arm: add uart dcc support

Serial driver via the EmbeddedICE macrocell's DCC channel using
co-processor 14.

It does include a timeout to ensure that the system does not
totally freeze when there is nothing connected to read.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

2 files changed, 227 insertions, 0 deletions

diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 0f980ab..d0efd73 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -25,6 +25,7 @@ include $(TOPDIR)/config.mk
 
 LIB	:= $(obj)libserial.a
 
+COBJS-$(CONFIG_ARM_DCC) += arm_dcc.o
 COBJS-$(CONFIG_ATMEL_USART) += atmel_usart.o
 COBJS-$(CONFIG_MCFUART) += mcfuart.o
 COBJS-$(CONFIG_NS9750_UART) += ns9750_serial.o
diff --git a/drivers/serial/arm_dcc.c b/drivers/serial/arm_dcc.c
new file mode 100644
index 0000000..5a7fb6b
--- /dev/null
+++ b/drivers/serial/arm_dcc.c
@@ -0,0 +1,226 @@
+/*
+ * Copyright (C) 2004-2007 ARM Limited.
+ * Copyright (C) 2008 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.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.
+ *
+ * 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
+ *
+ * As a special exception, if other files instantiate templates or use macros
+ * or inline functions from this file, or you compile this file and link it
+ * with other works to produce a work based on this file, this file does not
+ * by itself cause the resulting work to be covered by the GNU General Public
+ * License. However the source code for this file must still be made available
+ * in accordance with section (3) of the GNU General Public License.
+
+ * This exception does not invalidate any other reasons why a work based on
+ * this file might be covered by the GNU General Public License.
+ */
+
+#include <common.h>
+#include <devices.h>
+
+#define DCC_ARM9_RBIT	(1 << 0)
+#define DCC_ARM9_WBIT	(1 << 1)
+#define DCC_ARM11_RBIT	(1 << 30)
+#define DCC_ARM11_WBIT	(1 << 29)
+
+#define read_core_id(x)	do {						\
+		__asm__ ("mrc p15, 0, %0, c0, c0, 0\n" : "=r" (x));	\
+		x = (x >> 4) & 0xFFF;					\
+		} while (0);
+
+/*
+ * ARM9
+ */
+#define write_arm9_dcc(x)	\
+		__asm__ volatile ("mcr p14, 0, %0, c1, c0, 0\n" : : "r" (x))
+
+#define read_arm9_dcc(x)	\
+		__asm__ volatile ("mrc p14, 0, %0, c1, c0, 0\n" : "=r" (x))
+
+#define status_arm9_dcc(x)	\
+		__asm__ volatile ("mrc p14, 0, %0, c0, c0, 0\n" : "=r" (x))
+
+#define can_read_arm9_dcc(x)	do {	\
+		status_arm9_dcc(x);	\
+		x &= DCC_ARM9_RBIT;	\
+		} while (0);
+
+#define can_write_arm9_dcc(x)	do {	\
+		status_arm9_dcc(x);	\
+		x &= DCC_ARM9_WBIT;	\
+		x = (x == 0);		\
+		} while (0);
+
+/*
+ * ARM11
+ */
+#define write_arm11_dcc(x)	\
+		__asm__ volatile ("mcr p14, 0, %0, c0, c5, 0\n" : : "r" (x))
+
+#define read_arm11_dcc(x)	\
+		__asm__ volatile ("mrc p14, 0, %0, c0, c5, 0\n" : "=r" (x))
+
+#define status_arm11_dcc(x)	\
+		__asm__ volatile ("mrc p14, 0, %0, c0, c1, 0\n" : "=r" (x))
+
+#define can_read_arm11_dcc(x)	do {	\
+		status_arm11_dcc(x);	\
+		x &= DCC_ARM11_RBIT;	\
+		} while (0);
+
+#define can_write_arm11_dcc(x)	do {	\
+		status_arm11_dcc(x);	\
+		x &= DCC_ARM11_WBIT;	\
+		x = (x == 0);		\
+		} while (0);
+
+#define TIMEOUT_COUNT 0x4000000
+
+static enum {
+	arm9_and_earlier,
+	arm11_and_later
+} arm_type = arm9_and_earlier;
+
+#ifndef CONFIG_ARM_DCC_MULTI
+#define arm_dcc_init serial_init
+void serial_setbrg(void) {}
+#define arm_dcc_getc serial_getc
+#define arm_dcc_putc serial_putc
+#define arm_dcc_puts serial_puts
+#define arm_dcc_tstc serial_tstc
+#endif
+
+int arm_dcc_init(void)
+{
+	register unsigned int id;
+
+	read_core_id(id);
+
+	if (id >= 0xb00)
+		arm_type = arm11_and_later;
+	else
+		arm_type = arm9_and_earlier;
+
+	return 0;
+}
+
+int arm_dcc_getc(void)
+{
+	int ch;
+	register unsigned int reg;
+
+	switch (arm_type) {
+	case arm11_and_later:
+		do {
+			can_read_arm11_dcc(reg);
+		} while (!reg);
+		read_arm11_dcc(ch);
+		break;
+
+	case arm9_and_earlier:
+	default:
+		do {
+			can_read_arm9_dcc(reg);
+		} while (!reg);
+		read_arm9_dcc(ch);
+		break;
+	}
+
+	return ch;
+}
+
+void arm_dcc_putc(char ch)
+{
+	register unsigned int reg;
+	unsigned int timeout_count = TIMEOUT_COUNT;
+
+	switch (arm_type) {
+	case arm11_and_later:
+		while (--timeout_count) {
+			can_write_arm11_dcc(reg);
+			if (reg)
+				break;
+		}
+		if (timeout_count == 0)
+			return;
+		else
+			write_arm11_dcc(ch);
+		break;
+
+	case arm9_and_earlier:
+	default:
+		while (--timeout_count) {
+			can_write_arm9_dcc(reg);
+			if (reg)
+				break;
+		}
+		if (timeout_count == 0)
+			return;
+		else
+			write_arm9_dcc(ch);
+		break;
+	}
+}
+
+void arm_dcc_puts(const char *s)
+{
+	while (*s)
+		arm_dcc_putc(*s++);
+}
+
+int arm_dcc_tstc(void)
+{
+	register unsigned int reg;
+
+	switch (arm_type) {
+	case arm11_and_later:
+		can_read_arm11_dcc(reg);
+		break;
+	case arm9_and_earlier:
+	default:
+		can_read_arm9_dcc(reg);
+		break;
+	}
+
+	return reg;
+}
+
+#ifdef CONFIG_ARM_DCC_MULTI
+static device_t arm_dcc_dev;
+
+int drv_arm_dcc_init(void)
+{
+	int rc;
+
+	/* Device initialization */
+	memset(&arm_dcc_dev, 0, sizeof(arm_dcc_dev));
+
+	strcpy(arm_dcc_dev.name, "dcc");
+	arm_dcc_dev.ext = 0;	/* No extensions */
+	arm_dcc_dev.flags = DEV_FLAGS_INPUT | DEV_FLAGS_OUTPUT;
+	arm_dcc_dev.tstc = arm_dcc_tstc;	/* 'tstc' function */
+	arm_dcc_dev.getc = arm_dcc_getc;	/* 'getc' function */
+	arm_dcc_dev.putc = arm_dcc_putc;	/* 'putc' function */
+	arm_dcc_dev.puts = arm_dcc_puts;	/* 'puts' function */
+
+	rc = device_register(&arm_dcc_dev);
+
+	if (rc == 0) {
+		arm_dcc_init();
+		return 1;
+	}
+
+	return 0;
+}
+#endif