drivers/mmc/host/tmio_mmc_dma.c - kernel/msm-4.9 - Gitiles

 /*
  * 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/dma-mapping.h>
 #include <linux/dmaengine.h>
 #include <linux/mfd/tmio.h>
 #include <linux/mmc/host.h>
 #include <linux/mmc/tmio.h>
 #include <linux/pagemap.h>
 #include <linux/scatterlist.h>

 #include "tmio_mmc.h"

 #define TMIO_MMC_MIN_DMA_LEN 8

 void tmio_mmc_enable_dma(struct tmio_mmc_host *host, bool enable)
 {
 	if (!host->chan_tx || !host->chan_rx)
 		return;

 #if defined(CONFIG_SUPERH) || defined(CONFIG_ARCH_SHMOBILE)
 	/* Switch DMA mode on or off - SuperH specific? */
 	sd_ctrl_write16(host, CTL_DMA_ENABLE, enable ? 2 : 0);
 #endif
 }

 void tmio_mmc_abort_dma(struct tmio_mmc_host *host)
 {
 	tmio_mmc_enable_dma(host, false);

 	if (host->chan_rx)
 		dmaengine_terminate_all(host->chan_rx);
 	if (host->chan_tx)
 		dmaengine_terminate_all(host->chan_tx);

 	tmio_mmc_enable_dma(host, true);
 }

 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 = dmaengine_prep_slave_sg(chan, sg, ret,
 			DMA_DEV_TO_MEM, 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 */
 		tmio_mmc_enable_dma(host, false);
 		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);
 	}

 	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 = dmaengine_prep_slave_sg(chan, sg, ret,
 			DMA_MEM_TO_DEV, 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 */
 		tmio_mmc_enable_dma(host, false);
 		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);
 	}

 	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);
 }

 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 || (!host->pdev->dev.of_node &&
 		(!pdata->dma->chan_priv_tx || !pdata->dma->chan_priv_rx)))
 		return;

 	if (!host->chan_tx && !host->chan_rx) {
 		struct resource *res = platform_get_resource(host->pdev,
 							     IORESOURCE_MEM, 0);
 		struct dma_slave_config cfg = {};
 		dma_cap_mask_t mask;
 		int ret;

 		if (!res)
 			return;

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

 		host->chan_tx = dma_request_slave_channel_compat(mask,
 					pdata->dma->filter, pdata->dma->chan_priv_tx,
 					&host->pdev->dev, "tx");
 		dev_dbg(&host->pdev->dev, "%s: TX: got channel %p\n", __func__,
 			host->chan_tx);

 		if (!host->chan_tx)
 			return;

 		if (pdata->dma->chan_priv_tx)
 			cfg.slave_id = pdata->dma->slave_id_tx;
 		cfg.direction = DMA_MEM_TO_DEV;
 		cfg.dst_addr = res->start + (CTL_SD_DATA_PORT << host->bus_shift);
 		cfg.src_addr = 0;
 		ret = dmaengine_slave_config(host->chan_tx, &cfg);
 		if (ret < 0)
 			goto ecfgtx;

 		host->chan_rx = dma_request_slave_channel_compat(mask,
 					pdata->dma->filter, pdata->dma->chan_priv_rx,
 					&host->pdev->dev, "rx");
 		dev_dbg(&host->pdev->dev, "%s: RX: got channel %p\n", __func__,
 			host->chan_rx);

 		if (!host->chan_rx)
 			goto ereqrx;

 		if (pdata->dma->chan_priv_rx)
 			cfg.slave_id = pdata->dma->slave_id_rx;
 		cfg.direction = DMA_DEV_TO_MEM;
 		cfg.src_addr = cfg.dst_addr;
 		cfg.dst_addr = 0;
 		ret = dmaengine_slave_config(host->chan_rx, &cfg);
 		if (ret < 0)
 			goto ecfgrx;

 		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:
 ecfgrx:
 	dma_release_channel(host->chan_rx);
 	host->chan_rx = NULL;
 ereqrx:
 ecfgtx:
 	dma_release_channel(host->chan_tx);
 	host->chan_tx = NULL;
 }

