/* * arch/v850/kernel/memcons.c -- Console I/O to a memory buffer * *  Copyright (C) 2001,02  NEC Corporation *  Copyright (C) 2001,02  Miles Bader <miles@gnu.org> * * This file is subject to the terms and conditions of the GNU General * Public License.  See the file COPYING in the main directory of this * archive for more details. * * Written by Miles Bader <miles@gnu.org> */ #include <linux/kernel.h>#include <linux/console.h>#include <linux/tty.h>#include <linux/tty_driver.h>#include <linux/init.h> /* If this device is enabled, the linker map should define start and   end points for its buffer. */extern char memcons_output[], memcons_output_end; /* Current offset into the buffer.  */static unsigned long memcons_offs = 0; /* Spinlock protecting memcons_offs.  */static DEFINE_SPINLOCK(memcons_lock);  static size_t write (const char *buf, size_t len){	unsigned long flags;	char *point; 	spin_lock_irqsave (memcons_lock, flags); 	point = memcons_output + memcons_offs;	if (point + len >= &memcons_output_end) {		len = &memcons_output_end - point;		memcons_offs = 0;	} else		memcons_offs += len; 	spin_unlock_irqrestore (memcons_lock, flags); 	memcpy (point, buf, len); 	return len;} /*  Low-level console. */ static void memcons_write (struct console *co, const char *buf, unsigned len){	while (len > 0)		len -= write (buf, len);} static struct tty_driver *tty_driver; static struct tty_driver *memcons_device (struct console *co, int *index){	*index = co->index;	return tty_driver;} static struct console memcons ={    .name	= "memcons",    .write	= memcons_write,    .device	= memcons_device,    .flags	= CON_PRINTBUFFER,    .index	= -1,}; void memcons_setup (void){	register_console (&memcons);	printk (KERN_INFO "Console: static memory buffer (memcons)\n");}/* Higher level TTY interface.  */ int memcons_tty_open (struct tty_struct *tty, struct file *filp){	return 0;} int memcons_tty_write (struct tty_struct *tty, const unsigned char *buf, int len){	return write (buf, len);} int memcons_tty_write_room (struct tty_struct *tty){	return &memcons_output_end - (memcons_output + memcons_offs);} int memcons_tty_chars_in_buffer (struct tty_struct *tty){	/* We have no buffer.  */	return 0;} static const struct tty_operations ops = {	.open = memcons_tty_open,	.write = memcons_tty_write,	.write_room = memcons_tty_write_room,	.chars_in_buffer = memcons_tty_chars_in_buffer,}; int __init memcons_tty_init (void){	int err;	struct tty_driver *driver = alloc_tty_driver(1);	if (!driver)		return -ENOMEM; 	driver->name = "memcons";	driver->major = TTY_MAJOR;	driver->minor_start = 64;	driver->type = TTY_DRIVER_TYPE_SYSCONS;	driver->init_termios = tty_std_termios;	tty_set_operations(driver, &ops);	err = tty_register_driver(driver);	if (err) {		put_tty_driver(driver);		return err;	}	tty_driver = driver;	return 0;}__initcall (memcons_tty_init);