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path: root/drivers/spi/dw_spi_mid.c
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/*
 * dw_spi_mid.c - special handling for DW core on Intel MID platform
 *
 * Copyright (c) 2009, Intel Corporation.
 *
 * 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 <linux/spi/dw_spi.h>

#ifdef CONFIG_SPI_DW_MID_DMA
#include <linux/intel_mid_dma.h>
#include <linux/pci.h>

struct mid_dma {
	struct intel_mid_dma_slave	dmas_tx;
	struct intel_mid_dma_slave	dmas_rx;
};

static bool mid_spi_dma_chan_filter(struct dma_chan *chan, void *param)
{
	struct dw_spi *dws = (struct dw_spi *)param;
	bool ret = false;

	if (!dws->dmac)
		goto out;

	if (chan->device->dev == &dws->dmac->dev)
		ret = true;

out:
	return ret;
}

static int mid_spi_dma_init(struct dw_spi *dws)
{
	struct mid_dma *dw_dma = dws->dma_priv;
	struct intel_mid_dma_slave *rxs, *txs;
	struct dma_slave_config *ds;
	dma_cap_mask_t mask;

	dws->txchan = NULL;
	dws->rxchan = NULL;

	/*get pci device for DMA*/
	dws->dmac = pci_get_device(PCI_VENDOR_ID_INTEL, 0x813, NULL);

	/* 1. Init rx channel */
	rxs = &dw_dma->dmas_rx;
	ds = &rxs->dma_slave;
	ds->direction = DMA_FROM_DEVICE;
	rxs->hs_mode = LNW_DMA_HW_HS;
	rxs->cfg_mode = LNW_DMA_PER_TO_MEM;
	ds->src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
	ds->dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
	ds->src_maxburst = 16;
	ds->dst_maxburst = 16;

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

	dws->rxchan = dma_request_channel(mask, mid_spi_dma_chan_filter, dws);
	if (!dws->rxchan)
		goto err_exit;
	dws->rxchan->private = rxs;

	/* 2. Init tx channel */
	txs = &dw_dma->dmas_tx;
	ds = &txs->dma_slave;

	ds->direction = DMA_TO_DEVICE;
	txs->hs_mode = LNW_DMA_HW_HS;
	txs->cfg_mode = LNW_DMA_MEM_TO_PER;
	ds->src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
	ds->dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
	ds->src_maxburst = 16;
	ds->dst_maxburst = 16;

	dma_cap_set(DMA_SLAVE, mask);
	dma_cap_set(DMA_MEMCPY, mask);

	dws->txchan = dma_request_channel(mask, mid_spi_dma_chan_filter, dws);
	if (!dws->txchan)
		goto free_rxchan;
	dws->txchan->private = txs;

	/* Set the dma done bit to 1 */
	dws->dma_inited = 1;
	return 0;

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

}

static void mid_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 mid_spi_dma_transfer(struct dw_spi *dws, int cs_change)
{
	struct dma_async_tx_descriptor *txdesc = NULL, *rxdesc = NULL;
	struct dma_chan *txchan, *rxchan;
	enum dma_ctrl_flags flag;
	u16 dma_ctrl = 0;

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

	dws->dma_chan_done = 0;

	/* 2. start the TX dma transfer */
	txchan = dws->txchan;
	rxchan = dws->rxchan;

	flag = DMA_PREP_INTERRUPT | DMA_CTRL_ACK;
	if (dws->tx_dma) {
		txdesc = txchan->device->device_prep_dma_memcpy(txchan,
				dws->dma_addr, dws->tx_dma,
				dws->len, flag);
		txdesc->callback = dw_spi_dma_done;
		txdesc->callback_param = dws;
	}

	/* 3. start the RX dma transfer */
	if (dws->rx_dma) {
		rxdesc = rxchan->device->device_prep_dma_memcpy(rxchan,
				dws->rx_dma, dws->dma_addr,
				dws->len, flag);
		rxdesc->callback = dw_spi_dma_done;
		rxdesc->callback_param = dws;
	}

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

	return 0;
}

static struct dw_spi_dma_ops mid_dma_ops = {
	.dma_init	= mid_spi_dma_init,
	.dma_exit	= mid_spi_dma_exit,
	.dma_transfer	= mid_spi_dma_transfer,
};
#endif

/* Some specific info for SPI0 controller on Moorestown */
/* HW info for MRST CLk Control Unit, one 32b reg */
#define MRST_SPI_CLK_BASE	100000000	/* 100m */
#define MRST_CLK_SPI0_REG	0xff11d86c
#define CLK_SPI_BDIV_OFFSET	0
#define CLK_SPI_BDIV_MASK	0x00000007
#define CLK_SPI_CDIV_OFFSET	9
#define CLK_SPI_CDIV_MASK	0x00000e00
#define CLK_SPI_CDIV_100M	0x0
#define CLK_SPI_CDIV_50M	0x1
#define CLK_SPI_CDIV_33M	0x2
#define CLK_SPI_CDIV_25M	0x3
#define CLK_SPI_DISABLE_OFFSET	8

int dw_spi_mid_init(struct dw_spi *dws)
{
	u32 *clk_reg, clk_cdiv;

	clk_reg = ioremap_nocache(MRST_CLK_SPI0_REG, 16);
	if (!clk_reg)
		return -ENOMEM;

	/* get SPI controller operating freq info */
	clk_cdiv  = ((*clk_reg) & CLK_SPI_CDIV_MASK) >> CLK_SPI_CDIV_OFFSET;
	dws->max_freq = MRST_SPI_CLK_BASE / (clk_cdiv + 1);
	iounmap(clk_reg);

	dws->num_cs = 16;
	dws->fifo_len = 40;	/* FIFO has 40 words buffer */

#ifdef CONFIG_SPI_DW_MID_DMA
	dws->dma_priv = kzalloc(sizeof(struct mid_dma), GFP_KERNEL);
	if (!dws->dma_priv)
		return -ENOMEM;
	dws->dma_ops = &mid_dma_ops;
#endif
	return 0;
}