[PATCH 2.6.17-rc1] [SERIAL] DCC(JTAG) serial and the console emulation support(revised#2)

[PATCH 2.6.17-rc1] [SERIAL] DCC(JTAG) serial and the console emulation support(revised#2)

[Hyok S. Choi]

From: Hyok S. Choi <hyok.choi@samsung.com>

Many of JTAG debuggers for ARM support DCC protocol over JTAG
connection, which is very useful to debug hardwares which has no
serial port. This patch adds DCC serial emulation and the console
support. System timer based polling method is used for the
emulation of serial input interrupt handling.

Signed-off-by: Hyok S. Choi <hyok.choi@samsung.com>
---

 drivers/serial/Kconfig      |   31 +++
 drivers/serial/Makefile     |    1 
 drivers/serial/dcc.c        |  450 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/serial_core.h |    3 
 4 files changed, 485 insertions(+), 0 deletions(-)

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 7d22dc0..dd67aab 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -352,6 +352,37 @@ config SERIAL_CLPS711X_CONSOLE
 	  your boot loader (lilo or loadlin) about how to pass options to the
 	  kernel at boot time.)
 
+config SERIAL_DCC
+	bool "JTAG ICE/ICD DCC serial port emulation support"
+	depends on ARM
+	select SERIAL_CORE
+	help
+	  This selects serial port emulation driver for ICE/ICD JTAG debugger
+	  (e.g. Trace32) for ARM architecture. You should make an terminal with
+	  DCC(JTAG1) protocol.
+
+	  if unsure, say N.
+ 
+config SERIAL_DCC_CONSOLE
+	bool "Support for console on JTAG ICE/ICD DCC"
+	depends on SERIAL_DCC
+	select SERIAL_CORE_CONSOLE
+	help
+	  Say Y here if you wish to use ICE/ICD JTAG DCC serial port emulation
+	  as the system console.
+
+	  if unsure, say N.
+
+config SERIAL_DCC_STDSERIAL
+	bool "Install JTAG ICE/ICD DCC as standard serial"
+	default y
+	depends on !SERIAL_8250 && SERIAL_DCC
+	help
+	  Say Y here if you want to install DCC driver as a normal serial port
+	  /dev/ttyS0 (major 4, minor 64). Otherwise, it appears as /dev/ttyJ0
+	  (major 4, minor 128) and can co-exist with other UARTs, such as
+	  8250/16C550 compatibles.
+
 config SERIAL_S3C2410
 	tristate "Samsung S3C2410 Serial port support"
 	depends on ARM && ARCH_S3C2410
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 0a71bf6..63f2462 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_SERIAL_8250_AU1X00) += 8250
 obj-$(CONFIG_SERIAL_AMBA_PL010) += amba-pl010.o
 obj-$(CONFIG_SERIAL_AMBA_PL011) += amba-pl011.o
 obj-$(CONFIG_SERIAL_CLPS711X) += clps711x.o
+obj-$(CONFIG_SERIAL_DCC) += dcc.o
 obj-$(CONFIG_SERIAL_PXA) += pxa.o
 obj-$(CONFIG_SERIAL_SA1100) += sa1100.o
 obj-$(CONFIG_SERIAL_S3C2410) += s3c2410.o
diff --git a/drivers/serial/dcc.c b/drivers/serial/dcc.c
new file mode 100644
index 0000000..cac29aa
--- /dev/null
+++ b/drivers/serial/dcc.c
@@ -0,0 +1,450 @@
+/*
+ *  linux/drivers/serial/dcc.c
+ *
+ *  serial port emulation driver for the JTAG DCC Terminal.
+ *
+ * DCC(JTAG1) protocol version for JTAG ICE/ICD Debuggers:
+ * 	Copyright (C) 2003, 2004, 2005 Hyok S. Choi (hyok.choi@samsung.com)
+ * 	SAMSUNG ELECTRONICS Co.,Ltd.
+ *
+ * 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.
+ *
+ *  Changelog:
+ *   Oct-2003 Hyok S. Choi	Created
+ *   Feb-2004 Hyok S. Choi	Updated for serial_core.c and 2.6 kernel
+ *   Mar-2005 Hyok S. Choi	renamed from T32 to DCC
+ *   Apr-2006 Hyok S. Choi	revised including the MAJOR number
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/tty.h>
+#include <linux/ioport.h>
+#include <linux/init.h>
+#include <linux/serial.h>
+#include <linux/console.h>
+#include <linux/sysrq.h>
+#include <linux/tty_flip.h>
+#include <linux/major.h>
+
+#include <asm/io.h>
+#include <asm/irq.h>
+
+#include <linux/serial_core.h>
+
+/*
+ * if real irq interrupt used for receiving character,
+ * uncomment below line and modify the DCC_IRQ to correct one.
+ * Unless polling method id used.
+ */
+//#define DCC_IRQ_USED
+//#define DCC_IRQ		(INT_N_EXT0)
+
+#ifndef  DCC_IRQ_USED
+static struct work_struct dcc_poll_task;
+static void dcc_poll(void *data);
+#endif
+
+#define UART_NR			1	/* we have only one JTAG port */
+
+#ifdef CONFIG_SERIAL_DCC_STDSERIAL
+/* use ttyS for emulation of standard serial driver */
+#define SERIAL_DCC_NAME		"ttyS"
+#define SERIAL_DCC_MINOR	64
+#define SERIAL_DCC_MAJOR	TTY_MAJOR
+#else
+/* use ttyJ0(128) */
+#define SERIAL_DCC_NAME		"ttyJ"
+#define SERIAL_DCC_MINOR	186
+#define SERIAL_DCC_MAJOR	204
+#endif
+
+/* DCC Status Bits */
+#define DCC_STATUS_RX		(1 << 0)
+#define DCC_STATUS_TX		(1 << 1)
+
+/* primitive JTAG1 protocol utilities */
+static inline u32 __dcc_getstatus(void)
+{
+	u32 ret;
+
+	asm("mrc p14, 0, %0, c0, c0	@ read comms ctrl reg"
+		: "=r" (ret));
+
+	return ret;
+}
+
+static inline char __dcc_getchar(void)
+{
+	char c;
+
+	asm("mrc p14, 0, %0, c1, c0	@ read comms data reg"
+		: "=r" (c));
+
+	return c;
+}
+
+static inline void __dcc_putchar(char c)
+{
+	asm("mcr p14, 0, %0, c1, c0	@ write a char"
+		: /* no output register */
+		: "r" (c));
+}
+/* end of JTAG1 dependencies */
+
+static void dcc_putchar(struct uart_port *port, int ch)
+{
+	while (__dcc_getstatus() & DCC_STATUS_TX)
+		cpu_relax();
+	__dcc_putchar((char)(ch & 0xFF));
+}
+
+static inline void xmit_string(struct uart_port *port, char *p, int len)
+{
+	for ( ; len; len--, p++)
+		dcc_putchar(port, *p);
+}
+
+static inline void dcc_transmit_buffer(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->info->xmit;
+	int pendings = uart_circ_chars_pending(xmit);
+
+	if (pendings + xmit->tail > UART_XMIT_SIZE) {
+		xmit_string(port, &(xmit->buf[xmit->tail]),
+			UART_XMIT_SIZE - xmit->tail);
+		xmit_string(port, &(xmit->buf[0]), xmit->head);
+	} else
+		xmit_string(port, &(xmit->buf[xmit->tail]), pendings);
+	
+	xmit->tail = (xmit->tail + pendings) & (UART_XMIT_SIZE-1);
+	port->icount.tx += pendings;
+}
+
+static inline void dcc_transmit_x_char(struct uart_port *port)
+{
+	dcc_putchar(port, port->x_char);
+	port->icount.tx++;
+	port->x_char = 0;
+}
+
+static void dcc_start_tx(struct uart_port *port)
+{
+	dcc_transmit_buffer(port);
+}
+
+static inline void dcc_rx_chars(struct uart_port *port)
+{
+	unsigned char ch;
+	struct tty_struct *tty = port->info->tty;
+
+	/*
+	 * check input.
+	 * checking JTAG flag is better to resolve the status test.
+	 * incount is NOT used for JTAG1 protocol.
+	 */
+
+	if (__dcc_getstatus() & DCC_STATUS_RX) {
+		/* for JTAG 1 protocol, incount is always 1. */
+		ch = __dcc_getchar();
+
+		if (tty) {
+			tty_insert_flip_char(tty, ch, TTY_NORMAL);
+			port->icount.rx++;
+			tty_flip_buffer_push(tty);
