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 * Thanks to Randy Dunlap for the original version of this code. 8 * 9 */ 10 11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 12 13 #include <linux/kernel.h> 14 #include <linux/module.h> 15 #include <linux/slab.h> 16 #include <linux/tty.h> 17 #include <linux/console.h> 18 #include <linux/serial.h> 19 #include <linux/usb.h> 20 #include <linux/usb/serial.h> 21 22 struct usbcons_info { 23 int magic; 24 int break_flag; 25 struct usb_serial_port *port; 26 }; 27 28 static struct usbcons_info usbcons_info; 29 static struct console usbcons; 30 31 /* 32 * ------------------------------------------------------------ 33 * USB Serial console driver 34 * 35 * Much of the code here is copied from drivers/char/serial.c 36 * and implements a phony serial console in the same way that 37 * serial.c does so that in case some software queries it, 38 * it will get the same results. 39 * 40 * Things that are different from the way the serial port code 41 * does things, is that we call the lower level usb-serial 42 * driver code to initialize the device, and we set the initial 43 * console speeds based on the command line arguments. 44 * ------------------------------------------------------------ 45 */ 46 47 static const struct tty_operations usb_console_fake_tty_ops = { 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 } 104 105 /* 106 * no need to check the index here: if the index is wrong, console 107 * code won't call us 108 */ 109 port = usb_serial_port_get_by_minor(co->index); 110 if (port == NULL) { 111 /* no device is connected yet, sorry :( */ 112 pr_err("No USB device connected to ttyUSB%i\n", co->index); 113 return -ENODEV; 114 } 115 serial = port->serial; 116 117 retval = usb_autopm_get_interface(serial->interface); 118 if (retval) 119 goto error_get_interface; 120 121 tty_port_tty_set(&port->port, NULL); 122 123 info->port = port; 124 125 ++port->port.count; 126 if (!tty_port_initialized(&port->port)) { 127 if (serial->type->set_termios) { 128 /* 129 * allocate a fake tty so the driver can initialize 130 * the termios structure, then later call set_termios to 131 * configure according to command line arguments 132 */ 133 tty = kzalloc(sizeof(*tty), GFP_KERNEL); 134 if (!tty) { 135 retval = -ENOMEM; 136 goto reset_open_count; 137 } 138 kref_init(&tty->kref); 139 tty->driver = usb_serial_tty_driver; 140 tty->index = co->index; 141 init_ldsem(&tty->ldisc_sem); 142 spin_lock_init(&tty->files_lock); 143 INIT_LIST_HEAD(&tty->tty_files); 144 kref_get(&tty->driver->kref); 145 __module_get(tty->driver->owner); 146 tty->ops = &usb_console_fake_tty_ops; 147 tty_init_termios(tty); 148 tty_port_tty_set(&port->port, tty); 149 } 150 151 /* only call the device specific open if this 152 * is the first time the port is opened */ 153 retval = serial->type->open(NULL, port); 154 if (retval) { 155 dev_err(&port->dev, "could not open USB console port\n"); 156 goto fail; 157 } 158 159 if (serial->type->set_termios) { 160 tty->termios.c_cflag = cflag; 161 tty_termios_encode_baud_rate(&tty->termios, baud, baud); 162 memset(&dummy, 0, sizeof(struct ktermios)); 163 serial->type->set_termios(tty, port, &dummy); 164 165 tty_port_tty_set(&port->port, NULL); 166 tty_save_termios(tty); 167 tty_kref_put(tty); 168 } 169 tty_port_set_initialized(&port->port, 1); 170 } 171 /* Now that any required fake tty operations are completed restore 172 * the tty port count */ 173 --port->port.count; 174 /* The console is special in terms of closing the device so 175 * indicate this port is now acting as a system console. */ 176 port->port.console = 1; 177 178 mutex_unlock(&serial->disc_mutex); 179 return retval; 180 181 fail: 182 tty_port_tty_set(&port->port, NULL); 183 tty_kref_put(tty); 184 reset_open_count: 185 port->port.count = 0; 186 info->port = NULL; 187 usb_autopm_put_interface(serial->interface); 188 error_get_interface: 189 usb_serial_put(serial); 190 mutex_unlock(&serial->disc_mutex); 191 return retval; 192 } 193 194 static void usb_console_write(struct console *co, 195 const char *buf, unsigned count) 196 { 197 static struct usbcons_info *info = &usbcons_info; 198 struct usb_serial_port *port = info->port; 199 struct usb_serial *serial; 200 int retval = -ENODEV; 201 202 if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED) 203 return; 204 serial = port->serial; 205 206 if (count == 0) 207 return; 208 209 dev_dbg(&port->dev, "%s - %d byte(s)\n", __func__, count); 210 211 if (!port->port.console) { 212 dev_dbg(&port->dev, "%s - port not opened\n", __func__); 213 return; 214 } 215 216 while (count) { 217 unsigned int i; 218 unsigned int lf; 219 /* search for LF so we can insert CR if necessary */ 220 for (i = 0, lf = 0 ; i < count ; i++) { 221 if (*(buf + i) == 10) { 222 lf = 1; 223 i++; 224 break; 225 } 226 } 227 /* pass on to the driver specific version of this function if 228 it is available */ 229 retval = serial->type->write(NULL, port, buf, i); 230 dev_dbg(&port->dev, "%s - write: %d\n", __func__, retval); 231 if (lf) { 232 /* append CR after LF */ 233 unsigned char cr = 13; 234 retval = serial->type->write(NULL, port, &cr, 1); 235 dev_dbg(&port->dev, "%s - write cr: %d\n", 236 __func__, retval); 237 } 238 buf += i; 239 count -= i; 240 } 241 } 242 243 static struct tty_driver *usb_console_device(struct console *co, int *index) 244 { 245 struct tty_driver **p = (struct tty_driver **)co->data; 246 247 if (!*p) 248 return NULL; 249 250 *index = co->index; 251 return *p; 252 } 253 254 static struct console usbcons = { 255 .name = "ttyUSB", 256 .write = usb_console_write, 257 .device = usb_console_device, 258 .setup = usb_console_setup, 259 .flags = CON_PRINTBUFFER, 260 .index = -1, 261 .data = &usb_serial_tty_driver, 262 }; 263 264 void usb_serial_console_disconnect(struct usb_serial *serial) 265 { 266 if (serial->port[0] && serial->port[0] == usbcons_info.port) { 267 usb_serial_console_exit(); 268 usb_serial_put(serial); 269 } 270 } 271 272 void usb_serial_console_init(int minor) 273 { 274 if (minor == 0) { 275 /* 276 * Call register_console() if this is the first device plugged 277 * in. If we call it earlier, then the callback to 278 * console_setup() will fail, as there is not a device seen by 279 * the USB subsystem yet. 280 */ 281 /* 282 * Register console. 283 * NOTES: 284 * console_setup() is called (back) immediately (from 285 * register_console). console_write() is called immediately 286 * from register_console iff CON_PRINTBUFFER is set in flags. 287 */ 288 pr_debug("registering the USB serial console.\n"); 289 register_console(&usbcons); 290 } 291 } 292 293 void usb_serial_console_exit(void) 294 { 295 if (usbcons_info.port) { 296 unregister_console(&usbcons); 297 usbcons_info.port->port.console = 0; 298 usbcons_info.port = NULL; 299 } 300 } 301 302