serial: sh-sci: Add more Serial Mode Register documentation

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/sh-sci.c

@@ -2064,7 +2064,7 @@ static void sci_reset(struct uart_port *port)
 static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
 			    struct ktermios *old)
 {
-	unsigned int baud, smr_val = 0, scr_val = 0, i;
+	unsigned int baud, smr_val = SCSMR_ASYNC, scr_val = 0, i;
 	unsigned int brr = 255, cks = 0, srr = 15, dl = 0, sccks = 0;
 	unsigned int brr1 = 255, cks1 = 0, srr1 = 15, dl1 = 0;
 	struct sci_port *s = to_sci_port(port);

drivers/tty/serial/sh-sci.h

@@ -35,12 +35,27 @@ enum {
 
 
 /* SCSMR (Serial Mode Register) */
+#define SCSMR_C_A	BIT(7)	/* Communication Mode */
+#define SCSMR_CSYNC	BIT(7)	/*   - Clocked synchronous mode */
+#define SCSMR_ASYNC	0	/*   - Asynchronous mode */
 #define SCSMR_CHR	BIT(6)	/* 7-bit Character Length */
 #define SCSMR_PE	BIT(5)	/* Parity Enable */
 #define SCSMR_ODD	BIT(4)	/* Odd Parity */
 #define SCSMR_STOP	BIT(3)	/* Stop Bit Length */
 #define SCSMR_CKS	0x0003	/* Clock Select */
 
+/* Serial Mode Register, SCIFA/SCIFB only bits */
+#define SCSMR_CKEDG	BIT(12)	/* Transmit/Receive Clock Edge Select */
+#define SCSMR_SRC_MASK	0x0700	/* Sampling Control */
+#define SCSMR_SRC_16	0x0000	/* Sampling rate 1/16 */
+#define SCSMR_SRC_5	0x0100	/* Sampling rate 1/5 */
+#define SCSMR_SRC_7	0x0200	/* Sampling rate 1/7 */
+#define SCSMR_SRC_11	0x0300	/* Sampling rate 1/11 */
+#define SCSMR_SRC_13	0x0400	/* Sampling rate 1/13 */
+#define SCSMR_SRC_17	0x0500	/* Sampling rate 1/17 */
+#define SCSMR_SRC_19	0x0600	/* Sampling rate 1/19 */
+#define SCSMR_SRC_27	0x0700	/* Sampling rate 1/27 */
+
 /* Serial Control Register, SCIFA/SCIFB only bits */
 #define SCSCR_TDRQE	BIT(15)	/* Tx Data Transfer Request Enable */
 #define SCSCR_RDRQE	BIT(14)	/* Rx Data Transfer Request Enable */