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Commit 93173054 authored by Guennadi Liakhovetski's avatar Guennadi Liakhovetski Committed by Chris Ball
Browse files

mmc: tmio_mmc: implement a bounce buffer for unaligned DMA 



For example, with SDIO WLAN cards, some transfers happen with buffers at
odd addresses, whereas the SH-Mobile DMA engine requires even addresses
for SDHI. This patch extends the tmio driver with a bounce buffer, that
is used for single entry scatter-gather lists both for sending and
receiving. If we ever encounter unaligned transfers with multi-element
sg lists, this patch will have to be extended. For now it just falls
back to PIO in this and other unsupported cases.

Signed-off-by: default avatarGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: default avatarSamuel Ortiz <sameo@linux.intel.com>
Signed-off-by: default avatarChris Ball <cjb@laptop.org>
parent e0bc6ff8

drivers/mmc/host/tmio_mmc.c

+83 −6
Original line number Diff line number Diff line
@@ -111,6 +111,8 @@ 
		sd_ctrl_write32((host), CTL_STATUS, ~(i)); \

	} while (0)



/* This is arbitrary, just noone needed any higher alignment yet */

#define MAX_ALIGN 4



struct tmio_mmc_host {

	void __iomem *ctl;
@@ -127,6 +129,7 @@ struct tmio_mmc_host { 


	/* pio related stuff */

	struct scatterlist      *sg_ptr;

	struct scatterlist      *sg_orig;

	unsigned int            sg_len;

	unsigned int            sg_off;
@@ -139,9 +142,13 @@ struct tmio_mmc_host { 
	struct tasklet_struct	dma_issue;

#ifdef CONFIG_TMIO_MMC_DMA

	unsigned int            dma_sglen;

	u8			bounce_buf[PAGE_CACHE_SIZE] __attribute__((aligned(MAX_ALIGN)));

	struct scatterlist	bounce_sg;

#endif

};



static void tmio_check_bounce_buffer(struct tmio_mmc_host *host);



static u16 sd_ctrl_read16(struct tmio_mmc_host *host, int addr)

{

	return readw(host->ctl + (addr << host->bus_shift));
@@ -180,6 +187,7 @@ static void tmio_mmc_init_sg(struct tmio_mmc_host *host, struct mmc_data *data) 
{

	host->sg_len = data->sg_len;

	host->sg_ptr = data->sg;

	host->sg_orig = data->sg;

	host->sg_off = 0;

}
@@ -438,6 +446,8 @@ static void tmio_mmc_do_data_irq(struct tmio_mmc_host *host) 
	if (data->flags & MMC_DATA_READ) {

		if (!host->chan_rx)

			disable_mmc_irqs(host, TMIO_MASK_READOP);

		else

			tmio_check_bounce_buffer(host);

		dev_dbg(&host->pdev->dev, "Complete Rx request %p\n",

			host->mrq);

	} else {
@@ -529,8 +539,7 @@ static void tmio_mmc_cmd_irq(struct tmio_mmc_host *host, 
			if (!host->chan_rx)

				enable_mmc_irqs(host, TMIO_MASK_READOP);

		} else {

			struct dma_chan *chan = host->chan_tx;

			if (!chan)

			if (!host->chan_tx)

				enable_mmc_irqs(host, TMIO_MASK_WRITEOP);

			else

				tasklet_schedule(&host->dma_issue);
@@ -612,6 +621,16 @@ static irqreturn_t tmio_mmc_irq(int irq, void *devid) 
}



#ifdef CONFIG_TMIO_MMC_DMA

static void tmio_check_bounce_buffer(struct tmio_mmc_host *host)

{

	if (host->sg_ptr == &host->bounce_sg) {

		unsigned long flags;

		void *sg_vaddr = tmio_mmc_kmap_atomic(host->sg_orig, &flags);

		memcpy(sg_vaddr, host->bounce_buf, host->bounce_sg.length);

		tmio_mmc_kunmap_atomic(sg_vaddr, &flags);

	}

}



static void tmio_mmc_enable_dma(struct tmio_mmc_host *host, bool enable)

{

#if defined(CONFIG_SUPERH) || defined(CONFIG_ARCH_SHMOBILE)
@@ -634,11 +653,35 @@ static void tmio_dma_complete(void *arg) 


static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host)

{

	struct scatterlist *sg = host->sg_ptr;

	struct scatterlist *sg = host->sg_ptr, *sg_tmp;

	struct dma_async_tx_descriptor *desc = NULL;

	struct dma_chan *chan = host->chan_rx;

	struct mfd_cell	*cell = host->pdev->dev.platform_data;

	struct tmio_mmc_data *pdata = cell->driver_data;

	dma_cookie_t cookie;

	int ret;

	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 >= MAX_ALIGN)) || !multiple)

		goto pio;



	/* 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(&host->pdev->dev, sg, host->sg_len, DMA_FROM_DEVICE);

	if (ret > 0) {
@@ -661,6 +704,7 @@ static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host) 
	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)
@@ -684,11 +728,39 @@ static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host) 


static void tmio_mmc_start_dma_tx(struct tmio_mmc_host *host)

{

	struct scatterlist *sg = host->sg_ptr;

	struct scatterlist *sg = host->sg_ptr, *sg_tmp;

	struct dma_async_tx_descriptor *desc = NULL;

	struct dma_chan *chan = host->chan_tx;

	struct mfd_cell	*cell = host->pdev->dev.platform_data;

	struct tmio_mmc_data *pdata = cell->driver_data;

	dma_cookie_t cookie;

	int ret;

	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 >= MAX_ALIGN)) || !multiple)

		goto pio;



	/* 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_vaddr, &flags);

		host->sg_ptr = &host->bounce_sg;

		sg = host->sg_ptr;

	}



	ret = dma_map_sg(&host->pdev->dev, sg, host->sg_len, DMA_TO_DEVICE);

	if (ret > 0) {
@@ -709,6 +781,7 @@ static void tmio_mmc_start_dma_tx(struct tmio_mmc_host *host) 
	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)
@@ -822,6 +895,10 @@ static void tmio_mmc_release_dma(struct tmio_mmc_host *host) 
	}

}

#else

static void tmio_check_bounce_buffer(struct tmio_mmc_host *host)

{

}



static void tmio_mmc_start_dma(struct tmio_mmc_host *host,

			       struct mmc_data *data)

{

include/linux/mfd/tmio.h

+1 −0
Original line number Diff line number Diff line
@@ -66,6 +66,7 @@ void tmio_core_mmc_clk_div(void __iomem *cnf, int shift, int state); 
struct tmio_mmc_dma {

	void *chan_priv_tx;

	void *chan_priv_rx;

	int alignment_shift;

};



/*