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Subject[PATCH 2.6.16-git] [SERIAL] Adds DCC(JTAG) serial and the console emulation support (revised)
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 | 493 +++++++++++++++++++++++++++++++++++++++++++
include/linux/serial_core.h | 3
4 files changed, 528 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..449e04d
--- /dev/null
+++ b/drivers/serial/dcc.c
@@ -0,0 +1,493 @@
+/*
+ * 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
+#define DCC_POLL_RUN 0
+#define DCC_POLL_STOP 1
+#define DCC_POLL_STOPPED 2
+static struct work_struct dcc_poll_task;
+static void dcc_poll(void *data);
+static int dcc_poll_state = DCC_POLL_STOPPED;
+#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
+#else
+/* use ttyJ0(128) */
+#define SERIAL_DCC_NAME "ttyJ"
+#define SERIAL_DCC_MINOR (64 + 64)
+#endif
+#define SERIAL_DCC_MAJOR TTY_MAJOR
+
+/* DCC Status Bits */
+#define DCC_STATUS_RX (1 << 0)
+#define DCC_STATUS_TX (1 << 1)
+
+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));
+}
+
+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_overrun_chars(struct uart_port *port)
+{
+ port->icount.overrun++;
+}
+
+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);
+
+ if (dcc_poll_state != DCC_POLL_RUN) {
+ dcc_poll_state = DCC_POLL_STOPPED;
+ goto dcc_poll_stop;
+ }
+
+ dcc_rx_chars(port);
+ dcc_tx_chars(port);
+
+ schedule_delayed_work(&dcc_poll_task, 1);
+
+dcc_poll_stop:
+ 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 */
+ /* Initialize the work, and shcedule it. */
+ INIT_WORK(&dcc_poll_task, dcc_poll, port);
+ spin_lock(&port->lock);
+ if (dcc_poll_state != DCC_POLL_RUN)
+ dcc_poll_state = DCC_POLL_RUN;
+ schedule_delayed_work(&dcc_poll_task, 1);
+ spin_unlock(&port->lock);
+#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);
+ dcc_poll_state = DCC_POLL_STOP;
+ 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;
+
+ 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>
-
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