[RFC] [PATCH v2 3/3] spi: omap2-mcspi: Use the SPI framework to handle DMA mapping
From: Franklin S Cooper Jr
Date: Mon Jun 27 2016 - 10:54:23 EST
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@xxxxxx>
---
drivers/spi/spi-omap2-mcspi.c | 107 ++++++++++++++----------------------------
1 file changed, 34 insertions(+), 73 deletions(-)
diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index c47f958..e26dabf 100644
--- a/drivers/spi/spi-omap2-mcspi.c
+++ b/drivers/spi/spi-omap2-mcspi.c
@@ -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;
@@ -449,7 +446,8 @@ 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;
+ struct sg_table *cloned_table = NULL;
+ unsigned int count, transfer_reduction = 0;
u32 l;
int elements = 0;
int word_len, element_count;
@@ -457,7 +455,6 @@ omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_transfer *xfer,
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
@@ -465,7 +462,7 @@ omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_transfer *xfer,
* normal mode.
*/
if (mcspi->fifo_depth == 0)
- dma_count -= es;
+ transfer_reduction = es;
word_len = cs->word_len;
l = mcspi_cached_chconf0(spi);
@@ -479,7 +476,6 @@ 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);
@@ -488,13 +484,21 @@ 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;
+
+ /*
+ * Get a cloned copy of the rx sgl whose transfer count has
+ * has been reduced by transfer_reduction.
+ */
+ cloned_table = sg_table_clone(&xfer->rx_sg,
+ count - transfer_reduction, GFP_KERNEL);
- sg_init_table(&sg, 1);
- sg_dma_address(&sg) = xfer->rx_dma;
- sg_dma_len(&sg) = dma_count;
+ if (IS_ERR(cloned_table))
+ return 0;
- tx = dmaengine_prep_slave_sg(mcspi_dma->dma_rx, &sg, 1,
+ tx = dmaengine_prep_slave_sg(mcspi_dma->dma_rx,
+ cloned_table->sgl,
+ cloned_table->nents,
DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT |
DMA_CTRL_ACK);
if (tx) {
@@ -510,8 +514,8 @@ 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);
+
+ sg_free_table(cloned_table);
if (mcspi->fifo_depth > 0)
return count;
@@ -628,8 +632,6 @@ 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;
@@ -1087,7 +1089,7 @@ static void omap2_mcspi_cleanup(struct spi_device *spi)
gpio_free(spi->cs_gpio);
}
-static int omap2_mcspi_work_one(struct omap2_mcspi *mcspi,
+static int omap2_mcspi_transfer_one(struct spi_master *master,
struct spi_device *spi, struct spi_transfer *t)
{
@@ -1098,7 +1100,7 @@ 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;
@@ -1106,7 +1108,7 @@ static int omap2_mcspi_work_one(struct omap2_mcspi *mcspi,
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;
@@ -1166,7 +1168,8 @@ 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);
@@ -1177,7 +1180,8 @@ 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);
@@ -1246,55 +1250,11 @@ 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)
@@ -1374,6 +1334,7 @@ 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;
--
2.7.0