drivers/input/serio/serport.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Input device TTY line discipline
   4  *
   5  * Copyright (c) 1999-2002 Vojtech Pavlik
   6  *
   7  * This is a module that converts a tty line into a much simpler
   8  * 'serial io port' abstraction that the input device drivers use.
   9  */
  10
  11
  12 #include <linux/uaccess.h>
  13 #include <linux/kernel.h>
  14 #include <linux/sched.h>
  15 #include <linux/slab.h>
  16 #include <linux/module.h>
  17 #include <linux/init.h>
  18 #include <linux/serio.h>
  19 #include <linux/tty.h>
  20 #include <linux/compat.h>
  21
  22 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
  23 MODULE_DESCRIPTION("Input device TTY line discipline");
  24 MODULE_LICENSE("GPL");
  25 MODULE_ALIAS_LDISC(N_MOUSE);
  26
  27 #define SERPORT_BUSY    1
  28 #define SERPORT_ACTIVE  2
  29 #define SERPORT_DEAD    3
  30
  31 struct serport {
  32         struct tty_struct *tty;
  33         wait_queue_head_t wait;
  34         struct serio *serio;
  35         struct serio_device_id id;
  36         spinlock_t lock;
  37         unsigned long flags;
  38 };
  39
  40 /*
  41  * Callback functions from the serio code.
  42  */
  43
  44 static int serport_serio_write(struct serio *serio, unsigned char data)
  45 {
  46         struct serport *serport = serio->port_data;
  47         return -(serport->tty->ops->write(serport->tty, &data, 1) != 1);
  48 }
  49
  50 static int serport_serio_open(struct serio *serio)
  51 {
  52         struct serport *serport = serio->port_data;
  53         unsigned long flags;
  54
  55         spin_lock_irqsave(&serport->lock, flags);
  56         set_bit(SERPORT_ACTIVE, &serport->flags);
  57         spin_unlock_irqrestore(&serport->lock, flags);
  58
  59         return 0;
  60 }
  61
  62
  63 static void serport_serio_close(struct serio *serio)
  64 {
  65         struct serport *serport = serio->port_data;
  66         unsigned long flags;
  67
  68         spin_lock_irqsave(&serport->lock, flags);
  69         clear_bit(SERPORT_ACTIVE, &serport->flags);
  70         spin_unlock_irqrestore(&serport->lock, flags);
  71 }
  72
  73 /*
  74  * serport_ldisc_open() is the routine that is called upon setting our line
  75  * discipline on a tty. It prepares the serio struct.
  76  */
  77
  78 static int serport_ldisc_open(struct tty_struct *tty)
  79 {
  80         struct serport *serport;
  81
  82         if (!capable(CAP_SYS_ADMIN))
  83                 return -EPERM;
  84
  85         serport = kzalloc(sizeof(*serport), GFP_KERNEL);
  86         if (!serport)
  87                 return -ENOMEM;
  88
  89         serport->tty = tty;
  90         spin_lock_init(&serport->lock);
  91         init_waitqueue_head(&serport->wait);
  92
  93         tty->disc_data = serport;
  94         tty->receive_room = 256;
  95         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
  96
  97         return 0;
  98 }
  99
 100 /*
 101  * serport_ldisc_close() is the opposite of serport_ldisc_open()
 102  */
 103
 104 static void serport_ldisc_close(struct tty_struct *tty)
 105 {
 106         struct serport *serport = tty->disc_data;
 107
 108         kfree(serport);
 109 }
 110
 111 /*
 112  * serport_ldisc_receive() is called by the low level tty driver when characters
 113  * are ready for us. We forward the characters and flags, one by one to the
 114  * 'interrupt' routine.
 115  */
 116
 117 static void serport_ldisc_receive(struct tty_struct *tty, const u8 *cp,
 118                                   const u8 *fp, size_t count)
 119 {
 120         struct serport *serport = tty->disc_data;
 121         unsigned long flags;
 122         unsigned int ch_flags = 0;
 123         int i;
 124
 125         spin_lock_irqsave(&serport->lock, flags);
 126
 127         if (!test_bit(SERPORT_ACTIVE, &serport->flags))
 128                 goto out;
 129
 130         for (i = 0; i < count; i++) {
 131                 if (fp) {
 132                         switch (fp[i]) {
 133                         case TTY_FRAME:
 134                                 ch_flags = SERIO_FRAME;
 135                                 break;
 136
 137                         case TTY_PARITY:
 138                                 ch_flags = SERIO_PARITY;
 139                                 break;
 140
 141                         default:
 142                                 ch_flags = 0;
 143                                 break;
 144                         }
 145                 }
 146
 147                 serio_interrupt(serport->serio, cp[i], ch_flags);
 148         }
 149
 150 out:
 151         spin_unlock_irqrestore(&serport->lock, flags);
 152 }
 153
 154 /*
 155  * serport_ldisc_read() just waits indefinitely if everything goes well.
 156  * However, when the serio driver closes the serio port, it finishes,
 157  * returning 0 characters.
