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         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 100
 101         return 0;
 102 }
 103
 104 /*
 105  * serport_ldisc_close() is the opposite of serport_ldisc_open()
 106  */
 107
 108 static void serport_ldisc_close(struct tty_struct *tty)
 109 {
 110         struct serport *serport = (struct serport *) tty->disc_data;
 111
 112         kfree(serport);
 113 }
 114
 115 /*
 116  * serport_ldisc_receive() is called by the low level tty driver when characters
 117  * are ready for us. We forward the characters, one by one to the 'interrupt'
 118  * routine.
 119  *
 120  * FIXME: We should get pt_regs from the tty layer and forward them to
 121  *        serio_interrupt here.
 122  */
 123
 124 static void serport_ldisc_receive(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
 125 {
 126         struct serport *serport = (struct serport*) tty->disc_data;
 127         unsigned long flags;
 128         int i;
 129
 130         spin_lock_irqsave(&serport->lock, flags);
 131
 132         if (!test_bit(SERPORT_ACTIVE, &serport->flags))
 133                 goto out;
 134
 135         for (i = 0; i < count; i++)
 136                 serio_interrupt(serport->serio, cp[i], 0, NULL);
 137
 138 out:
 139         spin_unlock_irqrestore(&serport->lock, flags);
 140 }
 141
 142 /*
 143  * serport_ldisc_room() reports how much room we do have for receiving data.
 144  * Although we in fact have infinite room, we need to specify some value
 145  * here, and 256 seems to be reasonable.
 146  */
 147
 148 static int serport_ldisc_room(struct tty_struct *tty)
 149 {
 150         return 256;
 151 }
 152
 153 /*
 154  * serport_ldisc_read() just waits indefinitely if everything goes well.
 155  * However, when the serio driver closes the serio port, it finishes,
 156  * returning 0 characters.
 157  */
 158
 159 static ssize_t serport_ldisc_read(struct tty_struct * tty, struct file * file, unsigned char __user * buf, size_t nr)
 160 {
 161         struct serport *serport = (struct serport*) tty->disc_data;
 162         struct serio *serio;
 163         char name[64];
 164
 165         if (test_and_set_bit(SERPORT_BUSY, &serport->flags))
 166                 return -EBUSY;
 167
 168         serport->serio = serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
 169         if (!serio)
 170                 return -ENOMEM;
 171
 172         strlcpy(serio->name, "Serial port", sizeof(serio->name));
 173         snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", tty_name(tty, name));
 174         serio->id = serport->id;
 175         serio->id.type = SERIO_RS232;
 176         serio->write = serport_serio_write;
 177         serio->open = serport_serio_open;
 178         serio->close = serport_serio_close;
 179         serio->port_data = serport;
 180
 181         serio_register_port(serport->serio);
 182         printk(KERN_INFO "serio: Serial port %s\n", tty_name(tty, name));
 183
 184         wait_event_interruptible(serport->wait, test_bit(SERPORT_DEAD, &serport->flags));
 185         serio_unregister_port(serport->serio);
 186         serport->serio = NULL;
 187
 188         clear_bit(SERPORT_DEAD, &serport->flags);
 189         clear_bit(SERPORT_BUSY, &serport->flags);
 190
 191         return 0;
 192 }
 193
 194 /*
 195  * serport_ldisc_ioctl() allows to set the port protocol, and device ID
 196  */
 197
 198 static int serport_ldisc_ioctl(struct tty_struct * tty, struct file * file, unsigned int cmd, unsigned long arg)
 199 {
 200         struct serport *serport = (struct serport*) tty->disc_data;
 201         unsigned long type;
 202
 203         if (cmd == SPIOCSTYPE) {
 204                 if (get_user(type, (unsigned long __user *) arg))
 205                         return -EFAULT;
 206
 207                 serport->id.proto = type & 0x000000ff;
 208                 serport->id.id    = (type & 0x0000ff00) >> 8;
 209                 serport->id.extra = (type & 0x00ff0000) >> 16;
 210
 211                 return 0;
 212         }
 213
 214         return -EINVAL;
 215 }
 216
 217 static void serport_ldisc_write_wakeup(struct tty_struct * tty)
 218 {
 219         struct serport *serport = (struct serport *) tty->disc_data;
 220         unsigned long flags;
 221
 222         spin_lock_irqsave(&serport->lock, flags);
 223         if (test_bit(SERPORT_ACTIVE, &serport->flags))
 224                 serio_drv_write_wakeup(serport->serio);
 225         spin_unlock_irqrestore(&serport->lock, flags);
 226 }
 227
 228 /*
 229  * The line discipline structure.
 230  */
 231
 232 static struct tty_ldisc serport_ldisc = {
 233         .owner =        THIS_MODULE,
 234         .name =         "input",
 235         .open =         serport_ldisc_open,
 236         .close =        serport_ldisc_close,
 237         .read =         serport_ldisc_read,
 238         .ioctl =        serport_ldisc_ioctl,
 239         .receive_buf =  serport_ldisc_receive,
 240         .receive_room = serport_ldisc_room,
 241         .write_wakeup = serport_ldisc_write_wakeup
 242 };
 243
 244 /*
 245  * The functions for insering/removing us as a module.
 246  */
 247
 248 static int __init serport_init(void)
 249 {
 250         int retval;
 251         retval = tty_register_ldisc(N_MOUSE, &serport_ldisc);
 252         if (retval)
 253                 printk(KERN_ERR "serport.c: Error registering line discipline.\n");
 254
 255         return  retval;
 256 }
 257
 258 static void __exit serport_exit(void)
 259 {
 260         tty_unregister_ldisc(N_MOUSE);
 261 }
 262
 263 module_init(serport_init);
 264 module_exit(serport_exit);