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