This allows the switching between transfer modes between 'transmit only', 'receive only' and 'transmit and receive' modes. Due to the design of the SPI block, changing transfer modes requires that the block be disabled; in doing so the chipselect line is inherently deasserted and (usually) the attached device discards its state. Consequentially, switching modes requires that a platform-specific chipselect function has been defined so that the chipselect is not dropped during the change.
Signed-off-by: George Shore <[email protected]> --- drivers/spi/dw_spi.c | 16 ++++++++++++++++ 1 files changed, 16 insertions(+), 0 deletions(-) diff --git a/drivers/spi/dw_spi.c b/drivers/spi/dw_spi.c index 4f91554..a1c195f 100644 --- a/drivers/spi/dw_spi.c +++ b/drivers/spi/dw_spi.c @@ -537,6 +537,22 @@ static void pump_transfers(unsigned long data) } message->state = RUNNING_STATE; + /* + * Adjust transfer mode if necessary. Requires platform dependent + * chipselect mechanism. + */ + if (dws->cs_control) { + if (dws->rx && dws->tx) + chip->tmode = 0x00; + else if (dws->rx) + chip->tmode = 0x02; + else + chip->tmode = 0x01; + + cr0 &= ~(0x3 << SPI_MODE_OFFSET); + cr0 |= (chip->tmode << SPI_TMOD_OFFSET); + } + /* Check if current transfer is a DMA transaction */ dws->dma_mapped = map_dma_buffers(dws); -- 1.6.6.264.gd0743 ------------------------------------------------------------------------------ Throughout its 18-year history, RSA Conference consistently attracts the world's best and brightest in the field, creating opportunities for Conference attendees to learn about information security's most important issues through interactions with peers, luminaries and emerging and established companies. http://p.sf.net/sfu/rsaconf-dev2dev _______________________________________________ spi-devel-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/spi-devel-general
