kernel/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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/slab.h>
  19 #include <linux/tty.h>
  20 #include <linux/console.h>
  21 #include <linux/serial.h>
  22 #include <linux/usb.h>
  23 #include <linux/usb/serial.h>
  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         if (options) {
  74                 baud = simple_strtoul(options, NULL, 10);
  75                 s = options;
  76                 while (*s >= '0' && *s <= '9')
  77                         s++;
  78                 if (*s)
  79                         parity = *s++;
  80                 if (*s)
  81                         bits   = *s++ - '0';
  82                 if (*s)
  83                         doflow = (*s++ == 'r');
  84         }
  85
  86         /* Sane default */
  87         if (baud == 0)
  88                 baud = 9600;
  89
  90         switch (bits) {
  91         case 7:
  92                 cflag |= CS7;
  93                 break;
  94         default:
  95         case 8:
  96                 cflag |= CS8;
  97                 break;
  98         }
  99         switch (parity) {
 100         case 'o': case 'O':
 101                 cflag |= PARODD;
 102                 break;
 103         case 'e': case 'E':
 104                 cflag |= PARENB;
 105                 break;
 106         }
 107         co->cflag = cflag;
 108
 109         /*
 110          * no need to check the index here: if the index is wrong, console
 111          * code won't call us
 112          */
 113         port = usb_serial_port_get_by_minor(co->index);
 114         if (port == NULL) {
 115                 /* no device is connected yet, sorry :( */
 116                 pr_err("No USB device connected to ttyUSB%i\n", co->index);
 117                 return -ENODEV;
 118         }
 119         serial = port->serial;
 120
 121         retval = usb_autopm_get_interface(serial->interface);
 122         if (retval)
 123                 goto error_get_interface;
 124
 125         tty_port_tty_set(&port->port, NULL);
 126
 127         info->port = port;
 128
 129         ++port->port.count;
 130         if (!test_bit(ASYNCB_INITIALIZED, &port->port.flags)) {
 131                 if (serial->type->set_termios) {
 132                         /*
 133                          * allocate a fake tty so the driver can initialize
 134                          * the termios structure, then later call set_termios to
 135                          * configure according to command line arguments
 136                          */
 137                         tty = kzalloc(sizeof(*tty), GFP_KERNEL);
 138                         if (!tty) {
 139                                 retval = -ENOMEM;
 140                                 goto reset_open_count;
 141                         }
 142                         kref_init(&tty->kref);
 143                         tty->driver = usb_serial_tty_driver;
 144                         tty->index = co->index;
 145                         init_ldsem(&tty->ldisc_sem);
 146                         INIT_LIST_HEAD(&tty->tty_files);
 147                         kref_get(&tty->driver->kref);
 148                         __module_get(tty->driver->owner);
 149                         tty->ops = &usb_console_fake_tty_ops;
 150                         if (tty_init_termios(tty)) {
 151                                 retval = -ENOMEM;
 152                                 goto put_tty;
 153                         }
 154                         tty_port_tty_set(&port->port, tty);
 155                 }
 156
 157                 /* only call the device specific open if this
 158                  * is the first time the port is opened */
 159                 retval = serial->type->open(NULL, port);
 160                 if (retval) {
 161                         dev_err(&port->dev, "could not open USB console port\n");
 162                         goto fail;
 163                 }
 164
 165                 if (serial->type->set_termios) {
 166                         tty->termios.c_cflag = cflag;
 167                         tty_termios_encode_baud_rate(&tty->termios, baud, baud);
 168                         memset(&dummy, 0, sizeof(struct ktermios));
 169                         serial->type->set_termios(tty, port, &dummy);
 170
 171                         tty_port_tty_set(&port->port, NULL);
 172                         tty_kref_put(tty);
 173                 }
 174                 set_bit(ASYNCB_INITIALIZED, &port->port.flags);
 175         }
 176         /* Now that any required fake tty operations are completed restore
 177          * the tty port count */
 178         --port->port.count;
 179         /* The console is special in terms of closing the device so
