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