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