 180          * indicate this port is now acting as a system console. */
 181         port->port.console = 1;
 182
 183         mutex_unlock(&serial->disc_mutex);
 184         return retval;
 185
 186  fail:
 187         tty_port_tty_set(&port->port, NULL);
 188  put_tty:
 189         tty_kref_put(tty);
 190  reset_open_count:
 191         port->port.count = 0;
 192         usb_autopm_put_interface(serial->interface);
 193  error_get_interface:
 194         usb_serial_put(serial);
 195         mutex_unlock(&serial->disc_mutex);
 196         return retval;
 197 }
 198
 199 static void usb_console_write(struct console *co,
 200                                         const char *buf, unsigned count)
 201 {
 202         static struct usbcons_info *info = &usbcons_info;
 203         struct usb_serial_port *port = info->port;
 204         struct usb_serial *serial;
 205         int retval = -ENODEV;
 206
 207         if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED)
 208                 return;
 209         serial = port->serial;
 210
 211         if (count == 0)
 212                 return;
 213
 214         dev_dbg(&port->dev, "%s - %d byte(s)\n", __func__, count);
 215
 216         if (!port->port.console) {
 217                 dev_dbg(&port->dev, "%s - port not opened\n", __func__);
 218                 return;
 219         }
 220
 221         while (count) {
 222                 unsigned int i;
 223                 unsigned int lf;
 224                 /* search for LF so we can insert CR if necessary */
 225                 for (i = 0, lf = 0 ; i < count ; i++) {
 226                         if (*(buf + i) == 10) {
 227                                 lf = 1;
 228                                 i++;
 229                                 break;
 230                         }
 231                 }
 232                 /* pass on to the driver specific version of this function if
 233                    it is available */
 234                 retval = serial->type->write(NULL, port, buf, i);
 235                 dev_dbg(&port->dev, "%s - write: %d\n", __func__, retval);
 236                 if (lf) {
 237                         /* append CR after LF */
 238                         unsigned char cr = 13;
 239                         retval = serial->type->write(NULL, port, &cr, 1);
 240                         dev_dbg(&port->dev, "%s - write cr: %d\n",
 241                                                         __func__, retval);
 242                 }
 243                 buf += i;
 244                 count -= i;
 245         }
 246 }
 247
 248 static struct tty_driver *usb_console_device(struct console *co, int *index)
 249 {
 250         struct tty_driver **p = (struct tty_driver **)co->data;
 251
 252         if (!*p)
 253                 return NULL;
 254
 255         *index = co->index;
 256         return *p;
 257 }
 258
 259 static struct console usbcons = {
 260         .name =         "ttyUSB",
 261         .write =        usb_console_write,
 262         .device =       usb_console_device,
 263         .setup =        usb_console_setup,
 264         .flags =        CON_PRINTBUFFER,
 265         .index =        -1,
 266         .data =         &usb_serial_tty_driver,
 267 };
 268
 269 void usb_serial_console_disconnect(struct usb_serial *serial)
 270 {
 271         if (serial && serial->port && serial->port[0]
 272                                 && serial->port[0] == usbcons_info.port) {
 273                 usb_serial_console_exit();
 274                 usb_serial_put(serial);
 275         }
 276 }
 277
 278 void usb_serial_console_init(int minor)
 279 {
 280         if (minor == 0) {
 281                 /*
 282                  * Call register_console() if this is the first device plugged
 283                  * in.  If we call it earlier, then the callback to
 284                  * console_setup() will fail, as there is not a device seen by
 285                  * the USB subsystem yet.
 286                  */
 287                 /*
 288                  * Register console.
 289                  * NOTES:
 290                  * console_setup() is called (back) immediately (from
 291                  * register_console). console_write() is called immediately
 292                  * from register_console iff CON_PRINTBUFFER is set in flags.
 293                  */
 294                 pr_debug("registering the USB serial console.\n");
 295                 register_console(&usbcons);
 296         }
 297 }
 298
 299 void usb_serial_console_exit(void)
 300 {
 301         if (usbcons_info.port) {
 302                 unregister_console(&usbcons);
 303                 usbcons_info.port->port.console = 0;
 304                 usbcons_info.port = NULL;
 305         }
 306 }
 307