[PATCH v2 2/3] mmc: davinci_mmc: convert to DMA engine API

[Matt Porter <mporter@ti.com>]

Removes use of the DaVinci EDMA private DMA API and replaces
it with use of the DMA engine API.

Signed-off-by: Matt Porter <mporter@ti.com>
---
 drivers/mmc/host/davinci_mmc.c |  271 ++++++++++++----------------------------
 1 file changed, 82 insertions(+), 189 deletions(-)

diff --git a/drivers/mmc/host/davinci_mmc.c b/drivers/mmc/host/davinci_mmc.c
index 7cf6c62..c5e1eeb 100644
--- a/drivers/mmc/host/davinci_mmc.c
+++ b/drivers/mmc/host/davinci_mmc.c
@@ -30,11 +30,12 @@
 #include <linux/io.h>
 #include <linux/irq.h>
 #include <linux/delay.h>
+#include <linux/dmaengine.h>
 #include <linux/dma-mapping.h>
+#include <linux/edma.h>
 #include <linux/mmc/mmc.h>
 
 #include <mach/mmc.h>
-#include <mach/edma.h>
 
 /*
  * Register Definitions
@@ -200,21 +201,13 @@ struct mmc_davinci_host {
 	u32 bytes_left;
 
 	u32 rxdma, txdma;
+	struct dma_chan *dma_tx;
+	struct dma_chan *dma_rx;
 	bool use_dma;
 	bool do_dma;
 	bool sdio_int;
 	bool active_request;
 
-	/* Scatterlist DMA uses one or more parameter RAM entries:
-	 * the main one (associated with rxdma or txdma) plus zero or
-	 * more links.  The entries for a given transfer differ only
-	 * by memory buffer (address, length) and link field.
-	 */
-	struct edmacc_param	tx_template;
-	struct edmacc_param	rx_template;
-	unsigned		n_link;
-	u32			links[MAX_NR_SG - 1];
-
 	/* For PIO we walk scatterlists one segment at a time. */
 	unsigned int		sg_len;
 	struct scatterlist *sg;
@@ -410,153 +403,74 @@ static void mmc_davinci_start_command(struct mmc_davinci_host *host,
 
 static void davinci_abort_dma(struct mmc_davinci_host *host)
 {
-	int sync_dev;
+	struct dma_chan *sync_dev;
 
 	if (host->data_dir == DAVINCI_MMC_DATADIR_READ)
-		sync_dev = host->rxdma;
+		sync_dev = host->dma_rx;
 	else
-		sync_dev = host->txdma;
-
-	edma_stop(sync_dev);
-	edma_clean_channel(sync_dev);
-}
-
-static void
-mmc_davinci_xfer_done(struct mmc_davinci_host *host, struct mmc_data *data);
-
-static void mmc_davinci_dma_cb(unsigned channel, u16 ch_status, void *data)
-{
-	if (DMA_COMPLETE != ch_status) {
-		struct mmc_davinci_host *host = data;
-
-		/* Currently means:  DMA Event Missed, or "null" transfer
-		 * request was seen.  In the future, TC errors (like bad
-		 * addresses) might be presented too.
-		 */
-		dev_warn(mmc_dev(host->mmc), "DMA %s error\n",
-			(host->data->flags & MMC_DATA_WRITE)
-				? "write" : "read");
-		host->data->error = -EIO;
-		mmc_davinci_xfer_done(host, host->data);
-	}
-}
-
-/* Set up tx or rx template, to be modified and updated later */
-static void __init mmc_davinci_dma_setup(struct mmc_davinci_host *host,
-		bool tx, struct edmacc_param *template)
-{
-	unsigned	sync_dev;
-	const u16	acnt = 4;
-	const u16	bcnt = rw_threshold >> 2;
-	const u16	ccnt = 0;
-	u32		src_port = 0;
-	u32		dst_port = 0;
-	s16		src_bidx, dst_bidx;
-	s16		src_cidx, dst_cidx;
-
-	/*
-	 * A-B Sync transfer:  each DMA request is for one "frame" of
-	 * rw_threshold bytes, broken into "acnt"-size chunks repeated
-	 * "bcnt" times.  Each segment needs "ccnt" such frames; since
-	 * we tell the block layer our mmc->max_seg_size limit, we can
-	 * trust (later) that it's within bounds.
-	 *
-	 * The FIFOs are read/written in 4-byte chunks (acnt == 4) and
-	 * EDMA will optimize memory operations to use larger bursts.
-	 */
-	if (tx) {
-		sync_dev = host->txdma;
-
-		/* src_prt, ccnt, and link to be set up later */
-		src_bidx = acnt;
-		src_cidx = acnt * bcnt;
-
-		dst_port = host->mem_res->start + DAVINCI_MMCDXR;
-		dst_bidx = 0;
-		dst_cidx = 0;
-	} else {
-		sync_dev = host->rxdma;
-
-		src_port = host->mem_res->start + DAVINCI_MMCDRR;
-		src_bidx = 0;
-		src_cidx = 0;
-
-		/* dst_prt, ccnt, and link to be set up later */
-		dst_bidx = acnt;
-		dst_cidx = acnt * bcnt;
-	}
-
-	/*
-	 * We can't use FIFO mode for the FIFOs because MMC FIFO addresses
-	 * are not 256-bit (32-byte) aligned.  So we use INCR, and the W8BIT
-	 * parameter is ignored.
-	 */
-	edma_set_src(sync_dev, src_port, INCR, W8BIT);
-	edma_set_dest(sync_dev, dst_port, INCR, W8BIT);
+		sync_dev = host->dma_tx;
 
