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spi: omap2-mcspi: Use the SPI framework to handle DMA mapping
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Currently, the driver handles mapping buffers to be used by the DMA.
However, there are times that the current mapping implementation will
fail for certain buffers. Fortunately, the SPI framework can detect
and map buffers so its usable by the DMA.

Update the driver to utilize the SPI framework for buffer
mapping instead. Also incorporate hooks that the framework uses to
determine if the DMA can or can not be used.

This will result in the original omap2_mcspi_transfer_one function being
deleted and omap2_mcspi_work_one being renamed to
omap2_mcspi_transfer_one. Previously transfer_one was only responsible
for mapping and work_one handled the transfer. But now only transferring
needs to be handled by the driver.

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
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Franklin S Cooper Jr authored and Mark Brown committed Jul 8, 2016
1 parent 2b32e98 commit 0ba1870
Showing 1 changed file with 56 additions and 76 deletions.
132 changes: 56 additions & 76 deletions drivers/spi/spi-omap2-mcspi.c
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Original file line number Diff line number Diff line change
Expand Up @@ -419,16 +419,13 @@ static void omap2_mcspi_tx_dma(struct spi_device *spi,

if (mcspi_dma->dma_tx) {
struct dma_async_tx_descriptor *tx;
struct scatterlist sg;

dmaengine_slave_config(mcspi_dma->dma_tx, &cfg);

sg_init_table(&sg, 1);
sg_dma_address(&sg) = xfer->tx_dma;
sg_dma_len(&sg) = xfer->len;

tx = dmaengine_prep_slave_sg(mcspi_dma->dma_tx, &sg, 1,
DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
tx = dmaengine_prep_slave_sg(mcspi_dma->dma_tx, xfer->tx_sg.sgl,
xfer->tx_sg.nents,
DMA_MEM_TO_DEV,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (tx) {
tx->callback = omap2_mcspi_tx_callback;
tx->callback_param = spi;
Expand All @@ -449,23 +446,25 @@ omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_transfer *xfer,
{
struct omap2_mcspi *mcspi;
struct omap2_mcspi_dma *mcspi_dma;
unsigned int count, dma_count;
unsigned int count, transfer_reduction = 0;
struct scatterlist *sg_out[2];
int nb_sizes = 0, out_mapped_nents[2], ret, x;
size_t sizes[2];
u32 l;
int elements = 0;
int word_len, element_count;
struct omap2_mcspi_cs *cs = spi->controller_state;
mcspi = spi_master_get_devdata(spi->master);
mcspi_dma = &mcspi->dma_channels[spi->chip_select];
count = xfer->len;
dma_count = xfer->len;

/*
* In the "End-of-Transfer Procedure" section for DMA RX in OMAP35x TRM
* it mentions reducing DMA transfer length by one element in master
* normal mode.
*/
if (mcspi->fifo_depth == 0)
dma_count -= es;
transfer_reduction = es;

word_len = cs->word_len;
l = mcspi_cached_chconf0(spi);
Expand All @@ -479,7 +478,6 @@ omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_transfer *xfer,

if (mcspi_dma->dma_rx) {
struct dma_async_tx_descriptor *tx;
struct scatterlist sg;

dmaengine_slave_config(mcspi_dma->dma_rx, &cfg);

Expand All @@ -488,15 +486,38 @@ omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_transfer *xfer,
* configured in turbo mode.
*/
if ((l & OMAP2_MCSPI_CHCONF_TURBO) && mcspi->fifo_depth == 0)
dma_count -= es;
transfer_reduction += es;

sg_init_table(&sg, 1);
sg_dma_address(&sg) = xfer->rx_dma;
sg_dma_len(&sg) = dma_count;
if (transfer_reduction) {
/* Split sgl into two. The second sgl won't be used. */
sizes[0] = count - transfer_reduction;
sizes[1] = transfer_reduction;
nb_sizes = 2;
} else {
/*
* Don't bother splitting the sgl. This essentially
* clones the original sgl.
*/
sizes[0] = count;
nb_sizes = 1;
}

ret = sg_split(xfer->rx_sg.sgl, xfer->rx_sg.nents,
0, nb_sizes,
sizes,
sg_out, out_mapped_nents,
GFP_KERNEL);

tx = dmaengine_prep_slave_sg(mcspi_dma->dma_rx, &sg, 1,
DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT |
DMA_CTRL_ACK);
if (ret < 0) {
dev_err(&spi->dev, "sg_split failed\n");
return 0;
}

tx = dmaengine_prep_slave_sg(mcspi_dma->dma_rx,
sg_out[0],
out_mapped_nents[0],
DMA_DEV_TO_MEM,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (tx) {
tx->callback = omap2_mcspi_rx_callback;
tx->callback_param = spi;
Expand All @@ -510,8 +531,9 @@ omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_transfer *xfer,
omap2_mcspi_set_dma_req(spi, 1, 1);

wait_for_completion(&mcspi_dma->dma_rx_completion);
dma_unmap_single(mcspi->dev, xfer->rx_dma, count,
DMA_FROM_DEVICE);

for (x = 0; x < nb_sizes; x++)
kfree(sg_out[x]);

if (mcspi->fifo_depth > 0)
return count;
Expand Down Expand Up @@ -628,8 +650,6 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)

if (tx != NULL) {
wait_for_completion(&mcspi_dma->dma_tx_completion);
dma_unmap_single(mcspi->dev, xfer->tx_dma, xfer->len,
DMA_TO_DEVICE);

if (mcspi->fifo_depth > 0) {
irqstat_reg = mcspi->base + OMAP2_MCSPI_IRQSTATUS;
Expand Down Expand Up @@ -1087,8 +1107,9 @@ static void omap2_mcspi_cleanup(struct spi_device *spi)
gpio_free(spi->cs_gpio);
}

static int omap2_mcspi_work_one(struct omap2_mcspi *mcspi,
struct spi_device *spi, struct spi_transfer *t)
static int omap2_mcspi_transfer_one(struct spi_master *master,
struct spi_device *spi,
struct spi_transfer *t)
{

