source: trunk/bitbang_spi.c

/*
 * This file is part of the flashrom project.
 *
 * Copyright (C) 2009, 2010 Carl-Daniel Hailfinger
 *
 * 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; version 2 of the License.
 *
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include "flash.h"
#include "programmer.h"
#include "spi.h"

/* Note that CS# is active low, so val=0 means the chip is active. */
static void bitbang_spi_set_cs(const struct bitbang_spi_master * const master, int val)
{
        master->set_cs(val);
}

static void bitbang_spi_set_sck(const struct bitbang_spi_master * const master, int val)
{
        master->set_sck(val);
}

static void bitbang_spi_set_mosi(const struct bitbang_spi_master * const master, int val)
{
        master->set_mosi(val);
}

static int bitbang_spi_get_miso(const struct bitbang_spi_master * const master)
{
        return master->get_miso();
}

static void bitbang_spi_request_bus(const struct bitbang_spi_master * const master)
{
        if (master->request_bus)
                master->request_bus();
}

static void bitbang_spi_release_bus(const struct bitbang_spi_master * const master)
{
        if (master->release_bus)
                master->release_bus();
}

static int bitbang_spi_send_command(struct flashctx *flash,
                                    unsigned int writecnt, unsigned int readcnt,
                                    const unsigned char *writearr,
                                    unsigned char *readarr);

static const struct spi_programmer spi_programmer_bitbang = {
        .type           = SPI_CONTROLLER_BITBANG,
        .max_data_read  = MAX_DATA_READ_UNLIMITED,
        .max_data_write = MAX_DATA_WRITE_UNLIMITED,
        .command        = bitbang_spi_send_command,
        .multicommand   = default_spi_send_multicommand,
        .read           = default_spi_read,
        .write_256      = default_spi_write_256,
        .write_aai      = default_spi_write_aai,
};

#if 0 // until it is needed
static int bitbang_spi_shutdown(const struct bitbang_spi_master *master)
{
        /* FIXME: Run bitbang_spi_release_bus here or per command? */
        return 0;
}
#endif

int bitbang_spi_init(const struct bitbang_spi_master *master)
{
        struct spi_programmer pgm = spi_programmer_bitbang;
        /* BITBANG_SPI_INVALID is 0, so if someone forgot to initialize ->type,
         * we catch it here. Same goes for missing initialization of bitbanging
         * functions.
         */
        if (!master || master->type == BITBANG_SPI_INVALID || !master->set_cs ||
            !master->set_sck || !master->set_mosi || !master->get_miso ||
            (master->request_bus && !master->release_bus) ||
            (!master->request_bus && master->release_bus)) {
                msg_perr("Incomplete SPI bitbang master setting!\n"
                         "Please report a bug at flashrom@flashrom.org\n");
                return ERROR_FLASHROM_BUG;
        }

        pgm.data = master;
        register_spi_programmer(&pgm);

        /* Only mess with the bus if we're sure nobody else uses it. */
        bitbang_spi_request_bus(master);
        bitbang_spi_set_cs(master, 1);
        bitbang_spi_set_sck(master, 0);
        bitbang_spi_set_mosi(master, 0);
        /* FIXME: Release SPI bus here and request it again for each command or
         * don't release it now and only release it on programmer shutdown?
         */
        bitbang_spi_release_bus(master);
        return 0;
}

static uint8_t bitbang_spi_rw_byte(const struct bitbang_spi_master *master,
                                   uint8_t val)
{
        uint8_t ret = 0;
        int i;

        for (i = 7; i >= 0; i--) {
                bitbang_spi_set_mosi(master, (val >> i) & 1);
                programmer_delay(master->half_period);
                bitbang_spi_set_sck(master, 1);
                ret <<= 1;
                ret |= bitbang_spi_get_miso(master);
                programmer_delay(master->half_period);
                bitbang_spi_set_sck(master, 0);
        }
        return ret;
}

static int bitbang_spi_send_command(struct flashctx *flash,
                                    unsigned int writecnt, unsigned int readcnt,
                                    const unsigned char *writearr,
                                    unsigned char *readarr)
{
        int i;
        const struct bitbang_spi_master *master = flash->pgm->spi.data;

        /* FIXME: Run bitbang_spi_request_bus here or in programmer init?
         * Requesting and releasing the SPI bus is handled in here to allow the
         * programmer to use its own SPI engine for native accesses.
         */
        bitbang_spi_request_bus(master);
        bitbang_spi_set_cs(master, 0);
        for (i = 0; i < writecnt; i++)
                bitbang_spi_rw_byte(master, writearr[i]);
        for (i = 0; i < readcnt; i++)
                readarr[i] = bitbang_spi_rw_byte(master, 0);

        programmer_delay(master->half_period);
        bitbang_spi_set_cs(master, 1);
        programmer_delay(master->half_period);
        /* FIXME: Run bitbang_spi_release_bus here or in programmer init? */
        bitbang_spi_release_bus(master);

        return 0;
}