1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * USB Serial Console driver 4 * 5 * Copyright (C) 2001 - 2002 Greg Kroah-Hartman (greg@kroah.com) 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License version 9 * 2 as published by the Free Software Foundation. 10 * 11 * Thanks to Randy Dunlap for the original version of this code. 12 * 13 */ 14 15 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 16 17 #include <linux/kernel.h> 18 #include <linux/module.h> 19 #include <linux/slab.h> 20 #include <linux/tty.h> 21 #include <linux/console.h> 22 #include <linux/serial.h> 23 #include <linux/usb.h> 24 #include <linux/usb/serial.h> 25 26 struct usbcons_info { 27 int magic; 28 int break_flag; 29 struct usb_serial_port *port; 30 }; 31 32 static struct usbcons_info usbcons_info; 33 static struct console usbcons; 34 35 /* 36 * ------------------------------------------------------------ 37 * USB Serial console driver 38 * 39 * Much of the code here is copied from drivers/char/serial.c 40 * and implements a phony serial console in the same way that 41 * serial.c does so that in case some software queries it, 42 * it will get the same results. 43 * 44 * Things that are different from the way the serial port code 45 * does things, is that we call the lower level usb-serial 46 * driver code to initialize the device, and we set the initial 47 * console speeds based on the command line arguments. 48 * ------------------------------------------------------------ 49 */ 50 51 static const struct tty_operations usb_console_fake_tty_ops = { 52 }; 53 54 /* 55 * The parsing of the command line works exactly like the 56 * serial.c code, except that the specifier is "ttyUSB" instead 57 * of "ttyS". 58 */ 59 static int usb_console_setup(struct console *co, char *options) 60 { 61 struct usbcons_info *info = &usbcons_info; 62 int baud = 9600; 63 int bits = 8; 64 int parity = 'n'; 65 int doflow = 0; 66 int cflag = CREAD | HUPCL | CLOCAL; 67 char *s; 68 struct usb_serial *serial; 69 struct usb_serial_port *port; 70 int retval; 71 struct tty_struct *tty = NULL; 72 struct ktermios dummy; 73 74 if (options) { 75 baud = simple_strtoul(options, NULL, 10); 76 s = options; 77 while (*s >= '0' && *s <= '9') 78 s++; 79 if (*s) 80 parity = *s++; 81 if (*s) 82 bits = *s++ - '0'; 83 if (*s) 84 doflow = (*s++ == 'r'); 85 } 86 87 /* Sane default */ 88 if (baud == 0) 89 baud = 9600; 90 91 switch (bits) { 92 case 7: 93 cflag |= CS7; 94 break; 95 default: 96 case 8: 97 cflag |= CS8; 98 break; 99 } 100 switch (parity) { 101 case 'o': case 'O': 102 cflag |= PARODD; 103 break; 104 case 'e': case 'E': 105 cflag |= PARENB; 106 break; 107 } 108 co->cflag = cflag; 109 110 /* 111 * no need to check the index here: if the index is wrong, console 112 * code won't call us 113 */ 114 port = usb_serial_port_get_by_minor(co->index); 115 if (port == NULL) { 116 /* no device is connected yet, sorry :( */ 117 pr_err("No USB device connected to ttyUSB%i\n", co->index); 118 return -ENODEV; 119 } 120 serial = port->serial; 121 122 retval = usb_autopm_get_interface(serial->interface); 123 if (retval) 124 goto error_get_interface; 125 126 tty_port_tty_set(&port->port, NULL); 127 128 info->port = port; 129 130 ++port->port.count; 131 if (!tty_port_initialized(&port->port)) { 132 if (serial->type->set_termios) { 133 /* 134 * allocate a fake tty so the driver can initialize 135 * the termios structure, then later call set_termios to 136 * configure according to command line arguments 137 */ 138 tty = kzalloc(sizeof(*tty), GFP_KERNEL); 139 if (!tty) { 140 retval = -ENOMEM; 141 goto