[PATCH 09/10] fpga-manager: altera-ps-spi: use bitrev8x4

[Alan Tull]

From: Joshua Clayton <stillcompil...@gmail.com>

Speed up bit reversal by using hardware bit reversal
Add extra code to handle less than 4byte remnants, if any

Signed-off-by: Joshua Clayton <stillcompil...@gmail.com>
Signed-off-by: Alan Tull <at...@kernel.org>
---
 drivers/fpga/altera-ps-spi.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/fpga/altera-ps-spi.c b/drivers/fpga/altera-ps-spi.c
index 0db8def668ed..14f14efdf0d5 100644
--- a/drivers/fpga/altera-ps-spi.c
+++ b/drivers/fpga/altera-ps-spi.c
@@ -149,12 +149,23 @@ static int altera_ps_write_init(struct fpga_manager *mgr,
 
 static void rev_buf(char *buf, size_t len)
 {
-       const char *fw_end = (buf + len);
+       u32 *fw32 = (u32 *)buf;
+       size_t extra_bytes = (len & 0x03);
+       const u32 *fw_end = (u32 *)(buf + len - extra_bytes);
 
        /* set buffer to lsb first */
-       while (buf < fw_end) {
-               *buf = bitrev8(*buf);
-               buf++;
+       while (fw32 < fw_end) {
+               *fw32 = bitrev8x4(*fw32);
+               fw32++;
+       }
+
+       if (extra_bytes) {
+               buf = (char *)fw_end;
+               while (extra_bytes) {
+                       *buf = bitrev8(*buf);
+                       buf++;
+                       extra_bytes--;
+               }
        }
 }
 
-- 
2.11.0