned > 0 ? size_aligned : size;

        esp_err_t err = sdmmc_io_rw_extended(card, function, addr,
                SD_ARG_CMD53_READ | SD_ARG_CMD53_INCREMENT,
                pc_dst, will_transfer);
        if (err != ESP_OK) {
            return err;
        }
        pc_dst += will_transfer;
        size -= will_transfer;
        addr += will_transfer;
    }
    return ESP_OK;
}

esp_err_t sdmmc_io_write_bytes(sdmmc_card_t* card, uint32_t function,
        uint32_t addr, const void* src, size_t size)
{
    /* same host quirk as in sdmmc_io_read_bytes */
    const uint8_t *pc_src = (const uint8_t*) src;

    while (size > 0) {
        size_t size_aligned = size & (~3);
        size_t will_transfer = size_aligned > 0 ? size_aligned : size;

        esp_err_t err = sdmmc_io_rw_extended(card, function, addr,
                SD_ARG_CMD53_WRITE | SD_ARG_CMD53_INCREMENT,
                (void*) pc_src, will_transfer);
        if (err != ESP_OK) {
            return err;
        }
        pc_src += will_transfer;
        size -= will_transfer;
        addr += will_transfer;
    }
    return ESP_OK;
}

esp_err_t sdmmc_io_read_blocks(sdmmc_card_t* card, uint32_t function,
        uint32_t addr, void* dst, size_t size)
{
    if (size % 4 != 0) {
        return ESP_ERR_INVALID_SIZE;
    }
    return sdmmc_io_rw_extended(card, function, addr,
            SD_ARG_CMD53_READ | SD_ARG_CMD53_INCREMENT | SD_ARG_CMD53_BLOCK_MODE,
            dst, size);
}

esp_err_t sdmmc_io_write_blocks(sdmmc_card_t* card, uint32_t function,
        uint32_t addr, const void* src, size_t size)
{
    if (size % 4 != 0) {
        return ESP_ERR_INVALID_SIZE;
    }
    return sdmmc_io_rw_extended(card, function, addr,
            SD_ARG_CMD53_WRITE | SD_ARG_CMD53_INCREMENT | SD_ARG_CMD53_BLOCK_MODE,
            (void*) src, size);
}

esp_err_t sdmmc_io_enable_int(sdmmc_card_t* card)
{
    if (card->host.io_int_enable == NULL) {
        return ESP_ERR_NOT_SUPPORTED;
    }
    return (*card->host.io_int_enable)(card->host.slot);
}

esp_err_t sdmmc_io_wait_int(sdmmc_card_t* card, TickType_t timeout_ticks)
{
    if (card->host.io_int_wait == NULL) {
        return ESP_ERR_NOT_SUPPORTED;
    }
    return (*card->host.io_int_wait)(card->host.slot, timeout_ticks);
}