/* * Tiny Serial driver * * Copyright (C) 2002-2004 Greg Kroah-Hartman (greg@kroah.com) * *	This program is free software; you can redistribute it and/or modify *	it under the terms of the GNU General Public License as published by *	the Free Software Foundation, version 2 of the License. * * This driver shows how to create a minimal serial driver.  It does not rely on * any backing hardware, but creates a timer that emulates data being received * from some kind of hardware. */#include <linux/kernel.h>#include <linux/errno.h>#include <linux/init.h>#include <linux/slab.h>#include <linux/tty.h>#include <linux/tty_flip.h>#include <linux/serial.h>#include <linux/serial_core.h>#include <linux/module.h>#define DRIVER_AUTHOR "Greg Kroah-Hartman <greg@kroah.com>"#define DRIVER_DESC "Tiny serial driver"/* Module information */MODULE_AUTHOR( DRIVER_AUTHOR );MODULE_DESCRIPTION( DRIVER_DESC );MODULE_LICENSE("GPL");#define DELAY_TIME		HZ * 2	/* 2 seconds per character */#define TINY_DATA_CHARACTER	't'#define TINY_SERIAL_MAJOR	240	/* experimental range */#define TINY_SERIAL_MINORS	1	/* only have one minor */#define UART_NR			1	/* only use one port */#define TINY_SERIAL_NAME	"ttytiny"#define MY_NAME			TINY_SERIAL_NAMEstatic struct timer_list *timer;static void tiny_stop_tx(struct uart_port *port, unsigned int tty_stop){}static void tiny_stop_rx(struct uart_port *port){}static void tiny_enable_ms(struct uart_port *port){}static void tiny_tx_chars(struct uart_port *port){	struct circ_buf *xmit = &port->info->xmit;	int count;	if (port->x_char) {		pr_debug("wrote %2x", port->x_char);		port->icount.tx++;		port->x_char = 0;		return;	}	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {		tiny_stop_tx(port, 0);		return;	}	count = port->fifosize >> 1;	do {		pr_debug("wrote %2x", xmit->buf[xmit->tail]);		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);		port->icount.tx++;		if (uart_circ_empty(xmit))			break;	} while (--count > 0);	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)		uart_write_wakeup(port);	if (uart_circ_empty(xmit))		tiny_stop_tx(port, 0);}static void tiny_start_tx(struct uart_port *port, unsigned int tty_start){}static void tiny_timer(unsigned long data){	struct uart_port *port;	struct tty_struct *tty;	port = (struct uart_port *)data;	if (!port)		return;	if (!port->info)		return;	tty = port->info->tty;	if (!tty)		return;	/* add one character to the tty port */	/* this doesn't actually push the data through unless tty->low_latency is set */	tty_insert_flip_char(tty, TINY_DATA_CHARACTER, 0);	tty_flip_buffer_push(tty);	/* resubmit the timer again */	timer->expires = jiffies + DELAY_TIME;	add_timer(timer);	/* see if we have any data to transmit */	tiny_tx_chars(port);}static unsigned int tiny_tx_empty(struct uart_port *port){	return 0;}static unsigned int tiny_get_mctrl(struct uart_port *port){	return 0;}static void tiny_set_mctrl(struct uart_port *port, unsigned int mctrl){}static void tiny_break_ctl(struct uart_port *port, int break_state){}static void tiny_set_termios(struct uart_port *port,			     struct termios *new, struct termios *old){	int baud, quot, cflag = new->c_cflag;	/* get the byte size */	switch (cflag & CSIZE) {	case CS5:		printk(KERN_DEBUG " - data bits = 5\n");		break;	case CS6:		printk(KERN_DEBUG " - data bits = 6\n");		break;	case CS7:		printk(KERN_DEBUG " - data bits = 7\n");		break;	default: // CS8		printk(KERN_DEBUG " - data bits = 8\n");		break;	}	/* determine the parity */	if (cflag & PARENB)		if (cflag & PARODD)			pr_debug(" - parity = odd\n");		else			pr_debug(" - parity = even\n");	else		pr_debug(" - parity = none\n");	/* figure out the stop bits requested */	if (cflag & CSTOPB)		pr_debug(" - stop bits = 2\n");	else		pr_debug(" - stop bits = 1\n");	/* figure out the flow control settings */	if (cflag & CRTSCTS)		pr_debug(" - RTS/CTS is enabled\n");	else		pr_debug(" - RTS/CTS is disabled\n");	/* Set baud rate */        baud = uart_get_baud_rate(port, new, old, 0, port->uartclk/16);        quot = uart_get_divisor(port, baud);		//UART_PUT_DIV_LO(port, (quot & 0xff));	//UART_PUT_DIV_HI(port, ((quot & 0xf00) >> 8));}static int tiny_startup(struct uart_port *port){	/* this is the first time this port is opened */	/* do any hardware initialization needed here */	/* create our timer and submit it */	if (!timer) {		timer = kmalloc(sizeof(*timer), GFP_KERNEL);		if (!timer)			return -ENOMEM;	}	timer->data = (unsigned long)port;	timer->expires = jiffies + DELAY_TIME;	timer->function = tiny_timer;	add_timer(timer);	return 0;}static void tiny_shutdown(struct uart_port *port){	/* The port is being closed by the last user. */	/* Do any hardware specific stuff here */	/* shut down our timer */	del_timer(timer);}static const char *tiny_type(struct uart_port *port){	return "tinytty";}static void tiny_release_port(struct uart_port *port){}static int tiny_request_port(struct uart_port *port){	return 0;}static void tiny_config_port(struct uart_port *port, int flags){}static int tiny_verify_port(struct uart_port *port, struct serial_struct *ser){	return 0;}static struct uart_ops tiny_ops = {	.tx_empty	= tiny_tx_empty,	.set_mctrl	= tiny_set_mctrl,	.get_mctrl	= tiny_get_mctrl,	.stop_tx	= tiny_stop_tx,	.start_tx	= tiny_start_tx,	.stop_rx	= tiny_stop_rx,	.enable_ms	= tiny_enable_ms,	.break_ctl	= tiny_break_ctl,	.startup	= tiny_startup,	.shutdown	= tiny_shutdown,	.set_termios	= tiny_set_termios,	.type		= tiny_type,	.release_port	= tiny_release_port,	.request_port	= tiny_request_port,	.config_port	= tiny_config_port,	.verify_port	= tiny_verify_port,};static struct uart_port tiny_port = {	.ops		= &tiny_ops,};static struct uart_driver tiny_reg = {	.owner		= THIS_MODULE,	.driver_name	= TINY_SERIAL_NAME,	.dev_name	= TINY_SERIAL_NAME,	.major		= TINY_SERIAL_MAJOR,	.minor		= TINY_SERIAL_MINORS,	.nr		= UART_NR,};static int __init tiny_init(void){	int result;	printk(KERN_INFO "Tiny serial driver loaded\n");	result = uart_register_driver(&tiny_reg);	if (result)		return result;	result = uart_add_one_port(&tiny_reg, &tiny_port);	if (result)		uart_unregister_driver(&tiny_reg);	return result;}module_init(tiny_init);