spi/bitbang: add support for SPI_MASTER_NO_{TX, RX} modes
This patch adds a new flags argument to bitbang_txrx_be_cpha0 and
bitbang_txrx_be_cpha1 transfer functions. This enables support for
SPI_MASTER_NO_{TX,RX} transfer modes. The change should have no impact
on speed of the existing drivers. bitbank_txrx_* functions are usually
inlined into the drivers. When the argument is equal to constant zero,
the optimizer would be able to eliminate the dead code (flags checks)
easily. Tested on ARM and GCC 4.4.x and in all cases the checks were
eliminated in the inlined function.
Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/drivers/spi/spi_bitbang_txrx.h b/drivers/spi/spi_bitbang_txrx.h
index fc033bb..c16bf85 100644
--- a/drivers/spi/spi_bitbang_txrx.h
+++ b/drivers/spi/spi_bitbang_txrx.h
@@ -44,7 +44,7 @@
static inline u32
bitbang_txrx_be_cpha0(struct spi_device *spi,
- unsigned nsecs, unsigned cpol,
+ unsigned nsecs, unsigned cpol, unsigned flags,
u32 word, u8 bits)
{
/* if (cpol == 0) this is SPI_MODE_0; else this is SPI_MODE_2 */
@@ -53,7 +53,8 @@
for (word <<= (32 - bits); likely(bits); bits--) {
/* setup MSB (to slave) on trailing edge */
- setmosi(spi, word & (1 << 31));
+ if ((flags & SPI_MASTER_NO_TX) == 0)
+ setmosi(spi, word & (1 << 31));
spidelay(nsecs); /* T(setup) */
setsck(spi, !cpol);
@@ -61,7 +62,8 @@
/* sample MSB (from slave) on leading edge */
word <<= 1;
- word |= getmiso(spi);
+ if ((flags & SPI_MASTER_NO_RX) == 0)
+ word |= getmiso(spi);
setsck(spi, cpol);
}
return word;
@@ -69,7 +71,7 @@
static inline u32
bitbang_txrx_be_cpha1(struct spi_device *spi,
- unsigned nsecs, unsigned cpol,
+ unsigned nsecs, unsigned cpol, unsigned flags,
u32 word, u8 bits)
{
/* if (cpol == 0) this is SPI_MODE_1; else this is SPI_MODE_3 */
@@ -79,7 +81,8 @@
/* setup MSB (to slave) on leading edge */
setsck(spi, !cpol);
- setmosi(spi, word & (1 << 31));
+ if ((flags & SPI_MASTER_NO_TX) == 0)
+ setmosi(spi, word & (1 << 31));
spidelay(nsecs); /* T(setup) */
setsck(spi, cpol);
@@ -87,7 +90,8 @@
/* sample MSB (from slave) on trailing edge */
word <<= 1;
- word |= getmiso(spi);
+ if ((flags & SPI_MASTER_NO_RX) == 0)
+ word |= getmiso(spi);
}
return word;
}