-	edma_set_src_index(sync_dev, src_bidx, src_cidx);
-	edma_set_dest_index(sync_dev, dst_bidx, dst_cidx);
-
-	edma_set_transfer_params(sync_dev, acnt, bcnt, ccnt, 8, ABSYNC);
-
-	edma_read_slot(sync_dev, template);
-
-	/* don't bother with irqs or chaining */
-	template->opt |= EDMA_CHAN_SLOT(sync_dev) << 12;
+	dmaengine_terminate_all(sync_dev);
 }
 
-static void mmc_davinci_send_dma_request(struct mmc_davinci_host *host,
+static int mmc_davinci_send_dma_request(struct mmc_davinci_host *host,
 		struct mmc_data *data)
 {
-	struct edmacc_param	*template;
-	int			channel, slot;
-	unsigned		link;
-	struct scatterlist	*sg;
-	unsigned		sg_len;
-	unsigned		bytes_left = host->bytes_left;
-	const unsigned		shift = ffs(rw_threshold) - 1;
+	struct dma_chan *chan;
+	struct dma_async_tx_descriptor *desc;
+	int ret = 0;
 
 	if (host->data_dir == DAVINCI_MMC_DATADIR_WRITE) {
-		template = &host->tx_template;
-		channel = host->txdma;
+		struct dma_slave_config dma_tx_conf = {
+			.direction = DMA_MEM_TO_DEV,
+			.dst_addr = host->mem_res->start + DAVINCI_MMCDXR,
+			.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES,
+			.dst_maxburst =
+				rw_threshold / DMA_SLAVE_BUSWIDTH_4_BYTES,
+		};
+		chan = host->dma_tx;
+		dmaengine_slave_config(host->dma_tx, &dma_tx_conf);
+
+		desc = dmaengine_prep_slave_sg(host->dma_tx,
+				data->sg,
+				host->sg_len,
+				DMA_MEM_TO_DEV,
+				DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+		if (!desc) {
+			dev_dbg(mmc_dev(host->mmc),
+				"failed to allocate DMA TX descriptor");
+			ret = -1;
+			goto out;
+		}
 	} else {
-		template = &host->rx_template;
-		channel = host->rxdma;
-	}
-
-	/* We know sg_len and ccnt will never be out of range because
-	 * we told the mmc layer which in turn tells the block layer
-	 * to ensure that it only hands us one scatterlist segment
-	 * per EDMA PARAM entry.  Update the PARAM
-	 * entries needed for each segment of this scatterlist.
-	 */
-	for (slot = channel, link = 0, sg = data->sg, sg_len = host->sg_len;
-			sg_len-- != 0 && bytes_left;
-			sg = sg_next(sg), slot = host->links[link++]) {
-		u32		buf = sg_dma_address(sg);
-		unsigned	count = sg_dma_len(sg);
-
-		template->link_bcntrld = sg_len
-				? (EDMA_CHAN_SLOT(host->links[link]) << 5)
-				: 0xffff;
-
-		if (count > bytes_left)
-			count = bytes_left;
-		bytes_left -= count;
-
-		if (host->data_dir == DAVINCI_MMC_DATADIR_WRITE)
-			template->src = buf;
-		else
-			template->dst = buf;
-		template->ccnt = count >> shift;
-
-		edma_write_slot(slot, template);
+		struct dma_slave_config dma_rx_conf = {
+			.direction = DMA_DEV_TO_MEM,
+			.src_addr = host->mem_res->start + DAVINCI_MMCDRR,
+			.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES,
+			.src_maxburst =
+				rw_threshold / DMA_SLAVE_BUSWIDTH_4_BYTES,
+		};
+		chan = host->dma_rx;
+		dmaengine_slave_config(host->dma_rx, &dma_rx_conf);
+
+		desc = dmaengine_prep_slave_sg(host->dma_rx,
+				data->sg,
+				host->sg_len,
+				DMA_DEV_TO_MEM,
+				DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+		if (!desc) {
+			dev_dbg(mmc_dev(host->mmc),
+				"failed to allocate DMA RX descriptor");
+			ret = -1;
+			goto out;
+		}
 	}
 