+		}
+	}
+}
+
+static inline void dcc_tx_chars(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->info->xmit;
+
+	if (port->x_char) {
+		dcc_transmit_x_char(port);
+		return; 
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+		return;
+
+	dcc_transmit_buffer(port);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+}
+
+#ifdef DCC_IRQ_USED /* real IRQ used */
+static irqreturn_t dcc_int(int irq, void *dev_id, struct pt_regs *regs)
+{
+	struct uart_port *port = dev_id;
+	int handled = 0;
+
+	spin_lock(&port->lock);
+	
+	dcc_rx_chars(port);
+	dcc_tx_chars(port);
+
+	handled = 1;
+	spin_unlock(&port->lock);
+	
+	return IRQ_RETVAL(handled);
+}
+#else /* emulation by scheduled work */
+static void dcc_poll(void *data)
+{
+	struct uart_port *port = data;
+
+	spin_lock(&port->lock);
+	
+	dcc_rx_chars(port);
+	dcc_tx_chars(port);
+
+	schedule_delayed_work(&dcc_poll_task, 1);
+
+	spin_unlock(&port->lock);
+}
+#endif /* end of DCC_IRQ_USED */
+
+static unsigned int dcc_tx_empty(struct uart_port *port)
+{
+	return TIOCSER_TEMT;
+}
+
+static unsigned int dcc_get_mctrl(struct uart_port *port)
+{
+	return TIOCM_CTS | TIOCM_DSR | TIOCM_CD;
+}
+
+static int dcc_startup(struct uart_port *port)
+{
+#ifdef DCC_IRQ_USED /* real IRQ used */
+	int retval;
+
+	/* Allocate the IRQ */
+	retval = request_irq(port->irq, dcc_int, SA_INTERRUPT,
+			     "serial_dcc", port);
+	if (retval)
+		return retval;
+#else /* emulation */
+	/* shcedule the polling work */
+	schedule_delayed_work(&dcc_poll_task, 1);
+#endif
+
+	return 0;
+}
+
+static void dcc_shutdown(struct uart_port *port)
+{
+#ifdef DCC_IRQ_USED /* real IRQ used */
+	free_irq(port->irq, port);
+#else
+	spin_lock(&port->lock);
+	cancel_rearming_delayed_work(&dcc_poll_task);
+	spin_unlock(&port->lock);
+#endif
+}
+
+static void dcc_set_termios(struct uart_port *port, struct termios *termios,
+		   struct termios *old)
+{
+#ifdef DCC_IRQ_USED
+	unsigned long flags;
+#endif
+	unsigned int baud, quot;
+
+	/*
+	 * We don't support parity, stop bits, or anything other
+	 * than 8 bits, so clear these termios flags.
+	 */
+	termios->c_cflag &= ~(CSIZE | CSTOPB | PARENB | PARODD | CREAD);
+	termios->c_cflag |= CS8;
+
+	/*
+	 * We don't appear to support any error conditions either.
+	 */
+	termios->c_iflag &= ~(INPCK | IGNPAR | IGNBRK | BRKINT);
+
+	/*
+	 * Ask the core to calculate the divisor for us.
+	 */
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); 
+	quot = uart_get_divisor(port, baud);
+
+#ifdef DCC_IRQ_USED
+	spin_lock_irqsave(&port->lock, flags);
+#endif
+
+	uart_update_timeout(port, termios->c_cflag, baud);
+
+#ifdef DCC_IRQ_USED
+	spin_unlock_irqrestore(&port->lock, flags);
+#endif
+}
+
+static const char * dcc_type(struct uart_port *port)
+{
+	return port->type == PORT_DCC_JTAG1 ? "DCC" : NULL;
+}
+
+static int dcc_request_port(struct uart_port *port)
+{
+	return 0;
+}
+
+/*
+ * Configure/autoconfigure the port.
+ */
+static void dcc_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE) {
+		port->type = PORT_DCC_JTAG1;
+		dcc_request_port(port);
+	}
+}
+
+/*
+ * verify the new serial_struct (for TIOCSSERIAL).
+ */
+static int dcc_verify_port(struct uart_port *port, struct serial_struct *ser)
+{
+	int ret = 0;
+	if (ser->type != PORT_UNKNOWN && ser->type != PORT_DCC_JTAG1)
+		ret = -EINVAL;
+	if (ser->irq < 0 || ser->irq >= NR_IRQS)
+		ret = -EINVAL;
+	if (ser->baud_base < 9600)
+		ret = -EINVAL;
+	return ret;
+}
+
+/* dummy operation handlers for uart_ops */
+static void dcc_dummy_ops(struct uart_port *port)
+{
+}
+static void dcc_dummy_ops_ui(struct uart_port *port, unsigned int ui)
+{
+}
+static void dcc_dummy_ops_i(struct uart_port *port, int i)
+{
+}
+
+static struct uart_ops dcc_pops = {
+	.tx_empty	= dcc_tx_empty,
+	.set_mctrl	= dcc_dummy_ops_ui,
+	.get_mctrl	= dcc_get_mctrl,
+	.stop_tx	= dcc_dummy_ops,
+	.start_tx	= dcc_start_tx,
+	.stop_rx	= dcc_dummy_ops,
+	.enable_ms	= dcc_dummy_ops,
+	.break_ctl	= dcc_dummy_ops_i,
+	.startup	= dcc_startup,
+	.shutdown	= dcc_shutdown,
+	.set_termios	= dcc_set_termios,
+	.type		= dcc_type,
+	.release_port	= dcc_dummy_ops,
+	.request_port	= dcc_request_port,
+	.config_port	= dcc_config_port,
+	.verify_port	= dcc_verify_port,
+};
+
+static struct uart_port dcc_port = {
+	.membase	= (char*)0x12345678,	/* we need these garbages */
+	.mapbase	= 0x12345678,		/* for serial_core.c */
+	.iotype		= UPIO_MEM,	
+#ifdef DCC_IRQ_USED
+	.irq		= DCC_IRQ,
+#else
+	.irq		= 0,
+#endif
+	.uartclk	= 14745600,
+	.fifosize	= 0,
+	.ops		= &dcc_pops,
+	.flags		= UPF_BOOT_AUTOCONF,
+	.line		= 0,
+};
+
+
+#ifdef CONFIG_SERIAL_DCC_CONSOLE
+static void dcc_console_write(struct console *co, const char *s, unsigned int count)
+{
+	uart_console_write(&dcc_port, s, count, dcc_putchar);
+}
+
+static int __init dcc_console_setup(struct console *co, char *options)
+{
+	struct uart_port *port = &dcc_port;
+	int baud = 9600;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	return uart_set_options(port, co, baud, parity, bits, flow);
+}
+
+extern struct uart_driver dcc_reg;
+static struct console dcc_console = {
+	.name		= SERIAL_DCC_NAME,
+	.write		= dcc_console_write,
+	.device		= uart_console_device,
+	.setup		= dcc_console_setup,
+	.flags		= CON_PRINTBUFFER,
+	.index		= -1,
+	.data		= &dcc_reg,
+};
+
+static int __init dcc_console_init(void)
+{
+	register_console(&dcc_console);
+	return 0;
+}
+console_initcall(dcc_console_init);
+
+#define DCC_CONSOLE	&dcc_console
+#else
+#define DCC_CONSOLE	NULL
+#endif
+
+static struct uart_driver dcc_reg = {
+	.owner		= THIS_MODULE,
+	.driver_name	= SERIAL_DCC_NAME,
+	.dev_name	= SERIAL_DCC_NAME,
+	.major		= SERIAL_DCC_MAJOR,
+	.minor		= SERIAL_DCC_MINOR,
+	.nr		= UART_NR,
+	.cons		= DCC_CONSOLE,
+};
+
+static int __init dcc_init(void)
+{
+	int ret;
+
+	printk(KERN_INFO "DCC: JTAG1 Serial emulation driver driver $Revision: 1.1 $\n");
+
+	ret = uart_register_driver(&dcc_reg);
+
+	if (ret)
+		return ret;
+
+#ifndef DCC_IRQ_USED
+	/* initialize the poll work */
+	INIT_WORK(&dcc_poll_task, dcc_poll, &dcc_port);
+#endif
+
+	uart_add_one_port(&dcc_reg, &dcc_port);
+
+	return 0;
+}
+
+__initcall(dcc_init);
+
+MODULE_DESCRIPTION("DCC(JTAG1) JTAG debugger console emulation driver");
+MODULE_AUTHOR("Hyok S. Choi <hyok.choi@samsung.com>");
+MODULE_SUPPORTED_DEVICE(SERIAL_DCC_NAME);
+MODULE_LICENSE("GPL");
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index c32e60e..561bc6a 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -130,6 +130,9 @@
 /* SUN4V Hypervisor Console */
 #define PORT_SUNHV	72
 
