linux-kernel - [PATCH v2 11/13] serial: 8250_exar: Use BIT() in exar_ee

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Message-ID: <20240503171917.2921250-12-andriy.shevchenko@linux.intel.com>
Date: Fri,  3 May 2024 20:16:03 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Parker Newman <pnewman@...necttech.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>
Subject: [PATCH v2 11/13] serial: 8250_exar: Use BIT() in exar_ee_read()

Use BIT() in exar_ee_read() like other functions do.

While at it, explain the EEPROM type and the dummy bit requirement.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 drivers/tty/serial/8250/8250_exar.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index 306bc6d7c141..93d2c8dd3cd8 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -324,6 +324,7 @@ static inline u8 exar_ee_read_bit(struct exar8250 *priv)
  * @ee_addr: Offset of EEPROM to read word from
  *
  * Read a single 16bit word from an Exar UART's EEPROM.
+ * The type of the EEPROM is AT93C46D.
  *
  * Return: EEPROM word
  */
@@ -340,13 +341,13 @@ static u16 exar_ee_read(struct exar8250 *priv, u8 ee_addr)
 	exar_ee_write_bit(priv, 0);
 
 	// Send address to read from
-	for (i = 1 << (UART_EXAR_REGB_EE_ADDR_SIZE - 1); i; i >>= 1)
-		exar_ee_write_bit(priv, (ee_addr & i));
+	for (i = UART_EXAR_REGB_EE_ADDR_SIZE - 1; i >= 0; i--)
+		exar_ee_write_bit(priv, ee_addr & BIT(i));
 
-	// Read data 1 bit at a time
-	for (i = 0; i <= UART_EXAR_REGB_EE_DATA_SIZE; i++) {
-		data <<= 1;
-		data |= exar_ee_read_bit(priv);
+	// Read data 1 bit at a time starting with a dummy bit
+	for (i = UART_EXAR_REGB_EE_DATA_SIZE; i >= 0; i--) {
+		if (exar_ee_read_bit(priv))
+			data |= BIT(i);
 	}
 
 	exar_ee_deselect(priv);
-- 
2.43.0.rc1.1336.g36b5255a03ac