circuitpython/shared-module/sdcardio/SDCard.c

/*
 * This file is part of the Micro Python project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2020 Jeff Epler for Adafruit Industries
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

// This implementation largely follows the structure of adafruit_sdcard.py

#include "shared-bindings/busio/SPI.h"
#include "shared-bindings/digitalio/DigitalInOut.h"
#include "shared-bindings/sdcardio/SDCard.h"
#include "shared-bindings/time/__init__.h"
#include "shared-bindings/util.h"
#include "shared-module/sdcardio/SDCard.h"

#include "py/mperrno.h"

#if 0
#define DEBUG_PRINT(...) ((void)mp_printf(&mp_plat_print,##__VA_ARGS__))
#else
#define DEBUG_PRINT(...) ((void)0)
#endif

#define CMD_TIMEOUT (200)

#define R1_IDLE_STATE (1 << 0)
#define R1_ILLEGAL_COMMAND (1 << 2)

#define TOKEN_CMD25 (0xFC)
#define TOKEN_STOP_TRAN (0xFD)
#define TOKEN_DATA (0xFE)

STATIC bool lock_and_configure_bus(sdcardio_sdcard_obj_t *self) {
    if (!common_hal_busio_spi_try_lock(self->bus)) {
        return false;
    }
    common_hal_busio_spi_configure(self->bus, self->baudrate, 0, 0, 8);
    common_hal_digitalio_digitalinout_set_value(&self->cs, false);
    return true;
}

STATIC void lock_bus_or_throw(sdcardio_sdcard_obj_t *self) {
    if (!lock_and_configure_bus(self)) {
        mp_raise_OSError(EAGAIN);
    }
}

STATIC void clock_card(sdcardio_sdcard_obj_t *self, int bytes) {
    uint8_t buf[] = {0xff};
    common_hal_digitalio_digitalinout_set_value(&self->cs, true);
    for (int i = 0; i < bytes; i++) {
        common_hal_busio_spi_write(self->bus, buf, 1);
    }
}

STATIC void extraclock_and_unlock_bus(sdcardio_sdcard_obj_t *self) {
    clock_card(self, 1);
    common_hal_busio_spi_unlock(self->bus);
}

static uint8_t CRC7(const uint8_t *data, uint8_t n) {
    uint8_t crc = 0;
    for (uint8_t i = 0; i < n; i++) {
        uint8_t d = data[i];
        for (uint8_t j = 0; j < 8; j++) {
            crc <<= 1;
            if ((d & 0x80) ^ (crc & 0x80)) {
                crc ^= 0x09;
            }
            d <<= 1;
        }
    }
    return (crc << 1) | 1;
}

#define READY_TIMEOUT_NS (300 * 1000 * 1000) // 300ms
STATIC int wait_for_ready(sdcardio_sdcard_obj_t *self) {
    uint64_t deadline = common_hal_time_monotonic_ns() + READY_TIMEOUT_NS;
    while (common_hal_time_monotonic_ns() < deadline) {
        uint8_t b;
        common_hal_busio_spi_read(self->bus, &b, 1, 0xff);
        if (b == 0xff) {
            return 0;
        }
    }
    return -ETIMEDOUT;
}

// Note: this is never called while "in cmd25" (in fact, it's only used by `exit_cmd25`)
STATIC bool cmd_nodata(sdcardio_sdcard_obj_t *self, int cmd, int response) {
    uint8_t cmdbuf[2] = {cmd, 0xff};

    assert(!self->in_cmd25);

    common_hal_busio_spi_write(self->bus, cmdbuf, sizeof(cmdbuf));

    // Wait for the response (response[7] == response)
    for (int i = 0; i < CMD_TIMEOUT; i++) {
        common_hal_busio_spi_read(self->bus, cmdbuf, 1, 0xff);
        if (cmdbuf[0] == response) {
            return 0;
        }
    }
    return -EIO;
}


STATIC int exit_cmd25(sdcardio_sdcard_obj_t *self) {
    if (self->in_cmd25) {
        DEBUG_PRINT("exit cmd25\n");
        self->in_cmd25 = false;
        return cmd_nodata(self, TOKEN_STOP_TRAN, 0);
    }
    return 0;
}

// In Python API, defaults are response=None, data_block=True, wait=True
STATIC int cmd(sdcardio_sdcard_obj_t *self, int cmd, int arg, void *response_buf, size_t response_len, bool data_block, bool wait) {
    int r = exit_cmd25(self);
    if (r < 0) {
        return r;
    }

