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omap_hsmmc: Implement scatter-gather emulation
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Instead of using the bounce buffer, using scatter-gather emulation
(as in the OMAP1/2 MMC driver) removes the need of one extra memory
copy and improves performance.

Signed-off-by: Juha Yrjola <juha.yrjola@solidboot.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
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Juha Yrjola authored and Pierre Ossman committed Mar 24, 2009
1 parent 4a694dc commit 0ccd76d
Showing 1 changed file with 95 additions and 77 deletions.
172 changes: 95 additions & 77 deletions drivers/mmc/host/omap_hsmmc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -100,9 +100,6 @@
#define OMAP_MMC1_DEVID 0
#define OMAP_MMC2_DEVID 1

#define OMAP_MMC_DATADIR_NONE 0
#define OMAP_MMC_DATADIR_READ 1
#define OMAP_MMC_DATADIR_WRITE 2
#define MMC_TIMEOUT_MS 20
#define OMAP_MMC_MASTER_CLOCK 96000000
#define DRIVER_NAME "mmci-omap-hs"
Expand Down Expand Up @@ -138,16 +135,14 @@ struct mmc_omap_host {
resource_size_t mapbase;
unsigned int id;
unsigned int dma_len;
unsigned int dma_dir;
unsigned int dma_sg_idx;
unsigned char bus_mode;
unsigned char datadir;
u32 *buffer;
u32 bytesleft;
int suspended;
int irq;
int carddetect;
int use_dma, dma_ch;
int initstr;
int slot_id;
int dbclk_enabled;
int response_busy;
Expand Down Expand Up @@ -281,6 +276,15 @@ mmc_omap_start_command(struct mmc_omap_host *host, struct mmc_command *cmd,
OMAP_HSMMC_WRITE(host->base, CMD, cmdreg);
}

static int
mmc_omap_get_dma_dir(struct mmc_omap_host *host, struct mmc_data *data)
{
if (data->flags & MMC_DATA_WRITE)
return DMA_TO_DEVICE;
else
return DMA_FROM_DEVICE;
}

/*
* Notify the transfer complete to MMC core
*/
Expand All @@ -300,9 +304,7 @@ mmc_omap_xfer_done(struct mmc_omap_host *host, struct mmc_data *data)

if (host->use_dma && host->dma_ch != -1)
dma_unmap_sg(mmc_dev(host->mmc), data->sg, host->dma_len,
host->dma_dir);

host->datadir = OMAP_MMC_DATADIR_NONE;
mmc_omap_get_dma_dir(host, data));

if (!data->error)
data->bytes_xfered += data->blocks * (data->blksz);
Expand Down Expand Up @@ -352,13 +354,12 @@ static void mmc_dma_cleanup(struct mmc_omap_host *host, int errno)

if (host->use_dma && host->dma_ch != -1) {
dma_unmap_sg(mmc_dev(host->mmc), host->data->sg, host->dma_len,
host->dma_dir);
mmc_omap_get_dma_dir(host, host->data));
omap_free_dma(host->dma_ch);
host->dma_ch = -1;
up(&host->sem);
}
host->data = NULL;
host->datadir = OMAP_MMC_DATADIR_NONE;
}

/*
Expand Down Expand Up @@ -592,6 +593,55 @@ static irqreturn_t omap_mmc_cd_handler(int irq, void *dev_id)
return IRQ_HANDLED;
}

static int mmc_omap_get_dma_sync_dev(struct mmc_omap_host *host,
struct mmc_data *data)
{
int sync_dev;

if (data->flags & MMC_DATA_WRITE) {
if (host->id == OMAP_MMC1_DEVID)
sync_dev = OMAP24XX_DMA_MMC1_TX;
else
sync_dev = OMAP24XX_DMA_MMC2_TX;
} else {
if (host->id == OMAP_MMC1_DEVID)
sync_dev = OMAP24XX_DMA_MMC1_RX;
else
sync_dev = OMAP24XX_DMA_MMC2_RX;
}
return sync_dev;
}

