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Commit b1178b21 authored by Michael Williamson's avatar Michael Williamson Committed by Grant Likely
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spi/davinci: Support DMA transfers larger than 65535 words 



The current davinci SPI driver, in DMA mode, is limited to 65535
words for a single transfer.  Modify the driver by configuring a
3 dimensional EDMA transfer to support up to 65535x65535
words.

Signed-off-by: default avatarMichael Williamson <michael.williamson@criticallink.com>
Tested-by: default avatarStefano Babic <sbabic@denx.de>
Signed-off-by: default avatarGrant Likely <grant.likely@secretlab.ca>
parent d09519e4

drivers/spi/davinci_spi.c

+25 −8
Original line number Diff line number Diff line
@@ -571,6 +571,7 @@ static int davinci_spi_bufs(struct spi_device *spi, struct spi_transfer *t) 
		unsigned long tx_reg, rx_reg;

		struct edmacc_param param;

		void *rx_buf;

		int b, c;



		dma = &dspi->dma;
@@ -599,14 +600,30 @@ static int davinci_spi_bufs(struct spi_device *spi, struct spi_transfer *t) 
			}

		}



		/*

		 * If number of words is greater than 65535, then we need

		 * to configure a 3 dimension transfer.  Use the BCNTRLD

		 * feature to allow for transfers that aren't even multiples

		 * of 65535 (or any other possible b size) by first transferring

		 * the remainder amount then grabbing the next N blocks of

		 * 65535 words.

		 */



		c = dspi->wcount / (SZ_64K - 1);	/* N 65535 Blocks */

		b = dspi->wcount - c * (SZ_64K - 1);	/* Remainder */

		if (b)

			c++;

		else

			b = SZ_64K - 1;



		param.opt = TCINTEN | EDMA_TCC(dma->tx_channel);

		param.src = t->tx_buf ? t->tx_dma : tx_reg;

		param.a_b_cnt = dspi->wcount << 16 | data_type;

		param.a_b_cnt = b << 16 | data_type;

		param.dst = tx_reg;

		param.src_dst_bidx = t->tx_buf ? data_type : 0;

		param.link_bcntrld = 0xffff;

		param.src_dst_cidx = 0;

		param.ccnt = 1;

		param.link_bcntrld = 0xffffffff;

		param.src_dst_cidx = t->tx_buf ? data_type : 0;

		param.ccnt = c;

		edma_write_slot(dma->tx_channel, &param);

		edma_link(dma->tx_channel, dma->dummy_param_slot);
@@ -643,12 +660,12 @@ static int davinci_spi_bufs(struct spi_device *spi, struct spi_transfer *t) 


		param.opt = TCINTEN | EDMA_TCC(dma->rx_channel);

		param.src = rx_reg;

		param.a_b_cnt = dspi->rcount << 16 | data_type;

		param.a_b_cnt = b << 16 | data_type;

		param.dst = t->rx_dma;

		param.src_dst_bidx = (t->rx_buf ? data_type : 0) << 16;

		param.link_bcntrld = 0xffff;

		param.src_dst_cidx = 0;

		param.ccnt = 1;

		param.link_bcntrld = 0xffffffff;

		param.src_dst_cidx = (t->rx_buf ? data_type : 0) << 16;

		param.ccnt = c;

		edma_write_slot(dma->rx_channel, &param);



		if (pdata->cshold_bug)