[PATCH v2] spi: atmel: Implements transfers with bounce buffer
Nicolas Ferre
nicolas.ferre at microchip.com
Tue Dec 19 02:25:48 PST 2017
On 12/12/2017 at 16:37, Radu Pirea wrote:
> This patch enables DMA transfers for Atmel SAM9 SoCs and implements a bounce
> buffer for transfers which have vmalloc allocated buffers. Those buffers are
> not cache coherent even if they have been transformed into sg lists. UBIFS
> is affected by this cache coherency issue.
>
> In this patch I also reverted "spi: atmel: fix corrupted data issue on SAM9
> family SoCs"(7094576ccdc3acfe1e06a1e2ab547add375baf7f).
>
>
> Signed-off-by: Radu Pirea <radu.pirea at microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre at microchip.com>
Best regards,
Nicolas
> ---
> Please ignore the previous version. I messed up with file names.
> drivers/spi/spi-atmel.c | 113 +++++++++++++++++++++++++++++++++++-------------
> 1 file changed, 84 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
> index f95da36..198b4cd 100644
> --- a/drivers/spi/spi-atmel.c
> +++ b/drivers/spi/spi-atmel.c
> @@ -291,6 +291,10 @@ struct atmel_spi {
> struct spi_transfer *current_transfer;
> int current_remaining_bytes;
> int done_status;
> + dma_addr_t dma_addr_rx_bbuf;
> + dma_addr_t dma_addr_tx_bbuf;
> + void *addr_rx_bbuf;
> + void *addr_tx_bbuf;
>
> struct completion xfer_completion;
>
> @@ -436,6 +440,11 @@ static void atmel_spi_unlock(struct atmel_spi *as) __releases(&as->lock)
> spin_unlock_irqrestore(&as->lock, as->flags);
> }
>
> +static inline bool atmel_spi_is_vmalloc_xfer(struct spi_transfer *xfer)
> +{
> + return is_vmalloc_addr(xfer->tx_buf) || is_vmalloc_addr(xfer->rx_buf);
> +}
> +
> static inline bool atmel_spi_use_dma(struct atmel_spi *as,
> struct spi_transfer *xfer)
> {
> @@ -448,7 +457,12 @@ static bool atmel_spi_can_dma(struct spi_master *master,
> {
> struct atmel_spi *as = spi_master_get_devdata(master);
>
> - return atmel_spi_use_dma(as, xfer);
> + if (IS_ENABLED(CONFIG_SOC_SAM_V4_V5))
> + return atmel_spi_use_dma(as, xfer) &&
> + !atmel_spi_is_vmalloc_xfer(xfer);
> + else
> + return atmel_spi_use_dma(as, xfer);
> +
> }
>
> static int atmel_spi_dma_slave_config(struct atmel_spi *as,
> @@ -594,6 +608,11 @@ static void dma_callback(void *data)
> struct spi_master *master = data;
> struct atmel_spi *as = spi_master_get_devdata(master);
>
> + if (is_vmalloc_addr(as->current_transfer->rx_buf) &&
> + IS_ENABLED(CONFIG_SOC_SAM_V4_V5)) {
> + memcpy(as->current_transfer->rx_buf, as->addr_rx_bbuf,
> + as->current_transfer->len);
> + }
> complete(&as->xfer_completion);
> }
>
> @@ -744,17 +763,41 @@ static int atmel_spi_next_xfer_dma_submit(struct spi_master *master,
> goto err_exit;
>
> /* Send both scatterlists */
> - rxdesc = dmaengine_prep_slave_sg(rxchan,
> - xfer->rx_sg.sgl, xfer->rx_sg.nents,
> - DMA_FROM_DEVICE,
> - DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> + if (atmel_spi_is_vmalloc_xfer(xfer) &&
> + IS_ENABLED(CONFIG_SOC_SAM_V4_V5)) {
> + rxdesc = dmaengine_prep_slave_single(rxchan,
> + as->dma_addr_rx_bbuf,
> + xfer->len,
> + DMA_FROM_DEVICE,
> + DMA_PREP_INTERRUPT |
> + DMA_CTRL_ACK);
> + } else {
> + rxdesc = dmaengine_prep_slave_sg(rxchan,
> + xfer->rx_sg.sgl,
> + xfer->rx_sg.nents,
> + DMA_FROM_DEVICE,
> + DMA_PREP_INTERRUPT |
> + DMA_CTRL_ACK);
> + }
> if (!rxdesc)
> goto err_dma;
>
