drivers/spi/spi-c2000-dma.c

/*
 * Copyright (c) 2012, Mindspeed Technologies.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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 <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>

#include "spi-dw.h"

#include "spi-c2000-dma.h"

struct spi_dma {
        struct spi_dma_slave      dmas_tx;
        struct spi_dma_slave      dmas_rx;
};

/* optional */
static bool spi_dma_chan_filter(struct dma_chan *chan, void *param)
{
        struct dw_spi *dws = param;

        return dws->master && (&dws->master->dev == chan->device->dev);
}

static int spi_dma_init(struct dw_spi *dws)
{
        struct spi_dma *dw_dma = dws->dma_priv;
        struct spi_dma_slave *rxs, *txs;
        dma_cap_mask_t mask;

        dma_cap_zero(mask);
        dma_cap_set(DMA_SLAVE, mask);

        /* 1. Init rx channel */
        dws->rxchan = dma_request_channel(mask, spi_dma_chan_filter, dws);
        if (!dws->rxchan)
                goto err_exit;
        rxs = &dw_dma->dmas_rx;
        rxs->hs_mode = LNW_DMA_HW_HS;
        rxs->cfg_mode = LNW_DMA_PER_TO_MEM;
        dws->rxchan->private = rxs;

        /* 2. Init tx channel */
        dws->txchan = dma_request_channel(mask, spi_dma_chan_filter, dws);
        if (!dws->txchan)
                goto free_rxchan;
        txs = &dw_dma->dmas_tx;
        txs->hs_mode = LNW_DMA_HW_HS;
        txs->cfg_mode = LNW_DMA_MEM_TO_PER;
        dws->txchan->private = txs;

        dws->dma_inited = 1;
        return 0;

free_rxchan:
        dma_release_channel(dws->rxchan);
err_exit:
        return -1;

}

static void spi_dma_exit(struct dw_spi *dws)
{
        dma_release_channel(dws->txchan);
        dma_release_channel(dws->rxchan);
}

/*
 * dws->dma_chan_done is cleared before the dma transfer starts,
 * callback for rx/tx channel will each increment it by 1.
 * Reaching 2 means the whole spi transaction is done.
 */
static void dw_spi_dma_done(void *arg)
{
        struct dw_spi *dws = arg;

        if (++dws->dma_chan_done != 2)
                return;
        dw_spi_xfer_done(dws);
}

static int spi_dma_transfer(struct dw_spi *dws, int cs_change)
{
        struct dma_async_tx_descriptor *txdesc = NULL, *rxdesc = NULL;
        struct dma_chan *txchan, *rxchan;
        struct dma_slave_config txconf, rxconf;
        u16 dma_ctrl = 0;

        /* 1. setup DMA related registers */
        if (cs_change) {
                spi_enable_chip(dws, 0);
                dw_writew(dws, DW_SPI_DMARDLR, 0xf);
                dw_writew(dws, DW_SPI_DMATDLR, 0x10);
                if (dws->tx_dma)
                        dma_ctrl |= 0x2;
                if (dws->rx_dma)
                        dma_ctrl |= 0x1;
                dw_writew(dws, DW_SPI_DMACR, dma_ctrl);
                spi_enable_chip(dws, 1);
        }

        dws->dma_chan_done = 0;
        txchan = dws->txchan;
        rxchan = dws->rxchan;

        /* 2. Prepare the TX dma transfer */
        txconf.direction = DMA_TO_DEVICE;
        txconf.dst_addr = dws->dma_addr;
        txconf.dst_maxburst = LNW_DMA_MSIZE_16;
        txconf.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
        txconf.dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;

        txchan->device->device_control(txchan, DMA_SLAVE_CONFIG,
                                       (unsigned long) &txconf);

        memset(&dws->tx_sgl, 0, sizeof(dws->tx_sgl));
        dws->tx_sgl.dma_address = dws->tx_dma;
        dws->tx_sgl.length = dws->len;

        txdesc = txchan->device->device_prep_slave_sg(txchan,
                                &dws->tx_sgl,
                                1,
                                DMA_TO_DEVICE,
                                DMA_PREP_INTERRUPT | DMA_COMPL_SKIP_DEST_UNMAP);
        txdesc->callback = dw_spi_dma_done;
        txdesc->callback_param = dws;

        /* 3. Prepare the RX dma transfer */
        rxconf.direction = DMA_FROM_DEVICE;
        rxconf.src_addr = dws->dma_addr;
        rxconf.src_maxburst = LNW_DMA_MSIZE_16;
        rxconf.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
        rxconf.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;

        rxchan->device->device_control(rxchan, DMA_SLAVE_CONFIG,
                                       (unsigned long) &rxconf);

        memset(&dws->rx_sgl, 0, sizeof(dws->rx_sgl));
        dws->rx_sgl.dma_address = dws->rx_dma;
        dws->rx_sgl.length = dws->len;

        rxdesc = rxchan->device->device_prep_slave_sg(rxchan,
                                &dws->rx_sgl,
                                1,
                                DMA_FROM_DEVICE,
                                DMA_PREP_INTERRUPT | DMA_COMPL_SKIP_DEST_UNMAP);
        rxdesc->callback = dw_spi_dma_done;
        rxdesc->callback_param = dws;

        /* rx must be started before tx due to spi instinct */
        rxdesc->tx_submit(rxdesc);
        txdesc->tx_submit(txdesc);
        return 0;
}

static struct dw_spi_dma_ops spi_dma_ops = {
        .dma_init       = spi_dma_init,
        .dma_exit       = spi_dma_exit,
        .dma_transfer   = spi_dma_transfer,
};

int dw_spi_dma_init(struct dw_spi *dws)
{
        dws->dma_priv = kzalloc(sizeof(struct spi_dma), GFP_KERNEL);
        if (!dws->dma_priv)
                return -ENOMEM;

        dws->dma_ops = &spi_dma_ops;

        return 0;
}