/*
 * Copyright (C) 2007 Atmel Corporation
 *
 * 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>
#include <malloc.h>

#include <asm/io.h>

#include <asm/arch/clk.h>
#include <asm/arch/memory-map.h>

#include "atmel_spi.h"

void spi_init()
{

}

struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
                        unsigned int max_hz, unsigned int mode)
{
        struct atmel_spi_slave  *as;
        unsigned int            scbr;
        u32                     csrx;
        void                    *regs;

        if (cs > 3 || !spi_cs_is_valid(bus, cs))
                return NULL;

        switch (bus) {
        case 0:
                regs = (void *)SPI0_BASE;
                break;
#ifdef SPI1_BASE
        case 1:
                regs = (void *)SPI1_BASE;
                break;
#endif
#ifdef SPI2_BASE
        case 2:
                regs = (void *)SPI2_BASE;
                break;
#endif
#ifdef SPI3_BASE
        case 3:
                regs = (void *)SPI3_BASE;
                break;
#endif
        default:
                return NULL;
        }


        scbr = (get_spi_clk_rate(bus) + max_hz - 1) / max_hz;
        if (scbr > ATMEL_SPI_CSRx_SCBR_MAX)
                /* Too low max SCK rate */
                return NULL;
        if (scbr < 1)
                scbr = 1;

        csrx = ATMEL_SPI_CSRx_SCBR(scbr);
        csrx |= ATMEL_SPI_CSRx_BITS(ATMEL_SPI_BITS_8);
        if (!(mode & SPI_CPHA))
                csrx |= ATMEL_SPI_CSRx_NCPHA;
        if (mode & SPI_CPOL)
                csrx |= ATMEL_SPI_CSRx_CPOL;

        as = malloc(sizeof(struct atmel_spi_slave));
        if (!as)
                return NULL;

        as->slave.bus = bus;
        as->slave.cs = cs;
        as->regs = regs;
        as->mr = ATMEL_SPI_MR_MSTR | ATMEL_SPI_MR_MODFDIS
                        | ATMEL_SPI_MR_PCS(~(1 << cs) & 0xf);
        spi_writel(as, CSR(cs), csrx);

        return &as->slave;
}

void spi_free_slave(struct spi_slave *slave)
{
        struct atmel_spi_slave *as = to_atmel_spi(slave);

        free(as);
}

int spi_claim_bus(struct spi_slave *slave)
{
        struct atmel_spi_slave *as = to_atmel_spi(slave);

        /* Enable the SPI hardware */
        spi_writel(as, CR, ATMEL_SPI_CR_SPIEN);

        /*
         * Select the slave. This should set SCK to the correct
         * initial state, etc.
         */
        spi_writel(as, MR, as->mr);

        return 0;
}

void spi_release_bus(struct spi_slave *slave)
{
        struct atmel_spi_slave *as = to_atmel_spi(slave);

        /* Disable the SPI hardware */
        spi_writel(as, CR, ATMEL_SPI_CR_SPIDIS);
}

int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
                const void *dout, void *din, unsigned long flags)
{
        struct atmel_spi_slave *as = to_atmel_spi(slave);
        unsigned int    len_tx;
        unsigned int    len_rx;
        unsigned int    len;
        int             ret;
        u32             status;
        const u8        *txp = dout;
        u8              *rxp = din;
        u8              value;

        ret = 0;
        if (bitlen == 0)
                /* Finish any previously submitted transfers */
                goto out;

        /*
         * TODO: The controller can do non-multiple-of-8 bit
         * transfers, but this driver currently doesn't support it.
         *
         * It's also not clear how such transfers are supposed to be
         * represented as a stream of bytes...this is a limitation of
         * the current SPI interface.
         */
        if (bitlen % 8) {
                /* Errors always terminate an ongoing transfer */
                flags |= SPI_XFER_END;
                goto out;
        }

        len = bitlen / 8;

        /*
         * The controller can do automatic CS control, but it is
         * somewhat quirky, and it doesn't really buy us much anyway
         * in the context of U-Boot.
         */
        if (flags & SPI_XFER_BEGIN)
                spi_cs_activate(slave);

        for (len_tx = 0, len_rx = 0; len_rx < len; ) {
                status = spi_readl(as, SR);

                if (status & ATMEL_SPI_SR_OVRES)
                        return -1;

                if (len_tx < len && (status & ATMEL_SPI_SR_TDRE)) {
                        if (txp)
                                value = *txp++;
                        else
                                value = 0;
                        spi_writel(as, TDR, value);
                        len_tx++;
                }
                if (status & ATMEL_SPI_SR_RDRF) {
                        value = spi_readl(as, RDR);
                        if (rxp)
                                *rxp++ = value;
                        len_rx++;
                }
        }

out:
        if (flags & SPI_XFER_END) {
                /*
                 * Wait until the transfer is completely done before
                 * we deactivate CS.
                 */
                do {
                        status = spi_readl(as, SR);
                } while (!(status & ATMEL_SPI_SR_TXEMPTY));

                spi_cs_deactivate(slave);
        }

        return 0;
}