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(struct 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 = (struct 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 unsigned char *cp, char *fp, int count) 118 { 119 struct serport *serport = (struct serport*) tty->disc_data; 120 unsigned long flags; 121 unsigned int ch_flags = 0; 122 int i; 123 124 spin_lock_irqsave(&serport->lock, flags); 125 126 if (!test_bit(SERPORT_ACTIVE, &serport->flags)) 127 goto out; 128 129 for (i = 0; i < count; i++) { 130 if (fp) { 131 switch (fp[i]) { 132 case TTY_FRAME: 133 ch_flags = SERIO_FRAME; 134 break; 135 136 case TTY_PARITY: 137 ch_flags = SERIO_PARITY; 138 break; 139 140 default: 141 ch_flags = 0; 142 break; 143 } 144 } 145 146 serio_interrupt(serport->serio, cp[i], ch_flags); 147 } 148 149 out: 150 spin_unlock_irqrestore(&serport->lock, flags); 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; 163 164 if (test_and_set_bit(SERPORT_BUSY, &serport->flags)) 165 return -EBUSY; 166 167 serport->serio = serio = kzalloc(sizeof(struct serio), GFP_KERNEL); 168 if (!serio) 169 return -ENOMEM; 170 171 strlcpy(serio->name, "Serial port", sizeof(serio->name)); 172 snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", tty_name(tty)); 173 serio->id = serport->id; 174 serio->id.type = SERIO_RS232; 175 serio->write = serport_serio_write; 176 serio->open = serport_serio_open; 177 serio->close = serport_serio_close; 178 serio->port_data = serport; 179 serio->dev.parent = tty->dev; 180 181 serio_register_port(serport->serio); 182 printk(KERN_INFO "serio: Serial port %s\n", tty_name(tty)); 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 static void serport_set_type(struct tty_struct *tty, unsigned long type) 195 { 196 struct serport *serport = tty->disc_data; 197 198 serport->id.proto = type & 0x000000ff; 199 serport->id.id = (type & 0x0000ff00) >> 8; 200 serport->id.extra = (type & 0x00ff0000) >> 16; 201 } 202 203 /* 204 * serport_ldisc_ioctl() allows to set the port protocol, and device ID 205 */ 206 207 static int serport_ldisc_ioctl(struct tty_struct *tty, struct file *file, 208 unsigned int cmd, unsigned long arg) 209 { 210 if (cmd == SPIOCSTYPE) { 211 unsigned long type; 212 213 if (get_user(type, (unsigned long __user *) arg)) 214 return -EFAULT; 215 216 serport_set_type(tty, type); 217 return 0; 218 } 219 220 return -EINVAL; 221 } 222 223 #ifdef CONFIG_COMPAT 224 #define COMPAT_SPIOCSTYPE _IOW('q', 0x01, compat_ulong_t) 225 static int serport_ldisc_compat_ioctl(struct tty_struct *tty, 226 struct file *file, 227 unsigned int cmd, unsigned long arg) 228 { 229 if (cmd == COMPAT_SPIOCSTYPE) { 230 void __user *uarg = compat_ptr(arg); 231 compat_ulong_t compat_type; 232 233 if (get_user(compat_type, (compat_ulong_t __user *)uarg)) 234 return -EFAULT; 235 236 serport_set_type(tty, compat_type); 237 return 0; 238 } 239 240 return -EINVAL; 241 } 242 #endif 243 244 static int serport_ldisc_hangup(struct tty_struct *tty) 245 { 246 struct serport *serport = (struct serport *) tty->disc_data; 247 unsigned long flags; 248 249 spin_lock_irqsave(&serport->lock, flags); 250 set_bit(SERPORT_DEAD, &serport->flags); 251 spin_unlock_irqrestore(&serport->lock, flags); 252 253 wake_up_interruptible(&serport->wait); 254 return 0; 255 } 256 257 static void serport_ldisc_write_wakeup(struct tty_struct * tty) 258 { 259 struct serport *serport = (struct serport *) tty->disc_data; 260 unsigned long flags; 261 262 spin_lock_irqsave(&serport->lock, flags); 263 if (test_bit(SERPORT_ACTIVE, &serport->flags)) 264 serio_drv_write_wakeup(serport->serio); 265 spin_unlock_irqrestore(&serport->lock, flags); 266 } 267 268 /* 269 * The line discipline structure. 270 */ 271 272 static struct tty_ldisc_ops serport_ldisc = { 273 .owner = THIS_MODULE, 274 .name = "input", 275 .open = serport_ldisc_open, 276 .close = serport_ldisc_close, 277 .read = serport_ldisc_read, 278 .ioctl = serport_ldisc_ioctl, 279 #ifdef CONFIG_COMPAT 280 .compat_ioctl = serport_ldisc_compat_ioctl, 281 #endif 282 .receive_buf = serport_ldisc_receive, 283 .hangup = serport_ldisc_hangup, 284 .write_wakeup = serport_ldisc_write_wakeup 285 }; 286 287 /* 288 * The functions for insering/removing us as a module. 289 */ 290 291 static int __init serport_init(void) 292 { 293 int retval; 294 retval = tty_register_ldisc(N_MOUSE, &serport_ldisc); 295 if (retval) 296 printk(KERN_ERR "serport.c: Error registering line discipline.\n"); 297 298 return retval; 299 } 300 301 static void __exit serport_exit(void) 302 { 303 tty_unregister_ldisc(N_MOUSE); 304 } 305 306 module_init(serport_init); 307 module_exit(serport_exit); 308