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 */
usb_console_setup(struct console * co,char * options)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
usb_console_write(struct console * co,const char * buf,unsigned count)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
usb_console_device(struct console * co,int * index)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
usb_serial_console_disconnect(struct usb_serial * serial)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
usb_serial_console_init(int minor)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
usb_serial_console_exit(void)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