reset_open_count; 142 } 143 kref_init(&tty->kref); 144 tty->driver = usb_serial_tty_driver; 145 tty->index = co->index; 146 init_ldsem(&tty->ldisc_sem); 147 spin_lock_init(&tty->files_lock); 148 INIT_LIST_HEAD(&tty->tty_files); 149 kref_get(&tty->driver->kref); 150 __module_get(tty->driver->owner); 151 tty->ops = &usb_console_fake_tty_ops; 152 tty_init_termios(tty); 153 tty_port_tty_set(&port->port, tty); 154 } 155 156 /* only call the device specific open if this 157 * is the first time the port is opened */ 158 retval = serial->type->open(NULL, port); 159 if (retval) { 160 dev_err(&port->dev, "could not open USB console port\n"); 161 goto fail; 162 } 163 164 if (serial->type->set_termios) { 165 tty->termios.c_cflag = cflag; 166 tty_termios_encode_baud_rate(&tty->termios, baud, baud); 167 memset(&dummy, 0, sizeof(struct ktermios)); 168 serial->type->set_termios(tty, port, &dummy); 169 170 tty_port_tty_set(&port->port, NULL); 171 tty_kref_put(tty); 172 } 173 tty_port_set_initialized(&port->port, 1); 174 } 175 /* Now that any required fake tty operations are completed restore 176 * the tty port count */ 177 --port->port.count; 178 /* The console is special in terms of closing the device so 179 * indicate this port is now acting as a system console. */ 180 port->port.console = 1; 181 182 mutex_unlock(&serial->disc_mutex); 183 return retval; 184 185 fail: 186 tty_port_tty_set(&port->port, NULL); 187 tty_kref_put(tty); 188 reset_open_count: 189 port->port.count = 0; 190 info->port = NULL; 191 usb_autopm_put_interface(serial->interface); 192 error_get_interface: 193 usb_serial_put(serial); 194 mutex_unlock(&serial->disc_mutex); 195 return retval; 196 } 197 198 static void usb_console_write(struct console *co, 199 const char *buf, unsigned count) 200 { 201 static struct usbcons_info *info = &usbcons_info; 202 struct usb_serial_port *port = info->port; 203 struct usb_serial *serial; 204 int retval = -ENODEV; 205 206 if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED) 207 return; 208 serial = port->serial; 209 210 if (count == 0) 211 return; 212 213 dev_dbg(&port->dev, "%s - %d byte(s)\n", __func__, count); 214 215 if (!port->port.console) { 216 dev_dbg(&port->dev, "%s - port not opened\n", __func__); 217 return; 218 } 219 220 while (count) { 221 unsigned int i; 222 unsigned int lf; 223 /* search for LF so we can insert CR if necessary */ 224 for (i = 0, lf = 0 ; i < count ; i++) { 225 if (*(buf + i) == 10) { 226 lf = 1; 227 i++; 228 break; 229 } 230 } 231 /* pass on to the driver specific version of this function if 232 it is available */ 233 retval = serial->type->write(NULL, port, buf, i); 234 dev_dbg(&port->dev, "%s - write: %d\n", __func__, retval); 235 if (lf) { 236 /* append CR after LF */ 237 unsigned char cr = 13; 238 retval = serial->type->write(NULL, port, &cr, 1); 239 dev_dbg(&port->dev, "%s - write cr: %d\n", 240 __func__, retval); 241 } 242 buf += i; 243 count -= i; 244 } 245 } 246 247 static struct tty_driver *usb_console_device(struct console *co, int *index) 248 { 249 struct tty_driver **p = (struct tty_driver **)co->data; 250 251 if (!*p) 252 return NULL; 253 254 *index = co->index; 255 return *p; 256 } 257 258 static struct console usbcons = { 259 .name = "ttyUSB", 260 .write = usb_console_write, 261 .device = usb_console_device, 262 .setup = usb_console_setup, 263 .flags = CON_PRINTBUFFER, 264 .index = -1, 265 .data = &usb_serial_tty_driver, 266 }; 267 268 void usb_serial_console_disconnect(struct usb_serial *serial) 269 { 270 if (serial->port[0] && 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 } 305 306