serial/serial_arc - add driver for ARC UART

Driver for non-standard on-chip UART, instantiated in the ARC (Synopsys)
FPGA Boards such as ARCAngel4/ML50x

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

Cc: Mischa Jonker <mjonker@synopsys.com>
Cc: Francois Bedard <fbedard@synopsys.com>
Cc: Tom Rini <trini@ti.com>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Stefano Babic <sbabic@denx.de>

drivers/serial/Makefile

@@ -34,6 +34,7 @@ obj-$(CONFIG_ZYNQ_SERIAL) += serial_zynq.o
 obj-$(CONFIG_BFIN_SERIAL) += serial_bfin.o
 obj-$(CONFIG_FSL_LPUART) += serial_lpuart.o
 obj-$(CONFIG_MXS_AUART) += mxs_auart.o
+obj-$(CONFIG_ARC_SERIAL) += serial_arc.o
 
 ifndef CONFIG_SPL_BUILD
 obj-$(CONFIG_USB_TTY) += usbtty.o

drivers/serial/serial.c

@@ -160,6 +160,7 @@ serial_initfunc(sa1100_serial_initialize);
 serial_initfunc(sh_serial_initialize);
 serial_initfunc(arm_dcc_initialize);
 serial_initfunc(mxs_auart_initialize);
+serial_initfunc(arc_serial_initialize);
 
 /**
  * serial_register() - Register serial driver with serial driver core
@@ -253,6 +254,7 @@ void serial_initialize(void)
 	sh_serial_initialize();
 	arm_dcc_initialize();
 	mxs_auart_initialize();
+	arc_serial_initialize();
 
 	serial_assign(default_serial_console()->name);
 }

drivers/serial/serial_arc.c

@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <common.h>
+#include <serial.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct arc_serial_regs {
+	unsigned int id0;
+	unsigned int id1;
+	unsigned int id2;
+	unsigned int id3;
+	unsigned int data;
+	unsigned int status;
+	unsigned int baudl;
+	unsigned int baudh;
+};
+
+/* Bit definitions of STATUS register */
+#define UART_RXEMPTY		(1 << 5)
+#define UART_OVERFLOW_ERR	(1 << 1)
+#define UART_TXEMPTY		(1 << 7)
+
+struct arc_serial_regs *regs;
+
+static void arc_serial_setbrg(void)
+{
+	int arc_console_baud;
+
+	if (!gd->baudrate)
+		gd->baudrate = CONFIG_BAUDRATE;
+
+	arc_console_baud = gd->cpu_clk / (gd->baudrate * 4) - 1;
+	writel(arc_console_baud & 0xff, &regs->baudl);
+	writel((arc_console_baud & 0xff00) >> 8, &regs->baudh);
+}
+
+static int arc_serial_init(void)
+{
+	regs = (struct arc_serial_regs *)CONFIG_ARC_UART_BASE;
+	serial_setbrg();
+	return 0;
+}
+
+static void arc_serial_putc(const char c)
+{
+	if (c == '\n')
+		arc_serial_putc('\r');
+
+	while (!(readl(&regs->status) & UART_TXEMPTY))
+		;
+
+	writel(c, &regs->data);
+}
+
+static int arc_serial_tstc(void)
+{
+	return !(readl(&regs->status) & UART_RXEMPTY);
+}
+
+static int arc_serial_getc(void)
+{
+	while (!arc_serial_tstc())
+		;
+
+	/* Check for overflow errors */
+	if (readl(&regs->status) & UART_OVERFLOW_ERR)
+		return 0;
+
+	return readl(&regs->data) & 0xFF;
+}
+
+static void arc_serial_puts(const char *s)
+{
+	while (*s)
+		arc_serial_putc(*s++);
+}
+
+static struct serial_device arc_serial_drv = {
+	.name	= "arc_serial",
+	.start	= arc_serial_init,
+	.stop	= NULL,
+	.setbrg	= arc_serial_setbrg,
+	.putc	= arc_serial_putc,
+	.puts	= arc_serial_puts,
+	.getc	= arc_serial_getc,
+	.tstc	= arc_serial_tstc,
+};
+
+void arc_serial_initialize(void)
+{
+	serial_register(&arc_serial_drv);
+}
+
+__weak struct serial_device *default_serial_console(void)
+{
+	return &arc_serial_drv;
+}