From 052dc7c45d8f685fb3720a08331ba3e91e87937e Mon Sep 17 00:00:00 2001 From: George Shore Date: Thu, 21 Jan 2010 11:40:52 +0000 Subject: spi/dw_spi: conditional transfer mode changes 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 Signed-off-by: Grant Likely --- drivers/spi/dw_spi.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'drivers/spi') diff --git a/drivers/spi/dw_spi.c b/drivers/spi/dw_spi.c index 3853df5db05..e434320fded 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); -- cgit v1.2.3-70-g09d2