/* We only enable one channel at a time -- the one whose message is
Expand All @@ -1098,15 +1119,15 @@ static int omap2_mcspi_work_one(struct omap2_mcspi *mcspi,
* chipselect with the FORCE bit ... CS != channel enable.
*/

struct spi_master *master;
struct omap2_mcspi *mcspi;
struct omap2_mcspi_dma *mcspi_dma;
struct omap2_mcspi_cs *cs;
struct omap2_mcspi_device_config *cd;
int par_override = 0;
int status = 0;
u32 chconf;

master = spi->master;
mcspi = spi_master_get_devdata(master);
mcspi_dma = mcspi->dma_channels + spi->chip_select;
cs = spi->controller_state;
cd = spi->controller_data;
Expand Down Expand Up @@ -1166,7 +1187,8 @@ static int omap2_mcspi_work_one(struct omap2_mcspi *mcspi,
unsigned count;

if ((mcspi_dma->dma_rx && mcspi_dma->dma_tx) &&
(t->len >= DMA_MIN_BYTES))
master->cur_msg_mapped &&
master->can_dma(master, spi, t))
omap2_mcspi_set_fifo(spi, t, 1);

omap2_mcspi_set_enable(spi, 1);
Expand All @@ -1177,7 +1199,8 @@ static int omap2_mcspi_work_one(struct omap2_mcspi *mcspi,
+ OMAP2_MCSPI_TX0);

if ((mcspi_dma->dma_rx && mcspi_dma->dma_tx) &&
(t->len >= DMA_MIN_BYTES))
master->cur_msg_mapped &&
master->can_dma(master, spi, t))
count = omap2_mcspi_txrx_dma(spi, t);
else
count = omap2_mcspi_txrx_pio(spi, t);
Expand Down Expand Up @@ -1246,55 +1269,11 @@ static int omap2_mcspi_prepare_message(struct spi_master *master,
return 0;
}

static int omap2_mcspi_transfer_one(struct spi_master *master,
struct spi_device *spi, struct spi_transfer *t)
static bool omap2_mcspi_can_dma(struct spi_master *master,
struct spi_device *spi,
struct spi_transfer *xfer)
{
struct omap2_mcspi *mcspi;
struct omap2_mcspi_dma *mcspi_dma;
const void *tx_buf = t->tx_buf;
void *rx_buf = t->rx_buf;
unsigned len = t->len;

mcspi = spi_master_get_devdata(master);
mcspi_dma = mcspi->dma_channels + spi->chip_select;

if ((len && !(rx_buf || tx_buf))) {
dev_dbg(mcspi->dev, "transfer: %d Hz, %d %s%s, %d bpw\n",
t->speed_hz,
len,
tx_buf ? "tx" : "",
rx_buf ? "rx" : "",
t->bits_per_word);
return -EINVAL;
}

if (len < DMA_MIN_BYTES)
goto skip_dma_map;

if (mcspi_dma->dma_tx && tx_buf != NULL) {
t->tx_dma = dma_map_single(mcspi->dev, (void *) tx_buf,
len, DMA_TO_DEVICE);
if (dma_mapping_error(mcspi->dev, t->tx_dma)) {
dev_dbg(mcspi->dev, "dma %cX %d bytes error\n",
'T', len);
return -EINVAL;
}
}
if (mcspi_dma->dma_rx && rx_buf != NULL) {
t->rx_dma = dma_map_single(mcspi->dev, rx_buf, t->len,
DMA_FROM_DEVICE);
if (dma_mapping_error(mcspi->dev, t->rx_dma)) {
dev_dbg(mcspi->dev, "dma %cX %d bytes error\n",
'R', len);
if (tx_buf != NULL)
dma_unmap_single(mcspi->dev, t->tx_dma,
len, DMA_TO_DEVICE);
return -EINVAL;
}
}

skip_dma_map:
return omap2_mcspi_work_one(mcspi, spi, t);
return (xfer->len >= DMA_MIN_BYTES);
}

static int omap2_mcspi_master_setup(struct omap2_mcspi *mcspi)
Expand Down Expand Up @@ -1374,6 +1353,7 @@ static int omap2_mcspi_probe(struct platform_device *pdev)
master->setup = omap2_mcspi_setup;
master->auto_runtime_pm = true;
master->prepare_message = omap2_mcspi_prepare_message;
master->can_dma = omap2_mcspi_can_dma;
master->transfer_one = omap2_mcspi_transfer_one;
master->set_cs = omap2_mcspi_set_cs;
master->cleanup = omap2_mcspi_cleanup;
Expand Down

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