5896l1.txt0100664000204600003300000000457707504177052011475 0ustar jillljedit5896l1 Listing 1. The struct tty_driver struct tty_driver { int magic; /* magic number for this structure */ const char *driver_name; const char *name; int name_base; /* offset of printed name */ short major; /* major device number */ short minor_start; /* start of minor device number*/ short num; /* number of devices */ short type; /* type of tty driver */ short subtype; /* subtype of tty driver */ struct termios init_termios; /* Initial termios */ int flags; /* tty driver flags */ int *refcount; /* for loadable tty drivers */ struct proc_dir_entry *proc_entry; /* /proc fs entry */ struct tty_driver *other; /* only used for the PTY driver */ /* * Pointer to the tty data structures */ struct tty_struct **table; struct termios **termios; struct termios **termios_locked; void *driver_state; /* only used for the PTY driver */ /* * Interface routines from the upper tty layer to the tty * driver. */ int (*open)(struct tty_struct * tty, struct file * filp); void (*close)(struct tty_struct * tty, struct file * filp); int (*write)(struct tty_struct * tty, int from_user, const unsigned char *buf, int count); void (*put_char)(struct tty_struct *tty, unsigned char ch); void (*flush_chars)(struct tty_struct *tty); int (*write_room)(struct tty_struct *tty); int (*chars_in_buffer)(struct tty_struct *tty); int (*ioctl)(struct tty_struct *tty, struct file * file, unsigned int cmd, unsigned long arg); void (*set_termios)(struct tty_struct *tty, struct termios * old); void (*throttle)(struct tty_struct * tty); void (*unthrottle)(struct tty_struct * tty); void (*stop)(struct tty_struct *tty); void (*start)(struct tty_struct *tty); void (*hangup)(struct tty_struct *tty); void (*break_ctl)(struct tty_struct *tty, int state); void (*flush_buffer)(struct tty_struct *tty); void (*set_ldisc)(struct tty_struct *tty); void (*wait_until_sent)(struct tty_struct *tty, int timeout); void (*send_xchar)(struct tty_struct *tty, char ch); int (*read_proc)(char *page, char **start, off_t off, int count, int *eof, void *data); int (*write_proc)(struct file *file, const char *buffer, unsigned long count, void *data); /* * linked list pointers */ struct tty_driver *next; struct tty_driver *prev; }; 5896l2.txt0100664000204600003300000000245407500163577011471 0ustar jillljedit5896l2 Listing 2. #define TINY_TTY_MAJOR 240 /* experimental range */ #define TINY_TTY_MINORS 255 /* use the whole major up */ static int tty_refcount; static struct tty_struct *tiny_tty[TINY_TTY_MINORS]; static struct termios *tiny_termios[TINY_TTY_MINORS]; static struct termios *tiny_termios_locked[TINY_TTY_MINORS]; static struct tty_driver tiny_tty_driver { magic: TTY_DRIVER_MAGIC, driver_name: "tiny_tty", #ifdef CONFIG_DEVFS_FS name: "tts/ttty%d", #else name: "ttty", #endif major: TINY_TTY_MAJOR, num: TINY_TTY_MINORS, type: TTY_DRIVER_TYPE_SERIAL, subtype: SERIAL_TYPE_NORMAL, flags: TTY_DRIVER_REAL_RAW | TTY_DRIVER_NO_DEVFS, refcount: &tiny_refcount, table: tiny_tty, termios: tiny_termios, termios_locked: tiny_termios_locked, open: tiny_open, close: tiny_close, write: tiny_write, write_room: tiny_write_room, }; static int __init tiny_init (void) { /* register the tty driver */ tiny_tty_driver.init_termios = tty_std_termios; tiny_tty_driver.init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL; if (tty_register_driver (&tiny_tty_driver)) { printk (KERN_ERR "failed to register tiny tty driver"); return -1; return 0; } static void __exit tiny_exit (void) { tty_unregister_driver (&tiny_tty_driver); } module_init (tiny_init); module_exit (tiny_exit); 5896l3.txt0100664000204600003300000001466607500163577011502 0ustar jillljedit5896 Listing 3. The tiny_tty.c Driver /* * 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; either version 2 of the License, or * (at your option) any later version. * * 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 #include #include #include #include #include #include #include #include #include #define DRIVER_VERSION "v1.0" #define DRIVER_AUTHOR "Greg Kroah-Hartman " #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 255 /* use the whole major up */ 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; }; static int tiny_refcount; static struct tty_driver tiny_tty_driver; static struct tty_struct *tiny_tty[TINY_TTY_MINORS]; static struct termios *tiny_termios[TINY_TTY_MINORS]; static struct termios *tiny_termios_locked[TINY_TTY_MINORS]; static struct tiny_serial *tiny_table[TINY_TTY_MINORS]; /* initially all NULL */ static void tiny_timer (unsigned long data) { struct tiny_serial *tiny = (struct tiny_serial *)data; struct tty_struct *tty; if (!tiny) return; tty = tiny->tty; if (tty->flip.count >= TTY_FLIPBUF_SIZE) tty_flip_buffer_push(tty); /* add two characters 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_insert_flip_char(tty, '\n', 0); tty_flip_buffer_push(tty); tty_schedule_flip (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 * filp) { struct tiny_serial *tiny; struct timer_list *timer; MOD_INC_USE_COUNT; /* initialize the pointer incase something fails */ tty->driver_data = NULL; /* get the serial object associated with this tty pointer */ tiny = tiny_table[minor(tty->device)]; if (tiny == NULL) { /* first time accessing this device, let's create it */ tiny = kmalloc (sizeof (*tiny), GFP_KERNEL); if (!tiny) { MOD_DEC_USE_COUNT; return -ENOMEM; } init_MUTEX (&tiny->sem); tiny->open_count = 0; tiny->timer = NULL; tiny_table[minor(tty->device)] = 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); MOD_DEC_USE_COUNT; return -ENOMEM; } tiny->timer = timer; } init_timer (tiny->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 */ return; } --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); } MOD_DEC_USE_COUNT; up (&tiny->sem); } static void tiny_close (struct tty_struct *tty, struct file * filp) { struct tiny_serial *tiny = tty->driver_data; if (!tiny) { return; } do_close (tiny); } static int tiny_write (struct tty_struct * tty, int from_user, const unsigned char *buf, int count) { struct tiny_serial *tiny = tty->driver_data; int retval = -EINVAL; if (!tiny) { return -ENODEV; } down (&tiny->sem); if (!tiny->open_count) { /* port was not opened */ goto exit; } /* now send the data out the harware port */ retval = count; exit: up (&tiny->sem); return retval; } static int tiny_write_room (struct tty_struct *tty) { struct tiny_serial *tiny = tty->driver_data; int room; if (!tiny) { return -ENODEV; } down (&tiny->sem); if (!tiny->open_count) { /* port was not opened */ return -EINVAL; } /* calculate how much room is left in the device */ room = 255; up (&tiny->sem); return room; } static struct tty_driver tiny_tty_driver = { magic: TTY_DRIVER_MAGIC, driver_name: "tiny_tty", #ifndef CONFIG_DEVFS_FS name: "ttty", #else name: "tts/ttty%d", #endif major: TINY_TTY_MAJOR, num: TINY_TTY_MINORS, type: TTY_DRIVER_TYPE_SERIAL, subtype: SERIAL_TYPE_NORMAL, flags: TTY_DRIVER_REAL_RAW, refcount: &tiny_refcount, table: tiny_tty, termios: tiny_termios, termios_locked: tiny_termios_locked, open: tiny_open, close: tiny_close, write: tiny_write, write_room: tiny_write_room, }; static int __init tiny_init(void) { /* register the tty driver */ tiny_tty_driver.init_termios = tty_std_termios; tiny_tty_driver.init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL; if (tty_register_driver (&tiny_tty_driver)) { printk (KERN_ERR "failed to register tiny tty driver\n"); return -1; } printk (KERN_INFO DRIVER_DESC " " DRIVER_VERSION "\n"); return 0; } static void __exit tiny_exit(void) { struct tiny_serial *tiny; int 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);