serial: add S3C64XX serial driver

Based on the original S3C64XX UART driver by Samsung for U-Boot 1.1.6.

Signed-off-by: Guennadi Liakhovetski <lg@denx.de>

drivers/serial/Makefile

@@ -30,6 +30,7 @@ COBJS-$(CONFIG_MCFUART) += mcfuart.o
 COBJS-$(CONFIG_NS9750_UART) += ns9750_serial.o
 COBJS-y += ns16550.o
 COBJS-$(CONFIG_DRIVER_S3C4510_UART) += s3c4510b_uart.o
+COBJS-$(CONFIG_S3C64XX) += s3c64xx.o
 COBJS-y += serial.o
 COBJS-$(CONFIG_MAX3100_SERIAL) += serial_max3100.o
 COBJS-y += serial_pl010.o

drivers/serial/s3c64xx.c

+/*
+ * (C) Copyright 2002
+ * Gary Jennejohn, DENX Software Engineering, <gj@denx.de>
+ *
+ * (C) Copyright 2008
+ * Guennadi Liakhovetki, DENX Software Engineering, <lg@denx.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#include <common.h>
+
+#include <s3c6400.h>
+
+#ifdef CONFIG_SERIAL1
+#define UART_NR	S3C64XX_UART0
+
+#elif defined(CONFIG_SERIAL2)
+#define UART_NR	S3C64XX_UART1
+
+#elif defined(CONFIG_SERIAL3)
+#define UART_NR	S3C64XX_UART2
+
+#else
+#error "Bad: you didn't configure serial ..."
+#endif
+
+#define barrier() asm volatile("" ::: "memory")
+
+/*
+ * The coefficient, used to calculate the baudrate on S3C6400 UARTs is
+ * calculated as
+ * C = UBRDIV * 16 + number_of_set_bits_in_UDIVSLOT
+ * however, section 31.6.11 of the datasheet doesn't recomment using 1 for 1,
+ * 3 for 2, ... (2^n - 1) for n, instead, they suggest using these constants:
+ */
+static const int udivslot[] = {
+	0,
+	0x0080,
+	0x0808,
+	0x0888,
+	0x2222,
+	0x4924,
+	0x4a52,
+	0x54aa,
+	0x5555,
+	0xd555,
+	0xd5d5,
+	0xddd5,
+	0xdddd,
+	0xdfdd,
+	0xdfdf,
+	0xffdf,
+};
+
+void serial_setbrg(void)
+{
+	DECLARE_GLOBAL_DATA_PTR;
+	s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
+	u32 pclk = get_PCLK();
+	u32 baudrate = gd->baudrate;
+	int i;
+
+	i = (pclk / baudrate) % 16;
+
+	uart->UBRDIV = pclk / baudrate / 16 - 1;
+	uart->UDIVSLOT = udivslot[i];
+
+	for (i = 0; i < 100; i++)
+		barrier();
+}
+
+/*
+ * Initialise the serial port with the given baudrate. The settings
+ * are always 8 data bits, no parity, 1 stop bit, no start bits.
+ */
+int serial_init(void)
+{
+	s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
+
+	/* reset and enable FIFOs, set triggers to the maximum */
+	uart->UFCON = 0xff;
+	uart->UMCON = 0;
+	/* 8N1 */
+	uart->ULCON = 3;
+	/* No interrupts, no DMA, pure polling */
+	uart->UCON = 5;
+
+	serial_setbrg();
+
+	return 0;
+}
+
+/*
+ * Read a single byte from the serial port. Returns 1 on success, 0
+ * otherwise. When the function is succesfull, the character read is
+ * written into its argument c.
+ */
+int serial_getc(void)
+{
+	s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
+
+	/* wait for character to arrive */
+	while (!(uart->UTRSTAT & 0x1));
+
+	return uart->URXH & 0xff;
+}
+
+#ifdef CONFIG_HWFLOW
+static int hwflow;		/* turned off by default */
+int hwflow_onoff(int on)
+{
+	switch (on) {
+	case 1:
+		hwflow = 1;	/* turn on */
+		break;
+	case -1:
+		hwflow = 0;	/* turn off */
+		break;
+	}
+	return hwflow;
+}
+#endif
+
+#ifdef CONFIG_MODEM_SUPPORT
+static int be_quiet;
+void disable_putc(void)
+{
+	be_quiet = 1;
+}
+
+void enable_putc(void)
+{
+	be_quiet = 0;
+}
+#endif
+
+
+/*
+ * Output a single byte to the serial port.
+ */
+void serial_putc(const char c)
+{
+	s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
+
+#ifdef CONFIG_MODEM_SUPPORT
+	if (be_quiet)
+		return;
+#endif
+
+	/* wait for room in the tx FIFO */
+	while (!(uart->UTRSTAT & 0x2));
+
+#ifdef CONFIG_HWFLOW
+	/* Wait for CTS up */
+	while (hwflow && !(uart->UMSTAT & 0x1));
+#endif
+
+	uart->UTXH = c;
+
+	/* If \n, also do \r */
+	if (c == '\n')
+		serial_putc('\r');
+}
+
+/*
+ * Test whether a character is in the RX buffer
+ */
+int serial_tstc(void)
+{
+	s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
+
+	return uart->UTRSTAT & 0x1;
+}
+
+void serial_puts(const char *s)
+{
+	while (*s)
+		serial_putc(*s++);
+}