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Commit f2d937f3 authored by Jason Wessel's avatar Jason Wessel Committed by Ingo Molnar
Browse files

consoles: polling support, kgdboc 



polled console handling support, to access a console in an irq-less
way while in debug or irq context.

absolutely zero impact as long as CONFIG_CONSOLE_POLL is disabled.
(which is the default)

[ jan.kiszka@siemens.com: lots of cleanups ]
[ mingo@elte.hu: redesign, splitups, cleanups. ]

Signed-off-by: default avatarJason Wessel <jason.wessel@windriver.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarJan Kiszka <jan.kiszka@web.de>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent dc7d5527

drivers/char/tty_io.c

+47 −0
Original line number Original line Diff line number Diff line
@@ -1155,6 +1155,48 @@ static struct tty_driver *get_tty_driver(dev_t device, int *index) 
	return NULL;

	return NULL;

}

}





#ifdef CONFIG_CONSOLE_POLL



/**

 *	tty_find_polling_driver	-	find device of a polled tty

 *	@name: name string to match

 *	@line: pointer to resulting tty line nr

 *

 *	This routine returns a tty driver structure, given a name

 *	and the condition that the tty driver is capable of polled

 *	operation.

 */

struct tty_driver *tty_find_polling_driver(char *name, int *line)

{

	struct tty_driver *p, *res = NULL;

	int tty_line = 0;

	char *str;



	mutex_lock(&tty_mutex);

	/* Search through the tty devices to look for a match */

	list_for_each_entry(p, &tty_drivers, tty_drivers) {

		str = name + strlen(p->name);

		tty_line = simple_strtoul(str, &str, 10);

		if (*str == ',')

			str++;

		if (*str == '\0')

			str = 0;



		if (tty_line >= 0 && tty_line <= p->num && p->poll_init &&

				!p->poll_init(p, tty_line, str)) {



			res = p;

			*line = tty_line;

			break;

		}

	}

	mutex_unlock(&tty_mutex);



	return res;

}

EXPORT_SYMBOL_GPL(tty_find_polling_driver);

#endif



/**

/**

 *	tty_check_change	-	check for POSIX terminal changes

 *	tty_check_change	-	check for POSIX terminal changes

 *	@tty: tty to check

 *	@tty: tty to check
@@ -3850,6 +3892,11 @@ void tty_set_operations(struct tty_driver *driver, 
	driver->write_proc = op->write_proc;

	driver->write_proc = op->write_proc;

	driver->tiocmget = op->tiocmget;

	driver->tiocmget = op->tiocmget;

	driver->tiocmset = op->tiocmset;

	driver->tiocmset = op->tiocmset;

#ifdef CONFIG_CONSOLE_POLL

	driver->poll_init = op->poll_init;

	driver->poll_get_char = op->poll_get_char;

	driver->poll_put_char = op->poll_put_char;

#endif

}

}

drivers/serial/8250.c

+58 −0
Original line number Original line Diff line number Diff line
@@ -1740,6 +1740,60 @@ static inline void wait_for_xmitr(struct uart_8250_port *up, int bits) 
	}

	}

}

}





#ifdef CONFIG_CONSOLE_POLL

/*

 * Console polling routines for writing and reading from the uart while

 * in an interrupt or debug context.

 */



static int serial8250_get_poll_char(struct uart_port *port)

{

	struct uart_8250_port *up = (struct uart_8250_port *)port;

	unsigned char lsr = serial_inp(up, UART_LSR);



	while (!(lsr & UART_LSR_DR))

		lsr = serial_inp(up, UART_LSR);



	return serial_inp(up, UART_RX);

}





static void serial8250_put_poll_char(struct uart_port *port,

			 unsigned char c)

{

	unsigned int ier;

	struct uart_8250_port *up = (struct uart_8250_port *)port;



	/*

	 *	First save the IER then disable the interrupts

	 */

	ier = serial_in(up, UART_IER);

	if (up->capabilities & UART_CAP_UUE)

		serial_out(up, UART_IER, UART_IER_UUE);

	else

		serial_out(up, UART_IER, 0);



	wait_for_xmitr(up, BOTH_EMPTY);

	/*

	 *	Send the character out.

	 *	If a LF, also do CR...

	 */

	serial_out(up, UART_TX, c);

	if (c == 10) {

		wait_for_xmitr(up, BOTH_EMPTY);

		serial_out(up, UART_TX, 13);

	}



	/*

	 *	Finally, wait for transmitter to become empty

	 *	and restore the IER

	 */

	wait_for_xmitr(up, BOTH_EMPTY);

	serial_out(up, UART_IER, ier);

}



#endif /* CONFIG_CONSOLE_POLL */



static int serial8250_startup(struct uart_port *port)

static int serial8250_startup(struct uart_port *port)

{

{

	struct uart_8250_port *up = (struct uart_8250_port *)port;

	struct uart_8250_port *up = (struct uart_8250_port *)port;
@@ -2386,6 +2440,10 @@ static struct uart_ops serial8250_pops = { 
	.request_port	= serial8250_request_port,

	.request_port	= serial8250_request_port,

	.config_port	= serial8250_config_port,

	.config_port	= serial8250_config_port,

	.verify_port	= serial8250_verify_port,

	.verify_port	= serial8250_verify_port,

#ifdef CONFIG_CONSOLE_POLL

	.poll_get_char = serial8250_get_poll_char,

	.poll_put_char = serial8250_put_poll_char,

#endif

};

