Thank you very much for you help.

BTW, for cat < /dev/my_tty1 can see here something wrong?
as I understand tiny_timer function sends data to tty level
by calling tty_flip_buffer_push(tty).

Is this enough to support cat < /dev/my_tty1?


>On Wed, Feb 21, 2007 at 06:03:16PM +0300, Mockern wrote:
>> I tried to check cat operations for tiny_tty driver from LDD book. 
>> 
>> What is wrong with cat operation here?
>> 
>> Here is the output from strace cat hello > /dev/my_tty1
>> 
>> [EMAIL PROTECTED]:/home# strace cat hello > /dev/my_tty1
>> execve("/bin/cat", ["cat", "hello"], [/* 12 vars */]) = 0
>> brk(0)                                  = 0x7d000
>> open("/etc/ld.so.preload", O_RDONLY)    = -1 ENOENT (No such file or 
>> directory)
>> open("/etc/ld.so.cache", O_RDONLY)      = 3
>> fstat64(3, {st_mode=S_IFREG|0644, st_size=5664, ...}) = 0
>> old_mmap(NULL, 5664, PROT_READ, MAP_PRIVATE, 3, 0) = 0x40017000
>> close(3)                                = 0
>> open("/lib/libm.so.6", O_RDONLY)        = 3
>> read(3, "\177ELF\1\1\1a\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0\250B\0\000"..., 512) 
>> = 51
>> 2
>> fstat64(3, {st_mode=S_IFREG|0755, st_size=480324, ...}) = 0
>> old_mmap(NULL, 506412, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x40020000
>> mprotect(0x40093000, 35372, PROT_NONE)  = 0
>> old_mmap(0x40098000, 16384, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 
>> 0x70
>> 000) = 0x40098000
>> close(3)                                = 0
>> open("/lib/libcrypt.so.1", O_RDONLY)    = 3
>> read(3, "\177ELF\1\1\1a\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0\260\10\0"..., 512) = 
>> 512
>> fstat64(3, {st_mode=S_IFREG|0755, st_size=19940, ...}) = 0
>> old_mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) 
>> = 0
>> x40019000
>> old_mmap(NULL, 211220, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x4009c000
>> mprotect(0x400a1000, 190740, PROT_NONE) = 0
>> old_mmap(0x400a4000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 
>> 0) =
>>  0x400a4000
>> old_mmap(0x400a9000, 157972, PROT_READ|PROT_WRITE, 
>> MAP_PRIVATE|MAP_FIXED|MAP_ANO
>> NYMOUS, -1, 0) = 0x400a9000
>> close(3)                                = 0
>> open("/lib/libc.so.6", O_RDONLY)        = 3
>> read(3, "\177ELF\1\1\1a\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0\330p\1\000"..., 512) 
>> = 51
>> 2
>> fstat64(3, {st_mode=S_IFREG|0755, st_size=1240024, ...}) = 0
>> old_mmap(NULL, 1257088, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x400d0000
>> mprotect(0x401f5000, 56960, PROT_NONE)  = 0
>> old_mmap(0x401f8000, 36864, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 
>> 0x12
>> 0000) = 0x401f8000
>> old_mmap(0x40201000, 7808, PROT_READ|PROT_WRITE, 
>> MAP_PRIVATE|MAP_FIXED|MAP_ANONY
>> MOUS, -1, 0) = 0x40201000
>> close(3)                                = 0
>> munmap(0x40017000, 5664)                = 0
>> getuid32()                              = 0
>> getgid32()                              = 0
>> setgid32(0)                             = 0
>> setuid32(0)                             = 0
>> brk(0)                                  = 0x7d000
>> brk(0x9e000)                            = 0x9e000
>> brk(0)                                  = 0x9e000
>> open("hello", O_RDONLY)                 = 3
>> read(3, "123456789", 8192)              = 9
>> write(1, "123456789", 9)                = -1 EINVAL (Invalid 
>> argument)//??????????
