ARM: SAMSUNG: serial: Add FRACVAL support for newer UART

Add support for the FRACVAL register on the newer UART blocks which provides
the same function as UDIVSLOT register but the FRACVAL is easier to implement.
To support UDIVSLOT register, UDIVSLOT table search is necessary though
supporting FRACVAL only needs the index value of UDIVSLOT table.
Signed-off-by: Jongpill Lee <boyko.lee@samsung.com>
Acked-by: Changhwan Youn <chaos.youn@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/plat-samsung/include/plat/regs-serial.h

@@ -259,6 +259,8 @@ struct s3c2410_uartcfg {
 	unsigned short	   flags;
 	upf_t		   uart_flags;	 /* default uart flags */
 
+	unsigned int	   has_fracval;
+
 	unsigned long	   ucon;	 /* value of ucon for port */
 	unsigned long	   ulcon;	 /* value of ulcon for port */
 	unsigned long	   ufcon;	 /* value of ufcon for port */

drivers/serial/samsung.c

@@ -705,9 +705,14 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
 	if (ourport->info->has_divslot) {
 		unsigned int div = ourport->baudclk_rate / baud;
 
+		if (cfg->has_fracval) {
+			udivslot = (div & 15);
+			dbg("fracval = %04x\n", udivslot);
+		} else {
 			udivslot = udivslot_table[div & 15];
 			dbg("udivslot = %04x (div %d)\n", udivslot, div & 15);
 		}
+	}
 
 	switch (termios->c_cflag & CSIZE) {
 	case CS5: