drivers/input/serio/serport.c

   1 /*
   2  * Input device TTY line discipline
   3  *
   4  * Copyright (c) 1999-2002 Vojtech Pavlik
   5  *
   6  * This is a module that converts a tty line into a much simpler
   7  * 'serial io port' abstraction that the input device drivers use.
   8  */
   9
  10 /*
  11  * This program is free software; you can redistribute it and/or modify it
  12  * under the terms of the GNU General Public License version 2 as published by
  13  * the Free Software Foundation.
  14  */
  15
  16 #include <asm/uaccess.h>
  17 #include <linux/kernel.h>
  18 #include <linux/slab.h>
  19 #include <linux/module.h>
  20 #include <linux/init.h>
  21 #include <linux/serio.h>
  22 #include <linux/tty.h>
  23
  24 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
  25 MODULE_DESCRIPTION("Input device TTY line discipline");
  26 MODULE_LICENSE("GPL");
  27 MODULE_ALIAS_LDISC(N_MOUSE);
  28
  29 #define SERPORT_BUSY    1
  30 #define SERPORT_ACTIVE  2
  31 #define SERPORT_DEAD    3
  32
  33 struct serport {
  34         struct tty_struct *tty;
  35         wait_queue_head_t wait;
  36         struct serio *serio;
  37         struct serio_device_id id;
  38         spinlock_t lock;
  39         unsigned long flags;
  40 };
  41
  42 /*
  43  * Callback functions from the serio code.
  44  */
  45
  46 static int serport_serio_write(struct serio *serio, unsigned char data)
  47 {
  48         struct serport *serport = serio->port_data;
  49         return -(serport->tty->driver->write(serport->tty, &data, 1) != 1);
  50 }
  51
  52 static int serport_serio_open(struct serio *serio)
  53 {
  54         struct serport *serport = serio->port_data;
  55         unsigned long flags;
  56
  57         spin_lock_irqsave(&serport->lock, flags);
  58         set_bit(SERPORT_ACTIVE, &serport->flags);
  59         spin_unlock_irqrestore(&serport->lock, flags);
  60
  61         return 0;
  62 }
  63
  64
  65 static void serport_serio_close(struct serio *serio)
  66 {
  67         struct serport *serport = serio->port_data;
  68         unsigned long flags;
  69
  70         spin_lock_irqsave(&serport->lock, flags);
  71         clear_bit(SERPORT_ACTIVE, &serport->flags);
  72         set_bit(SERPORT_DEAD, &serport->flags);
  73         spin_unlock_irqrestore(&serport->lock, flags);
  74
  75         wake_up_interruptible(&serport->wait);
  76 }
  77
  78 /*
  79  * serport_ldisc_open() is the routine that is called upon setting our line
  80  * discipline on a tty. It prepares the serio struct.
  81  */
  82
  83 static int serport_ldisc_open(struct tty_struct *tty)
  84 {
  85         struct serport *serport;
  86
  87         if (!capable(CAP_SYS_ADMIN))
  88                 return -EPERM;
  89
  90         serport = kzalloc(sizeof(struct serport), GFP_KERNEL);
  91         if (!serport)
  92                 return -ENOMEM;
  93
  94         serport->tty = tty;
  95         spin_lock_init(&serport->lock);
  96         init_waitqueue_head(&serport->wait);
  97
  98         tty->disc_data = serport;
  99         tty->receive_room = 256;
 100         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 101
 102         return 0;
 103 }
 104
 105 /*
 106  * serport_ldisc_close() is the opposite of serport_ldisc_open()
 107  */
 108
 109 static void serport_ldisc_close(struct tty_struct *tty)
 110 {
 111         struct serport *serport = (struct serport *) tty->disc_data;
 112
 113         kfree(serport);
 114 }
 115
 116 /*
 117  * serport_ldisc_receive() is called by the low level tty driver when characters
 118  * are ready for us. We forward the characters, one by one to the 'interrupt'
 119  * routine.
 120  */
 121
 122 static void serport_ldisc_receive(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
 123 {
 124         struct serport *serport = (struct serport*) tty->disc_data;
 125         unsigned long flags;
 126         int i;
 127
 128         spin_lock_irqsave(&serport->lock, flags);
 129
 130         if (!test_bit(SERPORT_ACTIVE, &serport->flags))
 131                 goto out;
 132
 133         for (i = 0; i < count; i++)
 134                 serio_interrupt(serport->serio, cp[i], 0);
 135
 136 out:
 137         spin_unlock_irqrestore(&serport->lock, flags);
 138 }
 139
 140 /*
 141  * serport_ldisc_read() just waits indefinitely if everything goes well.
