mfd: qnap-mcu: Move checksum verification to its own function

We'll need the checksum check in a second place in the future, so
move the verification code to a separate function.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patch.msgid.link/20251113165218.449616-4-heiko@sntech.de
Signed-off-by: Lee Jones <lee@kernel.org>

diff --git a/drivers/mfd/qnap-mcu.c b/drivers/mfd/qnap-mcu.c
index 1f4741cad875cb7261f56c73c07c8aa9d2d735ee..558c3bc07ed392e4dc00f6a7f5322701bbd1ca71 100644 (file)
--- a/drivers/mfd/qnap-mcu.c
+++ b/drivers/mfd/qnap-mcu.c
@@ -78,6 +78,13 @@ static u8 qnap_mcu_csum(const u8 *buf, size_t size)
        return csum;
 }
 
+static bool qnap_mcu_verify_checksum(const u8 *buf, size_t size)
+{
+       u8 crc = qnap_mcu_csum(buf, size - QNAP_MCU_CHECKSUM_SIZE);
+
+       return crc == buf[size - QNAP_MCU_CHECKSUM_SIZE];
+}
+
 static int qnap_mcu_write(struct qnap_mcu *mcu, const u8 *data, u8 data_size)
 {
        unsigned char tx[QNAP_MCU_TX_BUFFER_SIZE];
@@ -150,7 +157,6 @@ int qnap_mcu_exec(struct qnap_mcu *mcu,
        size_t length = reply_data_size + QNAP_MCU_CHECKSUM_SIZE;
        struct qnap_mcu_reply *reply = &mcu->reply;
        int ret = 0;
-       u8 crc;
 
        if (length > sizeof(rx)) {
                dev_err(&mcu->serdev->dev, "expected data too big for receive buffer");
@@ -175,8 +181,7 @@ int qnap_mcu_exec(struct qnap_mcu *mcu,
                return -ETIMEDOUT;
        }
 
-       crc = qnap_mcu_csum(rx, reply->received - QNAP_MCU_CHECKSUM_SIZE);
-       if (crc != rx[reply->received - QNAP_MCU_CHECKSUM_SIZE]) {
+       if (!qnap_mcu_verify_checksum(rx, reply->received)) {
                dev_err(&mcu->serdev->dev, "Invalid Checksum received\n");
                return -EPROTO;
        }