xref: /openbmc/linux/drivers/usb/serial/console.c (revision 2c684d89)
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/module.h>
18 #include <linux/slab.h>
19 #include <linux/tty.h>
20 #include <linux/console.h>
21 #include <linux/serial.h>
22 #include <linux/usb.h>
23 #include <linux/usb/serial.h>
24 
25 struct usbcons_info {
26 	int			magic;
27 	int			break_flag;
28 	struct usb_serial_port	*port;
29 };
30 
31 static struct usbcons_info usbcons_info;
32 static struct console usbcons;
33 
34 /*
35  * ------------------------------------------------------------
36  * USB Serial console driver
37  *
38  * Much of the code here is copied from drivers/char/serial.c
39  * and implements a phony serial console in the same way that
40  * serial.c does so that in case some software queries it,
41  * it will get the same results.
42  *
43  * Things that are different from the way the serial port code
44  * does things, is that we call the lower level usb-serial
45  * driver code to initialize the device, and we set the initial
46  * console speeds based on the command line arguments.
47  * ------------------------------------------------------------
48  */
49 
50 static const struct tty_operations usb_console_fake_tty_ops = {
51 };
52 
53 /*
54  * The parsing of the command line works exactly like the
55  * serial.c code, except that the specifier is "ttyUSB" instead
56  * of "ttyS".
57  */
58 static int usb_console_setup(struct console *co, char *options)
59 {
60 	struct usbcons_info *info = &usbcons_info;
61 	int baud = 9600;
62 	int bits = 8;
63 	int parity = 'n';
64 	int doflow = 0;
65 	int cflag = CREAD | HUPCL | CLOCAL;
66 	char *s;
67 	struct usb_serial *serial;
68 	struct usb_serial_port *port;
69 	int retval;
70 	struct tty_struct *tty = NULL;
71 	struct ktermios dummy;
72 
73 	if (options) {
74 		baud = simple_strtoul(options, NULL, 10);
75 		s = options;
76 		while (*s >= '0' && *s <= '9')
77 			s++;
78 		if (*s)
79 			parity = *s++;
80 		if (*s)
81 			bits   = *s++ - '0';
82 		if (*s)
83 			doflow = (*s++ == 'r');
84 	}
85 
86 	/* Sane default */
87 	if (baud == 0)
88 		baud = 9600;
89 
90 	switch (bits) {
91 	case 7:
92 		cflag |= CS7;
93 		break;
94 	default:
95 	case 8:
96 		cflag |= CS8;
97 		break;
98 	}
99 	switch (parity) {
100 	case 'o': case 'O':
101 		cflag |= PARODD;
102 		break;
103 	case 'e': case 'E':
104 		cflag |= PARENB;
105 		break;
106 	}
107 	co->cflag = cflag;
108 
109 	/*
110 	 * no need to check the index here: if the index is wrong, console
111 	 * code won't call us
112 	 */
113 	port = usb_serial_port_get_by_minor(co->index);
114 	if (port == NULL) {
115 		/* no device is connected yet, sorry :( */
116 		pr_err("No USB device connected to ttyUSB%i\n", co->index);
117 		return -ENODEV;
118 	}
119 	serial = port->serial;
120 
121 	retval = usb_autopm_get_interface(serial->interface);
122 	if (retval)
123 		goto error_get_interface;
124 
125 	tty_port_tty_set(&port->port, NULL);
126 
127 	info->port = port;
128 
129 	++port->port.count;
130 	if (!test_bit(ASYNCB_INITIALIZED, &port->port.flags)) {
131 		if (serial->type->set_termios) {
132 			/*
133 			 * allocate a fake tty so the driver can initialize
134 			 * the termios structure, then later call set_termios to
135 			 * configure according to command line arguments
136 			 */
137 			tty = kzalloc(sizeof(*tty), GFP_KERNEL);
138 			if (!tty) {
139 				retval = -ENOMEM;
140 				goto reset_open_count;
141 			}
142 			kref_init(&tty->kref);
143 			tty->driver = usb_serial_tty_driver;
144 			tty->index = co->index;
145 			init_ldsem(&tty->ldisc_sem);
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 			if (tty_init_termios(tty)) {
151 				retval = -ENOMEM;
152 				goto put_tty;
153 			}
154 			tty_port_tty_set(&port->port, tty);
155 		}
156 
157 		/* only call the device specific open if this
158 		 * is the first time the port is opened */
159 		retval = serial->type->open(NULL, port);
160 		if (retval) {
161 			dev_err(&port->dev, "could not open USB console port\n");
162 			goto fail;
163 		}
164 