 142  * However, when the serio driver closes the serio port, it finishes,
 143  * returning 0 characters.
 144  */
 145
 146 static ssize_t serport_ldisc_read(struct tty_struct * tty, struct file * file, unsigned char __user * buf, size_t nr)
 147 {
 148         struct serport *serport = (struct serport*) tty->disc_data;
 149         struct serio *serio;
 150         char name[64];
 151
 152         if (test_and_set_bit(SERPORT_BUSY, &serport->flags))
 153                 return -EBUSY;
 154
 155         serport->serio = serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
 156         if (!serio)
 157                 return -ENOMEM;
 158
 159         strlcpy(serio->name, "Serial port", sizeof(serio->name));
 160         snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", tty_name(tty, name));
 161         serio->id = serport->id;
 162         serio->id.type = SERIO_RS232;
 163         serio->write = serport_serio_write;
 164         serio->open = serport_serio_open;
 165         serio->close = serport_serio_close;
 166         serio->port_data = serport;
 167
 168         serio_register_port(serport->serio);
 169         printk(KERN_INFO "serio: Serial port %s\n", tty_name(tty, name));
 170
 171         wait_event_interruptible(serport->wait, test_bit(SERPORT_DEAD, &serport->flags));
 172         serio_unregister_port(serport->serio);
 173         serport->serio = NULL;
 174
 175         clear_bit(SERPORT_DEAD, &serport->flags);
 176         clear_bit(SERPORT_BUSY, &serport->flags);
 177
 178         return 0;
 179 }
 180
 181 /*
 182  * serport_ldisc_ioctl() allows to set the port protocol, and device ID
 183  */
 184
 185 static int serport_ldisc_ioctl(struct tty_struct * tty, struct file * file, unsigned int cmd, unsigned long arg)
 186 {
 187         struct serport *serport = (struct serport*) tty->disc_data;
 188         unsigned long type;
 189
 190         if (cmd == SPIOCSTYPE) {
 191                 if (get_user(type, (unsigned long __user *) arg))
 192                         return -EFAULT;
 193
 194                 serport->id.proto = type & 0x000000ff;
 195                 serport->id.id    = (type & 0x0000ff00) >> 8;
 196                 serport->id.extra = (type & 0x00ff0000) >> 16;
 197
 198                 return 0;
 199         }
 200
 201         return -EINVAL;
 202 }
 203
 204 static void serport_ldisc_write_wakeup(struct tty_struct * tty)
 205 {
 206         struct serport *serport = (struct serport *) tty->disc_data;
 207         unsigned long flags;
 208
 209         spin_lock_irqsave(&serport->lock, flags);
 210         if (test_bit(SERPORT_ACTIVE, &serport->flags))
 211                 serio_drv_write_wakeup(serport->serio);
 212         spin_unlock_irqrestore(&serport->lock, flags);
 213 }
 214
 215 /*
 216  * The line discipline structure.
 217  */
 218
 219 static struct tty_ldisc serport_ldisc = {
 220         .owner =        THIS_MODULE,
 221         .name =         "input",
 222         .open =         serport_ldisc_open,
 223         .close =        serport_ldisc_close,
 224         .read =         serport_ldisc_read,
 225         .ioctl =        serport_ldisc_ioctl,
 226         .receive_buf =  serport_ldisc_receive,
 227         .write_wakeup = serport_ldisc_write_wakeup
 228 };
 229
 230 /*
 231  * The functions for insering/removing us as a module.
 232  */
 233
 234 static int __init serport_init(void)
 235 {
 236         int retval;
 237         retval = tty_register_ldisc(N_MOUSE, &serport_ldisc);
 238         if (retval)
 239                 printk(KERN_ERR "serport.c: Error registering line discipline.\n");
 240
 241         return  retval;
 242 }
 243
 244 static void __exit serport_exit(void)
 245 {
 246         tty_unregister_ldisc(N_MOUSE);
 247 }
 248
 249 module_init(serport_init);
 250 module_exit(serport_exit);