drivers/usb/serial/console.c

   1 /*
   2  * USB Serial Console driver
   3  *
   4  * Copyright (C) 2001 - 2002 Greg Kroah-Hartman (greg@kroah.com)
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License version
   8  *      2 as published by the Free Software Foundation.
   9  *
  10  * Thanks to Randy Dunlap for the original version of this code.
  11  *
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/init.h>
  16 #include <linux/slab.h>
  17 #include <linux/tty.h>
  18 #include <linux/console.h>
  19 #include <linux/serial.h>
  20 #include <linux/usb.h>
  21 #include <linux/usb/serial.h>
  22
  23 static int debug;
  24
  25 struct usbcons_info {
  26         int                     magic;
  27         int                     break_flag;
  28         struct usb_serial_port  *port;
  29 };
  30
  31 static struct usbcons_info usbcons_info;
  32 static struct console usbcons;
  33
  34 /*
  35  * ------------------------------------------------------------
  36  * USB Serial console driver
  37  *
  38  * Much of the code here is copied from drivers/char/serial.c
  39  * and implements a phony serial console in the same way that
  40  * serial.c does so that in case some software queries it,
  41  * it will get the same results.
  42  *
  43  * Things that are different from the way the serial port code
  44  * does things, is that we call the lower level usb-serial
  45  * driver code to initialize the device, and we set the initial
  46  * console speeds based on the command line arguments.
  47  * ------------------------------------------------------------
  48  */
  49
  50 static const struct tty_operations usb_console_fake_tty_ops = {
  51 };
  52
  53 /*
  54  * The parsing of the command line works exactly like the
  55  * serial.c code, except that the specifier is "ttyUSB" instead
  56  * of "ttyS".
  57  */
  58 static int usb_console_setup(struct console *co, char *options)
  59 {
  60         struct usbcons_info *info = &usbcons_info;
  61         int baud = 9600;
  62         int bits = 8;
  63         int parity = 'n';
  64         int doflow = 0;
  65         int cflag = CREAD | HUPCL | CLOCAL;
  66         char *s;
  67         struct usb_serial *serial;
  68         struct usb_serial_port *port;
  69         int retval;
  70         struct tty_struct *tty = NULL;
  71         struct ktermios dummy;
  72
  73         dbg("%s", __func__);
  74
  75         if (options) {
  76                 baud = simple_strtoul(options, NULL, 10);
  77                 s = options;
  78                 while (*s >= '0' && *s <= '9')
  79                         s++;
  80                 if (*s)
  81                         parity = *s++;
  82                 if (*s)
  83                         bits   = *s++ - '0';
  84                 if (*s)
  85                         doflow = (*s++ == 'r');
  86         }
  87
  88         /* Sane default */
  89         if (baud == 0)
  90                 baud = 9600;
  91
  92         switch (bits) {
  93         case 7:
  94                 cflag |= CS7;
  95                 break;
  96         default:
  97         case 8:
  98                 cflag |= CS8;
  99                 break;
 100         }
 101         switch (parity) {
 102         case 'o': case 'O':
 103                 cflag |= PARODD;
 104                 break;
 105         case 'e': case 'E':
 106                 cflag |= PARENB;
 107                 break;
 108         }
 109         co->cflag = cflag;
 110
 111         /*
 112          * no need to check the index here: if the index is wrong, console
 113          * code won't call us
 114          */
 115         serial = usb_serial_get_by_index(co->index);
 116         if (serial == NULL) {
 117                 /* no device is connected yet, sorry :( */
 118                 err("No USB device connected to ttyUSB%i", co->index);
 119                 return -ENODEV;
 120         }
 121
 122         retval = usb_autopm_get_interface(serial->interface);
 123         if (retval)
 124                 goto error_get_interface;
 125
 126         port = serial->port[co->index - serial->minor];
 127         tty_port_tty_set(&port->port, NULL);
 128
 129         info->port = port;
 130
 131         ++port->port.count;
 132         if (!test_bit(ASYNCB_INITIALIZED, &port->port.flags)) {
 133                 if (serial->type->set_termios) {
 134                         /*
 135                          * allocate a fake tty so the driver can initialize
 136                          * the termios structure, then later call set_termios to
 137                          * configure according to command line arguments
 138                          */
 139                         tty = kzalloc(sizeof(*tty), GFP_KERNEL);
 140                         if (!tty) {
 141                                 retval = -ENOMEM;
 142                                 err("no more memory");
 143                                 goto reset_open_count;
 144                         }
 145                         kref_init(&tty->kref);
 146                         tty->driver = usb_serial_tty_driver;
 147                         tty->index = co->index;
 148                         INIT_LIST_HEAD(&tty->tty_files);
 149                         kref_get(&tty->driver->kref);
 150                         tty->ops = &usb_console_fake_tty_ops;
 151                         if (tty_init_termios(tty)) {
 152                                 retval = -ENOMEM;
 153                                 err("no more memory");
 154                                 goto put_tty;
 155                         }
 156                         tty_port_tty_set(&port->port, tty);
 157                 }
 158
 159                 /* only call the device specific open if this
 160                  * is the first time the port is opened */
 161                 if (serial->type->open)
 162                         retval = serial->type->open(NULL, port);
 163                 else
 164                         retval = usb_serial_generic_open(NULL, port);
 165
 166                 if (retval) {
 167                         err("could not open USB console port");
