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authorMichael Buesch <mb@bu3sch.de>2009-02-20 15:38:49 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-02-20 17:57:49 -0800
commit01b24fee285b098c74318a8be801ef3711ec18d7 (patch)
tree60403f86f2198f4c5f81a1447e4bf3f107ede7d3
parentf6fcba7014f9cc535fa75ef98c008b24e49e2212 (diff)
downloadlinux-2.6.38-lt-ux500-01b24fee285b098c74318a8be801ef3711ec18d7.tar.gz
spi_bitbang: add more lowlevel function documentation
This adds more documentation of the lowlevel API to avoid future bugs. Signed-off-by: Michael Buesch <mb@bu3sch.de> Acked-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/spi/spi_bitbang.h7
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/spi/spi_bitbang.h b/include/linux/spi/spi_bitbang.h
index bf8de281b4e..eed4254bd50 100644
--- a/include/linux/spi/spi_bitbang.h
+++ b/include/linux/spi/spi_bitbang.h
@@ -83,6 +83,13 @@ extern int spi_bitbang_stop(struct spi_bitbang *spi);
* int getmiso(struct spi_device *);
* void spidelay(unsigned);
*
+ * setsck()'s is_on parameter is a zero/nonzero boolean.
+ *
+ * setmosi()'s is_on parameter is a zero/nonzero boolean.
+ *
+ * getmiso() is required to return 0 or 1 only. Any other value is invalid
+ * and will result in improper operation.
+ *
* A non-inlined routine would call bitbang_txrx_*() routines. The
* main loop could easily compile down to a handful of instructions,
* especially if the delay is a NOP (to run at peak speed).