* [RFC] [PATCH 1/3] lib/scatterlist: Add support to clone sg_table
2016-06-17 22:45 [RFC] [PATCH 0/3] scatterlist: Add support to clone sg_table Franklin S Cooper Jr
@ 2016-06-17 22:45 ` Franklin S Cooper Jr
2016-06-22 15:18 ` Mark Brown
2016-06-17 22:45 ` [RFC] [PATCH 2/3] spi: omap2-mcspi: Add comments for RX only DMA buffer workaround Franklin S Cooper Jr
2016-06-17 22:45 ` [RFC] [PATCH 3/3] spi: omap2-mcspi: Use the SPI framework to handle DMA mapping Franklin S Cooper Jr
2 siblings, 1 reply; 6+ messages in thread
From: Franklin S Cooper Jr @ 2016-06-17 22:45 UTC (permalink / raw)
To: broonie, linux-kernel, linux-spi, david.s.gordon, akpm, nsekhar,
vigneshr, peter.ujfalusi
Cc: Franklin S Cooper Jr
Occasionally there are times you need to tweak a S/G table while
maintaining the original table. This function will duplicate the passed
in S/G table along with its chained sgl and return a pointer to the cloned
copy.
The function also supports passing in a length that can be equal or less
than the original chained S/G list length. This can reduce the length of
the chained S/G list.
Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
---
include/linux/scatterlist.h | 2 +
lib/scatterlist.c | 93 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 95 insertions(+)
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index cb3c8fe..9a109da 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -247,6 +247,8 @@ struct scatterlist *sg_next(struct scatterlist *);
struct scatterlist *sg_last(struct scatterlist *s, unsigned int);
void sg_init_table(struct scatterlist *, unsigned int);
void sg_init_one(struct scatterlist *, const void *, unsigned int);
+struct sg_table *sg_table_clone(struct sg_table *orig_table, u64 len,
+ gfp_t gfp_mask);
int sg_split(struct scatterlist *in, const int in_mapped_nents,
const off_t skip, const int nb_splits,
const size_t *split_sizes,
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 004fc70..15a0142 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -180,6 +180,99 @@ static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
return kmalloc(nents * sizeof(struct scatterlist), gfp_mask);
}
+/*
+ * sg_clone - Duplicate an existing chained sgl
+ * @orig_sgl: Original sg list to be duplicated
+ * @len: Total length of sg while taking chaining into account
+ * @gfp_mask: GFP allocation mask
+ *
+ * Description:
+ * Clone a chained sgl. This cloned copy may be modified in some ways while
+ * keeping the original sgl in tact. Also allow the cloned copy to have
+ * a smaller length than the original which may reduce the sgl total
+ * sg entries.
+ *
+ * Returns:
+ * Pointer to new kmalloced sg list, ERR_PTR() on error
+ *
+ */
+static struct scatterlist *sg_clone(struct scatterlist *orig_sgl, u64 len,
+ gfp_t gfp_mask)
+{
+ unsigned int nents;
+ unsigned long page_link;
+ struct scatterlist *sgl, *head;
+
+ nents = sg_nents_for_len(orig_sgl, len);
+
+ if (nents < 0)
+ return ERR_PTR(-EINVAL);
+
+ head = sg_kmalloc(nents, gfp_mask);
+
+ if (!head)
+ return ERR_PTR(-ENOMEM);
+
+ sgl = head;
+
+ sg_init_table(sgl, nents);
+
+ for (; sgl; orig_sgl = sg_next(orig_sgl), sgl = sg_next(sgl)) {
+
+ page_link = sgl->page_link;
+
+ *sgl = *orig_sgl;
+
+ sgl->page_link = page_link;
+
+ if (sg_is_last(sgl))
+ sg_dma_len(sgl) = len;
+ else
+ len -= sg_dma_len(sgl);
+ }
+
+ return head;
+}
+
+/*
+ * sg_table_clone - Duplicate an existing sg_table including chained sgl
+ * @orig_table: Original sg_table to be duplicated
+ * @len: Total length of sg while taking chaining into account
+ * @gfp_mask: GFP allocation mask
+ *
+ * Description:
+ * Clone a sg_table along with chained sgl. This cloned copy may be
+ * modified in some ways while keeping the original table and sgl in tact.
+ * Also allow the cloned sgl copy to have a smaller length than the original
+ * which may reduce the sgl total sg entries.
+ *
+ * Returns:
+ * Pointer to new kmalloced sg_table, ERR_PTR() on error
+ *
+ */
+struct sg_table *sg_table_clone(struct sg_table *orig_table, u64 len,
+ gfp_t gfp_mask)
+{
+ struct sg_table *table;
+
+ table = kmalloc(sizeof(struct sg_table),gfp_mask);
+
+ if (!table)
+ return ERR_PTR(-ENOMEM);
+
+ table->sgl = sg_clone(orig_table->sgl,len,gfp_mask);
+
+ if (IS_ERR(table->sgl)) {
+ kfree(table);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ table->nents = table->orig_nents = sg_nents(table->sgl);
+
+ return table;
+}
+EXPORT_SYMBOL(sg_table_clone);
+
static void sg_kfree(struct scatterlist *sg, unsigned int nents)
{
if (nents == SG_MAX_SINGLE_ALLOC) {
--
1.9.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [RFC] [PATCH 3/3] spi: omap2-mcspi: Use the SPI framework to handle DMA mapping
2016-06-17 22:45 [RFC] [PATCH 0/3] scatterlist: Add support to clone sg_table Franklin S Cooper Jr
2016-06-17 22:45 ` [RFC] [PATCH 1/3] lib/scatterlist: " Franklin S Cooper Jr
2016-06-17 22:45 ` [RFC] [PATCH 2/3] spi: omap2-mcspi: Add comments for RX only DMA buffer workaround Franklin S Cooper Jr
@ 2016-06-17 22:45 ` Franklin S Cooper Jr
2 siblings, 0 replies; 6+ messages in thread
From: Franklin S Cooper Jr @ 2016-06-17 22:45 UTC (permalink / raw)
To: broonie, linux-kernel, linux-spi, david.s.gordon, akpm, nsekhar,
vigneshr, peter.ujfalusi
Cc: Franklin S Cooper Jr
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>
---
drivers/spi/spi-omap2-mcspi.c | 109 ++++++++++++++----------------------------
1 file changed, 36 insertions(+), 73 deletions(-)
diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index c47f958..84ba671 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 +484,22 @@ 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 sg_table whose transfer count
+ * 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 +515,9 @@ 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);
+
+ kfree(cloned_table->sgl);
+ kfree(cloned_table);
if (mcspi->fifo_depth > 0)
return count;
@@ -628,8 +634,6 @@ 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 +1091,7 @@ 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 +1102,7 @@ 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 +1110,7 @@ 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 +1170,8 @@ 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 +1182,8 @@ 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 +1252,11 @@ 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 +1336,7 @@ 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;
--
1.9.1
^ permalink raw reply related [flat|nested] 6+ messages in thread