diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/spi/atmel_spi.c | 57 |
1 files changed, 45 insertions, 12 deletions
diff --git a/drivers/spi/atmel_spi.c b/drivers/spi/atmel_spi.c index 7524a84bdd5..01ad6320d96 100644 --- a/drivers/spi/atmel_spi.c +++ b/drivers/spi/atmel_spi.c @@ -184,18 +184,39 @@ static void atmel_spi_next_message(struct spi_master *master) atmel_spi_next_xfer(master, msg); } -static void +/* + * For DMA, tx_buf/tx_dma have the same relationship as rx_buf/rx_dma: + * - The buffer is either valid for CPU access, else NULL + * - If the buffer is valid, so is its DMA addresss + * + * This driver manages the dma addresss unless message->is_dma_mapped. + */ +static int atmel_spi_dma_map_xfer(struct atmel_spi *as, struct spi_transfer *xfer) { + struct device *dev = &as->pdev->dev; + xfer->tx_dma = xfer->rx_dma = INVALID_DMA_ADDRESS; - if (xfer->tx_buf) - xfer->tx_dma = dma_map_single(&as->pdev->dev, + if (xfer->tx_buf) { + xfer->tx_dma = dma_map_single(dev, (void *) xfer->tx_buf, xfer->len, DMA_TO_DEVICE); - if (xfer->rx_buf) - xfer->rx_dma = dma_map_single(&as->pdev->dev, + if (dma_mapping_error(xfer->tx_dma)) + return -ENOMEM; + } + if (xfer->rx_buf) { + xfer->rx_dma = dma_map_single(dev, xfer->rx_buf, xfer->len, DMA_FROM_DEVICE); + if (dma_mapping_error(xfer->tx_dma)) { + if (xfer->tx_buf) + dma_unmap_single(dev, + xfer->tx_dma, xfer->len, + DMA_TO_DEVICE); + return -ENOMEM; + } + } + return 0; } static void atmel_spi_dma_unmap_xfer(struct spi_master *master, @@ -398,8 +419,9 @@ static int atmel_spi_setup(struct spi_device *spi) scbr = ((bus_hz + spi->max_speed_hz - 1) / spi->max_speed_hz); if (scbr >= (1 << SPI_SCBR_SIZE)) { - dev_dbg(&spi->dev, "setup: %d Hz too slow, scbr %u\n", - spi->max_speed_hz, scbr); + dev_dbg(&spi->dev, + "setup: %d Hz too slow, scbr %u; min %ld Hz\n", + spi->max_speed_hz, scbr, bus_hz/255); return -EINVAL; } } else @@ -465,12 +487,19 @@ static int atmel_spi_transfer(struct spi_device *spi, struct spi_message *msg) dev_dbg(&spi->dev, "no protocol options yet\n"); return -ENOPROTOOPT; } - } - /* scrub dcache "early" */ - if (!msg->is_dma_mapped) { - list_for_each_entry(xfer, &msg->transfers, transfer_list) - atmel_spi_dma_map_xfer(as, xfer); + /* + * DMA map early, for performance (empties dcache ASAP) and + * better fault reporting. This is a DMA-only driver. + * + * NOTE that if dma_unmap_single() ever starts to do work on + * platforms supported by this driver, we would need to clean + * up mappings for previously-mapped transfers. + */ + if (!msg->is_dma_mapped) { + if (atmel_spi_dma_map_xfer(as, xfer) < 0) + return -ENOMEM; + } } list_for_each_entry(xfer, &msg->transfers, transfer_list) { @@ -537,6 +566,10 @@ static int __init atmel_spi_probe(struct platform_device *pdev) as = spi_master_get_devdata(master); + /* + * Scratch buffer is used for throwaway rx and tx data. + * It's coherent to minimize dcache pollution. + */ as->buffer = dma_alloc_coherent(&pdev->dev, BUFFER_SIZE, &as->buffer_dma, GFP_KERNEL); if (!as->buffer) |