>> write(2, "cat: ", 5cat: )                    = 5
>> write(2, "Write Error", 11Write Error)             = 11
>> write(2, ": Invalid argument\n", 19: Invalid argument
>> )    = 19
>> close(3)                                = 0
>> io_submit(0, 0x40200164, 0 <unfinished ... exit status 0>
>> Process 1432 detached
>> [EMAIL PROTECTED]:/home#
>> 
>> ------------------------------------------------------------------------------------
>> 
>> /*
>>  * Tiny TTY driver
>>  *
>>  * Copyright (C) 2002-2004 Greg Kroah-Hartman ([EMAIL PROTECTED])
>>  *
>>  *   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 tty 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/config.h>
>> #include <linux/kernel.h>
>> #include <linux/errno.h>
>> #include <linux/init.h>
>> #include <linux/module.h>
>> #include <linux/slab.h>
>> #include <linux/wait.h>
>> #include <linux/tty.h>
>> #include <linux/tty_driver.h>
>> #include <linux/tty_flip.h>
>> #include <linux/serial.h>
>> #include <asm/uaccess.h>
>> 
>> 
>> #define DRIVER_VERSION "v2.0"
>> #define DRIVER_AUTHOR "Greg Kroah-Hartman <[EMAIL PROTECTED]>"
>> #define DRIVER_DESC "Tiny TTY 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_TTY_MAJOR               240     /* experimental range */
>> #define TINY_TTY_MINORS              4       /* only have 4 devices */
>> 
>> struct tiny_serial {
>>      struct tty_struct       *tty;           /* pointer to the tty for this 
>> device */
>>      int                     open_count;     /* number of times this port 
>> has been opened */
>>      struct semaphore        sem;            /* locks this structure */
>>      struct timer_list       *timer;
>> 
>>      /* for tiocmget and tiocmset functions */
>>      int                     msr;            /* MSR shadow */
>>      int                     mcr;            /* MCR shadow */
>> 
>>      /* for ioctl fun */
>>      struct serial_struct    serial;
>>      wait_queue_head_t       wait;
>>      struct async_icount     icount;
>> };
>> 
>> static struct tiny_serial *tiny_table[TINY_TTY_MINORS];      /* initially 
>> all NULL */
>> 
>> 
>> static void tiny_timer(unsigned long timer_data)
>> {
>>      struct tiny_serial *tiny = (struct tiny_serial *)timer_data;
>>      struct tty_struct *tty;
>>      int i;
>>      char data[1] = {TINY_DATA_CHARACTER};
>>      int data_size = 1;
>> 
>>      if (!tiny)
>>              return;
>> 
>>      tty = tiny->tty;
>> 
>>      /* send the data to the tty layer for users to read.  This doesn't
>>       * actually push the data through unless tty->low_latency is set */
>>      for (i = 0; i < data_size; ++i) {
>>              if (tty->flip.count >= TTY_FLIPBUF_SIZE)
>>                      tty_flip_buffer_push(tty);
>>              tty_insert_flip_char(tty, data[i], TTY_NORMAL);
>>      }
>>      tty_flip_buffer_push(tty);
>> 
>>      /* resubmit the timer again */
>>      tiny->timer->expires = jiffies + DELAY_TIME;
>>      add_timer(tiny->timer);
>> }
>> 
>> static int tiny_open(struct tty_struct *tty, struct file *file)
>> {
>>      struct tiny_serial *tiny;
>>      struct timer_list *timer;
>>      int index;
>> 
>>      /* initialize the pointer in case something fails */
>>      tty->driver_data = NULL;
>> 
>>      /* get the serial object associated with this tty pointer */
>>      index = tty->index;
>>      tiny = tiny_table[index];
>>      if (tiny == NULL) {
>>              /* first time accessing this device, let's create it */
>>              tiny = kmalloc(sizeof(*tiny), GFP_KERNEL);
>>              if (!tiny)
>>                      return -ENOMEM;
>> 
>>              init_MUTEX(&tiny->sem);
>>              tiny->open_count = 0;
>>              tiny->timer = NULL;
>> 
>>              tiny_table[index] = tiny;
>>      }
>> 
>>      down(&tiny->sem);
>> 
>>      /* save our structure within the tty structure */
>>      tty->driver_data = tiny;
>>      tiny->tty = tty;
>> 
>>      ++tiny->open_count;
>>      if (tiny->open_count == 1) {
>>              /* this is the first time this port is opened */
>>              /* do any hardware initialization needed here */
>> 
>>              /* create our timer and submit it */
>>              if (!tiny->timer) {
>>                      timer = kmalloc(sizeof(*timer), GFP_KERNEL);
>>                      if (!timer) {
>>                              up(&tiny->sem);
>>                              return -ENOMEM;
>>                      }
>>                      tiny->timer = timer;
>>              }
>>              tiny->timer->data = (unsigned long )tiny;
>>              tiny->timer->expires = jiffies + DELAY_TIME;
>>              tiny->timer->function = tiny_timer;
>>              add_timer(tiny->timer);
>>      }
>> 
>>      up(&tiny->sem);
>>      return 0;
>> }
>> 
>> static void do_close(struct tiny_serial *tiny)
>> {
>>      down(&tiny->sem);
>> 
>>      if (!tiny->open_count) {
>>              /* port was never opened */
>>              goto exit;
>>      }
>> 
>>      --tiny->open_count;
>>      if (tiny->open_count <= 0) {
>>              /* The port is being closed by the last user. */
>>              /* Do any hardware specific stuff here */
>> 
>>              /* shut down our timer */
>>              del_timer(tiny->timer);
>>      }
>> exit:
>>      up(&tiny->sem);
>> }
>> 
>> static void tiny_close(struct tty_struct *tty, struct file *file)
>> {
>>      struct tiny_serial *tiny = tty->driver_data;
>> 
>>      if (tiny)
>>              do_close(tiny);
>> }
>> 
>> static int tiny_write(struct tty_struct *tty, const unsigned char *buffer, 
>> int count)
>> {
>>      struct tiny_serial *tiny = tty->driver_data;
>>      int i;
>>      int retval = -EINVAL;
>
>Here you set retval to EINVAL.
>
>>      if (!tiny)
>>              return -ENODEV;
>> 
>>      down(&tiny->sem);
>> 
>>      if (!tiny->open_count)
>>              /* port was not opened */
>>              goto exit;
>> 
>>      /* fake sending the data out a hardware port by
>>       * writing it to the kernel debug log.
>>       */
>>      printk(KERN_DEBUG "%s - ", __FUNCTION__);
>>      for (i = 0; i < count; ++i)
>>              printk("%02x ", buffer[i]);
>>      printk("\n");
>> 
>> exit:
>>      up(&tiny->sem);
>>      return retval;
>
>Now you return it.  You never changed it.  No wonder cat receives
>'EINVAL' as a response to its write request.  This is obviously not what
>you intended.
>
>> }
>> 
>> static int tiny_write_room(struct tty_struct *tty)
>> {
>>      struct tiny_serial *tiny = tty->driver_data;
>>      int room = -EINVAL;
>> 
>>      if (!tiny)
>>              return -ENODEV;
>> 
>>      down(&tiny->sem);
>> 
>>      if (!tiny->open_count) {
>>              /* port was not opened */
>>              goto exit;
>>      }
>> 
>>      /* calculate how much room is left in the device */
>>      room = 255;
>> 
>> exit:
>>      up(&tiny->sem);
>>      return room;
>> }
>> 
>> #define RELEVANT_IFLAG(iflag) ((iflag) & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))
>> 
>> static void tiny_set_termios(struct tty_struct *tty, struct termios 
>> *old_termios)
>> {
>>      unsigned int cflag;
>> 
>>      cflag = tty->termios->c_cflag;
>> 
>>      /* check that they really want us to change something */
>>      if (old_termios) {
>>              if ((cflag == old_termios->c_cflag) &&
>>                  (RELEVANT_IFLAG(tty->termios->c_iflag) ==
>>                   RELEVANT_IFLAG(old_termios->c_iflag))) {
>>                      printk(KERN_DEBUG " - nothing to change...\n");
>>                      return;
>>              }
>>      }
>> 
>>      /* 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:
>>              case CS8:
>>                      printk(KERN_DEBUG " - data bits = 8\n");
>>                      break;
>>      }
>> 
>>      /* determine the parity */
>>      if (cflag & PARENB)
>>              if (cflag & PARODD)
>>                      printk(KERN_DEBUG " - parity = odd\n");
>>              else
>>                      printk(KERN_DEBUG " - parity = even\n");
>>      else