static void mmc_omap_config_dma_params(struct mmc_omap_host *host,
struct mmc_data *data,
struct scatterlist *sgl)
{
int blksz, nblk, dma_ch;

dma_ch = host->dma_ch;
if (data->flags & MMC_DATA_WRITE) {
omap_set_dma_dest_params(dma_ch, 0, OMAP_DMA_AMODE_CONSTANT,
(host->mapbase + OMAP_HSMMC_DATA), 0, 0);
omap_set_dma_src_params(dma_ch, 0, OMAP_DMA_AMODE_POST_INC,
sg_dma_address(sgl), 0, 0);
} else {
omap_set_dma_src_params(dma_ch, 0, OMAP_DMA_AMODE_CONSTANT,
(host->mapbase + OMAP_HSMMC_DATA), 0, 0);
omap_set_dma_dest_params(dma_ch, 0, OMAP_DMA_AMODE_POST_INC,
sg_dma_address(sgl), 0, 0);
}

blksz = host->data->blksz;
nblk = sg_dma_len(sgl) / blksz;

omap_set_dma_transfer_params(dma_ch, OMAP_DMA_DATA_TYPE_S32,
blksz / 4, nblk, OMAP_DMA_SYNC_FRAME,
mmc_omap_get_dma_sync_dev(host, data),
!(data->flags & MMC_DATA_WRITE));

omap_start_dma(dma_ch);
}

/*
* DMA call back function
*/
Expand All @@ -605,6 +655,14 @@ static void mmc_omap_dma_cb(int lch, u16 ch_status, void *data)
if (host->dma_ch < 0)
return;

host->dma_sg_idx++;
if (host->dma_sg_idx < host->dma_len) {
/* Fire up the next transfer. */
mmc_omap_config_dma_params(host, host->data,
host->data->sg + host->dma_sg_idx);
return;
}

omap_free_dma(host->dma_ch);
host->dma_ch = -1;
/*
Expand All @@ -614,39 +672,29 @@ static void mmc_omap_dma_cb(int lch, u16 ch_status, void *data)
up(&host->sem);
}

/*
* Configure dma src and destination parameters
*/
static int mmc_omap_config_dma_param(int sync_dir, struct mmc_omap_host *host,
struct mmc_data *data)
{
if (sync_dir == 0) {
omap_set_dma_dest_params(host->dma_ch, 0,
OMAP_DMA_AMODE_CONSTANT,
(host->mapbase + OMAP_HSMMC_DATA), 0, 0);
omap_set_dma_src_params(host->dma_ch, 0,
OMAP_DMA_AMODE_POST_INC,
sg_dma_address(&data->sg[0]), 0, 0);
} else {
omap_set_dma_src_params(host->dma_ch, 0,
OMAP_DMA_AMODE_CONSTANT,
(host->mapbase + OMAP_HSMMC_DATA), 0, 0);
omap_set_dma_dest_params(host->dma_ch, 0,
OMAP_DMA_AMODE_POST_INC,
sg_dma_address(&data->sg[0]), 0, 0);
}
return 0;
}
/*
* Routine to configure and start DMA for the MMC card
*/
static int
mmc_omap_start_dma_transfer(struct mmc_omap_host *host, struct mmc_request *req)
{
int sync_dev, sync_dir = 0;
int dma_ch = 0, ret = 0, err = 1;
int dma_ch = 0, ret = 0, err = 1, i;
struct mmc_data *data = req->data;

/* Sanity check: all the SG entries must be aligned by block size. */
for (i = 0; i < host->dma_len; i++) {
struct scatterlist *sgl;

sgl = data->sg + i;
if (sgl->length % data->blksz)
return -EINVAL;
}
if ((data->blksz % 4) != 0)
/* REVISIT: The MMC buffer increments only when MSB is written.
* Return error for blksz which is non multiple of four.
*/
return -EINVAL;