 158  */
 159
 160 static ssize_t serport_ldisc_read(struct tty_struct * tty, struct file * file,
 161                                   u8 *kbuf, size_t nr, void **cookie,
 162                                   unsigned long offset)
 163 {
 164         struct serport *serport = tty->disc_data;
 165         struct serio *serio;
 166
 167         if (test_and_set_bit(SERPORT_BUSY, &serport->flags))
 168                 return -EBUSY;
 169
 170         serport->serio = serio = kzalloc(sizeof(*serio), GFP_KERNEL);
 171         if (!serio)
 172                 return -ENOMEM;
 173
 174         strscpy(serio->name, "Serial port", sizeof(serio->name));
 175         snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", tty_name(tty));
 176         serio->id = serport->id;
 177         serio->id.type = SERIO_RS232;
 178         serio->write = serport_serio_write;
 179         serio->open = serport_serio_open;
 180         serio->close = serport_serio_close;
 181         serio->port_data = serport;
 182         serio->dev.parent = tty->dev;
 183
 184         serio_register_port(serport->serio);
 185         printk(KERN_INFO "serio: Serial port %s\n", tty_name(tty));
 186
 187         wait_event_interruptible(serport->wait, test_bit(SERPORT_DEAD, &serport->flags));
 188         serio_unregister_port(serport->serio);
 189         serport->serio = NULL;
 190
 191         clear_bit(SERPORT_DEAD, &serport->flags);
 192         clear_bit(SERPORT_BUSY, &serport->flags);
 193
 194         return 0;
 195 }
 196
 197 static void serport_set_type(struct tty_struct *tty, unsigned long type)
 198 {
 199         struct serport *serport = tty->disc_data;
 200
 201         serport->id.proto = type & 0x000000ff;
 202         serport->id.id    = (type & 0x0000ff00) >> 8;
 203         serport->id.extra = (type & 0x00ff0000) >> 16;
 204 }
 205
 206 /*
 207  * serport_ldisc_ioctl() allows to set the port protocol, and device ID
 208  */
 209
 210 static int serport_ldisc_ioctl(struct tty_struct *tty, unsigned int cmd,
 211                                unsigned long arg)
 212 {
 213         if (cmd == SPIOCSTYPE) {
 214                 unsigned long type;
 215
 216                 if (get_user(type, (unsigned long __user *) arg))
 217                         return -EFAULT;
 218
 219                 serport_set_type(tty, type);
 220                 return 0;
 221         }
 222
 223         return -EINVAL;
 224 }
 225
 226 #ifdef CONFIG_COMPAT
 227 #define COMPAT_SPIOCSTYPE       _IOW('q', 0x01, compat_ulong_t)
 228 static int serport_ldisc_compat_ioctl(struct tty_struct *tty,
 229                                        unsigned int cmd, unsigned long arg)
 230 {
 231         if (cmd == COMPAT_SPIOCSTYPE) {
 232                 void __user *uarg = compat_ptr(arg);
 233                 compat_ulong_t compat_type;
 234
 235                 if (get_user(compat_type, (compat_ulong_t __user *)uarg))
 236                         return -EFAULT;
 237
 238                 serport_set_type(tty, compat_type);
 239                 return 0;
 240         }
 241
 242         return -EINVAL;
 243 }
 244 #endif
 245
 246 static void serport_ldisc_hangup(struct tty_struct *tty)
 247 {
 248         struct serport *serport = tty->disc_data;
 249         unsigned long flags;
 250
 251         spin_lock_irqsave(&serport->lock, flags);
 252         set_bit(SERPORT_DEAD, &serport->flags);
 253         spin_unlock_irqrestore(&serport->lock, flags);
 254
 255         wake_up_interruptible(&serport->wait);
 256 }
 257
 258 static void serport_ldisc_write_wakeup(struct tty_struct * tty)
 259 {
 260         struct serport *serport = tty->disc_data;
 261         unsigned long flags;
 262
 263         spin_lock_irqsave(&serport->lock, flags);
 264         if (test_bit(SERPORT_ACTIVE, &serport->flags))
 265                 serio_drv_write_wakeup(serport->serio);
 266         spin_unlock_irqrestore(&serport->lock, flags);
 267 }
 268
 269 /*
 270  * The line discipline structure.
 271  */
 272
 273 static struct tty_ldisc_ops serport_ldisc = {
 274         .owner =        THIS_MODULE,
 275         .num =          N_MOUSE,
 276         .name =         "input",
 277         .open =         serport_ldisc_open,
 278         .close =        serport_ldisc_close,
 279         .read =         serport_ldisc_read,
 280         .ioctl =        serport_ldisc_ioctl,
 281 #ifdef CONFIG_COMPAT
 282         .compat_ioctl = serport_ldisc_compat_ioctl,
 283 #endif
 284         .receive_buf =  serport_ldisc_receive,
 285         .hangup =       serport_ldisc_hangup,
 286         .write_wakeup = serport_ldisc_write_wakeup
 287 };
 288
 289 /*
 290  * The functions for insering/removing us as a module.
 291  */
 292
 293 static int __init serport_init(void)
 294 {
 295         int retval;
 296         retval = tty_register_ldisc(&serport_ldisc);
 297         if (retval)
 298                 printk(KERN_ERR "serport.c: Error registering line discipline.\n");
 299
 300         return  retval;
 301 }
 302
 303 static void __exit serport_exit(void)
 304 {
 305         tty_unregister_ldisc(&serport_ldisc);
 306 }
 307
 308 module_init(serport_init);
 309 module_exit(serport_exit);