 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;
 	}
 }
	/*
	* 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/dma-mapping.h>
	#include <linux/dmaengine.h>
	#include <linux/mfd/tmio.h>
	#include <linux/mmc/host.h>
	#include <linux/mmc/tmio.h>
	#include <linux/pagemap.h>
	#include <linux/scatterlist.h>

	#include "tmio_mmc.h"

	#define TMIO_MMC_MIN_DMA_LEN 8

	void tmio_mmc_enable_dma(struct tmio_mmc_host *host, bool enable)
	{
	if (!host->chan_tx \|\| !host->chan_rx)
	return;

	#if defined(CONFIG_SUPERH) \|\| defined(CONFIG_ARCH_SHMOBILE)
	/* Switch DMA mode on or off - SuperH specific? */
	sd_ctrl_write16(host, CTL_DMA_ENABLE, enable ? 2 : 0);
	#endif
	}

	void tmio_mmc_abort_dma(struct tmio_mmc_host *host)
	{
	tmio_mmc_enable_dma(host, false);

	if (host->chan_rx)
	dmaengine_terminate_all(host->chan_rx);
	if (host->chan_tx)
	dmaengine_terminate_all(host->chan_tx);

	tmio_mmc_enable_dma(host, true);
	}

	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 = dmaengine_prep_slave_sg(chan, sg, ret,
	DMA_DEV_TO_MEM, 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 */
	tmio_mmc_enable_dma(host, false);
	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);
	}

	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 = dmaengine_prep_slave_sg(chan, sg, ret,
	DMA_MEM_TO_DEV, 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 */
	tmio_mmc_enable_dma(host, false);
	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);
	}

	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);
	}

	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 \|\| (!host->pdev->dev.of_node &&
	(!pdata->dma->chan_priv_tx \|\| !pdata->dma->chan_priv_rx)))
	return;

	if (!host->chan_tx && !host->chan_rx) {
	struct resource *res = platform_get_resource(host->pdev,
	IORESOURCE_MEM, 0);
	struct dma_slave_config cfg = {};
	dma_cap_mask_t mask;
	int ret;

	if (!res)
	return;

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

	host->chan_tx = dma_request_slave_channel_compat(mask,
	pdata->dma->filter, pdata->dma->chan_priv_tx,
	&host->pdev->dev, "tx");
	dev_dbg(&host->pdev->dev, "%s: TX: got channel %p\n", __func__,
	host->chan_tx);

	if (!host->chan_tx)
	return;

	if (pdata->dma->chan_priv_tx)
	cfg.slave_id = pdata->dma->slave_id_tx;
	cfg.direction = DMA_MEM_TO_DEV;
	cfg.dst_addr = res->start + (CTL_SD_DATA_PORT << host->bus_shift);
	cfg.src_addr = 0;
	ret = dmaengine_slave_config(host->chan_tx, &cfg);
	if (ret < 0)
	goto ecfgtx;

	host->chan_rx = dma_request_slave_channel_compat(mask,
	pdata->dma->filter, pdata->dma->chan_priv_rx,
	&host->pdev->dev, "rx");
	dev_dbg(&host->pdev->dev, "%s: RX: got channel %p\n", __func__,
	host->chan_rx);

	if (!host->chan_rx)
	goto ereqrx;

	if (pdata->dma->chan_priv_rx)
	cfg.slave_id = pdata->dma->slave_id_rx;
	cfg.direction = DMA_DEV_TO_MEM;
	cfg.src_addr = cfg.dst_addr;
	cfg.dst_addr = 0;
	ret = dmaengine_slave_config(host->chan_rx, &cfg);
	if (ret < 0)
	goto ecfgrx;

	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:
	ecfgrx:
	dma_release_channel(host->chan_rx);
	host->chan_rx = NULL;
	ereqrx:
	ecfgtx:
	dma_release_channel(host->chan_tx);
	host->chan_tx = NULL;
	}

	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;
	}
	}