[PATCH v5 5/7] char: xillybus: Integer arithmetic improvements

[Eli Billauer <eli.billauer@gmail.com>]

Choose unsigned integers instead of signed where natural and required to
ensure defined overflow behavoir.

Simplify an arithmetic expression too.

No functional change is expected, as the relevant variables normally never
reach values where this transition matters.

Assisted-by: Deepseek:v4-pro Kimi:K2.6 ChatGPT:GPT-5.5 Claude:Sonnet-4.6
Assisted-by: Sashiko-0.2.5:gemini-3.1-pro-preview
Signed-off-by: Eli Billauer <eli.billauer@gmail.com>
---

Notes:
    Changelog:
    =========
    
    Changes v4->v5:
     -- Use unsigned literal ("1U") instead of signed to ensure defined
        behavior when left-shifted (in response to Sashiko's remark)
    
    No change on v3->v4.
    
    Changes v2->v3:
     -- Add Assisted-by tag to description
    
    No change on v1->v2.

 drivers/char/xillybus/xillybus_core.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/char/xillybus/xillybus_core.c b/drivers/char/xillybus/xillybus_core.c
index 7acebc1e6050..3ae95e6b17e9 100644
--- a/drivers/char/xillybus/xillybus_core.c
+++ b/drivers/char/xillybus/xillybus_core.c
@@ -343,7 +343,8 @@ static int xilly_map_single(struct xilly_endpoint *ep,
 static int xilly_get_dma_buffers(struct xilly_endpoint *ep,
 				 struct xilly_alloc_state *s,
 				 struct xilly_buffer **buffers,
-				 int bufnum, int bytebufsize)
+				 unsigned int bufnum,
+				 unsigned int bytebufsize)
 {
 	int i, rc;
 	dma_addr_t dma_addr;
@@ -431,8 +432,8 @@ static int xilly_setupchannels(struct xilly_endpoint *ep,
 	struct device *dev = ep->dev;
 	int i, entry, rc;
 	struct xilly_channel *channel;
-	int channelnum, bufnum, bufsize, format, is_writebuf;
-	int bytebufsize;
+	unsigned int channelnum, bufnum, bufsize, format, is_writebuf;
+	unsigned int bytebufsize;
 	int synchronous, allowpartial, exclusive_open, seekable;
 	int supports_nonempty;
 	int msg_buf_done = 0;
@@ -512,7 +513,7 @@ static int xilly_setupchannels(struct xilly_endpoint *ep,
 		format = (chandesc[1] >> 4) & 0x03;
 		allowpartial = (chandesc[1] >> 6) & 0x01;
 		synchronous = (chandesc[1] >> 7) & 0x01;
-		bufsize = 1 << (chandesc[2] & 0x1f);
+		bufsize = 1U << (chandesc[2] & 0x1f);
 		bufnum = 1 << (chandesc[3] & 0x0f);
 		exclusive_open = (chandesc[2] >> 7) & 0x01;
 		seekable = (chandesc[2] >> 6) & 0x01;
@@ -531,8 +532,7 @@ static int xilly_setupchannels(struct xilly_endpoint *ep,
 			channel->log2_element_size = ((format > 2) ?
 						      2 : format);
 
-			bytebufsize = bufsize *
-				(1 << channel->log2_element_size);
+			bytebufsize = bufsize << channel->log2_element_size;
 
 			buffers = devm_kcalloc(dev, bufnum,
 					       sizeof(struct xilly_buffer *),
@@ -589,7 +589,7 @@ static int xilly_setupchannels(struct xilly_endpoint *ep,
 static int xilly_scan_idt(struct xilly_endpoint *endpoint,
 			  struct xilly_idt_handle *idt_handle)
 {
-	int count = 0;
+	unsigned int count = 0;
 	unsigned char *idt = endpoint->channels[1]->wr_buffers[0]->addr;
 	unsigned char *end_of_idt = idt + endpoint->idtlen - 4;
 	unsigned char *scan;
-- 
2.34.1