/*
 * (C) Copyright 2002
 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
 *
 * Influenced by code from:
 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

#include <common.h>
#include <spi.h>

#if defined(CONFIG_SOFT_SPI)

#include <malloc.h>

/*-----------------------------------------------------------------------
 * Definitions
 */

#ifdef DEBUG_SPI
#define PRINTD(fmt,args...)     printf (fmt ,##args)
#else
#define PRINTD(fmt,args...)
#endif

struct soft_spi_slave {
        struct spi_slave slave;
        unsigned int mode;
};

static inline struct soft_spi_slave *to_soft_spi(struct spi_slave *slave)
{
        return container_of(slave, struct soft_spi_slave, slave);
}

/*=====================================================================*/
/*                         Public Functions                            */
/*=====================================================================*/

/*-----------------------------------------------------------------------
 * Initialization
 */
void spi_init (void)
{
#ifdef  SPI_INIT
        volatile immap_t *immr = (immap_t *)CFG_IMMR;

        SPI_INIT;
#endif
}

struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
                unsigned int max_hz, unsigned int mode)
{
        struct soft_spi_slave *ss;

        if (!spi_cs_is_valid(bus, cs))
                return NULL;

        ss = malloc(sizeof(struct soft_spi_slave));
        if (!ss)
                return NULL;

        ss->slave.bus = bus;
        ss->slave.cs = cs;
        ss->mode = mode;

        /* TODO: Use max_hz to limit the SCK rate */

        return &ss->slave;
}

void spi_free_slave(struct spi_slave *slave)
{
        struct soft_spi_slave *ss = to_soft_spi(slave);

        free(ss);
}

int spi_claim_bus(struct spi_slave *slave)
{
#ifdef CFG_IMMR
        volatile immap_t *immr = (immap_t *)CFG_IMMR;
#endif
        struct soft_spi_slave *ss = to_soft_spi(slave);

        /*
         * Make sure the SPI clock is in idle state as defined for
         * this slave.
         */
        if (ss->mode & SPI_CPOL)
                SPI_SCL(1);
        else
                SPI_SCL(0);

        return 0;
}

void spi_release_bus(struct spi_slave *slave)
{
        /* Nothing to do */
}

/*-----------------------------------------------------------------------
 * SPI transfer
 *
 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
 * "bitlen" bits in the SPI MISO port.  That's just the way SPI works.
 *
 * The source of the outgoing bits is the "dout" parameter and the
 * destination of the input bits is the "din" parameter.  Note that "dout"
 * and "din" can point to the same memory location, in which case the
 * input data overwrites the output data (since both are buffered by
 * temporary variables, this is OK).
 */
int  spi_xfer(struct spi_slave *slave, unsigned int bitlen,
                const void *dout, void *din, unsigned long flags)
{
#ifdef CFG_IMMR
        volatile immap_t *immr = (immap_t *)CFG_IMMR;
#endif
        struct soft_spi_slave *ss = to_soft_spi(slave);
        uchar           tmpdin  = 0;
        uchar           tmpdout = 0;
        const u8        *txd = dout;
        u8              *rxd = din;
        int             cpol = ss->mode & SPI_CPOL;
        int             cpha = ss->mode & SPI_CPHA;
        unsigned int    j;

        PRINTD("spi_xfer: slave %u:%u dout %08X din %08X bitlen %u\n",
                slave->bus, slave->cs, *(uint *)txd, *(uint *)rxd, bitlen);

        if (flags & SPI_XFER_BEGIN)
                spi_cs_activate(slave);

        for(j = 0; j < bitlen; j++) {
                /*
                 * Check if it is time to work on a new byte.
                 */
                if((j % 8) == 0) {
                        tmpdout = *txd++;
                        if(j != 0) {
                                *rxd++ = tmpdin;
                        }
                        tmpdin  = 0;
                }

                if (!cpha)
                        SPI_SCL(!cpol);
                SPI_SDA(tmpdout & 0x80);
                SPI_DELAY;
                if (cpha)
                        SPI_SCL(!cpol);
                else
                        SPI_SCL(cpol);
                tmpdin  <<= 1;
                tmpdin  |= SPI_READ;
                tmpdout <<= 1;
                SPI_DELAY;
                if (cpha)
                        SPI_SCL(cpol);
        }
        /*
         * If the number of bits isn't a multiple of 8, shift the last
         * bits over to left-justify them.  Then store the last byte
         * read in.
         */
        if((bitlen % 8) != 0)
                tmpdin <<= 8 - (bitlen % 8);
        *rxd++ = tmpdin;

        if (flags & SPI_XFER_END)
                spi_cs_deactivate(slave);

        return(0);
}

#endif  /* CONFIG_SOFT_SPI */