linux-kernel - [PATCH 1/2] w1: ds2406: use crc16() instead of crc16

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Message-ID: <20250513022115.39109-2-ebiggers@kernel.org>
Date: Mon, 12 May 2025 19:21:14 -0700
From: Eric Biggers <ebiggers@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: linux-crypto@...r.kernel.org,
	Ard Biesheuvel <ardb@...nel.org>,
	Krzysztof Kozlowski <krzk@...nel.org>
Subject: [PATCH 1/2] w1: ds2406: use crc16() instead of crc16_byte() loop

From: Eric Biggers <ebiggers@...gle.com>

Instead of looping through each byte and calling crc16_byte(), instead
just call crc16() on the whole buffer.  No functional change.

Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
 drivers/w1/slaves/w1_ds2406.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/drivers/w1/slaves/w1_ds2406.c b/drivers/w1/slaves/w1_ds2406.c
index 1cae9b243ff8..76026d615111 100644
--- a/drivers/w1/slaves/w1_ds2406.c
+++ b/drivers/w1/slaves/w1_ds2406.c
@@ -27,12 +27,10 @@ static ssize_t w1_f12_read_state(
 	const struct bin_attribute *bin_attr,
 	char *buf, loff_t off, size_t count)
 {
 	u8 w1_buf[6] = {W1_F12_FUNC_READ_STATUS, 7, 0, 0, 0, 0};
 	struct w1_slave *sl = kobj_to_w1_slave(kobj);
-	u16 crc = 0;
-	int i;
 	ssize_t rtnval = 1;
 
 	if (off != 0)
 		return 0;
 	if (!buf)
@@ -45,13 +43,11 @@ static ssize_t w1_f12_read_state(
 		return -EIO;
 	}
 
 	w1_write_block(sl->master, w1_buf, 3);
 	w1_read_block(sl->master, w1_buf+3, 3);
-	for (i = 0; i < 6; i++)
-		crc = crc16_byte(crc, w1_buf[i]);
-	if (crc == 0xb001) /* good read? */
+	if (crc16(0, w1_buf, sizeof(w1_buf)) == 0xb001) /* good read? */
 		*buf = ((w1_buf[3]>>5)&3)|0x30;
 	else
 		rtnval = -EIO;
 
 	mutex_unlock(&sl->master->bus_mutex);
@@ -64,12 +60,10 @@ static ssize_t w1_f12_write_output(
 	const struct bin_attribute *bin_attr,
 	char *buf, loff_t off, size_t count)
 {
 	struct w1_slave *sl = kobj_to_w1_slave(kobj);
 	u8 w1_buf[6] = {W1_F12_FUNC_WRITE_STATUS, 7, 0, 0, 0, 0};
-	u16 crc = 0;
-	int i;
 	ssize_t rtnval = 1;
 
 	if (count != 1 || off != 0)
 		return -EFAULT;
 
@@ -81,13 +75,11 @@ static ssize_t w1_f12_write_output(
 	}
 
 	w1_buf[3] = (((*buf)&3)<<5)|0x1F;
 	w1_write_block(sl->master, w1_buf, 4);
 	w1_read_block(sl->master, w1_buf+4, 2);
-	for (i = 0; i < 6; i++)
-		crc = crc16_byte(crc, w1_buf[i]);
-	if (crc == 0xb001) /* good read? */
+	if (crc16(0, w1_buf, sizeof(w1_buf)) == 0xb001) /* good read? */
 		w1_write_8(sl->master, 0xFF);
 	else
 		rtnval = -EIO;
 
 	mutex_unlock(&sl->master->bus_mutex);
-- 
2.49.0