+/* DCC(JTAG) emulation port types */
+#define PORT_DCC_JTAG1	73
+
 #ifdef __KERNEL__
 
 #include <linux/config.h>

[PATCH 2.6.17-rc1] [SERIAL] DCC(JTAG) serial and the console emulation support(revised#2)

[Hyok S. Choi]

From: Hyok S. Choi <hyok.choi@samsung.com>

Many of JTAG debuggers for ARM support DCC protocol over JTAG
connection, which is very useful to debug hardwares which has no
serial port. This patch adds DCC serial emulation and the console
support. System timer based polling method is used for the
emulation of serial input interrupt handling.

Signed-off-by: Hyok S. Choi <hyok.choi@samsung.com>
---

 drivers/serial/Kconfig      |   31 +++
 drivers/serial/Makefile     |    1 
 drivers/serial/dcc.c        |  450 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/serial_core.h |    3 
 4 files changed, 485 insertions(+), 0 deletions(-)

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 7d22dc0..dd67aab 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -352,6 +352,37 @@ config SERIAL_CLPS711X_CONSOLE
 	  your boot loader (lilo or loadlin) about how to pass options to the
 	  kernel at boot time.)
 
+config SERIAL_DCC
+	bool "JTAG ICE/ICD DCC serial port emulation support"
+	depends on ARM
+	select SERIAL_CORE
+	help
+	  This selects serial port emulation driver for ICE/ICD JTAG debugger
+	  (e.g. Trace32) for ARM architecture. You should make an terminal with
+	  DCC(JTAG1) protocol.
+
+	  if unsure, say N.
+ 
+config SERIAL_DCC_CONSOLE
+	bool "Support for console on JTAG ICE/ICD DCC"
+	depends on SERIAL_DCC
+	select SERIAL_CORE_CONSOLE
+	help
+	  Say Y here if you wish to use ICE/ICD JTAG DCC serial port emulation
+	  as the system console.
+
+	  if unsure, say N.
+
+config SERIAL_DCC_STDSERIAL
+	bool "Install JTAG ICE/ICD DCC as standard serial"
+	default y
+	depends on !SERIAL_8250 && SERIAL_DCC
+	help
+	  Say Y here if you want to install DCC driver as a normal serial port
+	  /dev/ttyS0 (major 4, minor 64). Otherwise, it appears as /dev/ttyJ0
+	  (major 4, minor 128) and can co-exist with other UARTs, such as
+	  8250/16C550 compatibles.
+
 config SERIAL_S3C2410
 	tristate "Samsung S3C2410 Serial port support"
 	depends on ARM && ARCH_S3C2410
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 0a71bf6..63f2462 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_SERIAL_8250_AU1X00) += 8250
 obj-$(CONFIG_SERIAL_AMBA_PL010) += amba-pl010.o
 obj-$(CONFIG_SERIAL_AMBA_PL011) += amba-pl011.o
 obj-$(CONFIG_SERIAL_CLPS711X) += clps711x.o
+obj-$(CONFIG_SERIAL_DCC) += dcc.o
 obj-$(CONFIG_SERIAL_PXA) += pxa.o
 obj-$(CONFIG_SERIAL_SA1100) += sa1100.o
 obj-$(CONFIG_SERIAL_S3C2410) += s3c2410.o
diff --git a/drivers/serial/dcc.c b/drivers/serial/dcc.c
new file mode 100644
index 0000000..cac29aa
--- /dev/null
+++ b/drivers/serial/dcc.c
@@ -0,0 +1,450 @@
+/*
+ *  linux/drivers/serial/dcc.c
+ *
+ *  serial port emulation driver for the JTAG DCC Terminal.
+ *
+ * DCC(JTAG1) protocol version for JTAG ICE/ICD Debuggers:
+ * 	Copyright (C) 2003, 2004, 2005 Hyok S. Choi (hyok.choi@samsung.com)
+ * 	SAMSUNG ELECTRONICS Co.,Ltd.
+ *
+ * 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.
+ *
+ *  Changelog:
+ *   Oct-2003 Hyok S. Choi	Created
+ *   Feb-2004 Hyok S. Choi	Updated for serial_core.c and 2.6 kernel
+ *   Mar-2005 Hyok S. Choi	renamed from T32 to DCC
+ *   Apr-2006 Hyok S. Choi	revised including the MAJOR number
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/tty.h>
+#include <linux/ioport.h>
+#include <linux/init.h>
+#include <linux/serial.h>
+#include <linux/console.h>
+#include <linux/sysrq.h>
+#include <linux/tty_flip.h>
+#include <linux/major.h>
+
+#include <asm/io.h>
+#include <asm/irq.h>
+
+#include <linux/serial_core.h>
+
+/*
+ * if real irq interrupt used for receiving character,
+ * uncomment below line and modify the DCC_IRQ to correct one.
+ * Unless polling method id used.
+ */
+//#define DCC_IRQ_USED
+//#define DCC_IRQ		(INT_N_EXT0)
+
+#ifndef  DCC_IRQ_USED
+static struct work_struct dcc_poll_task;
+static void dcc_poll(void *data);
+#endif
+
+#define UART_NR			1	/* we have only one JTAG port */
+
+#ifdef CONFIG_SERIAL_DCC_STDSERIAL
+/* use ttyS for emulation of standard serial driver */
+#define SERIAL_DCC_NAME		"ttyS"
+#define SERIAL_DCC_MINOR	64
+#define SERIAL_DCC_MAJOR	TTY_MAJOR
+#else
+/* use ttyJ0(128) */
+#define SERIAL_DCC_NAME		"ttyJ"