    DEBUG_PRINT("cmd % 3d [%02x] arg=% 11d [%08x] len=%d%s%s\n", cmd, cmd, arg, arg, response_len, data_block ? " data" : "", wait ? " wait" : "");
    uint8_t cmdbuf[6];
    cmdbuf[0] = cmd | 0x40;
    cmdbuf[1] = (arg >> 24) & 0xff;
    cmdbuf[2] = (arg >> 16) & 0xff;
    cmdbuf[3] = (arg >> 8) & 0xff;
    cmdbuf[4] = arg & 0xff;
    cmdbuf[5] = CRC7(cmdbuf, 5);

    if (wait) {
        r = wait_for_ready(self);
        if (r < 0) {
            return r;
        }
    }

    common_hal_busio_spi_write(self->bus, cmdbuf, sizeof(cmdbuf));

    // Wait for the response (response[7] == 0)
    bool response_received = false;
    for (int i = 0; i < CMD_TIMEOUT; i++) {
        common_hal_busio_spi_read(self->bus, cmdbuf, 1, 0xff);
        if ((cmdbuf[0] & 0x80) == 0) {
            response_received = true;
            break;
        }
    }

    if (!response_received) {
        return -EIO;
    }

    if (response_buf) {

        if (data_block) {
            cmdbuf[1] = 0xff;
            do {
                // Wait for the start block byte
                common_hal_busio_spi_read(self->bus, cmdbuf + 1, 1, 0xff);
            } while (cmdbuf[1] != 0xfe);
        }

        common_hal_busio_spi_read(self->bus, response_buf, response_len, 0xff);

        if (data_block) {
            // Read and discard the CRC-CCITT checksum
            common_hal_busio_spi_read(self->bus, cmdbuf + 1, 2, 0xff);
        }

    }

    return cmdbuf[0];
}

STATIC int block_cmd(sdcardio_sdcard_obj_t *self, int cmd_, int block, void *response_buf, size_t response_len, bool data_block, bool wait) {
    return cmd(self, cmd_, block * self->cdv, response_buf, response_len, true, true);
}

STATIC mp_rom_error_text_t init_card_v1(sdcardio_sdcard_obj_t *self) {
    for (int i = 0; i < CMD_TIMEOUT; i++) {
        if (cmd(self, 41, 0, NULL, 0, true, true) == 0) {
            return NULL;
        }
    }
    return MP_ERROR_TEXT("timeout waiting for v1 card");
}

STATIC mp_rom_error_text_t init_card_v2(sdcardio_sdcard_obj_t *self) {
    for (int i = 0; i < CMD_TIMEOUT; i++) {
        uint8_t ocr[4];
        common_hal_time_delay_ms(50);
        cmd(self, 58, 0, ocr, sizeof(ocr), false, true);
        cmd(self, 55, 0, NULL, 0, true, true);
        if (cmd(self, 41, 0x40000000, NULL, 0, true, true) == 0) {
            cmd(self, 58, 0, ocr, sizeof(ocr), false, true);
            if ((ocr[0] & 0x40) != 0) {
                self->cdv = 1;
            }
            return NULL;
        }
    }
    return MP_ERROR_TEXT("timeout waiting for v2 card");
}

STATIC mp_rom_error_text_t init_card(sdcardio_sdcard_obj_t *self) {
    clock_card(self, 10);

    common_hal_digitalio_digitalinout_set_value(&self->cs, false);

    assert(!self->in_cmd25);
    self->in_cmd25 = false; // should be false already

    // CMD0: init card: should return _R1_IDLE_STATE (allow 5 attempts)
    {
        bool reached_idle_state = false;
        for (int i = 0; i < 5; i++) {
            // do not call cmd with wait=true, because that will return
            // prematurely if the idle state is not reached. we can't depend on
            // this when the card is not yet in SPI mode
            (void)wait_for_ready(self);
            if (cmd(self, 0, 0, NULL, 0, true, false) == R1_IDLE_STATE) {
                reached_idle_state = true;
                break;
            }
        }
        if (!reached_idle_state) {
            return MP_ERROR_TEXT("no SD card");
        }
    }

