ASoC: cs35l56: Prevent bad sign extension in cs35l56_read_silicon_uid()

Cast u8 values to u32 when using them to build a 32-bit unsigned value
that is then stored in a u64. This avoids the possibility of a bad sign
extension where the u8 is implicitly extended to an int, thus changing it
from an unsigned to a signed value.

Whether this is a real problem is debatable, but it does no harm to
ensure that the u8 are cast to a suitable type for shifting.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Fixes: e1830f66f6c6 ("ASoC: cs35l56: Add helper functions for amp calibration")
Link: https://msgid.link/r/20240227100042.99-1-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/sound/soc/codecs/cs35l56-shared.c b/sound/soc/codecs/cs35l56-shared.c
index 517beaad5cd5dd26851bb6c7741f7b0247ce53fd..e15f78c2bd832fe967a957471d28050a43c4637b 100644 (file)
--- a/sound/soc/codecs/cs35l56-shared.c
+++ b/sound/soc/codecs/cs35l56-shared.c
@@ -658,9 +658,10 @@ static int cs35l56_read_silicon_uid(struct cs35l56_base *cs35l56_base, u64 *uid)
                return ret;
        }
 
-       unique_id = pte.lot[2] | (pte.lot[1] << 8) | (pte.lot[0] << 16);
+       unique_id = (u32)pte.lot[2] | ((u32)pte.lot[1] << 8) | ((u32)pte.lot[0] << 16);
        unique_id <<= 32;
-       unique_id |= pte.x | (pte.y << 8) | (pte.wafer_id << 16) | (pte.dvs << 24);
+       unique_id |= (u32)pte.x | ((u32)pte.y << 8) | ((u32)pte.wafer_id << 16) |
+                    ((u32)pte.dvs << 24);
 
        dev_dbg(cs35l56_base->dev, "UniqueID = %#llx\n", unique_id);