drivers/char/joystick/serport.c

   1 /*
   2  * $Id: serport.c,v 1.4 2000/05/29 10:54:53 vojtech Exp $
   3  *
   4  *  Copyright (c) 1999-2000 Vojtech Pavlik
   5  *
   6  *  Sponsored by SuSE
   7  */
   8
   9 /*
  10  * This is a module that converts a tty line into a much simpler
  11  * 'serial io port' abstraction that the input device drivers use.
  12  */
  13
  14 /*
  15  * This program is free software; you can redistribute it and/or modify
  16  * it under the terms of the GNU General Public License as published by
  17  * the Free Software Foundation; either version 2 of the License, or
  18  * (at your option) any later version.
  19  *
  20  * This program is distributed in the hope that it will be useful,
  21  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  22  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23  * GNU General Public License for more details.
  24  *
  25  * You should have received a copy of the GNU General Public License
  26  * along with this program; if not, write to the Free Software
  27  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  28  *
  29  *  Should you need to contact me, the author, you can do so either by
  30  * e-mail - mail your message to <vojtech@ucw.cz>, or by paper mail:
  31  * Vojtech Pavlik, Ucitelska 1576, Prague 8, 182 00 Czech Republic
  32  */
  33
  34 #include <asm/uaccess.h>
  35 #include <linux/kernel.h>
  36 #include <linux/malloc.h>
  37 #include <linux/module.h>
  38 #include <linux/init.h>
  39 #include <linux/serio.h>
  40 #include <linux/tty.h>
  41
  42 struct serport {
  43         struct tty_struct *tty;
  44         wait_queue_head_t wait;
  45         struct serio serio;
  46 };
  47
  48 /*
  49  * Callback functions from the serio code.
  50  */
  51
  52 static int serport_serio_write(struct serio *serio, unsigned char data)
  53 {
  54         struct serport *serport = serio->driver;
  55         return -(serport->tty->driver.write(serport->tty, 0, &data, 1) != 1);
  56 }
  57
  58 static int serport_serio_open(struct serio *serio)
  59 {
  60         return 0;
  61 }
  62
  63 static void serport_serio_close(struct serio *serio)
  64 {
  65         struct serport *serport = serio->driver;
  66         wake_up_interruptible(&serport->wait);
  67 }
  68
  69 /*
  70  * serport_ldisc_open() is the routine that is called upon setting our line
  71  * discipline on a tty. It looks for the Mag, and if found, registers
  72  * it as a joystick device.
  73  */
  74
  75 static int serport_ldisc_open(struct tty_struct *tty)
  76 {
  77         struct serport *serport;
  78
  79         MOD_INC_USE_COUNT;
  80
  81         if (!(serport = kmalloc(sizeof(struct serport), GFP_KERNEL))) {
  82                 MOD_DEC_USE_COUNT;
  83                 return -ENOMEM;
  84         }
  85
  86         memset(serport, 0, sizeof(struct serport));
  87
  88         serport->tty = tty;
  89         tty->disc_data = serport;
  90
  91         serport->serio.type = SERIO_RS232;
  92         serport->serio.write = serport_serio_write;
  93         serport->serio.open = serport_serio_open;
  94         serport->serio.close = serport_serio_close;
  95         serport->serio.driver = serport;
  96
  97         init_waitqueue_head(&serport->wait);
  98
  99         return 0;
 100 }
 101
 102 /*
 103  * serport_ldisc_close() is the opposite of serport_ldisc_open()
 104  */
 105
 106 static void serport_ldisc_close(struct tty_struct *tty)
 107 {
 108         struct serport *serport = (struct serport*) tty->disc_data;
 109         kfree(serport);
 110         MOD_DEC_USE_COUNT;
 111 }
 112
 113 /*
 114  * serport_ldisc_receive() is called by the low level tty driver when characters
 115  * are ready for us. We forward the characters, one by one to the 'interrupt'
 116  * routine.
 117  */
 118
 119 static void serport_ldisc_receive(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
 120 {
 121         struct serport *serport = (struct serport*) tty->disc_data;
 122         int i;
 123         for (i = 0; i < count; i++)
 124                 if (serport->serio.dev)
 125                         serport->serio.dev->interrupt(&serport->serio, cp[i], 0);
 126 }
 127
 128 /*
 129  * serport_ldisc_room() reports how much room we do have for receiving data.
 130  * Although we in fact have infinite room, we need to specify some value
 131  * here, and 256 seems to be reasonable.
 132  */
 133
 134 static int serport_ldisc_room(struct tty_struct *tty)
 135 {
 136         return 256;
 137 }
 138
 139 /*
 140  * serport_ldisc_read() just waits indefinitely if everything goes well.
 141  * However, when the serio driver closes the serio port, it finishes,
 142  * returning 0 characters.
 143  */
 144
 145 static ssize_t serport_ldisc_read(struct tty_struct * tty, struct file * file, unsigned char * buf, size_t nr)
 146 {
 147         struct serport *serport = (struct serport*) tty->disc_data;
 148         DECLARE_WAITQUEUE(wait, current);
 149         char name[32];
 150
 151         sprintf(name, tty->driver.name, MINOR(tty->device) - tty->driver.minor_start);
 152
 153         serio_register_port(&serport->serio);
 154
 155         printk(KERN_INFO "serio%d: Serial port %s\n", serport->serio.number, name);
 156
 157         add_wait_queue(&serport->wait, &wait);
 158         current->state = TASK_INTERRUPTIBLE;
 159
 160         while(serport->serio.type && !signal_pending(current)) schedule();
 161
 162         current->state = TASK_RUNNING;
 163         remove_wait_queue(&serport->wait, &wait);
 164
 165         serio_unregister_port(&serport->serio);
 166
 167         return 0;
 168 }
 169
 170 /*
 171  * serport_ldisc_ioctl() allows to set the port protocol, and device ID
 172  */
 173
 174 static int serport_ldisc_ioctl(struct tty_struct * tty, struct file * file, unsigned int cmd, unsigned long arg)
 175 {
 176         struct serport *serport = (struct serport*) tty->disc_data;
 177
 178         switch (cmd) {
 179                 case SPIOCSTYPE:
 180                         return get_user(serport->serio.type, (unsigned long *) arg);
 181         }
 182
 183         return -EINVAL;
 184 }
 185
 186 /*
 187  * The line discipline structure.
 188  */
 189
 190 static struct tty_ldisc serport_ldisc = {
 191         name:           "input",
 192         open:           serport_ldisc_open,
 193         close:          serport_ldisc_close,
 194         read:           serport_ldisc_read,
 195         ioctl:          serport_ldisc_ioctl,
 196         receive_buf:    serport_ldisc_receive,
 197         receive_room:   serport_ldisc_room,
 198 };
 199
 200 /*
 201  * The functions for insering/removing us as a module.
 202  */
 203
 204 int __init serport_init(void)
 205 {
 206         if (tty_register_ldisc(N_MOUSE, &serport_ldisc)) {
 207                 printk(KERN_ERR "serport.c: Error registering line discipline.\n");
 208                 return -ENODEV;
 209         }
 210
 211         return  0;
 212 }
 213
 214 void __exit serport_exit(void)
 215 {
 216         tty_register_ldisc(N_MOUSE, NULL);
 217 }
 218
 219 module_init(serport_init);
 220 module_exit(serport_exit);