mmc: tmio: split core functionality, DMA and MFD glue

TMIO MMC chips contain an SD / SDIO IP core from Panasonic, similar to
the one, used in MN5774 and other MN57xx controllers. These IP cores are
included in many multifunction devices, in sh-mobile chips from Renesas,
in the latter case they can also use DMA. Some sh-mobile implementations
also have some other specialities, that MFD-based solutions don't have.
This makes supporting all these features in a monolithic driver inconveniet
and error-prone. This patch splits the driver into 3 parts: the core,
the MFD glue and the DMA support. In case of a modular build, two modules
will be built: mmc_tmio_core and mmc_tmio.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

1 files changed, 316 insertions, 0 deletions

diff --git a/drivers/mmc/host/tmio_mmc_dma.c b/drivers/mmc/host/tmio_mmc_dma.c
new file mode 100644
index 000000000000..c505278be43f
--- /dev/null
+++ b/drivers/mmc/host/tmio_mmc_dma.c
@@ -0,0 +1,316 @@
+/*
+ * linux/drivers/mmc/tmio_mmc_dma.c
+ *
+ * Copyright (C) 2010-2011 Guennadi Liakhovetski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * DMA function for TMIO MMC implementations
+ */
+
+#include <linux/device.h>
+#include <linux/dmaengine.h>
+#include <linux/mfd/tmio.h>
+#include <linux/mmc/host.h>
+#include <linux/pagemap.h>
+#include <linux/scatterlist.h>
+
+#include "tmio_mmc.h"
+
+#define TMIO_MMC_MIN_DMA_LEN 8
+
+static void tmio_mmc_enable_dma(struct tmio_mmc_host *host, bool enable)
+{
+#if defined(CONFIG_SUPERH) || defined(CONFIG_ARCH_SHMOBILE)
+	/* Switch DMA mode on or off - SuperH specific? */
+	writew(enable ? 2 : 0, host->ctl + (0xd8 << host->bus_shift));
+#endif
+}
+
+static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host)
+{
+	struct scatterlist *sg = host->sg_ptr, *sg_tmp;
+	struct dma_async_tx_descriptor *desc = NULL;
+	struct dma_chan *chan = host->chan_rx;
+	struct tmio_mmc_data *pdata = host->pdata;
+	dma_cookie_t cookie;
+	int ret, i;
+	bool aligned = true, multiple = true;
+	unsigned int align = (1 << pdata->dma->alignment_shift) - 1;
+
+	for_each_sg(sg, sg_tmp, host->sg_len, i) {
+		if (sg_tmp->offset & align)
+			aligned = false;
+		if (sg_tmp->length & align) {
+			multiple = false;
+			break;
+		}
+	}
+
+	if ((!aligned && (host->sg_len > 1 || sg->length > PAGE_CACHE_SIZE ||
+			  (align & PAGE_MASK))) || !multiple) {
+		ret = -EINVAL;
+		goto pio;
+	}
+
+	if (sg->length < TMIO_MMC_MIN_DMA_LEN) {
+		host->force_pio = true;
+		return;
+	}
+
+	tmio_mmc_disable_mmc_irqs(host, TMIO_STAT_RXRDY);
+
+	/* The only sg element can be unaligned, use our bounce buffer then */
+	if (!aligned) {
+		sg_init_one(&host->bounce_sg, host->bounce_buf, sg->length);
+		host->sg_ptr = &host->bounce_sg;
+		sg = host->sg_ptr;
+	}
+
+	ret = dma_map_sg(chan->device->dev, sg, host->sg_len, DMA_FROM_DEVICE);
+	if (ret > 0)
+		desc = chan->device->device_prep_slave_sg(chan, sg, ret,
+			DMA_FROM_DEVICE, DMA_CTRL_ACK);
+
+	if (desc) {
+		cookie = dmaengine_submit(desc);
