Re: LDD3: tiny_serial and tiny_tty

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hi there,
Since API have changed so much, you need to change the code in accordance.
I was having some problem for all drivers i was compiling with my .23 kernel

there is this guy who have updated all drivers for .25 kernel at this link:
http://www.cs.fsu.edu/~baker/devices/lxr/source/2.6.25/ldd-examples/

Hope this helps

-Anuz

On Wed, Oct 22, 2008 at 4:01 PM, luca ellero <lroluk@xxxxxxxxx> wrote:
Hi everybody,
I'm trying to compile the examples of LDD3 with kernel 2.6.22.
I get them from:

 http://www.oreilly.com.cn/codeexample/ldd3/

I have some problems/questions regarding tiny_tty.c and tiny_serial.c (tty directory concerning chapter 18)

1) Are they tty or uart drivers? What is the main difference between the two?
2) I managed to compile tiny_serial.c, with some modifications to the source (which I've reported at the end of my e-mail), but when I "cat /dev/ttytiny" nothing happens (I would expect to get the 't' char every 2 sec). With some printk I can see that the tiny_timer is running fine but it seems that the characters aren't pushed to user space.
3) I can't even compile tiny_tty.c. It seems the problem is in the change of the flip buffer implementation but I can find a good example of using this new code.

Thank you very much
regards
Luca

---------------------------------------------------------

/*
 * Tiny Serial driver
 *
 * Copyright (C) 2002-2004 Greg Kroah-Hartman (greg@xxxxxxxxx)
 *
 *      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@xxxxxxxxx>"
#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

static struct timer_list *timer;

static void tiny_stop_tx(struct uart_port *port)
{
}

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);
               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);
}

static void tiny_start_tx(struct uart_port *port)
{
}

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 ktermios *new, struct ktermios *old)
{
//      int baud, quot,
int  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;
       }
       init_timer(timer);
       timer->data = "" 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;

       tiny_port.type = PORT_16550A;


       result = uart_add_one_port(&tiny_reg, &tiny_port);
       if (result)
               uart_unregister_driver(&tiny_reg);

       return result;
}

static void __exit tiny_exit(void)
{
       uart_remove_one_port(&tiny_reg, &tiny_port);
       uart_unregister_driver(&tiny_reg);

}

module_init(tiny_init);
module_exit(tiny_exit);


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