/*
* If for some reason the DMA transfer is still active,
* we wait for timeout period and free the dma
Expand All @@ -665,49 +713,22 @@ mmc_omap_start_dma_transfer(struct mmc_omap_host *host, struct mmc_request *req)
return err;
}

if (!(data->flags & MMC_DATA_WRITE)) {
host->dma_dir = DMA_FROM_DEVICE;
if (host->id == OMAP_MMC1_DEVID)
sync_dev = OMAP24XX_DMA_MMC1_RX;
else
sync_dev = OMAP24XX_DMA_MMC2_RX;
} else {
host->dma_dir = DMA_TO_DEVICE;
if (host->id == OMAP_MMC1_DEVID)
sync_dev = OMAP24XX_DMA_MMC1_TX;
else
sync_dev = OMAP24XX_DMA_MMC2_TX;
}

ret = omap_request_dma(sync_dev, "MMC/SD", mmc_omap_dma_cb,
host, &dma_ch);
ret = omap_request_dma(mmc_omap_get_dma_sync_dev(host, data), "MMC/SD",
mmc_omap_dma_cb,host, &dma_ch);
if (ret != 0) {
dev_dbg(mmc_dev(host->mmc),
dev_err(mmc_dev(host->mmc),
"%s: omap_request_dma() failed with %d\n",
mmc_hostname(host->mmc), ret);
return ret;
}

host->dma_len = dma_map_sg(mmc_dev(host->mmc), data->sg,
data->sg_len, host->dma_dir);
data->sg_len, mmc_omap_get_dma_dir(host, data));
host->dma_ch = dma_ch;
host->dma_sg_idx = 0;

if (!(data->flags & MMC_DATA_WRITE))
mmc_omap_config_dma_param(1, host, data);
else
mmc_omap_config_dma_param(0, host, data);

if ((data->blksz % 4) == 0)
omap_set_dma_transfer_params(dma_ch, OMAP_DMA_DATA_TYPE_S32,
(data->blksz / 4), data->blocks, OMAP_DMA_SYNC_FRAME,
sync_dev, sync_dir);
else
/* REVISIT: The MMC buffer increments only when MSB is written.
* Return error for blksz which is non multiple of four.
*/
return -EINVAL;
mmc_omap_config_dma_params(host, data, data->sg);

omap_start_dma(dma_ch);
return 0;
}

Expand Down Expand Up @@ -757,7 +778,6 @@ mmc_omap_prepare_data(struct mmc_omap_host *host, struct mmc_request *req)
host->data = req->data;

if (req->data == NULL) {
host->datadir = OMAP_MMC_DATADIR_NONE;
OMAP_HSMMC_WRITE(host->base, BLK, 0);
return 0;
}
Expand All @@ -766,9 +786,6 @@ mmc_omap_prepare_data(struct mmc_omap_host *host, struct mmc_request *req)
| (req->data->blocks << 16));
set_data_timeout(host, req);

host->datadir = (req->data->flags & MMC_DATA_WRITE) ?
OMAP_MMC_DATADIR_WRITE : OMAP_MMC_DATADIR_READ;

if (host->use_dma) {
ret = mmc_omap_start_dma_transfer(host, req);
if (ret != 0) {
Expand Down Expand Up @@ -1027,10 +1044,11 @@ static int __init omap_mmc_probe(struct platform_device *pdev)
else
host->dbclk_enabled = 1;

#ifdef CONFIG_MMC_BLOCK_BOUNCE
mmc->max_phys_segs = 1;
mmc->max_hw_segs = 1;
#endif
/* Since we do only SG emulation, we can have as many segs
* as we want. */
mmc->max_phys_segs = 1024;
mmc->max_hw_segs = 1024;

mmc->max_blk_size = 512; /* Block Length at max can be 1024 */
mmc->max_blk_count = 0xFFFF; /* No. of Blocks is 16 bits */
mmc->max_req_size = mmc->max_blk_size * mmc->max_blk_count;
Expand Down

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