};





static struct uart_8250_port serial8250_ports[UART_NR];

static struct uart_8250_port serial8250_ports[UART_NR];

drivers/serial/Kconfig

+3 −0
Original line number Original line Diff line number Diff line
@@ -961,6 +961,9 @@ config SERIAL_CORE 
config SERIAL_CORE_CONSOLE

config SERIAL_CORE_CONSOLE

	bool

	bool





config CONSOLE_POLL

	bool



config SERIAL_68328

config SERIAL_68328

	bool "68328 serial support"

	bool "68328 serial support"

	depends on M68328 || M68EZ328 || M68VZ328

	depends on M68328 || M68EZ328 || M68VZ328

drivers/serial/Makefile

+1 −0
Original line number Original line Diff line number Diff line
@@ -66,4 +66,5 @@ obj-$(CONFIG_SERIAL_UARTLITE) += uartlite.o 
obj-$(CONFIG_SERIAL_NETX) += netx-serial.o

obj-$(CONFIG_SERIAL_NETX) += netx-serial.o

obj-$(CONFIG_SERIAL_OF_PLATFORM) += of_serial.o

obj-$(CONFIG_SERIAL_OF_PLATFORM) += of_serial.o

obj-$(CONFIG_SERIAL_KS8695) += serial_ks8695.o

obj-$(CONFIG_SERIAL_KS8695) += serial_ks8695.o

obj-$(CONFIG_KGDB_SERIAL_CONSOLE) += kgdboc.o

obj-$(CONFIG_SERIAL_QE) += ucc_uart.o
 
obj-$(CONFIG_SERIAL_QE) += ucc_uart.o

drivers/serial/kgdboc.c

0 → 100644
+163 −0
Original line number Original line Diff line number Diff line 
/*

 * Based on the same principle as kgdboe using the NETPOLL api, this

 * driver uses a console polling api to implement a gdb serial inteface

 * which is multiplexed on a console port.

 *

 * Maintainer: Jason Wessel <jason.wessel@windriver.com>

 *

 * 2007-2008 (c) Jason Wessel - Wind River Systems, Inc.

 *

 * This file is licensed under the terms of the GNU General Public

 * License version 2. This program is licensed "as is" without any

 * warranty of any kind, whether express or implied.

 */

#include <linux/kernel.h>

#include <linux/ctype.h>

#include <linux/kgdb.h>

#include <linux/tty.h>



#define MAX_CONFIG_LEN		40



static struct kgdb_io		kgdboc_io_ops;



/* -1 = init not run yet, 0 = unconfigured, 1 = configured. */

static int configured		= -1;



static char config[MAX_CONFIG_LEN];

static struct kparam_string kps = {

	.string			= config,

	.maxlen			= MAX_CONFIG_LEN,

};



static struct tty_driver	*kgdb_tty_driver;

static int			kgdb_tty_line;



static int kgdboc_option_setup(char *opt)

{

	if (strlen(opt) > MAX_CONFIG_LEN) {

		printk(KERN_ERR "kgdboc: config string too long\n");

		return -ENOSPC;

	}

	strcpy(config, opt);



	return 0;

}



__setup("kgdboc=", kgdboc_option_setup);



static int configure_kgdboc(void)

{

	struct tty_driver *p;

	int tty_line = 0;

	int err;



	err = kgdboc_option_setup(config);

	if (err || !strlen(config) || isspace(config[0]))

		goto noconfig;



	err = -ENODEV;



	p = tty_find_polling_driver(config, &tty_line);

	if (!p)

		goto noconfig;



	kgdb_tty_driver = p;

	kgdb_tty_line = tty_line;



	err = kgdb_register_io_module(&kgdboc_io_ops);

	if (err)

		goto noconfig;



	configured = 1;



	return 0;



noconfig:

	config[0] = 0;

	configured = 0;



	return err;

}



static int __init init_kgdboc(void)

{

	/* Already configured? */

	if (configured == 1)

		return 0;



	return configure_kgdboc();

}



static void cleanup_kgdboc(void)

{

	if (configured == 1)

		kgdb_unregister_io_module(&kgdboc_io_ops);

}



static int kgdboc_get_char(void)

{

	return kgdb_tty_driver->poll_get_char(kgdb_tty_driver, kgdb_tty_line);

}



static void kgdboc_put_char(u8 chr)

{

	kgdb_tty_driver->poll_put_char(kgdb_tty_driver, kgdb_tty_line, chr);

}



static int param_set_kgdboc_var(const char *kmessage, struct kernel_param *kp)

{

	if (strlen(kmessage) >= MAX_CONFIG_LEN) {

		printk(KERN_ERR "kgdboc: config string too long\n");

		return -ENOSPC;

	}



	/* Only copy in the string if the init function has not run yet */

	if (configured < 0) {

		strcpy(config, kmessage);

		return 0;

	}



	if (kgdb_connected) {

		printk(KERN_ERR

		       "kgdboc: Cannot reconfigure while KGDB is connected.\n");



		return -EBUSY;

	}



	strcpy(config, kmessage);



	if (configured == 1)

		cleanup_kgdboc();



	/* Go and configure with the new params. */

	return configure_kgdboc();

}



static void kgdboc_pre_exp_handler(void)

{

	/* Increment the module count when the debugger is active */

	if (!kgdb_connected)

		try_module_get(THIS_MODULE);

}



static void kgdboc_post_exp_handler(void)

{

	/* decrement the module count when the debugger detaches */

	if (!kgdb_connected)

		module_put(THIS_MODULE);

}



static struct kgdb_io kgdboc_io_ops = {

	.name			= "kgdboc",

	.read_char		= kgdboc_get_char,

	.write_char		= kgdboc_put_char,

	.pre_exception		= kgdboc_pre_exp_handler,

	.post_exception		= kgdboc_post_exp_handler,

};



module_init(init_kgdboc);

module_exit(cleanup_kgdboc);

module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644);

MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]");

MODULE_DESCRIPTION("KGDB Console TTY Driver");

MODULE_LICENSE("GPL");