    // CMD8: determine card version
    {
        uint8_t rb7[4];
        int response = cmd(self, 8, 0x1AA, rb7, sizeof(rb7), false, true);
        if (response == R1_IDLE_STATE) {
            mp_rom_error_text_t result = init_card_v2(self);
            if (result != NULL) {
                return result;
            }
        } else if (response == (R1_IDLE_STATE | R1_ILLEGAL_COMMAND)) {
            mp_rom_error_text_t result = init_card_v1(self);
            if (result != NULL) {
                return result;
            }
        } else {
            DEBUG_PRINT("Reading card version, response=0x%02x\n", response);
            return MP_ERROR_TEXT("couldn't determine SD card version");
        }
    }

    // CMD9: get number of sectors
    {
        uint8_t csd[16];
        int response = cmd(self, 9, 0, csd, sizeof(csd), true, true);
        if (response != 0) {
            return MP_ERROR_TEXT("no response from SD card");
        }
        int csd_version = (csd[0] & 0xC0) >> 6;
        if (csd_version >= 2) {
            return MP_ERROR_TEXT("SD card CSD format not supported");
        }

        if (csd_version == 1) {
            self->sectors = ((csd[8] << 8 | csd[9]) + 1) * 1024;
        } else {
            uint32_t block_length = 1 << (csd[5] & 0xF);
            uint32_t c_size = ((csd[6] & 0x3) << 10) | (csd[7] << 2) | ((csd[8] & 0xC) >> 6);
            uint32_t mult = 1 << (((csd[9] & 0x3) << 1 | (csd[10] & 0x80) >> 7) + 2);
            self->sectors = block_length / 512 * mult * (c_size + 1);
        }
    }

    // CMD16: set block length to 512 bytes
    {
        int response = cmd(self, 16, 512, NULL, 0, true, true);
        if (response != 0) {
            return MP_ERROR_TEXT("can't set 512 block size");
        }
    }

    return NULL;
}

void common_hal_sdcardio_sdcard_construct(sdcardio_sdcard_obj_t *self, busio_spi_obj_t *bus, const mcu_pin_obj_t *cs, int baudrate) {
    self->bus = bus;
    common_hal_digitalio_digitalinout_construct(&self->cs, cs);
    common_hal_digitalio_digitalinout_switch_to_output(&self->cs, true, DRIVE_MODE_PUSH_PULL);

    self->cdv = 512;
    self->sectors = 0;
    self->baudrate = 250000;

    lock_bus_or_throw(self);
    mp_rom_error_text_t result = init_card(self);
    extraclock_and_unlock_bus(self);

    if (result != NULL) {
        common_hal_digitalio_digitalinout_deinit(&self->cs);
        mp_raise_OSError_msg(result);
    }

    self->baudrate = baudrate;
}

void common_hal_sdcardio_sdcard_deinit(sdcardio_sdcard_obj_t *self) {
    if (!self->bus) {
        return;
    }
    common_hal_sdcardio_sdcard_sync(self);
    self->bus = 0;
    common_hal_digitalio_digitalinout_deinit(&self->cs);
}

STATIC void common_hal_sdcardio_check_for_deinit(sdcardio_sdcard_obj_t *self) {
    if (!self->bus) {
        raise_deinited_error();
    }
}

int common_hal_sdcardio_sdcard_get_blockcount(sdcardio_sdcard_obj_t *self) {
    common_hal_sdcardio_check_for_deinit(self);
    return self->sectors;
}

STATIC int readinto(sdcardio_sdcard_obj_t *self, void *buf, size_t size) {
    uint8_t aux[2] = {0, 0};
    while (aux[0] != 0xfe) {
        common_hal_busio_spi_read(self->bus, aux, 1, 0xff);
    }

    common_hal_busio_spi_read(self->bus, buf, size, 0xff);

    // Read checksum and throw it away
    common_hal_busio_spi_read(self->bus, aux, sizeof(aux), 0xff);
    return 0;
}

STATIC int readblocks(sdcardio_sdcard_obj_t *self, uint32_t start_block, mp_buffer_info_t *buf) {
    uint32_t nblocks = buf->len / 512;
    if (nblocks == 1) {
        //  Use CMD17 to read a single block
        return block_cmd(self, 17, start_block, buf->buf, buf->len, true, true);
    } else {
        //  Use CMD18 to read multiple blocks
        int r = block_cmd(self, 18, start_block, NULL, 0, true, true);
        if (r < 0) {
            return r;
        }

        uint8_t *ptr = buf->buf;
        while (nblocks--) {
            r = readinto(self, ptr, 512);
            if (r < 0) {
                return r;
            }
            ptr += 512;
        }