165 		if (serial->type->set_termios) {
166 			tty->termios.c_cflag = cflag;
167 			tty_termios_encode_baud_rate(&tty->termios, baud, baud);
168 			memset(&dummy, 0, sizeof(struct ktermios));
169 			serial->type->set_termios(tty, port, &dummy);
170 
171 			tty_port_tty_set(&port->port, NULL);
172 			tty_kref_put(tty);
173 		}
174 		set_bit(ASYNCB_INITIALIZED, &port->port.flags);
175 	}
176 	/* Now that any required fake tty operations are completed restore
177 	 * the tty port count */
178 	--port->port.count;
179 	/* The console is special in terms of closing the device so
180 	 * indicate this port is now acting as a system console. */
181 	port->port.console = 1;
182 
183 	mutex_unlock(&serial->disc_mutex);
184 	return retval;
185 
186  fail:
187 	tty_port_tty_set(&port->port, NULL);
188  put_tty:
189 	tty_kref_put(tty);
190  reset_open_count:
191 	port->port.count = 0;
192 	usb_autopm_put_interface(serial->interface);
193  error_get_interface:
194 	usb_serial_put(serial);
195 	mutex_unlock(&serial->disc_mutex);
196 	return retval;
197 }
198 
199 static void usb_console_write(struct console *co,
200 					const char *buf, unsigned count)
201 {
202 	static struct usbcons_info *info = &usbcons_info;
203 	struct usb_serial_port *port = info->port;
204 	struct usb_serial *serial;
205 	int retval = -ENODEV;
206 
207 	if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED)
208 		return;
209 	serial = port->serial;
210 
211 	if (count == 0)
212 		return;
213 
214 	dev_dbg(&port->dev, "%s - %d byte(s)\n", __func__, count);
215 
216 	if (!port->port.console) {
217 		dev_dbg(&port->dev, "%s - port not opened\n", __func__);
218 		return;
219 	}
220 
221 	while (count) {
222 		unsigned int i;
223 		unsigned int lf;
224 		/* search for LF so we can insert CR if necessary */
225 		for (i = 0, lf = 0 ; i < count ; i++) {
226 			if (*(buf + i) == 10) {
227 				lf = 1;
228 				i++;
229 				break;
230 			}
231 		}
232 		/* pass on to the driver specific version of this function if
233 		   it is available */
234 		retval = serial->type->write(NULL, port, buf, i);
235 		dev_dbg(&port->dev, "%s - write: %d\n", __func__, retval);
236 		if (lf) {
237 			/* append CR after LF */
238 			unsigned char cr = 13;
239 			retval = serial->type->write(NULL, port, &cr, 1);
240 			dev_dbg(&port->dev, "%s - write cr: %d\n",
241 							__func__, retval);
242 		}
243 		buf += i;
244 		count -= i;
245 	}
246 }
247 
248 static struct tty_driver *usb_console_device(struct console *co, int *index)
249 {
250 	struct tty_driver **p = (struct tty_driver **)co->data;
251 
252 	if (!*p)
253 		return NULL;
254 
255 	*index = co->index;
256 	return *p;
257 }
258 
259 static struct console usbcons = {
260 	.name =		"ttyUSB",
261 	.write =	usb_console_write,
262 	.device =	usb_console_device,
263 	.setup =	usb_console_setup,
264 	.flags =	CON_PRINTBUFFER,
265 	.index =	-1,
266 	.data = 	&usb_serial_tty_driver,
267 };
268 
269 void usb_serial_console_disconnect(struct usb_serial *serial)
270 {
271 	if (serial && serial->port && serial->port[0]
272 				&& serial->port[0] == usbcons_info.port) {
273 		usb_serial_console_exit();
274 		usb_serial_put(serial);
275 	}
276 }
277 
278 void usb_serial_console_init(int minor)
279 {
280 	if (minor == 0) {
281 		/*
282 		 * Call register_console() if this is the first device plugged
283 		 * in.  If we call it earlier, then the callback to
284 		 * console_setup() will fail, as there is not a device seen by
285 		 * the USB subsystem yet.
286 		 */
287 		/*
288 		 * Register console.
289 		 * NOTES:
290 		 * console_setup() is called (back) immediately (from
291 		 * register_console). console_write() is called immediately
292 		 * from register_console iff CON_PRINTBUFFER is set in flags.
293 		 */
294 		pr_debug("registering the USB serial console.\n");
295 		register_console(&usbcons);
296 	}
297 }
298 
299 void usb_serial_console_exit(void)
300 {
301 	if (usbcons_info.port) {
302 		unregister_console(&usbcons);
303 		usbcons_info.port->port.console = 0;
304 		usbcons_info.port = NULL;
305 	}
306 }
307 
308