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 = 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(struct 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); 310