aboutsummaryrefslogtreecommitdiffstats
path: root/openbsc/src/utils/rs232.c
blob: 01b8c7e3327b756b06404f5f854be0de6d96cc77 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
/* OpenBSC BS-11 T-Link interface using POSIX serial port */

/* (C) 2008-2009 by Harald Welte <laforge@gnumonks.org>
 *
 * All Rights Reserved
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <termios.h>
#include <fcntl.h>

#include <osmocom/core/select.h>
#include <osmocom/core/msgb.h>
#include <openbsc/debug.h>
#include <openbsc/gsm_data.h>
#include <openbsc/rs232.h>

/* adaption layer from GSM 08.59 + 12.21 to RS232 */

struct serial_handle {
	struct osmo_fd fd;
	struct llist_head tx_queue;

	struct msgb *rx_msg;
	unsigned int rxmsg_bytes_missing;

	unsigned int delay_ms;
	struct gsm_bts *bts;
};

/* FIXME: this needs to go */
static struct serial_handle _ser_handle, *ser_handle = &_ser_handle;

#define LAPD_HDR_LEN	10

static int handle_ser_write(struct osmo_fd *bfd);

/* callback from abis_nm */
int _abis_nm_sendmsg(struct msgb *msg, int to_trx_oml)
{
	struct serial_handle *sh = ser_handle;
	uint8_t *lapd;
	unsigned int len;

	msg->l2h = msg->data;

	/* prepend LAPD header */
	lapd = msgb_push(msg, LAPD_HDR_LEN);

	len = msg->len - 2;

	lapd[0] = (len >> 8) & 0xff;
	lapd[1] = len & 0xff; /* length of bytes startign at lapd[2] */
	lapd[2] = 0x00;
	lapd[3] = 0x07;
	lapd[4] = 0x01;
	lapd[5] = 0x3e;
	lapd[6] = 0x00;
	lapd[7] = 0x00;
	lapd[8] = msg->len - 10; /* length of bytes starting at lapd[10] */
	lapd[9] = lapd[8] ^ 0x38;

	msgb_enqueue(&sh->tx_queue, msg);
	sh->fd.when |= BSC_FD_WRITE;

	/* we try to immediately send */
	handle_ser_write(&sh->fd);

	return 0;
}

/* select.c callback in case we can write to the RS232 */
static int handle_ser_write(struct osmo_fd *bfd)
{
	struct serial_handle *sh = bfd->data;
	struct msgb *msg;
	int written;

	msg = msgb_dequeue(&sh->tx_queue);
	if (!msg) {
		bfd->when &= ~BSC_FD_WRITE;
		return 0;
	}

	DEBUGP(DMI, "RS232 TX: %s\n", osmo_hexdump(msg->data, msg->len));

	/* send over serial line */
	written = write(bfd->fd, msg->data, msg->len);
	if (written < msg->len) {
		perror("short write:");
		msgb_free(msg);
		return -1;
	}

	msgb_free(msg);
	usleep(sh->delay_ms*1000);

	return 0;
}

#define SERIAL_ALLOC_SIZE	300

/* select.c callback in case we can read from the RS232 */
static int handle_ser_read(struct osmo_fd *bfd)
{
	struct serial_handle *sh = bfd->data;
	struct msgb *msg;
	int rc = 0;

	if (!sh->rx_msg) {
		sh->rx_msg = msgb_alloc(SERIAL_ALLOC_SIZE, "RS232 Rx");
		sh->rx_msg->l2h = NULL;
		sh->rx_msg->dst = sh->bts->c0->rsl_link;
	}
	msg = sh->rx_msg;

	/* first read two byes to obtain length */
	if (msg->len < 2) {
		rc = read(sh->fd.fd, msg->tail, 2 - msg->len);
		if (rc < 0) {
			perror("ERROR reading from serial port");
			msgb_free(msg);
			return rc;
		}
		msgb_put(msg, rc);

		if (msg->len >= 2) {
			/* parse LAPD payload length */
			if (msg->data[0] != 0)
				fprintf(stderr, "Suspicious header byte 0: 0x%02x\n",
					msg->data[0]);

			sh->rxmsg_bytes_missing = msg->data[0] << 8;
			sh->rxmsg_bytes_missing += msg->data[1];

			if (sh->rxmsg_bytes_missing < LAPD_HDR_LEN -2)
				fprintf(stderr, "Invalid length in hdr: %u\n",
					sh->rxmsg_bytes_missing);
		}
	} else {
		/* try to read as many of the missing bytes as are available */
		rc = read(sh->fd.fd, msg->tail, sh->rxmsg_bytes_missing);
		if (rc < 0) {
			perror("ERROR reading from serial port");
			msgb_free(msg);
			return rc;
		}
		msgb_put(msg, rc);
		sh->rxmsg_bytes_missing -= rc;

		if (sh->rxmsg_bytes_missing == 0) {
			/* we have one complete message now */
			sh->rx_msg = NULL;

			if (msg->len > LAPD_HDR_LEN)
				msg->l2h = msg->data + LAPD_HDR_LEN;

			DEBUGP(DMI, "RS232 RX: %s\n", osmo_hexdump(msg->data, msg->len));
			rc = handle_serial_msg(msg);
		}
	}

	return rc;
}

/* select.c callback */
static int serial_fd_cb(struct osmo_fd *bfd, unsigned int what)
{
	int rc = 0;

	if (what & BSC_FD_READ)
		rc = handle_ser_read(bfd);

	if (rc < 0)
		return rc;

	if (what & BSC_FD_WRITE)
		rc = handle_ser_write(bfd);

	return rc;
}

int rs232_setup(const char *serial_port, unsigned int delay_ms,
		struct gsm_bts *bts)
{
	int rc, serial_fd;
	struct termios tio;

	serial_fd = open(serial_port, O_RDWR);
	if (serial_fd < 0) {
		perror("cannot open serial port:");
		return serial_fd;
	}

	/* set baudrate */
	rc = tcgetattr(serial_fd, &tio);
	if (rc < 0) {
		perror("tcgetattr()");
		return rc;
	}
	cfsetispeed(&tio, B19200);
	cfsetospeed(&tio, B19200);
	tio.c_cflag |=  (CREAD | CLOCAL | CS8);
	tio.c_cflag &= ~(PARENB | CSTOPB | CSIZE | CRTSCTS);
	tio.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
	tio.c_iflag |=  (INPCK | ISTRIP);
	tio.c_iflag &= ~(ISTRIP | IXON | IXOFF | IGNBRK | INLCR | ICRNL | IGNCR);
	tio.c_oflag &= ~(OPOST);
	rc = tcsetattr(serial_fd, TCSADRAIN, &tio);
	if (rc < 0) {
		perror("tcsetattr()");
		return rc;
	}

	INIT_LLIST_HEAD(&ser_handle->tx_queue);
	ser_handle->fd.fd = serial_fd;
	ser_handle->fd.when = BSC_FD_READ;
	ser_handle->fd.cb = serial_fd_cb;
	ser_handle->fd.data = ser_handle;
	ser_handle->delay_ms = delay_ms;
	ser_handle->bts = bts;
	rc = osmo_fd_register(&ser_handle->fd);
	if (rc < 0) {
		fprintf(stderr, "could not register FD: %s\n",
			strerror(rc));
		return rc;
	}

	return 0;
}