 168                         goto fail;
 169                 }
 170
 171                 if (serial->type->set_termios) {
 172                         tty->termios->c_cflag = cflag;
 173                         tty_termios_encode_baud_rate(tty->termios, baud, baud);
 174                         memset(&dummy, 0, sizeof(struct ktermios));
 175                         serial->type->set_termios(tty, port, &dummy);
 176
 177                         tty_port_tty_set(&port->port, NULL);
 178                         tty_kref_put(tty);
 179                 }
 180                 set_bit(ASYNCB_INITIALIZED, &port->port.flags);
 181         }
 182         /* Now that any required fake tty operations are completed restore
 183          * the tty port count */
 184         --port->port.count;
 185         /* The console is special in terms of closing the device so
 186          * indicate this port is now acting as a system console. */
 187         port->port.console = 1;
 188
 189         mutex_unlock(&serial->disc_mutex);
 190         return retval;
 191
 192  fail:
 193         tty_port_tty_set(&port->port, NULL);
 194  put_tty:
 195         tty_kref_put(tty);
 196  reset_open_count:
 197         port->port.count = 0;
 198         info->port = NULL;
 199         usb_autopm_put_interface(serial->interface);
 200  error_get_interface:
 201         usb_serial_put(serial);
 202         mutex_unlock(&serial->disc_mutex);
 203         return retval;
 204 }
 205
 206 static void usb_console_write(struct console *co,
 207                                         const char *buf, unsigned count)
 208 {
 209         static struct usbcons_info *info = &usbcons_info;
 210         struct usb_serial_port *port = info->port;
 211         struct usb_serial *serial;
 212         int retval = -ENODEV;
 213
 214         if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED)
 215                 return;
 216         serial = port->serial;
 217
 218         if (count == 0)
 219                 return;
 220
 221         dbg("%s - port %d, %d byte(s)", __func__, port->number, count);
 222
 223         if (!port->port.console) {
 224                 dbg("%s - port not opened", __func__);
 225                 return;
 226         }
 227
 228         while (count) {
 229                 unsigned int i;
 230                 unsigned int lf;
 231                 /* search for LF so we can insert CR if necessary */
 232                 for (i = 0, lf = 0 ; i < count ; i++) {
 233                         if (*(buf + i) == 10) {
 234                                 lf = 1;
 235                                 i++;
 236                                 break;
 237                         }
 238                 }
 239                 /* pass on to the driver specific version of this function if
 240                    it is available */
 241                 if (serial->type->write)
 242                         retval = serial->type->write(NULL, port, buf, i);
 243                 else
 244                         retval = usb_serial_generic_write(NULL, port, buf, i);
 245                 dbg("%s - return value : %d", __func__, retval);
 246                 if (lf) {
 247                         /* append CR after LF */
 248                         unsigned char cr = 13;
 249                         if (serial->type->write)
 250                                 retval = serial->type->write(NULL,
 251                                                                 port, &cr, 1);
 252                         else
 253                                 retval = usb_serial_generic_write(NULL,
 254                                                                 port, &cr, 1);
 255                         dbg("%s - return value : %d", __func__, retval);
 256                 }
 257                 buf += i;
 258                 count -= i;
 259         }
 260 }
 261
 262 static struct tty_driver *usb_console_device(struct console *co, int *index)
 263 {
 264         struct tty_driver **p = (struct tty_driver **)co->data;
 265
 266         if (!*p)
 267                 return NULL;
 268
 269         *index = co->index;
 270         return *p;
 271 }
 272
 273 static struct console usbcons = {
 274         .name =         "ttyUSB",
 275         .write =        usb_console_write,
 276         .device =       usb_console_device,
 277         .setup =        usb_console_setup,
 278         .flags =        CON_PRINTBUFFER,
 279         .index =        -1,
 280         .data =         &usb_serial_tty_driver,
 281 };
 282
 283 void usb_serial_console_disconnect(struct usb_serial *serial)
 284 {
 285         if (serial && serial->port && serial->port[0]
 286                                 && serial->port[0] == usbcons_info.port) {
 287                 usb_serial_console_exit();
 288                 usb_serial_put(serial);
 289         }
 290 }
 291
 292 void usb_serial_console_init(int serial_debug, int minor)
 293 {
 294         debug = serial_debug;
 295
 296         if (minor == 0) {
 297                 /*
 298                  * Call register_console() if this is the first device plugged
 299                  * in.  If we call it earlier, then the callback to
 300                  * console_setup() will fail, as there is not a device seen by
 301                  * the USB subsystem yet.
 302                  */
 303                 /*
 304                  * Register console.
 305                  * NOTES:
 306                  * console_setup() is called (back) immediately (from
 307                  * register_console). console_write() is called immediately
 308                  * from register_console iff CON_PRINTBUFFER is set in flags.
 309                  */
 310                 dbg("registering the USB serial console.");
 311                 register_console(&usbcons);
 312         }
 313 }
 314
 315 void usb_serial_console_exit(void)
 316 {
 317         if (usbcons_info.port) {
 318                 unregister_console(&usbcons);
 319                 usbcons_info.port->port.console = 0;
 320                 usbcons_info.port = NULL;
 321         }
 322 }
 323