>>              printk(KERN_DEBUG " - parity = none\n");
>> 
>>      /* figure out the stop bits requested */
>>      if (cflag & CSTOPB)
>>              printk(KERN_DEBUG " - stop bits = 2\n");
>>      else
>>              printk(KERN_DEBUG " - stop bits = 1\n");
>> 
>>      /* figure out the hardware flow control settings */
>>      if (cflag & CRTSCTS)
>>              printk(KERN_DEBUG " - RTS/CTS is enabled\n");
>>      else
>>              printk(KERN_DEBUG " - RTS/CTS is disabled\n");
>> 
>>      /* determine software flow control */
>>      /* if we are implementing XON/XOFF, set the start and
>>       * stop character in the device */
>>      if (I_IXOFF(tty) || I_IXON(tty)) {
>>              unsigned char stop_char  = STOP_CHAR(tty);
>>              unsigned char start_char = START_CHAR(tty);
>> 
>>              /* if we are implementing INBOUND XON/XOFF */
>>              if (I_IXOFF(tty))
>>                      printk(KERN_DEBUG " - INBOUND XON/XOFF is enabled, "
>>                              "XON = %2x, XOFF = %2x", start_char, stop_char);
>>              else
>>                      printk(KERN_DEBUG" - INBOUND XON/XOFF is disabled");
>> 
>>              /* if we are implementing OUTBOUND XON/XOFF */
>>              if (I_IXON(tty))
>>                      printk(KERN_DEBUG" - OUTBOUND XON/XOFF is enabled, "
>>                              "XON = %2x, XOFF = %2x", start_char, stop_char);
>>              else
>>                      printk(KERN_DEBUG" - OUTBOUND XON/XOFF is disabled");
>>      }
>> 
>>      /* get the baud rate wanted */
>>      printk(KERN_DEBUG " - baud rate = %d", tty_get_baud_rate(tty));
>> }
>> 
>> /* Our fake UART values */
>> #define MCR_DTR              0x01
>> #define MCR_RTS              0x02
>> #define MCR_LOOP     0x04
>> #define MSR_CTS              0x08
>> #define MSR_CD               0x10
>> #define MSR_RI               0x20
>> #define MSR_DSR              0x40
>> 
>> static int tiny_tiocmget(struct tty_struct *tty, struct file *file)
>> {
>>      struct tiny_serial *tiny = tty->driver_data;
>> 
>>      unsigned int result = 0;
>>      unsigned int msr = tiny->msr;
>>      unsigned int mcr = tiny->mcr;
>> 
>>      result = ((mcr & MCR_DTR)  ? TIOCM_DTR  : 0) |  /* DTR is set */
>>              ((mcr & MCR_RTS)  ? TIOCM_RTS  : 0) |   /* RTS is set */
>>              ((mcr & MCR_LOOP) ? TIOCM_LOOP : 0) |   /* LOOP is set */
>>              ((msr & MSR_CTS)  ? TIOCM_CTS  : 0) |   /* CTS is set */
>>              ((msr & MSR_CD)   ? TIOCM_CAR  : 0) |   /* Carrier detect is 
>> set*/
>>              ((msr & MSR_RI)   ? TIOCM_RI   : 0) |   /* Ring Indicator is 
>> set */
>>              ((msr & MSR_DSR)  ? TIOCM_DSR  : 0);    /* DSR is set */
>> 
>>      return result;
>> }
>> 
>> static int tiny_tiocmset(struct tty_struct *tty, struct file *file, unsigned 
>> int set, unsigned int clear)
>> {
>>      struct tiny_serial *tiny = tty->driver_data;
>>      unsigned int mcr = tiny->mcr;
>> 
>>      if (set & TIOCM_RTS)
>>              mcr |= MCR_RTS;
>>      if (set & TIOCM_DTR)
>>              mcr |= MCR_RTS;
>> 
>>      if (clear & TIOCM_RTS)
>>              mcr &= ~MCR_RTS;
>>      if (clear & TIOCM_DTR)
>>              mcr &= ~MCR_RTS;
>> 
>>      /* set the new MCR value in the device */
>>      tiny->mcr = mcr;
>>      return 0;
>> }
>> 
>> static int tiny_read_proc(char *page, char **start, off_t off, int count,
>>                           int *eof, void *data)
>> {
>>      struct tiny_serial *tiny;
>>      off_t begin = 0;
>>      int length = 0;
>>      int i;
>> 
>>      length += sprintf(page, "tinyserinfo:1.0 driver:%s\n", DRIVER_VERSION);
>>      for (i = 0; i < TINY_TTY_MINORS && length < PAGE_SIZE; ++i) {
>>              tiny = tiny_table[i];
>>              if (tiny == NULL)
>>                      continue;
>> 
>>              length += sprintf(page+length, "%d\n", i);
>>              if ((length + begin) > (off + count))
>>                      goto done;
>>              if ((length + begin) < off) {
>>                      begin += length;
