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
  31 struct serport {
  32         struct tty_struct *tty;
  33         wait_queue_head_t wait;
  34         struct serio *serio;
  35         unsigned long flags;
  36 };
  37
  38 /*
  39  * Callback functions from the serio code.
  40  */
  41
  42 static int serport_serio_write(struct serio *serio, unsigned char data)
  43 {
  44         struct serport *serport = serio->port_data;
  45         return -(serport->tty->driver->write(serport->tty, &data, 1) != 1);
  46 }
  47
  48 static void serport_serio_close(struct serio *serio)
  49 {
  50         struct serport *serport = serio->port_data;
  51
  52         serport->serio->id.type = 0;
  53         wake_up_interruptible(&serport->wait);
  54 }
  55
  56 /*
  57  * serport_ldisc_open() is the routine that is called upon setting our line
  58  * discipline on a tty. It prepares the serio struct.
  59  */
  60
  61 static int serport_ldisc_open(struct tty_struct *tty)
  62 {
  63         struct serport *serport;
  64         struct serio *serio;
  65         char name[64];
  66
  67         if (!capable(CAP_SYS_ADMIN))
  68                 return -EPERM;
  69
  70         serport = kmalloc(sizeof(struct serport), GFP_KERNEL);
  71         serio = kmalloc(sizeof(struct serio), GFP_KERNEL);
  72         if (unlikely(!serport || !serio)) {
  73                 kfree(serport);
  74                 kfree(serio);
  75                 return -ENOMEM;
  76         }
  77
  78         memset(serport, 0, sizeof(struct serport));
  79         serport->serio = serio;
  80         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
  81         serport->tty = tty;
  82         tty->disc_data = serport;
  83
  84         memset(serio, 0, sizeof(struct serio));
  85         strlcpy(serio->name, "Serial port", sizeof(serio->name));
  86         snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", tty_name(tty, name));
  87         serio->id.type = SERIO_RS232;
  88         serio->write = serport_serio_write;
  89         serio->close = serport_serio_close;
  90         serio->port_data = serport;
  91
  92         init_waitqueue_head(&serport->wait);
  93
  94         return 0;
  95 }
  96
  97 /*
  98  * serport_ldisc_close() is the opposite of serport_ldisc_open()
  99  */
 100
 101 static void serport_ldisc_close(struct tty_struct *tty)
 102 {
 103         struct serport *serport = (struct serport*) tty->disc_data;
 104         kfree(serport);
 105 }
 106
 107 /*
 108  * serport_ldisc_receive() is called by the low level tty driver when characters
 109  * are ready for us. We forward the characters, one by one to the 'interrupt'
 110  * routine.
 111  *
 112  * FIXME: We should get pt_regs from the tty layer and forward them to
 113  *        serio_interrupt here.
 114  */
 115
 116 static void serport_ldisc_receive(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
 117 {
 118         struct serport *serport = (struct serport*) tty->disc_data;
 119         int i;
 120         for (i = 0; i < count; i++)
 121                 serio_interrupt(serport->serio, cp[i], 0, NULL);
 122 }
 123
 124 /*
 125  * serport_ldisc_room() reports how much room we do have for receiving data.
 126  * Although we in fact have infinite room, we need to specify some value
 127  * here, and 256 seems to be reasonable.
 128  */
 129
 130 static int serport_ldisc_room(struct tty_struct *tty)
 131 {
 132         return 256;
 133 }
 134
 135 /*
 136  * serport_ldisc_read() just waits indefinitely if everything goes well.
 137  * However, when the serio driver closes the serio port, it finishes,
 138  * returning 0 characters.
 139  */
 140
 141 static ssize_t serport_ldisc_read(struct tty_struct * tty, struct file * file, unsigned char __user * buf, size_t nr)
 142 {
 143         struct serport *serport = (struct serport*) tty->disc_data;
 144         char name[64];
 145
 146         if (test_and_set_bit(SERPORT_BUSY, &serport->flags))
 147                 return -EBUSY;
 148
 149         serio_register_port(serport->serio);
 150         printk(KERN_INFO "serio: Serial port %s\n", tty_name(tty, name));
 151         wait_event_interruptible(serport->wait, !serport->serio->id.type);
 152         serio_unregister_port(serport->serio);
 153
 154         clear_bit(SERPORT_BUSY, &serport->flags);
 155
 156         return 0;
 157 }
 158
 159 /*
 160  * serport_ldisc_ioctl() allows to set the port protocol, and device ID
 161  */
 162
 163 static int serport_ldisc_ioctl(struct tty_struct * tty, struct file * file, unsigned int cmd, unsigned long arg)
 164 {
 165         struct serport *serport = (struct serport*) tty->disc_data;
 166         struct serio *serio = serport->serio;
 167         unsigned long type;
 168
 169         if (cmd == SPIOCSTYPE) {
 170                 if (get_user(type, (unsigned long __user *) arg))
 171                         return -EFAULT;
 172
 173                 serio->id.proto = type & 0x000000ff;
 174                 serio->id.id    = (type & 0x0000ff00) >> 8;
 175                 serio->id.extra = (type & 0x00ff0000) >> 16;
 176
 177                 return 0;
 178         }
 179
 180         return -EINVAL;
 181 }
 182
 183 static void serport_ldisc_write_wakeup(struct tty_struct * tty)
 184 {
 185         struct serport *sp = (struct serport *) tty->disc_data;
 186
 187         serio_drv_write_wakeup(sp->serio);
 188 }
 189
 190 /*
 191  * The line discipline structure.
 192  */
 193
 194 static struct tty_ldisc serport_ldisc = {
 195         .owner =        THIS_MODULE,
 196         .name =         "input",
 197         .open =         serport_ldisc_open,
 198         .close =        serport_ldisc_close,
 199         .read =         serport_ldisc_read,
 200         .ioctl =        serport_ldisc_ioctl,
 201         .receive_buf =  serport_ldisc_receive,
 202         .receive_room = serport_ldisc_room,
 203         .write_wakeup = serport_ldisc_write_wakeup
 204 };
 205
 206 /*
 207  * The functions for insering/removing us as a module.
 208  */
 209
 210 static int __init serport_init(void)
 211 {
 212         int retval;
 213         retval = tty_register_ldisc(N_MOUSE, &serport_ldisc);
 214         if (retval)
 215                 printk(KERN_ERR "serport.c: Error registering line discipline.\n");
 216
 217         return  retval;
 218 }
 219
 220 static void __exit serport_exit(void)
 221 {
 222         tty_register_ldisc(N_MOUSE, NULL);
 223 }
 224
 225 module_init(serport_init);
 226 module_exit(serport_exit);