/*
* Tiny TTY driver
*
* Copyright (C) 2002 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 using the 2.5
* kernel's serial driver layer. It does not rely on any backing hardware, but
* creates a timer that emulates data being received from some kind of
* hardware.
*
* Compiled this driver with:
CFLAGS = -Wall -O2 -fomit-frame-pointer -DMODULE -D__KERNEL__
IDIR = /path/to/linux-2.5/include/goes/here
tiny_serial.o::tiny_serial.c
$(CC) $(CFLAGS) -I$(IDIR) -c -o $@ $<
*/
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define DRIVER_VERSION "v1.0"
#define DRIVER_AUTHOR "Greg Kroah-Hartman "
#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_NAME
#define dbg(fmt, arg...) \
do { \
if (debug) \
printk (KERN_DEBUG "%s: %s: " fmt "\n", \
MY_NAME , __FUNCTION__ , ## arg); \
} while (0)
#define err(format, arg...) printk(KERN_ERR "%s: " format "\n" , MY_NAME , ## arg)
#define info(format, arg...) printk(KERN_INFO "%s: " format "\n" , MY_NAME , ## arg)
#define warn(format, arg...) printk(KERN_WARNING "%s: " format "\n" , MY_NAME , ## arg)
static int debug;
MODULE_PARM(debug, "i");
MODULE_PARM_DESC(debug, "Debugging mode enabled or not");
static struct timer_list *timer;
static void tiny_stop_tx(struct uart_port *port, unsigned int tty_stop)
{
dbg ();
}
static void tiny_stop_rx(struct uart_port *port)
{
dbg ();
}
static void tiny_enable_ms(struct uart_port *port)
{
dbg ();
}
static void tiny_tx_chars(struct uart_port *port)
{
struct circ_buf *xmit = &port->info->xmit;
int count;
dbg ();
if (port->x_char) {
dbg ("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 {
dbg ("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_event(port, EVT_WRITE_WAKEUP);
if (uart_circ_empty(xmit))
tiny_stop_tx(port, 0);
}
static void tiny_start_tx(struct uart_port *port, unsigned int tty_start)
{
dbg ();
}
static void tiny_timer (unsigned long data)
{
struct uart_port *port;
struct tty_struct *tty;
dbg ();
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_change_speed(struct uart_port *port, unsigned int cflag,
unsigned int iflag, unsigned int quot)
{
/* get the byte size */
switch (cflag & CSIZE) {
case CS5:
dbg ("data bits = 5");
break;
case CS6:
dbg ("data bits = 6");
break;
case CS7:
dbg ("data bits = 7");
break;
default: // CS8
dbg ("data bits = 8");
break;
}
/* determine the parity */
if (cflag & PARENB)
if (cflag & PARODD)
dbg (" - parity = odd\n");
else
dbg (" - parity = even\n");
else
dbg (" - parity = none\n");
/* figure out the stop bits requested */
if (cflag & CSTOPB)
dbg (" - stop bits = 2\n");
else
dbg (" - stop bits = 1\n");
/* figure out the flow control settings */
if (cflag & CRTSCTS)
dbg (" - RTS/CTS is enabled\n");
else
dbg (" - RTS/CTS is disabled\n");
/* Set baud rate */
//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,
.change_speed = tiny_change_speed,
.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;
info ("Tiny serial driver");
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);