spi: Introduce and use spi_bpw_to_bytes()

Merge series from Andy Shevchenko <andriy.shevchenko@linux.intel.com>:

Recently in the discussion with David the idea of having
a common helper popped up. The helper converts the given
bits per word to bytes. The result will always be power-of-two
(e.g. for 37 bits it returns 8 bytes) or 0 for 0 input.
More details are in the respective code comment.

This mini-series introduces it and replaces current users
under drivers/spi and we expect more (and possibly some
lurking in other subsystems).

1 files changed, 26 insertions, 0 deletions

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 834a09bd8ccc..c921ff902f0c 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -1341,6 +1341,32 @@ static inline bool spi_is_bpw_supported(struct spi_device *spi, u32 bpw)
 }
 
 /**
+ * spi_bpw_to_bytes - Covert bits per word to bytes
+ * @bpw: Bits per word
+ *
+ * This function converts the given @bpw to bytes. The result is always
+ * power-of-two, e.g.,
+ *
+ *  ===============    =================
+ *  Input (in bits)    Output (in bytes)
+ *  ===============    =================
+ *          5                   1
+ *          9                   2
+ *          21                  4
+ *          37                  8
+ *  ===============    =================
+ *
+ * It will return 0 for the 0 input.
+ *
+ * Returns:
+ * Bytes for the given @bpw.
+ */
+static inline u32 spi_bpw_to_bytes(u32 bpw)
+{
+	return roundup_pow_of_two(BITS_TO_BYTES(bpw));
+}
+
+/**
  * spi_controller_xfer_timeout - Compute a suitable timeout value
  * @ctlr: SPI device
  * @xfer: Transfer descriptor