+#define SERIAL_DCC_MINOR	186
+#define SERIAL_DCC_MAJOR	204
+#endif
+
+/* DCC Status Bits */
+#define DCC_STATUS_RX		(1 << 0)
+#define DCC_STATUS_TX		(1 << 1)
+
+/* primitive JTAG1 protocol utilities */
+static inline u32 __dcc_getstatus(void)
+{
+	u32 ret;
+
+	asm("mrc p14, 0, %0, c0, c0	@ read comms ctrl reg"
+		: "=r" (ret));
+
+	return ret;
+}
+
+static inline char __dcc_getchar(void)
+{
+	char c;
+
+	asm("mrc p14, 0, %0, c1, c0	@ read comms data reg"
+		: "=r" (c));
+
+	return c;
+}
+
+static inline void __dcc_putchar(char c)
+{
+	asm("mcr p14, 0, %0, c1, c0	@ write a char"
+		: /* no output register */
+		: "r" (c));
+}
+/* end of JTAG1 dependencies */
+
+static void dcc_putchar(struct uart_port *port, int ch)
+{
+	while (__dcc_getstatus() & DCC_STATUS_TX)
+		cpu_relax();
+	__dcc_putchar((char)(ch & 0xFF));
+}
+
+static inline void xmit_string(struct uart_port *port, char *p, int len)
+{
+	for ( ; len; len--, p++)
+		dcc_putchar(port, *p);
+}
+
+static inline void dcc_transmit_buffer(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->info->xmit;
+	int pendings = uart_circ_chars_pending(xmit);
+
+	if (pendings + xmit->tail > UART_XMIT_SIZE) {
+		xmit_string(port, &(xmit->buf[xmit->tail]),
+			UART_XMIT_SIZE - xmit->tail);
+		xmit_string(port, &(xmit->buf[0]), xmit->head);
+	} else
+		xmit_string(port, &(xmit->buf[xmit->tail]), pendings);
+	
+	xmit->tail = (xmit->tail + pendings) & (UART_XMIT_SIZE-1);
+	port->icount.tx += pendings;
+}
+
+static inline void dcc_transmit_x_char(struct uart_port *port)
+{
+	dcc_putchar(port, port->x_char);
+	port->icount.tx++;
+	port->x_char = 0;
+}
+
+static void dcc_start_tx(struct uart_port *port)
+{
+	dcc_transmit_buffer(port);
+}
+
+static inline void dcc_rx_chars(struct uart_port *port)
+{
+	unsigned char ch;
+	struct tty_struct *tty = port->info->tty;
+
+	/*
+	 * check input.
+	 * checking JTAG flag is better to resolve the status test.
+	 * incount is NOT used for JTAG1 protocol.
+	 */
+
+	if (__dcc_getstatus() & DCC_STATUS_RX) {
+		/* for JTAG 1 protocol, incount is always 1. */
+		ch = __dcc_getchar();
+
+		if (tty) {
+			tty_insert_flip_char(tty, ch, TTY_NORMAL);
+			port->icount.rx++;
+			tty_flip_buffer_push(tty);
+		}
+	}
+}
+
+static inline void dcc_tx_chars(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->info->xmit;
+
+	if (port->x_char) {
+		dcc_transmit_x_char(port);
+		return; 
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+		return;
+
+	dcc_transmit_buffer(port);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+}
+
+#ifdef DCC_IRQ_USED /* real IRQ used */
+static irqreturn_t dcc_int(int irq, void *dev_id, struct pt_regs *regs)
+{
+	struct uart_port *port = dev_id;
+	int handled = 0;
+
+	spin_lock(&port->lock);
+	
+	dcc_rx_chars(port);
+	dcc_tx_chars(port);
+
+	handled = 1;
+	spin_unlock(&port->lock);
+	
+	return IRQ_RETVAL(handled);
+}
+#else /* emulation by scheduled work */
+static void dcc_poll(void *data)
+{
+	struct uart_port *port = data;
+
+	spin_lock(&port->lock);
+	
+	dcc_rx_chars(port);
+	dcc_tx_chars(port);
+
+	schedule_delayed_work(&dcc_poll_task, 1);
+
+	spin_unlock(&port->lock);
+}
+#endif /* end of DCC_IRQ_USED */
+
+static unsigned int dcc_tx_empty(struct uart_port *port)
+{
+	return TIOCSER_TEMT;
+}
+
+static unsigned int dcc_get_mctrl(struct uart_port *port)
+{
+	return TIOCM_CTS | TIOCM_DSR | TIOCM_CD;
+}
+
+static int dcc_startup(struct uart_port *port)
+{
+#ifdef DCC_IRQ_USED /* real IRQ used */
+	int retval;
+
+	/* Allocate the IRQ */
+	retval = request_irq(port->irq, dcc_int, SA_INTERRUPT,
+			     "serial_dcc", port);
+	if (retval)
+		return retval;
+#else /* emulation */
+	/* shcedule the polling work */
+	schedule_delayed_work(&dcc_poll_task, 1);
+#endif
+
+	return 0;
+}
+
+static void dcc_shutdown(struct uart_port *port)
+{
+#ifdef DCC_IRQ_USED /* real IRQ used */
+	free_irq(port->irq, port);
+#else
+	spin_lock(&port->lock);
+	cancel_rearming_delayed_work(&dcc_poll_task);
+	spin_unlock(&port->lock);
+#endif
+}
+
+static void dcc_set_termios(struct uart_port *port, struct termios *termios,
+		   struct termios *old)
+{
+#ifdef DCC_IRQ_USED
+	unsigned long flags;
+#endif
+	unsigned int baud, quot;
+
+	/*
+	 * We don't support parity, stop bits, or anything other
+	 * than 8 bits, so clear these termios flags.
+	 */
+	termios->c_cflag &= ~(CSIZE | CSTOPB | PARENB | PARODD | CREAD);
