spi/dw_spi: add a FIFO depth detection
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>
diff --git a/drivers/spi/dw_spi.c b/drivers/spi/dw_spi.c
index f713af8..d948ef4 100644
--- a/drivers/spi/dw_spi.c
+++ b/drivers/spi/dw_spi.c
@@ -831,6 +831,22 @@
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)