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 54 guard(spinlock_irqsave)(&serport->lock); 55 set_bit(SERPORT_ACTIVE, &serport->flags); 56 57 return 0; 58 } 59 60 61 static void serport_serio_close(struct serio *serio) 62 { 63 struct serport *serport = serio->port_data; 64 65 guard(spinlock_irqsave)(&serport->lock); 66 clear_bit(SERPORT_ACTIVE, &serport->flags); 67 } 68 69 /* 70 * serport_ldisc_open() is the routine that is called upon setting our line 71 * discipline on a tty. It prepares the serio struct. 72 */ 73 74 static int serport_ldisc_open(struct tty_struct *tty) 75 { 76 struct serport *serport; 77 78 if (!capable(CAP_SYS_ADMIN)) 79 return -EPERM; 80 81 serport = kzalloc(sizeof(*serport), GFP_KERNEL); 82 if (!serport) 83 return -ENOMEM; 84 85 serport->tty = tty; 86 spin_lock_init(&serport->lock); 87 init_waitqueue_head(&serport->wait); 88 89 tty->disc_data = serport; 90 tty->receive_room = 256; 91 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 92 93 return 0; 94 } 95 96 /* 97 * serport_ldisc_close() is the opposite of serport_ldisc_open() 98 */ 99 100 static void serport_ldisc_close(struct tty_struct *tty) 101 { 102 struct serport *serport = tty->disc_data; 103 104 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 and flags, one by one to the 110 * 'interrupt' routine. 111 */ 112 113 static void serport_ldisc_receive(struct tty_struct *tty, const u8 *cp, 114 const u8 *fp, size_t count) 115 { 116 struct serport *serport = tty->disc_data; 117 unsigned int ch_flags = 0; 118 int i; 119 120 guard(spinlock_irqsave)(&serport->lock); 121 122 if (!test_bit(SERPORT_ACTIVE, &serport->flags)) 123 return; 124 125 for (i = 0; i < count; i++) { 126 if (fp) { 127 switch (fp[i]) { 128 case TTY_FRAME: 129 ch_flags = SERIO_FRAME; 130 break; 131 132 case TTY_PARITY: 133 ch_flags = SERIO_PARITY; 134 break; 135 136 default: 137 ch_flags = 0; 138 break; 139 } 140 } 141 142 serio_interrupt(serport->serio, cp[i], ch_flags); 143 } 144 } 145 146 /* 147 * serport_ldisc_read() just waits indefinitely if everything goes well. 148 * However, when the serio driver closes the serio port, it finishes, 149 * returning 0 characters. 150 */ 151 152 static ssize_t serport_ldisc_read(struct tty_struct * tty, struct file * file, 153 u8 *kbuf, size_t nr, void **cookie, 154 unsigned long offset) 155 { 156 struct serport *serport = tty->disc_data; 157 struct serio *serio; 158 159 if (test_and_set_bit(SERPORT_BUSY, &serport->flags)) 160 return -EBUSY; 161 162 serport->serio = serio = kzalloc(sizeof(*serio), GFP_KERNEL); 163 if (!serio) 164 return -ENOMEM; 165 166 strscpy(serio->name, "Serial port", sizeof(serio->name)); 167 snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", tty_name(tty)); 168 serio->id = serport->id; 169 serio->id.type = SERIO_RS232; 170 serio->write = serport_serio_write; 171 serio->open = serport_serio_open; 172 serio->close = serport_serio_close; 173 serio->port_data = serport; 174 serio->dev.parent = tty->dev; 175 176 serio_register_port(serport->serio); 177 printk(KERN_INFO "serio: Serial port %s\n", tty_name(tty)); 178 179 wait_event_interruptible(serport->wait, test_bit(SERPORT_DEAD, &serport->flags)); 180 serio_unregister_port(serport->serio); 181 serport->serio = NULL; 182 183 clear_bit(SERPORT_DEAD, &serport->flags); 184 clear_bit(SERPORT_BUSY, &serport->flags); 185 186 return 0; 187 } 188 189 static void serport_set_type(struct tty_struct *tty, unsigned long type) 190 { 191 struct serport *serport = tty->disc_data; 192 193 serport->id.proto = type & 0x000000ff; 194 serport->id.id = (type & 0x0000ff00) >> 8; 195 serport->id.extra = (type & 0x00ff0000) >> 16; 196 } 197 198 /* 199 * serport_ldisc_ioctl() allows to set the port protocol, and device ID 200 */ 201 202 static int serport_ldisc_ioctl(struct tty_struct *tty, unsigned int cmd, 203 unsigned long arg) 204 { 205 if (cmd == SPIOCSTYPE) { 206 unsigned long type; 207 208 if (get_user(type, (unsigned long __user *) arg)) 209 return -EFAULT; 210 211 serport_set_type(tty, type); 212 return 0; 213 } 214 215 return -EINVAL; 216 } 217 218 #ifdef CONFIG_COMPAT 219 #define COMPAT_SPIOCSTYPE _IOW('q', 0x01, compat_ulong_t) 220 static int serport_ldisc_compat_ioctl(struct tty_struct *tty, 221 unsigned int cmd, unsigned long arg) 222 { 223 if (cmd == COMPAT_SPIOCSTYPE) { 224 void __user *uarg = compat_ptr(arg); 225 compat_ulong_t compat_type; 226 227 if (get_user(compat_type, (compat_ulong_t __user *)uarg)) 228 return -EFAULT; 229 230 serport_set_type(tty, compat_type); 231 return 0; 232 } 233 234 return -EINVAL; 235 } 236 #endif 237 238 static void serport_ldisc_hangup(struct tty_struct *tty) 239 { 240 struct serport *serport = tty->disc_data; 241 242 scoped_guard(spinlock_irqsave, &serport->lock) 243 set_bit(SERPORT_DEAD, &serport->flags); 244 245 wake_up_interruptible(&serport->wait); 246 } 247 248 static void serport_ldisc_write_wakeup(struct tty_struct * tty) 249 { 250 struct serport *serport = tty->disc_data; 251 252 guard(spinlock_irqsave)(&serport->lock); 253 254 if (test_bit(SERPORT_ACTIVE, &serport->flags)) 255 serio_drv_write_wakeup(serport->serio); 256 } 257 258 /* 259 * The line discipline structure. 260 */ 261 262 static struct tty_ldisc_ops serport_ldisc = { 263 .owner = THIS_MODULE, 264 .num = N_MOUSE, 265 .name = "input", 266 .open = serport_ldisc_open, 267 .close = serport_ldisc_close, 268 .read = serport_ldisc_read, 269 .ioctl = serport_ldisc_ioctl, 270 #ifdef CONFIG_COMPAT 271 .compat_ioctl = serport_ldisc_compat_ioctl, 272 #endif 273 .receive_buf = serport_ldisc_receive, 274 .hangup = serport_ldisc_hangup, 275 .write_wakeup = serport_ldisc_write_wakeup 276 }; 277 278 /* 279 * The functions for insering/removing us as a module. 280 */ 281 282 static int __init serport_init(void) 283 { 284 int retval; 285 retval = tty_register_ldisc(&serport_ldisc); 286 if (retval) 287 printk(KERN_ERR "serport.c: Error registering line discipline.\n"); 288 289 return retval; 290 } 291 292 static void __exit serport_exit(void) 293 { 294 tty_unregister_ldisc(&serport_ldisc); 295 } 296 297 module_init(serport_init); 298 module_exit(serport_exit); 299