serial: 8250_keba: Add ICR defines

Add defines for better readability of the Indexed Control Register (ICR)
access. In enhanced mode SCR and LSR registers are used for ICR access.
The behavior of these register is different in this mode and that shall
be documented with dedicated defines.

Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Gerhard Engleder <eg@keba.com>
Link: https://patch.msgid.link/20251216193726.55449-3-gerhard@engleder-embedded.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_keba.c b/drivers/tty/serial/8250/8250_keba.c
index e9e59ce79138169fb81c03181296072e96b2db9b..149953c6a288103196efc376e810754bc1efb681 100644 (file)
--- a/drivers/tty/serial/8250/8250_keba.c
+++ b/drivers/tty/serial/8250/8250_keba.c
@@ -51,6 +51,10 @@ enum kuart_mode {
 #define KUART_CAPABILITY_RS232 BIT(KUART_MODE_RS232)
 #define KUART_CAPABILITY_MASK  GENMASK(3, 0)
 
+/* registers for Indexed Control Register access in enhanced mode */
+#define KUART_EMODE_ICR_OFFSET UART_SCR
+#define KUART_EMODE_ICR_VALUE  UART_LSR
+
 /* Additional Control Register DTR line configuration */
 #define UART_ACR_DTRLC_MASK            0x18
 #define UART_ACR_DTRLC_COMPAT          0x00
@@ -98,13 +102,13 @@ static void kuart_dtr_line_config(struct uart_8250_port *up, u8 dtrlc)
        u8 acr;
 
        /* set index register to 0 to access ACR register */
-       serial_out(up, UART_SCR, UART_ACR);
+       serial_out(up, KUART_EMODE_ICR_OFFSET, UART_ACR);
 
        /* set value register to 0x10 writing DTR mode (1,0) */
-       acr = serial_in(up, UART_LSR);
+       acr = serial_in(up, KUART_EMODE_ICR_VALUE);
        acr &= ~UART_ACR_DTRLC_MASK;
        acr |= dtrlc;
-       serial_out(up, UART_LSR, acr);
+       serial_out(up, KUART_EMODE_ICR_VALUE, acr);
 }
 
 static int kuart_rs485_config(struct uart_port *port, struct ktermios *termios,