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authorMichael Williamson <michael.williamson@criticallink.com>2011-03-14 11:49:02 -0400
committerGrant Likely <grant.likely@secretlab.ca>2011-03-14 13:17:04 -0600
commitb1178b21c6b9721a07fbd50762067a7c0ffa5a50 (patch)
tree048252f10af96adfc09c562214b51b0f4b4e0cae /drivers/spi
parentd09519e41a67eab22cc4566670431f9252b6786a (diff)
downloadop-kernel-dev-b1178b21c6b9721a07fbd50762067a7c0ffa5a50.zip
op-kernel-dev-b1178b21c6b9721a07fbd50762067a7c0ffa5a50.tar.gz
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: Michael Williamson <michael.williamson@criticallink.com> Tested-by: Stefano Babic <sbabic@denx.de> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Diffstat (limited to 'drivers/spi')
-rw-r--r--drivers/spi/davinci_spi.c33
1 files changed, 25 insertions, 8 deletions
diff --git a/drivers/spi/davinci_spi.c b/drivers/spi/davinci_spi.c
index 68ed377..e90c2d6 100644
--- a/drivers/spi/davinci_spi.c
+++ b/drivers/spi/davinci_spi.c
@@ -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)
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