+		if (cookie < 0) {
+			desc = NULL;
+			ret = cookie;
+		}
+	}
+	dev_dbg(&host->pdev->dev, "%s(): mapped %d -> %d, cookie %d, rq %p\n",
+		__func__, host->sg_len, ret, cookie, host->mrq);
+
+pio:
+	if (!desc) {
+		/* DMA failed, fall back to PIO */
+		if (ret >= 0)
+			ret = -EIO;
+		host->chan_rx = NULL;
+		dma_release_channel(chan);
+		/* Free the Tx channel too */
+		chan = host->chan_tx;
+		if (chan) {
+			host->chan_tx = NULL;
+			dma_release_channel(chan);
+		}
+		dev_warn(&host->pdev->dev,
+			 "DMA failed: %d, falling back to PIO\n", ret);
+		tmio_mmc_enable_dma(host, false);
+	}
+
+	dev_dbg(&host->pdev->dev, "%s(): desc %p, cookie %d, sg[%d]\n", __func__,
+		desc, cookie, host->sg_len);
+}
+
+static void tmio_mmc_start_dma_tx(struct tmio_mmc_host *host)
+{
+	struct scatterlist *sg = host->sg_ptr, *sg_tmp;
+	struct dma_async_tx_descriptor *desc = NULL;
+	struct dma_chan *chan = host->chan_tx;
+	struct tmio_mmc_data *pdata = host->pdata;
+	dma_cookie_t cookie;
+	int ret, i;
+	bool aligned = true, multiple = true;
+	unsigned int align = (1 << pdata->dma->alignment_shift) - 1;
+
+	for_each_sg(sg, sg_tmp, host->sg_len, i) {
+		if (sg_tmp->offset & align)
+			aligned = false;
+		if (sg_tmp->length & align) {
+			multiple = false;
+			break;
+		}
+	}
+
+	if ((!aligned && (host->sg_len > 1 || sg->length > PAGE_CACHE_SIZE ||
+			  (align & PAGE_MASK))) || !multiple) {
+		ret = -EINVAL;
+		goto pio;
+	}
+
+	if (sg->length < TMIO_MMC_MIN_DMA_LEN) {
+		host->force_pio = true;
+		return;
+	}
+
+	tmio_mmc_disable_mmc_irqs(host, TMIO_STAT_TXRQ);
+
+	/* The only sg element can be unaligned, use our bounce buffer then */
+	if (!aligned) {
+		unsigned long flags;
+		void *sg_vaddr = tmio_mmc_kmap_atomic(sg, &flags);
+		sg_init_one(&host->bounce_sg, host->bounce_buf, sg->length);
+		memcpy(host->bounce_buf, sg_vaddr, host->bounce_sg.length);
+		tmio_mmc_kunmap_atomic(sg, &flags, sg_vaddr);
+		host->sg_ptr = &host->bounce_sg;
+		sg = host->sg_ptr;
+	}
+
+	ret = dma_map_sg(chan->device->dev, sg, host->sg_len, DMA_TO_DEVICE);
+	if (ret > 0)
+		desc = chan->device->device_prep_slave_sg(chan, sg, ret,
+			DMA_TO_DEVICE, DMA_CTRL_ACK);
+
+	if (desc) {
+		cookie = dmaengine_submit(desc);
+		if (cookie < 0) {
+			desc = NULL;
+			ret = cookie;
+		}
+	}
+	dev_dbg(&host->pdev->dev, "%s(): mapped %d -> %d, cookie %d, rq %p\n",
+		__func__, host->sg_len, ret, cookie, host->mrq);
+
+pio:
+	if (!desc) {
+		/* DMA failed, fall back to PIO */
+		if (ret >= 0)
+			ret = -EIO;
+		host->chan_tx = NULL;
+		dma_release_channel(chan);
+		/* Free the Rx channel too */
+		chan = host->chan_rx;
+		if (chan) {
+			host->chan_rx = NULL;
+			dma_release_channel(chan);
+		}
+		dev_warn(&host->pdev->dev,
+			 "DMA failed: %d, falling back to PIO\n", ret);
+		tmio_mmc_enable_dma(host, false);
+	}
+
+	dev_dbg(&host->pdev->dev, "%s(): desc %p, cookie %d\n", __func__,
+		desc, cookie);
+}
+
+void tmio_mmc_start_dma(struct tmio_mmc_host *host,
+			       struct mmc_data *data)
+{
+	if (data->flags & MMC_DATA_READ) {