+	termios->c_cflag |= CS8;
+
+	/*
+	 * We don't appear to support any error conditions either.
+	 */
+	termios->c_iflag &= ~(INPCK | IGNPAR | IGNBRK | BRKINT);
+
+	/*
+	 * Ask the core to calculate the divisor for us.
+	 */
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); 
+	quot = uart_get_divisor(port, baud);
+
+#ifdef DCC_IRQ_USED
+	spin_lock_irqsave(&port->lock, flags);
+#endif
+
+	uart_update_timeout(port, termios->c_cflag, baud);
+
+#ifdef DCC_IRQ_USED
+	spin_unlock_irqrestore(&port->lock, flags);
+#endif
+}
+
+static const char * dcc_type(struct uart_port *port)
+{
+	return port->type == PORT_DCC_JTAG1 ? "DCC" : NULL;
+}
+
+static int dcc_request_port(struct uart_port *port)
+{
+	return 0;
+}
+
+/*
+ * Configure/autoconfigure the port.
+ */
+static void dcc_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE) {
+		port->type = PORT_DCC_JTAG1;
+		dcc_request_port(port);
+	}
+}
+
+/*
+ * verify the new serial_struct (for TIOCSSERIAL).
+ */
+static int dcc_verify_port(struct uart_port *port, struct serial_struct *ser)
+{
+	int ret = 0;
+	if (ser->type != PORT_UNKNOWN && ser->type != PORT_DCC_JTAG1)
+		ret = -EINVAL;
+	if (ser->irq < 0 || ser->irq >= NR_IRQS)
+		ret = -EINVAL;
+	if (ser->baud_base < 9600)
+		ret = -EINVAL;
+	return ret;
+}
+
+/* dummy operation handlers for uart_ops */
+static void dcc_dummy_ops(struct uart_port *port)
+{
+}
+static void dcc_dummy_ops_ui(struct uart_port *port, unsigned int ui)
+{
+}
+static void dcc_dummy_ops_i(struct uart_port *port, int i)
+{
+}
+
+static struct uart_ops dcc_pops = {
+	.tx_empty	= dcc_tx_empty,
+	.set_mctrl	= dcc_dummy_ops_ui,
+	.get_mctrl	= dcc_get_mctrl,
+	.stop_tx	= dcc_dummy_ops,
+	.start_tx	= dcc_start_tx,
+	.stop_rx	= dcc_dummy_ops,
+	.enable_ms	= dcc_dummy_ops,
+	.break_ctl	= dcc_dummy_ops_i,
+	.startup	= dcc_startup,
+	.shutdown	= dcc_shutdown,
+	.set_termios	= dcc_set_termios,
+	.type		= dcc_type,
+	.release_port	= dcc_dummy_ops,
+	.request_port	= dcc_request_port,
+	.config_port	= dcc_config_port,
+	.verify_port	= dcc_verify_port,
+};
+
+static struct uart_port dcc_port = {
+	.membase	= (char*)0x12345678,	/* we need these garbages */
+	.mapbase	= 0x12345678,		/* for serial_core.c */
+	.iotype		= UPIO_MEM,	
+#ifdef DCC_IRQ_USED
+	.irq		= DCC_IRQ,
+#else
+	.irq		= 0,
+#endif
+	.uartclk	= 14745600,
+	.fifosize	= 0,
+	.ops		= &dcc_pops,
+	.flags		= UPF_BOOT_AUTOCONF,
+	.line		= 0,
+};
+
+
+#ifdef CONFIG_SERIAL_DCC_CONSOLE
+static void dcc_console_write(struct console *co, const char *s, unsigned int count)
+{
+	uart_console_write(&dcc_port, s, count, dcc_putchar);
+}
+
+static int __init dcc_console_setup(struct console *co, char *options)
+{
+	struct uart_port *port = &dcc_port;
+	int baud = 9600;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	return uart_set_options(port, co, baud, parity, bits, flow);
+}
+
+extern struct uart_driver dcc_reg;
+static struct console dcc_console = {
+	.name		= SERIAL_DCC_NAME,
+	.write		= dcc_console_write,
+	.device		= uart_console_device,
+	.setup		= dcc_console_setup,
+	.flags		= CON_PRINTBUFFER,
+	.index		= -1,
+	.data		= &dcc_reg,
+};
+
+static int __init dcc_console_init(void)
+{
+	register_console(&dcc_console);
+	return 0;
+}
+console_initcall(dcc_console_init);
+
+#define DCC_CONSOLE	&dcc_console
+#else
+#define DCC_CONSOLE	NULL
+#endif
+
+static struct uart_driver dcc_reg = {
+	.owner		= THIS_MODULE,
+	.driver_name	= SERIAL_DCC_NAME,
+	.dev_name	= SERIAL_DCC_NAME,
+	.major		= SERIAL_DCC_MAJOR,
+	.minor		= SERIAL_DCC_MINOR,
+	.nr		= UART_NR,
+	.cons		= DCC_CONSOLE,
+};
+
+static int __init dcc_init(void)
+{
+	int ret;
+
+	printk(KERN_INFO "DCC: JTAG1 Serial emulation driver driver $Revision: 1.1 $\n");
+
+	ret = uart_register_driver(&dcc_reg);
+
+	if (ret)
+		return ret;
+
+#ifndef DCC_IRQ_USED
+	/* initialize the poll work */
+	INIT_WORK(&dcc_poll_task, dcc_poll, &dcc_port);
+#endif
+
+	uart_add_one_port(&dcc_reg, &dcc_port);
+
+	return 0;
+}
+
+__initcall(dcc_init);
+
+MODULE_DESCRIPTION("DCC(JTAG1) JTAG debugger console emulation driver");
+MODULE_AUTHOR("Hyok S. Choi <hyok.choi@samsung.com>");
+MODULE_SUPPORTED_DEVICE(SERIAL_DCC_NAME);
+MODULE_LICENSE("GPL");
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index c32e60e..561bc6a 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -130,6 +130,9 @@
 /* SUN4V Hypervisor Console */
 #define PORT_SUNHV	72
 
