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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
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+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)