+		if (host->chan_rx)
+			tmio_mmc_start_dma_rx(host);
+	} else {
+		if (host->chan_tx)
+			tmio_mmc_start_dma_tx(host);
+	}
+}
+
+static void tmio_mmc_issue_tasklet_fn(unsigned long priv)
+{
+	struct tmio_mmc_host *host = (struct tmio_mmc_host *)priv;
+	struct dma_chan *chan = NULL;
+
+	spin_lock_irq(&host->lock);
+
+	if (host && host->data) {
+		if (host->data->flags & MMC_DATA_READ)
+			chan = host->chan_rx;
+		else
+			chan = host->chan_tx;
+	}
+
+	spin_unlock_irq(&host->lock);
+
+	tmio_mmc_enable_mmc_irqs(host, TMIO_STAT_DATAEND);
+
+	if (chan)
+		dma_async_issue_pending(chan);
+}
+
+static void tmio_mmc_tasklet_fn(unsigned long arg)
+{
+	struct tmio_mmc_host *host = (struct tmio_mmc_host *)arg;
+
+	spin_lock_irq(&host->lock);
+
+	if (!host->data)
+		goto out;
+
+	if (host->data->flags & MMC_DATA_READ)
+		dma_unmap_sg(host->chan_rx->device->dev,
+			     host->sg_ptr, host->sg_len,
+			     DMA_FROM_DEVICE);
+	else
+		dma_unmap_sg(host->chan_tx->device->dev,
+			     host->sg_ptr, host->sg_len,
+			     DMA_TO_DEVICE);
+
+	tmio_mmc_do_data_irq(host);
+out:
+	spin_unlock_irq(&host->lock);
+}
+
+/* It might be necessary to make filter MFD specific */
+static bool tmio_mmc_filter(struct dma_chan *chan, void *arg)
+{
+	dev_dbg(chan->device->dev, "%s: slave data %p\n", __func__, arg);
+	chan->private = arg;
+	return true;
+}
+
+void tmio_mmc_request_dma(struct tmio_mmc_host *host, struct tmio_mmc_data *pdata)
+{
+	/* We can only either use DMA for both Tx and Rx or not use it at all */
+	if (pdata->dma) {
+		dma_cap_mask_t mask;
+
+		dma_cap_zero(mask);
+		dma_cap_set(DMA_SLAVE, mask);
+
+		host->chan_tx = dma_request_channel(mask, tmio_mmc_filter,
+						    pdata->dma->chan_priv_tx);
+		dev_dbg(&host->pdev->dev, "%s: TX: got channel %p\n", __func__,
+			host->chan_tx);
+
+		if (!host->chan_tx)
+			return;
+
+		host->chan_rx = dma_request_channel(mask, tmio_mmc_filter,
+						    pdata->dma->chan_priv_rx);
+		dev_dbg(&host->pdev->dev, "%s: RX: got channel %p\n", __func__,
+			host->chan_rx);
+
+		if (!host->chan_rx)
+			goto ereqrx;
+
+		host->bounce_buf = (u8 *)__get_free_page(GFP_KERNEL | GFP_DMA);
+		if (!host->bounce_buf)
+			goto ebouncebuf;
+
+		tasklet_init(&host->dma_complete, tmio_mmc_tasklet_fn, (unsigned long)host);
+		tasklet_init(&host->dma_issue, tmio_mmc_issue_tasklet_fn, (unsigned long)host);
+
+		tmio_mmc_enable_dma(host, true);
+
+		return;
+ebouncebuf:
+		dma_release_channel(host->chan_rx);
+		host->chan_rx = NULL;
+ereqrx:
+		dma_release_channel(host->chan_tx);
+		host->chan_tx = NULL;
+		return;
+	}
+}
+
+void tmio_mmc_release_dma(struct tmio_mmc_host *host)
+{
+	if (host->chan_tx) {
+		struct dma_chan *chan = host->chan_tx;
+		host->chan_tx = NULL;
+		dma_release_channel(chan);
+	}
+	if (host->chan_rx) {
+		struct dma_chan *chan = host->chan_rx;
+		host->chan_rx = NULL;
+		dma_release_channel(chan);
+	}
+	if (host->bounce_buf) {
+		free_pages((unsigned long)host->bounce_buf, 0);
+		host->bounce_buf = NULL;
+	}
+}