+/* DCC(JTAG) emulation port types */
+#define PORT_DCC_JTAG1	73
+
 #ifdef __KERNEL__
 
 #include <linux/config.h>

[PATCH 2.6.17-rc1] [SERIAL] DCC(JTAG) serial and the console emulation support(revised#2)

[Hyok S. Choi]

From: Hyok S. Choi <hyok.choi@samsung.com>

Many of JTAG debuggers for ARM support DCC protocol over JTAG
connection, which is very useful to debug hardwares which has no
serial port. This patch adds DCC serial emulation and the console
support. System timer based polling method is used for the
emulation of serial input interrupt handling.

Signed-off-by: Hyok S. Choi <hyok.choi@samsung.com>
---

 drivers/serial/Kconfig      |   31 +++
 drivers/serial/Makefile     |    1 
 drivers/serial/dcc.c        |  450 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/serial_core.h |    3 
 4 files changed, 485 insertions(+), 0 deletions(-)

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 7d22dc0..dd67aab 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -352,6 +352,37 @@ config SERIAL_CLPS711X_CONSOLE
 	  your boot loader (lilo or loadlin) about how to pass options to the
 	  kernel at boot time.)
 
+config SERIAL_DCC
+	bool "JTAG ICE/ICD DCC serial port emulation support"
+	depends on ARM
+	select SERIAL_CORE
+	help
+	  This selects serial port emulation driver for ICE/ICD JTAG debugger
+	  (e.g. Trace32) for ARM architecture. You should make an terminal with
+	  DCC(JTAG1) protocol.
+
+	  if unsure, say N.
+ 
+config SERIAL_DCC_CONSOLE
+	bool "Support for console on JTAG ICE/ICD DCC"
+	depends on SERIAL_DCC
+	select SERIAL_CORE_CONSOLE
+	help
+	  Say Y here if you wish to use ICE/ICD JTAG DCC serial port emulation
+	  as the system console.
+
+	  if unsure, say N.
+
+config SERIAL_DCC_STDSERIAL
+	bool "Install JTAG ICE/ICD DCC as standard serial"
+	default y
+	depends on !SERIAL_8250 && SERIAL_DCC
+	help
+	  Say Y here if you want to install DCC driver as a normal serial port
+	  /dev/ttyS0 (major 4, minor 64). Otherwise, it appears as /dev/ttyJ0
+	  (major 4, minor 128) and can co-exist with other UARTs, such as
+	  8250/16C550 compatibles.
+
 config SERIAL_S3C2410
 	tristate "Samsung S3C2410 Serial port support"
 	depends on ARM && ARCH_S3C2410
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 0a71bf6..63f2462 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_SERIAL_8250_AU1X00) += 8250
 obj-$(CONFIG_SERIAL_AMBA_PL010) += amba-pl010.o
 obj-$(CONFIG_SERIAL_AMBA_PL011) += amba-pl011.o
 obj-$(CONFIG_SERIAL_CLPS711X) += clps711x.o
+obj-$(CONFIG_SERIAL_DCC) += dcc.o
 obj-$(CONFIG_SERIAL_PXA) += pxa.o
 obj-$(CONFIG_SERIAL_SA1100) += sa1100.o
 obj-$(CONFIG_SERIAL_S3C2410) += s3c2410.o
diff --git a/drivers/serial/dcc.c b/drivers/serial/dcc.c
new file mode 100644
index 0000000..cac29aa
--- /dev/null
+++ b/drivers/serial/dcc.c
@@ -0,0 +1,450 @@
+/*
+ *  linux/drivers/serial/dcc.c
+ *
+ *  serial port emulation driver for the JTAG DCC Terminal.
+ *
+ * DCC(JTAG1) protocol version for JTAG ICE/ICD Debuggers:
+ * 	Copyright (C) 2003, 2004, 2005 Hyok S. Choi (hyok.choi@samsung.com)
+ * 	SAMSUNG ELECTRONICS Co.,Ltd.
+ *
+ * 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.
+ *
+ *  Changelog:
+ *   Oct-2003 Hyok S. Choi	Created
+ *   Feb-2004 Hyok S. Choi	Updated for serial_core.c and 2.6 kernel
+ *   Mar-2005 Hyok S. Choi	renamed from T32 to DCC
+ *   Apr-2006 Hyok S. Choi	revised including the MAJOR number
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/tty.h>
+#include <linux/ioport.h>
+#include <linux/init.h>
+#include <linux/serial.h>
+#include <linux/console.h>
+#include <linux/sysrq.h>
+#include <linux/tty_flip.h>
+#include <linux/major.h>
+
+#include <asm/io.h>
+#include <asm/irq.h>
+
+#include <linux/serial_core.h>
+
+/*
+ * if real irq interrupt used for receiving character,
+ * uncomment below line and modify the DCC_IRQ to correct one.
+ * Unless polling method id used.
+ */
+//#define DCC_IRQ_USED
+//#define DCC_IRQ		(INT_N_EXT0)
+
+#ifndef  DCC_IRQ_USED
+static struct work_struct dcc_poll_task;
+static void dcc_poll(void *data);
+#endif
+
+#define UART_NR			1	/* we have only one JTAG port */
+
+#ifdef CONFIG_SERIAL_DCC_STDSERIAL
+/* use ttyS for emulation of standard serial driver */
+#define SERIAL_DCC_NAME		"ttyS"
+#define SERIAL_DCC_MINOR	64
+#define SERIAL_DCC_MAJOR	TTY_MAJOR
+#else
+/* use ttyJ0(128) */
+#define SERIAL_DCC_NAME		"ttyJ"
+#define SERIAL_DCC_MINOR	186
+#define SERIAL_DCC_MAJOR	204
+#endif
+
+/* DCC Status Bits */
+#define DCC_STATUS_RX		(1 << 0)
+#define DCC_STATUS_TX		(1 << 1)
+
+/* primitive JTAG1 protocol utilities */
+static inline u32 __dcc_getstatus(void)
+{
+	u32 ret;
+
+	asm("mrc p14, 0, %0, c0, c0	@ read comms ctrl reg"
+		: "=r" (ret));
+
+	return ret;
+}
+
+static inline char __dcc_getchar(void)
+{
+	char c;
+
+	asm("mrc p14, 0, %0, c1, c0	@ read comms data reg"
+		: "=r" (c));
+
+	return c;
+}
+
+static inline void __dcc_putchar(char c)
+{
+	asm("mcr p14, 0, %0, c1, c0	@ write a char"
+		: /* no output register */
+		: "r" (c));
+}
+/* end of JTAG1 dependencies */
+
+static void dcc_putchar(struct uart_port *port, int ch)
+{
+	while (__dcc_getstatus() & DCC_STATUS_TX)
+		cpu_relax();
+	__dcc_putchar((char)(ch & 0xFF));
+}
+
+static inline void xmit_string(struct uart_port *port, char *p, int len)
+{
+	for ( ; len; len--, p++)
+		dcc_putchar(port, *p);
+}
+
+static inline void dcc_transmit_buffer(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->info->xmit;
+	int pendings = uart_circ_chars_pending(xmit);
+
+	if (pendings + xmit->tail > UART_XMIT_SIZE) {
+		xmit_string(port, &(xmit->buf[xmit->tail]),
+			UART_XMIT_SIZE - xmit->tail);
+		xmit_string(port, &(xmit->buf[0]), xmit->head);
+	} else
+		xmit_string(port, &(xmit->buf[xmit->tail]), pendings);
+	
+	xmit->tail = (xmit->tail + pendings) & (UART_XMIT_SIZE-1);
+	port->icount.tx += pendings;
+}
+
+static inline void dcc_transmit_x_char(struct uart_port *port)
+{
+	dcc_putchar(port, port->x_char);
+	port->icount.tx++;
+	port->x_char = 0;
+}
+
+static void dcc_start_tx(struct uart_port *port)
+{
+	dcc_transmit_buffer(port);
+}
+
+static inline void dcc_rx_chars(struct uart_port *port)
+{
+	unsigned char ch;
+	struct tty_struct *tty = port->info->tty;
+
+	/*
+	 * check input.
+	 * checking JTAG flag is better to resolve the status test.
+	 * incount is NOT used for JTAG1 protocol.
+	 */
+
+	if (__dcc_getstatus() & DCC_STATUS_RX) {
+		/* for JTAG 1 protocol, incount is always 1. */
+		ch = __dcc_getchar();
+
+		if (tty) {
+			tty_insert_flip_char(tty, ch, TTY_NORMAL);
+			port->icount.rx++;
