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-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 bf8de281b4ed..eed4254bd503 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).