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Message-ID: <1461577442-8853-3-git-send-email-vigneshr@ti.com>
Date: Mon, 25 Apr 2016 15:14:01 +0530
From: Vignesh R <vigneshr@...com>
To: Mark Brown <broonie@...nel.org>
CC: <linux-spi@...r.kernel.org>, <linux-omap@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, Vignesh R <vigneshr@...com>
Subject: [PATCH v2 2/3] 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@...com>
---
v2: use cur_msg_mapped flag to indicate success/failure of spi_map_buf()
drivers/spi/spi.c | 14 ++++++++++++++
include/linux/spi/spi.h | 4 ++++
2 files changed, 18 insertions(+)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 82126bbe69cf..f98c19addc07 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2725,6 +2725,7 @@ 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 ||
@@ -2750,9 +2751,22 @@ 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 */
--
2.8.1
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