        // End the multi-block read
        r = cmd(self, 12, 0, NULL, 0, true, false);

        // Return first status 0 or last before card ready (0xff)
        while (r != 0) {
            uint8_t single_byte;
            common_hal_busio_spi_read(self->bus, &single_byte, 1, 0xff);
            if (single_byte & 0x80) {
                return r;
            }
            r = single_byte;
        }
    }
    return 0;
}

int common_hal_sdcardio_sdcard_readblocks(sdcardio_sdcard_obj_t *self, uint32_t start_block, mp_buffer_info_t *buf) {
    common_hal_sdcardio_check_for_deinit(self);
    if (buf->len % 512 != 0) {
        mp_raise_ValueError(MP_ERROR_TEXT("Buffer length must be a multiple of 512"));
    }

    lock_and_configure_bus(self);
    int r = readblocks(self, start_block, buf);
    extraclock_and_unlock_bus(self);
    return r;
}

STATIC int _write(sdcardio_sdcard_obj_t *self, uint8_t token, void *buf, size_t size) {
    wait_for_ready(self);

    uint8_t cmd[2];
    cmd[0] = token;

    common_hal_busio_spi_write(self->bus, cmd, 1);
    common_hal_busio_spi_write(self->bus, buf, size);

    cmd[0] = cmd[1] = 0xff;
    common_hal_busio_spi_write(self->bus, cmd, 2);

    // Check the response
    // This differs from the traditional adafruit_sdcard handling,
    // but adafruit_sdcard also ignored the return value of SDCard._write(!)
    // so nobody noticed
    //
    //
    // Response is as follows:
    //  x x x 0 STAT 1
    //  7 6 5 4 3..1 0
    // with STATUS 010 indicating "data accepted", and other status bit
    // combinations indicating failure.
    // In practice, I was seeing cmd[0] as 0xe5, indicating success
    for (int i = 0; i < CMD_TIMEOUT; i++) {
        common_hal_busio_spi_read(self->bus, cmd, 1, 0xff);
        DEBUG_PRINT("i=%02d cmd[0] = 0x%02x\n", i, cmd[0]);
        if ((cmd[0] & 0b00010001) == 0b00000001) {
            if ((cmd[0] & 0x1f) != 0x5) {
                return -EIO;
            } else {
                break;
            }
        }
    }

    // Wait for the write to finish
    do {
        common_hal_busio_spi_read(self->bus, cmd, 1, 0xff);
    } while (cmd[0] == 0);

    // Success
    return 0;
}

STATIC int writeblocks(sdcardio_sdcard_obj_t *self, uint32_t start_block, mp_buffer_info_t *buf) {
    common_hal_sdcardio_check_for_deinit(self);
    uint32_t nblocks = buf->len / 512;

    DEBUG_PRINT("cmd25? %d next_block %d start_block %d\n", self->in_cmd25, self->next_block, start_block);

    if (!self->in_cmd25 || start_block != self->next_block) {
        DEBUG_PRINT("entering CMD25 at %d\n", (int)start_block);
        //  Use CMD25 to write multiple block
        int r = block_cmd(self, 25, start_block, NULL, 0, true, true);
        if (r < 0) {
            return r;
        }
        self->in_cmd25 = true;
    }

    self->next_block = start_block;

    uint8_t *ptr = buf->buf;
    while (nblocks--) {
        int r = _write(self, TOKEN_CMD25, ptr, 512);
        if (r < 0) {
            self->in_cmd25 = false;
            return r;
        }
        self->next_block++;
        ptr += 512;
    }

    return 0;
}

int common_hal_sdcardio_sdcard_sync(sdcardio_sdcard_obj_t *self) {
    common_hal_sdcardio_check_for_deinit(self);
    lock_and_configure_bus(self);
    int r = exit_cmd25(self);
    extraclock_and_unlock_bus(self);
    return r;
}

int common_hal_sdcardio_sdcard_writeblocks(sdcardio_sdcard_obj_t *self, uint32_t start_block, mp_buffer_info_t *buf) {
    common_hal_sdcardio_check_for_deinit(self);
    if (buf->len % 512 != 0) {
        mp_raise_ValueError(MP_ERROR_TEXT("Buffer length must be a multiple of 512"));
    }
    lock_and_configure_bus(self);
    int r = writeblocks(self, start_block, buf);
    extraclock_and_unlock_bus(self);
    return r;
}