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