opensteno_qmk/drivers/eeprom/eeprom_i2c.c

/* Copyright 2019 Nick Brassel (tzarc)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdint.h>
#include <string.h>

/*
    Note that the implementations of eeprom_XXXX_YYYY on AVR are normally
    provided by avr-libc. The same functions are reimplemented below and are
    rerouted to the external i2c equivalent.

    Seemingly, as this is compiled from within QMK, the object file generated
    during the build overrides the avr-libc implementation during the linking
    stage.

    On other platforms such as ARM, there are no provided implementations, so
    there is nothing to override during linkage.
*/

#include "wait.h"
#include "i2c_master.h"
#include "eeprom.h"
#include "eeprom_i2c.h"

// #define DEBUG_EEPROM_OUTPUT

#ifdef DEBUG_EEPROM_OUTPUT
#    include "print.h"
#endif  // DEBUG_EEPROM_OUTPUT

static inline void init_i2c_if_required(void) {
    static int done = 0;
    if (!done) {
        i2c_init();
        done = 1;
    }
}

static inline void fill_target_address(uint8_t *buffer, const void *addr) {
    intptr_t p = (intptr_t)addr;
    for (int i = 0; i < EXTERNAL_EEPROM_ADDRESS_SIZE; ++i) {
        buffer[EXTERNAL_EEPROM_ADDRESS_SIZE - 1 - i] = p & 0xFF;
        p >>= 8;
    }
}

void eeprom_driver_init(void) {}

void eeprom_driver_erase(void) {
    uint8_t buf[EXTERNAL_EEPROM_PAGE_SIZE];
    memset(buf, 0x00, EXTERNAL_EEPROM_PAGE_SIZE);
    for (intptr_t addr = 0; addr < EXTERNAL_EEPROM_BYTE_COUNT; addr += EXTERNAL_EEPROM_PAGE_SIZE) {
        eeprom_write_block(buf, (void *)addr, EXTERNAL_EEPROM_PAGE_SIZE);
    }
}

void eeprom_read_block(void *buf, const void *addr, size_t len) {
    uint8_t complete_packet[EXTERNAL_EEPROM_ADDRESS_SIZE];
    fill_target_address(complete_packet, addr);

    init_i2c_if_required();
    i2c_transmit(EXTERNAL_EEPROM_I2C_ADDRESS((intptr_t)addr), complete_packet, EXTERNAL_EEPROM_ADDRESS_SIZE, 100);
    i2c_receive(EXTERNAL_EEPROM_I2C_ADDRESS((intptr_t)addr), buf, len, 100);

#ifdef DEBUG_EEPROM_OUTPUT
    dprintf("[EEPROM R] 0x%04X: ", ((int)addr));
    for (size_t i = 0; i < len; ++i) {
        dprintf(" %02X", (int)(((uint8_t *)buf)[i]));
    }
    dprintf("\n");
#endif  // DEBUG_EEPROM_OUTPUT
}

void eeprom_write_block(const void *buf, void *addr, size_t len) {
    uint8_t  complete_packet[EXTERNAL_EEPROM_ADDRESS_SIZE + EXTERNAL_EEPROM_PAGE_SIZE];
    uint8_t *read_buf    = (uint8_t *)buf;
    intptr_t target_addr = (intptr_t)addr;

    init_i2c_if_required();
    while (len > 0) {
        intptr_t page_offset  = target_addr % EXTERNAL_EEPROM_PAGE_SIZE;
        int      write_length = EXTERNAL_EEPROM_PAGE_SIZE - page_offset;
        if (write_length > len) {
            write_length = len;
        }

        fill_target_address(complete_packet, (const void *)target_addr);
        for (uint8_t i = 0; i < write_length; i++) {
            complete_packet[EXTERNAL_EEPROM_ADDRESS_SIZE + i] = read_buf[i];
        }

#ifdef DEBUG_EEPROM_OUTPUT
        dprintf("[EEPROM W] 0x%04X: ", ((int)target_addr));
        for (uint8_t i = 0; i < write_length; i++) {
            dprintf(" %02X", (int)(read_buf[i]));
        }
        dprintf("\n");
#endif  // DEBUG_EEPROM_OUTPUT

        i2c_transmit(EXTERNAL_EEPROM_I2C_ADDRESS((intptr_t)addr), complete_packet, EXTERNAL_EEPROM_ADDRESS_SIZE + write_length, 100);
        wait_ms(EXTERNAL_EEPROM_WRITE_TIME);

        read_buf += write_length;
        target_addr += write_length;
        len -= write_length;
    }
}