+			tty_flip_buffer_push(tty);
+		}
+	}
+}
+
+static inline void dcc_tx_chars(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->info->xmit;
+
+	if (port->x_char) {
+		dcc_transmit_x_char(port);
+		return; 
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+		return;
+
+	dcc_transmit_buffer(port);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+}
+
+#ifdef DCC_IRQ_USED /* real IRQ used */
+static irqreturn_t dcc_int(int irq, void *dev_id, struct pt_regs *regs)
+{
+	struct uart_port *port = dev_id;
+	int handled = 0;
+
+	spin_lock(&port->lock);
+	
+	dcc_rx_chars(port);
+	dcc_tx_chars(port);
+
+	handled = 1;
+	spin_unlock(&port->lock);
+	
+	return IRQ_RETVAL(handled);
+}
+#else /* emulation by scheduled work */
+static void dcc_poll(void *data)
+{
+	struct uart_port *port = data;
+
+	spin_lock(&port->lock);
+	
+	dcc_rx_chars(port);
+	dcc_tx_chars(port);
+
+	schedule_delayed_work(&dcc_poll_task, 1);
+
+	spin_unlock(&port->lock);
+}
+#endif /* end of DCC_IRQ_USED */
+
+static unsigned int dcc_tx_empty(struct uart_port *port)
+{
+	return TIOCSER_TEMT;
+}
+
+static unsigned int dcc_get_mctrl(struct uart_port *port)
+{
+	return TIOCM_CTS | TIOCM_DSR | TIOCM_CD;
+}
+
+static int dcc_startup(struct uart_port *port)
+{
+#ifdef DCC_IRQ_USED /* real IRQ used */
+	int retval;
+
+	/* Allocate the IRQ */
+	retval = request_irq(port->irq, dcc_int, SA_INTERRUPT,
+			     "serial_dcc", port);
+	if (retval)
+		return retval;
+#else /* emulation */
+	/* shcedule the polling work */
+	schedule_delayed_work(&dcc_poll_task, 1);
+#endif
+
+	return 0;
+}
+
+static void dcc_shutdown(struct uart_port *port)
+{
+#ifdef DCC_IRQ_USED /* real IRQ used */
+	free_irq(port->irq, port);
+#else
+	spin_lock(&port->lock);
+	cancel_rearming_delayed_work(&dcc_poll_task);
+	spin_unlock(&port->lock);
+#endif
+}
+
+static void dcc_set_termios(struct uart_port *port, struct termios *termios,
+		   struct termios *old)
+{
+#ifdef DCC_IRQ_USED
+	unsigned long flags;
+#endif
+	unsigned int baud, quot;
+
+	/*
+	 * We don't support parity, stop bits, or anything other
+	 * than 8 bits, so clear these termios flags.
+	 */
+	termios->c_cflag &= ~(CSIZE | CSTOPB | PARENB | PARODD | CREAD);
+	termios->c_cflag |= CS8;
+
+	/*
+	 * We don't appear to support any error conditions either.
+	 */
+	termios->c_iflag &= ~(INPCK | IGNPAR | IGNBRK | BRKINT);
+
+	/*
+	 * Ask the core to calculate the divisor for us.
+	 */
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); 
+	quot = uart_get_divisor(port, baud);
+
+#ifdef DCC_IRQ_USED
+	spin_lock_irqsave(&port->lock, flags);
+#endif
+
+	uart_update_timeout(port, termios->c_cflag, baud);
+
+#ifdef DCC_IRQ_USED
+	spin_unlock_irqrestore(&port->lock, flags);
+#endif
+}
+
+static const char * dcc_type(struct uart_port *port)
+{
+	return port->type == PORT_DCC_JTAG1 ? "DCC" : NULL;
+}
+
+static int dcc_request_port(struct uart_port *port)
+{
+	return 0;
+}
+
+/*
+ * Configure/autoconfigure the port.
+ */
+static void dcc_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE) {
+		port->type = PORT_DCC_JTAG1;
+		dcc_request_port(port);
+	}
+}
+
+/*
+ * verify the new serial_struct (for TIOCSSERIAL).
+ */
+static int dcc_verify_port(struct uart_port *port, struct serial_struct *ser)
+{
+	int ret = 0;
+	if (ser->type != PORT_UNKNOWN && ser->type != PORT_DCC_JTAG1)
+		ret = -EINVAL;
+	if (ser->irq < 0 || ser->irq >= NR_IRQS)
+		ret = -EINVAL;
+	if (ser->baud_base < 9600)
+		ret = -EINVAL;
+	return ret;
+}
+
+/* dummy operation handlers for uart_ops */
+static void dcc_dummy_ops(struct uart_port *port)
+{
+}
+static void dcc_dummy_ops_ui(struct uart_port *port, unsigned int ui)
+{
+}
+static void dcc_dummy_ops_i(struct uart_port *port, int i)
+{
+}
+
+static struct uart_ops dcc_pops = {
+	.tx_empty	= dcc_tx_empty,
+	.set_mctrl	= dcc_dummy_ops_ui,
+	.get_mctrl	= dcc_get_mctrl,
+	.stop_tx	= dcc_dummy_ops,
+	.start_tx	= dcc_start_tx,
+	.stop_rx	= dcc_dummy_ops,
+	.enable_ms	= dcc_dummy_ops,
+	.break_ctl	= dcc_dummy_ops_i,
+	.startup	= dcc_startup,
+	.shutdown	= dcc_shutdown,
+	.set_termios	= dcc_set_termios,
+	.type		= dcc_type,
+	.release_port	= dcc_dummy_ops,
+	.request_port	= dcc_request_port,
+	.config_port	= dcc_config_port,
+	.verify_port	= dcc_verify_port,
+};
+
+static struct uart_port dcc_port = {
+	.membase	= (char*)0x12345678,	/* we need these garbages */
+	.mapbase	= 0x12345678,		/* for serial_core.c */
+	.iotype		= UPIO_MEM,	
+#ifdef DCC_IRQ_USED
+	.irq		= DCC_IRQ,
+#else
+	.irq		= 0,
+#endif
+	.uartclk	= 14745600,
+	.fifosize	= 0,
+	.ops		= &dcc_pops,
+	.flags		= UPF_BOOT_AUTOCONF,
+	.line		= 0,
+};
+
+
+#ifdef CONFIG_SERIAL_DCC_CONSOLE
+static void dcc_console_write(struct console *co, const char *s, unsigned int count)
+{
+	uart_console_write(&dcc_port, s, count, dcc_putchar);
+}
+
+static int __init dcc_console_setup(struct console *co, char *options)
+{
+	struct uart_port *port = &dcc_port;
+	int baud = 9600;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	return uart_set_options(port, co, baud, parity, bits, flow);
+}
+
+extern struct uart_driver dcc_reg;
+static struct console dcc_console = {
+	.name		= SERIAL_DCC_NAME,
+	.write		= dcc_console_write,
+	.device		= uart_console_device,
+	.setup		= dcc_console_setup,
+	.flags		= CON_PRINTBUFFER,
+	.index		= -1,
+	.data		= &dcc_reg,
+};
+
+static int __init dcc_console_init(void)
+{
+	register_console(&dcc_console);
+	return 0;
+}
+console_initcall(dcc_console_init);
+
+#define DCC_CONSOLE	&dcc_console
+#else
+#define DCC_CONSOLE	NULL
+#endif
+
+static struct uart_driver dcc_reg = {
+	.owner		= THIS_MODULE,
+	.driver_name	= SERIAL_DCC_NAME,
+	.dev_name	= SERIAL_DCC_NAME,
+	.major		= SERIAL_DCC_MAJOR,
+	.minor		= SERIAL_DCC_MINOR,
+	.nr		= UART_NR,
+	.cons		= DCC_CONSOLE,
+};
+
+static int __init dcc_init(void)
+{
+	int ret;
+
+	printk(KERN_INFO "DCC: JTAG1 Serial emulation driver driver $Revision: 1.1 $\n");
+
+	ret = uart_register_driver(&dcc_reg);
+
+	if (ret)
+		return ret;
+
+#ifndef DCC_IRQ_USED
+	/* initialize the poll work */
+	INIT_WORK(&dcc_poll_task, dcc_poll, &dcc_port);
+#endif
+
+	uart_add_one_port(&dcc_reg, &dcc_port);
+
+	return 0;
+}
+
+__initcall(dcc_init);
+
+MODULE_DESCRIPTION("DCC(JTAG1) JTAG debugger console emulation driver");
+MODULE_AUTHOR("Hyok S. Choi <hyok.choi@samsung.com>");
+MODULE_SUPPORTED_DEVICE(SERIAL_DCC_NAME);
+MODULE_LICENSE("GPL");
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index c32e60e..561bc6a 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -130,6 +130,9 @@
 /* SUN4V Hypervisor Console */
 #define PORT_SUNHV	72
 
