[U-Boot] [PATCH 3/7] S3C24XX: Add serial driver

[José Miguel Gonçalves]

Serial driver for the S3C24XX SoCs.

Signed-off-by: José Miguel Gonçalves <jose.goncalves at inov.pt>
---
 drivers/serial/Makefile         |    1 +
 drivers/serial/s3c24xx_serial.c |  146 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 147 insertions(+)
 create mode 100644 drivers/serial/s3c24xx_serial.c

diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 65d0f23..2cbdaac 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -52,6 +52,7 @@ COBJS-$(CONFIG_PL011_SERIAL) += serial_pl01x.o
 COBJS-$(CONFIG_PXA_SERIAL) += serial_pxa.o
 COBJS-$(CONFIG_SA1100_SERIAL) += serial_sa1100.o
 COBJS-$(CONFIG_S3C24X0_SERIAL) += serial_s3c24x0.o
+COBJS-$(CONFIG_S3C24XX_SERIAL) += s3c24xx_serial.o
 COBJS-$(CONFIG_S3C44B0_SERIAL) += serial_s3c44b0.o
 COBJS-$(CONFIG_XILINX_UARTLITE) += serial_xuartlite.o
 COBJS-$(CONFIG_SANDBOX_SERIAL) += sandbox.o
diff --git a/drivers/serial/s3c24xx_serial.c b/drivers/serial/s3c24xx_serial.c
new file mode 100644
index 0000000..11f13a5
--- /dev/null
+++ b/drivers/serial/s3c24xx_serial.c
@@ -0,0 +1,146 @@
+/*
+ * (C) Copyright 2012 INOV - INESC Inovacao
+ * Jose Goncalves <jose.goncalves at inov.pt>
+ *
+ * Based on drivers/serial/s3c64xx.c
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * 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 <asm/arch/s3c24xx_cpu.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#ifdef CONFIG_SERIAL0
+#define UART_NR	S3C24XX_UART0
+
+#elif defined(CONFIG_SERIAL1)
+#define UART_NR	S3C24XX_UART1
+
+#elif defined(CONFIG_SERIAL2)
+#define UART_NR	S3C24XX_UART2
+
+#elif defined(CONFIG_SERIAL3)
+#define UART_NR	S3C24XX_UART3
+
+#else
+#error "Bad: you didn't configure serial ..."
+#endif
+
+#define barrier() asm volatile("" ::: "memory")
+
+/*
+ * The coefficient, used to calculate the baudrate on S3C24XX UARTs is
+ * calculated as C = UBRDIV * 16 + number_of_set_bits_in_UDIVSLOT
+ * however, section 2.1.10 of the S3C2416 User's Manual doesn't recommend
+ * using 1 for 1, 3 for 2, ... (2^n - 1) for n, instead, they suggest using
+ * these constants:
+ */
+static const int udivslot[] = {
+	0x0000, 0x0080, 0x0808, 0x0888, 0x2222, 0x4924, 0x4A52, 0x54AA,
+	0x5555, 0xD555, 0xD5D5, 0xDDD5, 0xDDDD, 0xDFDD, 0xDFDF, 0xFFDF,
+};
+
+void serial_setbrg(void)
+{
+	s3c24xx_uart *const uart = s3c24xx_get_base_uart(UART_NR);
+	u32 pclk;
+	u32 baudrate;
+	int i;
+
+	pclk = get_PCLK();
+	baudrate = gd->baudrate;
+
+	uart->ubrdiv = (pclk / baudrate / 16) - 1;
+	uart->udivslot = udivslot[(pclk / baudrate) % 16];
+
+	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)
+{
+	s3c24xx_uart *const uart = s3c24xx_get_base_uart(UART_NR);
+
+	/* FIFO enable, Tx/Rx FIFO clear */
+	uart->ufcon = 0x07;
+	uart->umcon = 0x00;
+	/* Normal mode, No parity, 1 stop bit, 8 data bits */
+	uart->ulcon = 0x03;
+	/* Polling mode */
+	uart->ucon = 0x005;
+
+	serial_setbrg();
+
+	return 0;
+}
+
+/*
+ * Read a single byte from the serial port.
+ */
+int serial_getc(void)
+{
+	s3c24xx_uart *const uart = s3c24xx_get_base_uart(UART_NR);
+
+	/* Wait for character to arrive */
+	while (!(uart->utrstat & 0x1)) ;
+
+	return uart->urxh & 0xff;
+}
+
+/*
+ * Output a single byte to the serial port.
+ */
+void serial_putc(const char c)
+{
+	s3c24xx_uart *const uart = s3c24xx_get_base_uart(UART_NR);
+
+	/* Wait for room in the TX FIFO */
+	while (!(uart->utrstat & 0x2)) ;
+
+	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)
+{
+	s3c24xx_uart *const uart = s3c24xx_get_base_uart(UART_NR);
+
+	return uart->utrstat & 0x1;
+}
+
+/*
+ * Output a string to the serial port.
+ */
+void serial_puts(const char *s)
+{
+	while (*s)
+		serial_putc(*s++);
+}
-- 
1.7.9.5