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authorVignesh R <vigneshr@ti.com>2016-06-08 12:18:31 +0530
committerRich Felker <dalias@libc.org>2016-08-10 14:55:18 +0000
commitb6b30c341b38dfd8a4d4894039b816ee7c3889e3 (patch)
treee582fae145fff0dab8c194d4f68a77e3f13b3847
parentabbcda12c70557a74f19987105d044fc2a676feb (diff)
downloadlinux-sh-b6b30c341b38dfd8a4d4894039b816ee7c3889e3.tar.gz
spi: Add DMA support for spi_flash_read()
Few SPI devices provide accelerated read interfaces to read from SPI-NOR flash devices. These hardwares also support DMA to transfer data from flash to memory either via mem-to-mem DMA or dedicated slave DMA channels. Hence, add support for DMA in order to improve throughput and reduce CPU load. Use spi_map_buf() to get sg table for the buffer and pass it to SPI driver. Signed-off-by: Vignesh R <vigneshr@ti.com> Signed-off-by: Mark Brown <broonie@kernel.org>
-rw-r--r--drivers/spi/spi.c28
-rw-r--r--include/linux/spi/spi.h4
2 files changed, 32 insertions, 0 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 0239b45eed92..ae22e3327110 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -847,6 +847,20 @@ static int __spi_unmap_msg(struct spi_master *master, struct spi_message *msg)
return 0;
}
#else /* !CONFIG_HAS_DMA */
+static inline int spi_map_buf(struct spi_master *master,
+ struct device *dev, struct sg_table *sgt,
+ void *buf, size_t len,
+ enum dma_data_direction dir)
+{
+ return -EINVAL;
+}
+
+static inline void spi_unmap_buf(struct spi_master *master,
+ struct device *dev, struct sg_table *sgt,
+ enum dma_data_direction dir)
+{
+}
+
static inline int __spi_map_msg(struct spi_master *master,
struct spi_message *msg)
{
@@ -2722,6 +2736,7 @@ int spi_flash_read(struct spi_device *spi,
{
struct spi_master *master = spi->master;
+ struct device *rx_dev = NULL;
int ret;
if ((msg->opcode_nbits == SPI_NBITS_DUAL ||
@@ -2747,9 +2762,22 @@ int spi_flash_read(struct spi_device *spi,
return ret;
}
}
+
mutex_lock(&master->bus_lock_mutex);
+ if (master->dma_rx) {
+ rx_dev = master->dma_rx->device->dev;
+ ret = spi_map_buf(master, rx_dev, &msg->rx_sg,
+ msg->buf, msg->len,
+ DMA_FROM_DEVICE);
+ if (!ret)
+ msg->cur_msg_mapped = true;
+ }
ret = master->spi_flash_read(spi, msg);
+ if (msg->cur_msg_mapped)
+ spi_unmap_buf(master, rx_dev, &msg->rx_sg,
+ DMA_FROM_DEVICE);
mutex_unlock(&master->bus_lock_mutex);
+
if (master->auto_runtime_pm)
pm_runtime_put(master->dev.parent);
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 857a9a1d82b5..b51ea761b5c8 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -1141,6 +1141,8 @@ static inline ssize_t spi_w8r16be(struct spi_device *spi, u8 cmd)
* @opcode_nbits: number of lines to send opcode
* @addr_nbits: number of lines to send address
* @data_nbits: number of lines for data
+ * @rx_sg: Scatterlist for receive data read from flash
+ * @cur_msg_mapped: message has been mapped for DMA
*/
struct spi_flash_read_message {
void *buf;
@@ -1153,6 +1155,8 @@ struct spi_flash_read_message {
u8 opcode_nbits;
u8 addr_nbits;
u8 data_nbits;
+ struct sg_table rx_sg;
+ bool cur_msg_mapped;
};
/* SPI core interface for flash read support */