-	if (host->version == MMC_CTLR_VERSION_2)
-		edma_clear_event(channel);
+	dmaengine_submit(desc);
+	dma_async_issue_pending(chan);
 
-	edma_start(channel);
+out:
+	return ret;
 }
 
 static int mmc_davinci_start_dma_transfer(struct mmc_davinci_host *host,
@@ -564,6 +478,7 @@ static int mmc_davinci_start_dma_transfer(struct mmc_davinci_host *host,
 {
 	int i;
 	int mask = rw_threshold - 1;
+	int ret = 0;
 
 	host->sg_len = dma_map_sg(mmc_dev(host->mmc), data->sg, data->sg_len,
 				((data->flags & MMC_DATA_WRITE)
@@ -583,70 +498,48 @@ static int mmc_davinci_start_dma_transfer(struct mmc_davinci_host *host,
 	}
 
 	host->do_dma = 1;
-	mmc_davinci_send_dma_request(host, data);
+	ret = mmc_davinci_send_dma_request(host, data);
 
-	return 0;
+	return ret;
 }
 
 static void __init_or_module
 davinci_release_dma_channels(struct mmc_davinci_host *host)
 {
-	unsigned	i;
-
 	if (!host->use_dma)
 		return;
 
-	for (i = 0; i < host->n_link; i++)
-		edma_free_slot(host->links[i]);
-
-	edma_free_channel(host->txdma);
-	edma_free_channel(host->rxdma);
+	dma_release_channel(host->dma_tx);
+	dma_release_channel(host->dma_rx);
 }
 
 static int __init davinci_acquire_dma_channels(struct mmc_davinci_host *host)
 {
-	u32 link_size;
-	int r, i;
-
-	/* Acquire master DMA write channel */
-	r = edma_alloc_channel(host->txdma, mmc_davinci_dma_cb, host,
-			EVENTQ_DEFAULT);
-	if (r < 0) {
-		dev_warn(mmc_dev(host->mmc), "alloc %s channel err %d\n",
-				"tx", r);
-		return r;
-	}
-	mmc_davinci_dma_setup(host, true, &host->tx_template);
-
-	/* Acquire master DMA read channel */
-	r = edma_alloc_channel(host->rxdma, mmc_davinci_dma_cb, host,
-			EVENTQ_DEFAULT);
-	if (r < 0) {
-		dev_warn(mmc_dev(host->mmc), "alloc %s channel err %d\n",
-				"rx", r);
-		goto free_master_write;
+	int r;
+	dma_cap_mask_t mask;
+
+	dma_cap_zero(mask);
+	dma_cap_set(DMA_SLAVE, mask);
+
+	host->dma_tx =
+		dma_request_channel(mask, edma_filter_fn, &host->txdma);
+	if (!host->dma_tx) {
+		dev_err(mmc_dev(host->mmc), "Can't get dma_tx channel\n");
+		return -ENODEV;
 	}
-	mmc_davinci_dma_setup(host, false, &host->rx_template);
 
-	/* Allocate parameter RAM slots, which will later be bound to a
-	 * channel as needed to handle a scatterlist.
-	 */
-	link_size = min_t(unsigned, host->nr_sg, ARRAY_SIZE(host->links));
-	for (i = 0; i < link_size; i++) {
-		r = edma_alloc_slot(EDMA_CTLR(host->txdma), EDMA_SLOT_ANY);
-		if (r < 0) {
-			dev_dbg(mmc_dev(host->mmc), "dma PaRAM alloc --> %d\n",
-				r);
-			break;
-		}
-		host->links[i] = r;
+	host->dma_rx =
+		dma_request_channel(mask, edma_filter_fn, &host->rxdma);
+	if (!host->dma_rx) {
+		dev_err(mmc_dev(host->mmc), "Can't get dma_rx channel\n");
+		r = -ENODEV;
+		goto free_master_write;
 	}
-	host->n_link = i;
 
 	return 0;
 
 free_master_write:
-	edma_free_channel(host->txdma);
+	dma_release_channel(host->dma_tx);
 
 	return r;
 }
@@ -1359,7 +1252,7 @@ static int __init davinci_mmcsd_probe(struct platform_device *pdev)
 	 * Each hw_seg uses one EDMA parameter RAM slot, always one
 	 * channel and then usually some linked slots.
 	 */
-	mmc->max_segs		= 1 + host->n_link;
+	mmc->max_segs		= MAX_NR_SG;
 
 	/* EDMA limit per hw segment (one or two MBytes) */
 	mmc->max_seg_size	= MAX_CCNT * rw_threshold;
-- 
1.7.9.5