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spi/dw_spi: add a FIFO depth detection

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FIFO depth is configurable for each implementation of DW core,
so add a depth detection for those interface drivers who don't set
the fifo_len explicitly

Signed-off-by: Feng Tang <feng.tang@intel.com>
Acked-by: Jean-Hugues Deschenes <jean-hugues.deschenes@octasic.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This commit is contained in:
Feng Tang 2010-01-21 10:41:10 +08:00 committed by Grant Likely
parent 99147b5c41
commit c587b6fa05
1 changed files with 16 additions and 0 deletions
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16
drivers/spi/dw_spi.c
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@ -831,6 +831,22 @@ static void spi_hw_init(struct dw_spi *dws)
spi_mask_intr(dws, 0xff);
spi_enable_chip(dws, 1);
flush(dws);
/*
* Try to detect the FIFO depth if not set by interface driver,
* the depth could be from 2 to 256 from HW spec
*/
if (!dws->fifo_len) {
u32 fifo;
for (fifo = 2; fifo <= 257; fifo++) {
dw_writew(dws, txfltr, fifo);
if (fifo != dw_readw(dws, txfltr))
break;
}
dws->fifo_len = (fifo == 257) ? 0 : fifo;
dw_writew(dws, txfltr, 0);
}
}
int __devinit dw_spi_add_host(struct dw_spi *dws)