Commit 052dc7c4 authored Jan 21, 2010 by George Shore Committed by Grant Likely Jan 21, 2010

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 <george@georgeshore.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

parent f4aec798

drivers/spi/dw_spi.c

+16 −0

Original line number	Diff line number	Diff line
		@@ -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);