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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * USB Serial Console driver
4 *
5 * Copyright (C) 2001 - 2002 Greg Kroah-Hartman ([email protected])
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
22struct usbcons_info {
23 int magic;
24 int break_flag;
25 struct usb_serial_port *port;
26};
27
28static struct usbcons_info usbcons_info;
29static 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
47static 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 */
55static 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 if (doflow)
106 cflag |= CRTSCTS;
107
108 /*
109 * no need to check the index here: if the index is wrong, console
110 * code won't call us
111 */
112 port = usb_serial_port_get_by_minor(co->index);
113 if (port == NULL) {
114 /* no device is connected yet, sorry :( */
115 pr_err("No USB device connected to ttyUSB%i\n", co->index);
116 return -ENODEV;
117 }
118 serial = port->serial;
119
120 retval = usb_autopm_get_interface(serial->interface);
121 if (retval)
122 goto error_get_interface;
123
124 tty_port_tty_set(&port->port, NULL);
125
126 info->port = port;
127
128 ++port->port.count;
129 if (!tty_port_initialized(&port->port)) {
130 if (serial->type->set_termios) {
131 /*
132 * allocate a fake tty so the driver can initialize
133 * the termios structure, then later call set_termios to
134 * configure according to command line arguments
135 */
136 tty = kzalloc_obj(*tty);
137 if (!tty) {
138 retval = -ENOMEM;
139 goto reset_open_count;
140 }
141 kref_init(&tty->kref);
142 tty->driver = usb_serial_tty_driver;
143 tty->index = co->index;
144 init_ldsem(&tty->ldisc_sem);
145 spin_lock_init(&tty->files_lock);
146 INIT_LIST_HEAD(&tty->tty_files);
147 kref_get(&tty->driver->kref);
148 __module_get(tty->driver->owner);
149 tty->ops = &usb_console_fake_tty_ops;
150 tty_init_termios(tty);
151 tty_port_tty_set(&port->port, tty);
152 }
153
154 /* only call the device specific open if this
155 * is the first time the port is opened */
156 retval = serial->type->open(NULL, port);
157 if (retval) {
158 dev_err(&port->dev, "could not open USB console port\n");
159 goto fail;
160 }
161
162 if (serial->type->set_termios) {
163 tty->termios.c_cflag = cflag;
164 tty_termios_encode_baud_rate(&tty->termios, baud, baud);
165 memset(&dummy, 0, sizeof(struct ktermios));
166 serial->type->set_termios(tty, port, &dummy);
167
168 tty_port_tty_set(&port->port, NULL);
169 tty_save_termios(tty);
170 tty_kref_put(tty);
171 }
172 tty_port_set_initialized(&port->port, true);
173 }
174 /* Now that any required fake tty operations are completed restore
175 * the tty port count */
176 --port->port.count;
177 /* The console is special in terms of closing the device so
178 * indicate this port is now acting as a system console. */
179 port->port.console = 1;
180
181 mutex_unlock(&serial->disc_mutex);
182 return retval;
183
184 fail:
185 tty_port_tty_set(&port->port, NULL);
186 tty_kref_put(tty);
187 reset_open_count:
188 port->port.count = 0;
189 info->port = NULL;
190 usb_autopm_put_interface(serial->interface);
191 error_get_interface:
192 mutex_unlock(&serial->disc_mutex);
193 usb_serial_put(serial);
194 return retval;
195}
196
197static void usb_console_write(struct console *co,
198 const char *buf, unsigned count)
199{
200 static struct usbcons_info *info = &usbcons_info;
201 struct usb_serial_port *port = info->port;
202 struct usb_serial *serial;
203 int retval = -ENODEV;
204
205 if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED)
206 return;
207 serial = port->serial;
208
209 if (count == 0)
210 return;
211
212 dev_dbg(&port->dev, "%s - %d byte(s)\n", __func__, count);
213
214 if (!port->port.console) {
215 dev_dbg(&port->dev, "%s - port not opened\n", __func__);
216 return;
217 }
218
219 while (count) {
220 unsigned int i;
221 unsigned int lf;
222 /* search for LF so we can insert CR if necessary */
223 for (i = 0, lf = 0 ; i < count ; i++) {
224 if (*(buf + i) == 10) {
225 lf = 1;
226 i++;
227 break;
228 }
229 }
230 /* pass on to the driver specific version of this function if
231 it is available */
232 retval = serial->type->write(NULL, port, buf, i);
233 dev_dbg(&port->dev, "%s - write: %d\n", __func__, retval);
234 if (lf) {
235 /* append CR after LF */
236 unsigned char cr = 13;
237 retval = serial->type->write(NULL, port, &cr, 1);
238 dev_dbg(&port->dev, "%s - write cr: %d\n",
239 __func__, retval);
240 }
241 buf += i;
242 count -= i;
243 }
244}
245
246static struct tty_driver *usb_console_device(struct console *co, int *index)
247{
248 struct tty_driver **p = (struct tty_driver **)co->data;
249
250 if (!*p)
251 return NULL;
252
253 *index = co->index;
254 return *p;
255}
256
257static struct console usbcons = {
258 .name = "ttyUSB",
259 .write = usb_console_write,
260 .device = usb_console_device,
261 .setup = usb_console_setup,
262 .flags = CON_PRINTBUFFER,
263 .index = -1,
264 .data = &usb_serial_tty_driver,
265};
266
267void usb_serial_console_disconnect(struct usb_serial *serial)
268{
269 if (serial->port[0] && serial->port[0] == usbcons_info.port) {
270 usb_serial_console_exit();
271 usb_serial_put(serial);
272 }
273}
274
275void usb_serial_console_init(int minor)
276{
277 if (minor == 0) {
278 /*
279 * Call register_console() if this is the first device plugged
280 * in. If we call it earlier, then the callback to
281 * console_setup() will fail, as there is not a device seen by
282 * the USB subsystem yet.
283 */
284 /*
285 * Register console.
286 * NOTES:
287 * console_setup() is called (back) immediately (from
288 * register_console). console_write() is called immediately
289 * from register_console iff CON_PRINTBUFFER is set in flags.
290 */
291 pr_debug("registering the USB serial console.\n");
292 register_console(&usbcons);
293 }
294}
295
296void usb_serial_console_exit(void)
297{
298 if (usbcons_info.port) {
299 unregister_console(&usbcons);
300 usbcons_info.port->port.console = 0;
301 usbcons_info.port = NULL;
302 }
303}
304