> - txdesc = dmaengine_prep_slave_sg(txchan,
> - xfer->tx_sg.sgl, xfer->tx_sg.nents,
> - DMA_TO_DEVICE,
> - DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> + if (atmel_spi_is_vmalloc_xfer(xfer) &&
> + IS_ENABLED(CONFIG_SOC_SAM_V4_V5)) {
> + memcpy(as->addr_tx_bbuf, xfer->tx_buf, xfer->len);
> + txdesc = dmaengine_prep_slave_single(txchan,
> + as->dma_addr_tx_bbuf,
> + xfer->len, DMA_TO_DEVICE,
> + DMA_PREP_INTERRUPT |
> + DMA_CTRL_ACK);
> + } else {
> + txdesc = dmaengine_prep_slave_sg(txchan,
> + xfer->tx_sg.sgl,
> + xfer->tx_sg.nents,
> + DMA_TO_DEVICE,
> + DMA_PREP_INTERRUPT |
> + DMA_CTRL_ACK);
> + }
> if (!txdesc)
> goto err_dma;
>
> @@ -1426,27 +1469,7 @@ static void atmel_get_caps(struct atmel_spi *as)
>
> as->caps.is_spi2 = version > 0x121;
> as->caps.has_wdrbt = version >= 0x210;
> -#ifdef CONFIG_SOC_SAM_V4_V5
> - /*
> - * Atmel SoCs based on ARM9 (SAM9x) cores should not use spi_map_buf()
> - * since this later function tries to map buffers with dma_map_sg()
> - * even if they have not been allocated inside DMA-safe areas.
> - * On SoCs based on Cortex A5 (SAMA5Dx), it works anyway because for
> - * those ARM cores, the data cache follows the PIPT model.
> - * Also the L2 cache controller of SAMA5D2 uses the PIPT model too.
> - * In case of PIPT caches, there cannot be cache aliases.
> - * However on ARM9 cores, the data cache follows the VIVT model, hence
> - * the cache aliases issue can occur when buffers are allocated from
> - * DMA-unsafe areas, by vmalloc() for instance, where cache coherency is
> - * not taken into account or at least not handled completely (cache
> - * lines of aliases are not invalidated).
> - * This is not a theorical issue: it was reproduced when trying to mount
> - * a UBI file-system on a at91sam9g35ek board.
> - */
> - as->caps.has_dma_support = false;
> -#else
> as->caps.has_dma_support = version >= 0x212;
> -#endif
> as->caps.has_pdc_support = version < 0x212;
> }
>
> @@ -1592,6 +1615,30 @@ static int atmel_spi_probe(struct platform_device *pdev)
> as->use_pdc = true;
> }
>
> + if (IS_ENABLED(CONFIG_SOC_SAM_V4_V5)) {
> + as->addr_rx_bbuf = dma_alloc_coherent(&pdev->dev,
> + SPI_MAX_DMA_XFER,
> + &as->dma_addr_rx_bbuf,
> + GFP_KERNEL | GFP_DMA);
> + if (!as->addr_rx_bbuf) {
> + as->use_dma = false;
> + } else {
> + as->addr_tx_bbuf = dma_alloc_coherent(&pdev->dev,
> + SPI_MAX_DMA_XFER,
> + &as->dma_addr_tx_bbuf,
> + GFP_KERNEL | GFP_DMA);
> + if (!as->addr_tx_bbuf) {
> + as->use_dma = false;
> + dma_free_coherent(&pdev->dev, SPI_MAX_DMA_XFER,
> + as->addr_rx_bbuf,
> + as->dma_addr_rx_bbuf);
> + }
> + }
> + if(!as->use_dma)
> + dev_info(master->dev.parent,
> + " can not allocate dma coherent memory\n");
> + }
> +
> if (as->caps.has_dma_support && !as->use_dma)
> dev_info(&pdev->dev, "Atmel SPI Controller using PIO only\n");
>
> @@ -1665,6 +1712,14 @@ static int atmel_spi_remove(struct platform_device *pdev)
> if (as->use_dma) {
> atmel_spi_stop_dma(master);
> atmel_spi_release_dma(master);
> + if (IS_ENABLED(CONFIG_SOC_SAM_V4_V5)) {
> + dma_free_coherent(&pdev->dev, SPI_MAX_DMA_XFER,
> + as->addr_tx_bbuf,
> + as->dma_addr_tx_bbuf);
> + dma_free_coherent(&pdev->dev, SPI_MAX_DMA_XFER,
> + as->addr_rx_bbuf,
> + as->dma_addr_rx_bbuf);
> + }
> }
>
> spi_writel(as, CR, SPI_BIT(SWRST));
>
--
Nicolas Ferre
More information about the linux-arm-kernel
mailing list