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 #define SERPORT_ACTIVE 2 31 #define SERPORT_DEAD 3 32 33 struct serport { 34 struct tty_struct *tty; 35 wait_queue_head_t wait; 36 struct serio *serio; 37 struct serio_device_id id; 38 spinlock_t lock; 39 unsigned long flags; 40 }; 41 42 /* 43 * Callback functions from the serio code. 44 */ 45 46 static int serport_serio_write(struct serio *serio, unsigned char data) 47 { 48 struct serport *serport = serio->port_data; 49 return -(serport->tty->driver->write(serport->tty, &data, 1) != 1); 50 } 51 52 static int serport_serio_open(struct serio *serio) 53 { 54 struct serport *serport = serio->port_data; 55 unsigned long flags; 56 57 spin_lock_irqsave(&serport->lock, flags); 58 set_bit(SERPORT_ACTIVE, &serport->flags); 59 spin_unlock_irqrestore(&serport->lock, flags); 60 61 return 0; 62 } 63 64 65 static void serport_serio_close(struct serio *serio) 66 { 67 struct serport *serport = serio->port_data; 68 unsigned long flags; 69 70 spin_lock_irqsave(&serport->lock, flags); 71 clear_bit(SERPORT_ACTIVE, &serport->flags); 72 set_bit(SERPORT_DEAD, &serport->flags); 73 spin_unlock_irqrestore(&serport->lock, flags); 74 75 wake_up_interruptible(&serport->wait); 76 } 77 78 /* 79 * serport_ldisc_open() is the routine that is called upon setting our line 80 * discipline on a tty. It prepares the serio struct. 81 */ 82 83 static int serport_ldisc_open(struct tty_struct *tty) 84 { 85 struct serport *serport; 86 87 if (!capable(CAP_SYS_ADMIN)) 88 return -EPERM; 89 90 serport = kzalloc(sizeof(struct serport), GFP_KERNEL); 91 if (!serport) 92 return -ENOMEM; 93 94 serport->tty = tty; 95 spin_lock_init(&serport->lock); 96 init_waitqueue_head(&serport->wait); 97 98 tty->disc_data = serport; 99 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 100 101 return 0; 102 } 103 104 /* 105 * serport_ldisc_close() is the opposite of serport_ldisc_open() 106 */ 107 108 static void serport_ldisc_close(struct tty_struct *tty) 109 { 110 struct serport *serport = (struct serport *) tty->disc_data; 111 112 kfree(serport); 113 } 114 115 /* 116 * serport_ldisc_receive() is called by the low level tty driver when characters 117 * are ready for us. We forward the characters, one by one to the 'interrupt' 118 * routine. 119 * 120 * FIXME: We should get pt_regs from the tty layer and forward them to 121 * serio_interrupt here. 122 */ 123 124 static void serport_ldisc_receive(struct tty_struct *tty, const unsigned char *cp, char *fp, int count) 125 { 126 struct serport *serport = (struct serport*) tty->disc_data; 127 unsigned long flags; 128 int i; 129 130 spin_lock_irqsave(&serport->lock, flags); 131 132 if (!test_bit(SERPORT_ACTIVE, &serport->flags)) 133 goto out; 134 135 for (i = 0; i < count; i++) 136 serio_interrupt(serport->serio, cp[i], 0, NULL); 137 138 out: 139 spin_unlock_irqrestore(&serport->lock, flags); 140 } 141 142 /* 143 * serport_ldisc_room() reports how much room we do have for receiving data. 144 * Although we in fact have infinite room, we need to specify some value 145 * here, and 256 seems to be reasonable. 146 */ 147 148 static int serport_ldisc_room(struct tty_struct *tty) 149 { 150 return 256; 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 char name[64]; 164 165 if (test_and_set_bit(SERPORT_BUSY, &serport->flags)) 166 return -EBUSY; 167 168 serport->serio = serio = kzalloc(sizeof(struct serio), GFP_KERNEL); 169 if (!serio) 170 return -ENOMEM; 171 172 strlcpy(serio->name, "Serial port", sizeof(serio->name)); 173 snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", tty_name(tty, name)); 174 serio->id = serport->id; 175 serio->id.type = SERIO_RS232; 176 serio->write = serport_serio_write; 177 serio->open = serport_serio_open; 178 serio->close = serport_serio_close; 179 serio->port_data = serport; 180 181 serio_register_port(serport->serio); 182 printk(KERN_INFO "serio: Serial port %s\n", tty_name(tty, name)); 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 /* 195 * serport_ldisc_ioctl() allows to set the port protocol, and device ID 196 */ 197 198 static int serport_ldisc_ioctl(struct tty_struct * tty, struct file * file, unsigned int cmd, unsigned long arg) 199 { 200 struct serport *serport = (struct serport*) tty->disc_data; 201 unsigned long type; 202 203 if (cmd == SPIOCSTYPE) { 204 if (get_user(type, (unsigned long __user *) arg)) 205 return -EFAULT; 206 207 serport->id.proto = type & 0x000000ff; 208 serport->id.id = (type & 0x0000ff00) >> 8; 209 serport->id.extra = (type & 0x00ff0000) >> 16; 210 211 return 0; 212 } 213 214 return -EINVAL; 215 } 216 217 static void serport_ldisc_write_wakeup(struct tty_struct * tty) 218 { 219 struct serport *serport = (struct serport *) tty->disc_data; 220 unsigned long flags; 221 222 spin_lock_irqsave(&serport->lock, flags); 223 if (test_bit(SERPORT_ACTIVE, &serport->flags)) 224 serio_drv_write_wakeup(serport->serio); 225 spin_unlock_irqrestore(&serport->lock, flags); 226 } 227 228 /* 229 * The line discipline structure. 230 */ 231 232 static struct tty_ldisc serport_ldisc = { 233 .owner = THIS_MODULE, 234 .name = "input", 235 .open = serport_ldisc_open, 236 .close = serport_ldisc_close, 237 .read = serport_ldisc_read, 238 .ioctl = serport_ldisc_ioctl, 239 .receive_buf = serport_ldisc_receive, 240 .receive_room = serport_ldisc_room, 241 .write_wakeup = serport_ldisc_write_wakeup 242 }; 243 244 /* 245 * The functions for insering/removing us as a module. 246 */ 247 248 static int __init serport_init(void) 249 { 250 int retval; 251 retval = tty_register_ldisc(N_MOUSE, &serport_ldisc); 252 if (retval) 253 printk(KERN_ERR "serport.c: Error registering line discipline.\n"); 254 255 return retval; 256 } 257 258 static void __exit serport_exit(void) 259 { 260 tty_unregister_ldisc(N_MOUSE); 261 } 262 263 module_init(serport_init); 264 module_exit(serport_exit); 265