From: Martin Sperl <[email protected]> This does not require SPI_MASTER_MUST_RX/TX to be set any longer in a spi_master and by this avoids unnecessary memory allocations.
This impacts all spi_master with can_dma support when tx/rx_buf == NULL. Signed-off-by: Martin Sperl <[email protected]> --- drivers/spi/spi.c | 70 ++++++++++++++++++++++++++++++++--------------- include/linux/spi/spi.h | 4 +++ 2 files changed, 52 insertions(+), 22 deletions(-) Applies against for-next, but note that there will be a conflict if the patch "spi: add missing cleanup in spi_map_msg on error" is applied already. diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index d35c1a1..7e1a12c 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -471,12 +471,28 @@ static void spi_set_cs(struct spi_device *spi, bool enable) } #ifdef CONFIG_HAS_DMA +static void *__spi_map_alloc_page(struct spi_master *master, + enum dma_data_direction dir) +{ + void **buf = (dir == DMA_TO_DEVICE) ? + &master->dummy_page_tx : &master->dummy_page_rx; + + if (!*buf) { + *buf = devm_kzalloc(&master->dev, + PAGE_SIZE, + GFP_ATOMIC); + } + + return *buf; +} + static 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) { const bool vmalloced_buf = is_vmalloc_addr(buf); - const int desc_len = vmalloced_buf ? PAGE_SIZE : master->max_dma_len; + const int desc_len = (vmalloced_buf || (!buf)) ? + PAGE_SIZE : master->max_dma_len; const int sgs = DIV_ROUND_UP(len, desc_len); struct page *vm_page; void *sg_buf; @@ -490,7 +506,7 @@ static int spi_map_buf(struct spi_master *master, struct device *dev, for (i = 0; i < sgs; i++) { min = min_t(size_t, len, desc_len); - if (vmalloced_buf) { + if (buf && vmalloced_buf) { vm_page = vmalloc_to_page(buf); if (!vm_page) { sg_free_table(sgt); @@ -499,12 +515,20 @@ static int spi_map_buf(struct spi_master *master, struct device *dev, sg_set_page(&sgt->sgl[i], vm_page, min, offset_in_page(buf)); } else { - sg_buf = buf; + if (!buf) { + sg_buf = __spi_map_alloc_page(master, dir); + if (!sg_buf) { + sg_free_table(sgt); + return -ENOMEM; + } + } else { + sg_buf = buf; + } sg_set_buf(&sgt->sgl[i], sg_buf, min); } - - buf += min; + if (buf) + buf += min; len -= min; } @@ -546,23 +570,25 @@ static int __spi_map_msg(struct spi_master *master, struct spi_message *msg) if (!master->can_dma(master, msg->spi, xfer)) continue; - if (xfer->tx_buf != NULL) { - ret = spi_map_buf(master, tx_dev, &xfer->tx_sg, - (void *)xfer->tx_buf, xfer->len, - DMA_TO_DEVICE); - if (ret != 0) - return ret; - } - - if (xfer->rx_buf != NULL) { - ret = spi_map_buf(master, rx_dev, &xfer->rx_sg, - xfer->rx_buf, xfer->len, - DMA_FROM_DEVICE); - if (ret != 0) { - spi_unmap_buf(master, tx_dev, &xfer->tx_sg, - DMA_TO_DEVICE); - return ret; - } + /* potentially add a flag to spi_master + * (SPI_MASTER_MUST_TX_SG) to avoid unnecessary mapping + */ + ret = spi_map_buf(master, tx_dev, &xfer->tx_sg, + (void *)xfer->tx_buf, xfer->len, + DMA_TO_DEVICE); + if (ret != 0) + return ret; + + /* potentially add a flag to spi_master + * (SPI_MASTER_MUST_RX_SG) to avoid unnecessary mapping + */ + ret = spi_map_buf(master, rx_dev, &xfer->rx_sg, + xfer->rx_buf, xfer->len, + DMA_FROM_DEVICE); + if (ret != 0) { + spi_unmap_buf(master, tx_dev, &xfer->tx_sg, + DMA_TO_DEVICE); + return ret; } } diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index d673072..9ffa506 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -300,6 +300,8 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv) * @dma_rx: DMA receive channel * @dummy_rx: dummy receive buffer for full-duplex devices * @dummy_tx: dummy transmit buffer for full-duplex devices + * @dummy_page_rx: dummy page for full-duplex devices + * @dummy_page_tx: dummy page for full-duplex devices * * Each SPI master controller can communicate with one or more @spi_device * children. These make a small bus, sharing MOSI, MISO and SCK signals @@ -459,6 +461,8 @@ struct spi_master { /* dummy data for full duplex devices */ void *dummy_rx; void *dummy_tx; + void *dummy_page_tx; + void *dummy_page_rx; }; static inline void *spi_master_get_devdata(struct spi_master *master) -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
