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 <[email protected]> --- drivers/spi/spi.c | 15 +++++++++++++++ include/linux/spi/spi.h | 2 ++ 2 files changed, 17 insertions(+) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index de2f2f90d799..2fb97f5b79ab 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -2722,6 +2722,7 @@ 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 || @@ -2747,8 +2748,22 @@ 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 != 0) + goto err; + } ret = master->spi_flash_read(spi, msg); + if (master->dma_rx) + spi_unmap_buf(master, rx_dev, &msg->rx_sg, + DMA_FROM_DEVICE); + +err: 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..5b9c745eda92 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -1141,6 +1141,7 @@ 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 */ struct spi_flash_read_message { void *buf; @@ -1153,6 +1154,7 @@ struct spi_flash_read_message { u8 opcode_nbits; u8 addr_nbits; u8 data_nbits; + struct sg_table rx_sg; }; /* SPI core interface for flash read support */ -- 2.8.0
