[U-Boot] [PATCH v2] spi: soft_spi: Support NULL din/dout buffers
Andrew Ruder
andrew.ruder at elecsyscorp.com
Thu Apr 24 20:39:32 CEST 2014
This mirrors the conventions used in other SPI drivers (kirkwood,
davinci, atmel, et al) where the din/dout buffer can be NULL when the
received/transmitted data isn't important. This reduces the need for
allocating additional buffers when write-only/read-only functionality is
needed.
In the din == NULL case, the received data is simply not stored. In the
dout == NULL case, zeroes are transmitted.
Signed-off-by: Andrew Ruder <andrew.ruder at elecsyscorp.com>
Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj at jcrosoft.com>
Cc: Jagan Teki <jagannadh.teki at gmail.com>
---
Cleaned up errors/warnings from checkpatch.pl. I'm surprised they were flagged
by the script since the actual ERRORs were all on lines I didn't change but were
only included in the context.
scripts/checkpatch.pl 0001-spi-soft_spi-Support-NULL-din-dout-buffers.patch
total: 0 errors, 0 warnings, 0 checks, 31 lines checked
drivers/spi/soft_spi.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/drivers/spi/soft_spi.c b/drivers/spi/soft_spi.c
index 5d22351..c969be3 100644
--- a/drivers/spi/soft_spi.c
+++ b/drivers/spi/soft_spi.c
@@ -136,10 +136,14 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
/*
* Check if it is time to work on a new byte.
*/
- if((j % 8) == 0) {
- tmpdout = *txd++;
+ if ((j % 8) == 0) {
+ if (txd)
+ tmpdout = *txd++;
+ else
+ tmpdout = 0;
if(j != 0) {
- *rxd++ = tmpdin;
+ if (rxd)
+ *rxd++ = tmpdin;
}
tmpdin = 0;
}
@@ -164,9 +168,11 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
* bits over to left-justify them. Then store the last byte
* read in.
*/
- if((bitlen % 8) != 0)
- tmpdin <<= 8 - (bitlen % 8);
- *rxd++ = tmpdin;
+ if (rxd) {
+ if ((bitlen % 8) != 0)
+ tmpdin <<= 8 - (bitlen % 8);
+ *rxd++ = tmpdin;
+ }
if (flags & SPI_XFER_END)
spi_cs_deactivate(slave);
--
1.9.0.rc3.12.gbc97e2d
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