>>                      length = 0;
>>              }
>>      }
>>      *eof = 1;
>> done:
>>      if (off >= (length + begin))
>>              return 0;
>>      *start = page + (off-begin);
>>      return (count < begin+length-off) ? count : begin + length-off;
>> }
>> 
>> #define tiny_ioctl tiny_ioctl_tiocgserial
>> static int tiny_ioctl(struct tty_struct *tty, struct file *file, unsigned 
>> int cmd, unsigned long arg)
>> {
>>      struct tiny_serial *tiny = tty->driver_data;
>> 
>>      if (cmd == TIOCGSERIAL) {
>>              struct serial_struct tmp;
>> 
>>              if (!arg)
>>                      return -EFAULT;
>> 
>>              memset(&tmp, 0, sizeof(tmp));
>> 
>>              tmp.type                = tiny->serial.type;
>>              tmp.line                = tiny->serial.line;
>>              tmp.port                = tiny->serial.port;
>>              tmp.irq                 = tiny->serial.irq;
>>              tmp.flags               = ASYNC_SKIP_TEST | ASYNC_AUTO_IRQ;
>>              tmp.xmit_fifo_size      = tiny->serial.xmit_fifo_size;
>>              tmp.baud_base           = tiny->serial.baud_base;
>>              tmp.close_delay         = 5*HZ;
>>              tmp.closing_wait        = 30*HZ;
>>              tmp.custom_divisor      = tiny->serial.custom_divisor;
>>              tmp.hub6                = tiny->serial.hub6;
>>              tmp.io_type             = tiny->serial.io_type;
>> 
>>              if (copy_to_user((void __user *)arg, &tmp, sizeof(struct 
>> serial_struct)))
>>                      return -EFAULT;
>>              return 0;
>>      }
>>      return -ENOIOCTLCMD;
>> }
>> #undef tiny_ioctl
>> 
>> #define tiny_ioctl tiny_ioctl_tiocmiwait
>> static int tiny_ioctl(struct tty_struct *tty, struct file *file, unsigned 
>> int cmd, unsigned long arg)
>> {
>>      struct tiny_serial *tiny = tty->driver_data;
>> 
>>      if (cmd == TIOCMIWAIT) {
>>              DECLARE_WAITQUEUE(wait, current);
>>              struct async_icount cnow;
>>              struct async_icount cprev;
>> 
>>              cprev = tiny->icount;
>>              while (1) {
>>                      add_wait_queue(&tiny->wait, &wait);
>>                      set_current_state(TASK_INTERRUPTIBLE);
>>                      schedule();
>>                      remove_wait_queue(&tiny->wait, &wait);
>> 
>>                      /* see if a signal woke us up */
>>                      if (signal_pending(current))
>>                              return -ERESTARTSYS;
>> 
>>                      cnow = tiny->icount;
>>                      if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr &&
>>                          cnow.dcd == cprev.dcd && cnow.cts == cprev.cts)
>>                              return -EIO; /* no change => error */
>>                      if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
>>                          ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
>>                          ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
>>                          ((arg & TIOCM_CTS) && (cnow.cts != cprev.cts)) ) {
>>                              return 0;
>>                      }
>>                      cprev = cnow;
>>              }
>> 
>>      }
>>      return -ENOIOCTLCMD;
>> }
>> #undef tiny_ioctl
>> 
>> #define tiny_ioctl tiny_ioctl_tiocgicount
>> static int tiny_ioctl(struct tty_struct *tty, struct file *file,
>>                       unsigned int cmd, unsigned long arg)
>> {
>>      struct tiny_serial *tiny = tty->driver_data;
>> 
>>      if (cmd == TIOCGICOUNT) {
>>              struct async_icount cnow = tiny->icount;
>>              struct serial_icounter_struct icount;
>> 
>>              icount.cts      = cnow.cts;
>>              icount.dsr      = cnow.dsr;
>>              icount.rng      = cnow.rng;
>>              icount.dcd      = cnow.dcd;
>>              icount.rx       = cnow.rx;
>>              icount.tx       = cnow.tx;
>>              icount.frame    = cnow.frame;