+/* DCC(JTAG) emulation port types */
+#define PORT_DCC_JTAG1	73
+
 #ifdef __KERNEL__
 
 #include <linux/config.h>


-- 
Hyok
ARM Linux 2.6 MPU/noMMU Project http://opensrc.sec.samsung.com/

Re: [PATCH 2.6.17-rc1] [SERIAL] DCC(JTAG) serial and the console emulation support(revised#2)

[Russell King]

On Mon, Apr 03, 2006 at 08:24:10PM +0900, Hyok S. Choi wrote:

The number of comments is getting smaller.  Only two remaining.

> +	help
> +	  Say Y here if you want to install DCC driver as a normal serial port
> +	  /dev/ttyS0 (major 4, minor 64). Otherwise, it appears as /dev/ttyJ0
> +	  (major 4, minor 128) and can co-exist with other UARTs, such as
> +	  8250/16C550 compatibles.

Help doesn't match code.

> +static void dcc_shutdown(struct uart_port *port)
> +{
> +#ifdef DCC_IRQ_USED /* real IRQ used */
> +	free_irq(port->irq, port);
> +#else
> +	spin_lock(&port->lock);
> +	cancel_rearming_delayed_work(&dcc_poll_task);

cancel_rearming_delayed_work() might sleep due to it calling
flush_workqueue.  Therefore, you must not be holding a spinlock.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core

Re: [PATCH 2.6.17-rc1] [SERIAL] DCC(JTAG) serial and the console emulation support(revised#2)

[Hyok S. Choi]

On Tuesday 04 April 2006 04:44 am, Russell King wrote:
> On Mon, Apr 03, 2006 at 08:24:10PM +0900, Hyok S. Choi wrote:
> 
> > +static void dcc_shutdown(struct uart_port *port)
> > +{
> > +#ifdef DCC_IRQ_USED /* real IRQ used */
> > +	free_irq(port->irq, port);
> > +#else
> > +	spin_lock(&port->lock);
> > +	cancel_rearming_delayed_work(&dcc_poll_task);
> 
> cancel_rearming_delayed_work() might sleep due to it calling
> flush_workqueue.  Therefore, you must not be holding a spinlock.

Thus, I've just revised the code to lock around a counter variable
operation, which is used for life control of the polling task.
I've just posted the revised #3. :-)

-- 
Hyok
ARM Linux 2.6 MPU/noMMU Project http://opensrc.sec.samsung.com/

Re: [PATCH 2.6.17-rc1] [SERIAL] DCC(JTAG) serial and the console emulation support(revised#2)

[Russell King]

On Tue, Apr 04, 2006 at 11:27:06AM +0900, Hyok S. Choi wrote:
> On Tuesday 04 April 2006 04:44 am, Russell King wrote:
> > On Mon, Apr 03, 2006 at 08:24:10PM +0900, Hyok S. Choi wrote:
> > 
> > > +static void dcc_shutdown(struct uart_port *port)
> > > +{
> > > +#ifdef DCC_IRQ_USED /* real IRQ used */
> > > +	free_irq(port->irq, port);
> > > +#else
> > > +	spin_lock(&port->lock);
> > > +	cancel_rearming_delayed_work(&dcc_poll_task);
> > 
> > cancel_rearming_delayed_work() might sleep due to it calling
> > flush_workqueue.  Therefore, you must not be holding a spinlock.
> 
> Thus, I've just revised the code to lock around a counter variable
> operation, which is used for life control of the polling task.
> I've just posted the revised #3. :-)

Why do you think you need such complexity?

cancel_rearming_delayed_work() will wait until the poll task has
completed and has been removed from the system.  It's explicitly
designed for work handlers which self-rearm.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core

Re: [PATCH 2.6.17-rc1] [SERIAL] DCC(JTAG) serial and the console emulation support(revised#2)

[Hyok S. Choi]

On Tuesday 04 April 2006 05:20 pm, Russell King wrote:
> On Tue, Apr 04, 2006 at 11:27:06AM +0900, Hyok S. Choi wrote:
> > On Tuesday 04 April 2006 04:44 am, Russell King wrote:
> > > On Mon, Apr 03, 2006 at 08:24:10PM +0900, Hyok S. Choi wrote:
> > > 
> > > > +static void dcc_shutdown(struct uart_port *port)
> > > > +{
> > > > +#ifdef DCC_IRQ_USED /* real IRQ used */
> > > > +	free_irq(port->irq, port);
> > > > +#else
> > > > +	spin_lock(&port->lock);
> > > > +	cancel_rearming_delayed_work(&dcc_poll_task);
> > > 
> > > cancel_rearming_delayed_work() might sleep due to it calling
> > > flush_workqueue.  Therefore, you must not be holding a spinlock.
> > 
> > Thus, I've just revised the code to lock around a counter variable
> > operation, which is used for life control of the polling task.
> > I've just posted the revised #3. :-)
> 
> Why do you think you need such complexity?
> 
> cancel_rearming_delayed_work() will wait until the poll task has
> completed and has been removed from the system.  It's explicitly
> designed for work handlers which self-rearm.

Hmm.. Maybe you're right, because dcc_shutdown and dcc_startup, which
are the only functions that initiate or stop the work, will never be
called concurrently by different callers?

-- 
Hyok
ARM Linux 2.6 MPU/noMMU Project http://opensrc.sec.samsung.com/

Re: [PATCH 2.6.17-rc1] [SERIAL] DCC(JTAG) serial and the console emulation support(revised#2)

[Russell King]

On Tue, Apr 04, 2006 at 06:46:45PM +0900, Hyok S. Choi wrote:
> On Tuesday 04 April 2006 05:20 pm, Russell King wrote:
> > Why do you think you need such complexity?
> > 
> > cancel_rearming_delayed_work() will wait until the poll task has
> > completed and has been removed from the system.  It's explicitly
> > designed for work handlers which self-rearm.
> 
> Hmm.. Maybe you're right, because dcc_shutdown and dcc_startup, which
> are the only functions that initiate or stop the work, will never be
> called concurrently by different callers?

RTFD.  This behaviour _is_ documented.  Documentation/serial/driver:

  startup(port)
	Grab any interrupt resources and initialise any low level driver
	state.  Enable the port for reception.  It should not activate
	RTS nor DTR; this will be done via a separate call to set_mctrl.

	Locking: port_sem taken.
	Interrupts: globally disabled.

  shutdown(port)
	Disable the port, disable any break condition that may be in
	effect, and free any interrupt resources.  It should not disable
	RTS nor DTR; this will have already been done via a separate
	call to set_mctrl.

	Locking: port_sem taken.
	Interrupts: caller dependent.

If the port semaphore is taken prior to calling either function...

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core