>>              icount.overrun  = cnow.overrun;
>>              icount.parity   = cnow.parity;
>>              icount.brk      = cnow.brk;
>>              icount.buf_overrun = cnow.buf_overrun;
>> 
>>              if (copy_to_user((void __user *)arg, &icount, sizeof(icount)))
>>                      return -EFAULT;
>>              return 0;
>>      }
>>      return -ENOIOCTLCMD;
>> }
>> #undef tiny_ioctl
>> 
>> /* the real tiny_ioctl function.  The above is done to get the small 
>> functions in the book */
>> static int tiny_ioctl(struct tty_struct *tty, struct file *file,
>>                       unsigned int cmd, unsigned long arg)
>> {
>>      switch (cmd) {
>>      case TIOCGSERIAL:
>>              return tiny_ioctl_tiocgserial(tty, file, cmd, arg);
>>      case TIOCMIWAIT:
>>              return tiny_ioctl_tiocmiwait(tty, file, cmd, arg);
>>      case TIOCGICOUNT:
>>              return tiny_ioctl_tiocgicount(tty, file, cmd, arg);
>>      }
>> 
>>      return -ENOIOCTLCMD;
>> }
>> 
>> static struct tty_operations serial_ops = {
>>      .open = tiny_open,
>>      .close = tiny_close,
>>      .write = tiny_write,
>>      .write_room = tiny_write_room,
>>      .set_termios = tiny_set_termios,
>> };
>> 
>> static struct tty_driver *tiny_tty_driver;
>> 
>> static int __init tiny_init(void)
>> {
>>      int retval;
>>      int i;
>> 
>>      /* allocate the tty driver */
>>      tiny_tty_driver = alloc_tty_driver(TINY_TTY_MINORS);
>>      if (!tiny_tty_driver)
>>              return -ENOMEM;
>> 
>>      /* initialize the tty driver */
>>      tiny_tty_driver->owner = THIS_MODULE;
>>      tiny_tty_driver->driver_name = "tiny_tty";
>>      tiny_tty_driver->name = "ttty";
>>      tiny_tty_driver->devfs_name = "tts/ttty%d";
>>      tiny_tty_driver->major = TINY_TTY_MAJOR,
>>      tiny_tty_driver->type = TTY_DRIVER_TYPE_SERIAL,
>>      tiny_tty_driver->subtype = SERIAL_TYPE_NORMAL,
>>      tiny_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_NO_DEVFS,
>>      tiny_tty_driver->init_termios = tty_std_termios;
>>      tiny_tty_driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | 
>> CLOCAL;
>>      tty_set_operations(tiny_tty_driver, &serial_ops);
>> 
>>      /* hack to make the book purty, yet still use these functions in the
>>       * real driver.  They really should be set up in the serial_ops
>>       * structure above... */
>>      tiny_tty_driver->read_proc = tiny_read_proc;
>>      tiny_tty_driver->tiocmget = tiny_tiocmget;
>>      tiny_tty_driver->tiocmset = tiny_tiocmset;
>>      tiny_tty_driver->ioctl = tiny_ioctl;
>> 
>>      /* register the tty driver */
>>      retval = tty_register_driver(tiny_tty_driver);
>>      if (retval) {
>>              printk(KERN_ERR "failed to register tiny tty driver");
>>              put_tty_driver(tiny_tty_driver);
>>              return retval;
>>      }
>> 
>>      for (i = 0; i < TINY_TTY_MINORS; ++i)
>>              tty_register_device(tiny_tty_driver, i, NULL);
>> 
>>      printk(KERN_INFO DRIVER_DESC " " DRIVER_VERSION);
>>      return retval;
>> }
>> 
>> static void __exit tiny_exit(void)
>> {
>>      struct tiny_serial *tiny;
>>      int i;
>> 
>>      for (i = 0; i < TINY_TTY_MINORS; ++i)
>>              tty_unregister_device(tiny_tty_driver, i);
>>      tty_unregister_driver(tiny_tty_driver);
>> 
>>      /* shut down all of the timers and free the memory */
>>      for (i = 0; i < TINY_TTY_MINORS; ++i) {
>>              tiny = tiny_table[i];
>>              if (tiny) {
>>                      /* close the port */
>>                      while (tiny->open_count)
>>                              do_close(tiny);
>> 
>>                      /* shut down our timer and free the memory */
>>                      del_timer(tiny->timer);
>>                      kfree(tiny->timer);
>>                      kfree(tiny);
>>                      tiny_table[i] = NULL;
>>              }
>>      }
>> }
>> 
>> module_init(tiny_init);
>> module_exit(tiny_exit);
>
>--
>Len Sorensen
>-
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