summaryrefslogtreecommitdiffstats
path: root/drivers/tty/rpmsg_tty.c
blob: 60a2915f5cfec39323134607d41fa4d74584d660 (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
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2021 STMicroelectronics - All Rights Reserved
 *
 * The rpmsg tty driver implements serial communication on the RPMsg bus to makes
 * possible for user-space programs to send and receive rpmsg messages as a standard
 * tty protocol.
 *
 * The remote processor can instantiate a new tty by requesting a "rpmsg-tty" RPMsg service.
 * The "rpmsg-tty" service is directly used for data exchange. No flow control is implemented yet.
 */

#define pr_fmt(fmt)		KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/rpmsg.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>

#define RPMSG_TTY_NAME	"ttyRPMSG"
#define MAX_TTY_RPMSG	32

static DEFINE_IDR(tty_idr);	/* tty instance id */
static DEFINE_MUTEX(idr_lock);	/* protects tty_idr */

static struct tty_driver *rpmsg_tty_driver;

struct rpmsg_tty_port {
	struct tty_port		port;	 /* TTY port data */
	int			id;	 /* TTY rpmsg index */
	struct rpmsg_device	*rpdev;	 /* rpmsg device */
};

static int rpmsg_tty_cb(struct rpmsg_device *rpdev, void *data, int len, void *priv, u32 src)
{
	struct rpmsg_tty_port *cport = dev_get_drvdata(&rpdev->dev);
	int copied;

	if (!len)
		return -EINVAL;
	copied = tty_insert_flip_string(&cport->port, data, len);
	if (copied != len)
		dev_err_ratelimited(&rpdev->dev, "Trunc buffer: available space is %d\n", copied);
	tty_flip_buffer_push(&cport->port);

	return 0;
}

static int rpmsg_tty_install(struct tty_driver *driver, struct tty_struct *tty)
{
	struct rpmsg_tty_port *cport = idr_find(&tty_idr, tty->index);
	struct tty_port *port;

	tty->driver_data = cport;

	port = tty_port_get(&cport->port);
	return tty_port_install(port, driver, tty);
}

static void rpmsg_tty_cleanup(struct tty_struct *tty)
{
	tty_port_put(tty->port);
}

static int rpmsg_tty_open(struct tty_struct *tty, struct file *filp)
{
	return tty_port_open(tty->port, tty, filp);
}

static void rpmsg_tty_close(struct tty_struct *tty, struct file *filp)
{
	return tty_port_close(tty->port, tty, filp);
}

static ssize_t rpmsg_tty_write(struct tty_struct *tty, const u8 *buf,
			       size_t len)
{
	struct rpmsg_tty_port *cport = tty->driver_data;
	struct rpmsg_device *rpdev;
	int msg_max_size, msg_size;
	int ret;

	rpdev = cport->rpdev;

	msg_max_size = rpmsg_get_mtu(rpdev->ept);
	if (msg_max_size < 0)
		return msg_max_size;

	msg_size = min_t(unsigned int, len, msg_max_size);

	/*
	 * Use rpmsg_trysend instead of rpmsg_send to send the message so the caller is not
	 * hung until a rpmsg buffer is available. In such case rpmsg_trysend returns -ENOMEM.
	 */
	ret = rpmsg_trysend(rpdev->ept, (void *)buf, msg_size);
	if (ret) {
		dev_dbg_ratelimited(&rpdev->dev, "rpmsg_send failed: %d\n", ret);
		return ret;
	}

	return msg_size;
}

static unsigned int rpmsg_tty_write_room(struct tty_struct *tty)
{
	struct rpmsg_tty_port *cport = tty->driver_data;
	int size;

	size = rpmsg_get_mtu(cport->rpdev->ept);
	if (size < 0)
		return 0;

	return size;
}

static void rpmsg_tty_hangup(struct tty_struct *tty)
{
	tty_port_hangup(tty->port);
}

static const struct tty_operations rpmsg_tty_ops = {
	.install	= rpmsg_tty_install,
	.open		= rpmsg_tty_open,
	.close		= rpmsg_tty_close,
	.write		= rpmsg_tty_write,
	.write_room	= rpmsg_tty_write_room,
	.hangup		= rpmsg_tty_hangup,
	.cleanup	= rpmsg_tty_cleanup,
};

static struct rpmsg_tty_port *rpmsg_tty_alloc_cport(void)
{
	struct rpmsg_tty_port *cport;
	int ret;

	cport = kzalloc(sizeof(*cport), GFP_KERNEL);
	if (!cport)
		return ERR_PTR(-ENOMEM);

	mutex_lock(&idr_lock);
	ret = idr_alloc(&tty_idr, cport, 0, MAX_TTY_RPMSG, GFP_KERNEL);
	mutex_unlock(&idr_lock);

	if (ret < 0) {
		kfree(cport);
		return ERR_PTR(ret);
	}

	cport->id = ret;

	return cport;
}

static void rpmsg_tty_destruct_port(struct tty_port *port)
{
	struct rpmsg_tty_port *cport = container_of(port, struct rpmsg_tty_port, port);

	mutex_lock(&idr_lock);
	idr_remove(&tty_idr, cport->id);
	mutex_unlock(&idr_lock);

	kfree(cport);
}

static const struct tty_port_operations rpmsg_tty_port_ops = {
	.destruct = rpmsg_tty_destruct_port,
};


static int rpmsg_tty_probe(struct rpmsg_device *rpdev)
{
	struct rpmsg_tty_port *cport;
	struct device *dev = &rpdev->dev;
	struct device *tty_dev;
	int ret;

	cport = rpmsg_tty_alloc_cport();
	if (IS_ERR(cport))
		return dev_err_probe(dev, PTR_ERR(cport), "Failed to alloc tty port\n");

	tty_port_init(&cport->port);
	cport->port.ops = &rpmsg_tty_port_ops;

	tty_dev = tty_port_register_device(&cport->port, rpmsg_tty_driver,
					   cport->id, dev);
	if (IS_ERR(tty_dev)) {
		ret = dev_err_probe(dev, PTR_ERR(tty_dev), "Failed to register tty port\n");
		tty_port_put(&cport->port);
		return ret;
	}

	cport->rpdev = rpdev;

	dev_set_drvdata(dev, cport);

	dev_dbg(dev, "New channel: 0x%x -> 0x%x: " RPMSG_TTY_NAME "%d\n",
		rpdev->src, rpdev->dst, cport->id);

	return 0;
}

static void rpmsg_tty_remove(struct rpmsg_device *rpdev)
{
	struct rpmsg_tty_port *cport = dev_get_drvdata(&rpdev->dev);

	dev_dbg(&rpdev->dev, "Removing rpmsg tty device %d\n", cport->id);

	/* User hang up to release the tty */
	tty_port_tty_hangup(&cport->port, false);

	tty_unregister_device(rpmsg_tty_driver, cport->id);

	tty_port_put(&cport->port);
}

static struct rpmsg_device_id rpmsg_driver_tty_id_table[] = {
	{ .name	= "rpmsg-tty" },
	{ },
};
MODULE_DEVICE_TABLE(rpmsg, rpmsg_driver_tty_id_table);

static struct rpmsg_driver rpmsg_tty_rpmsg_drv = {
	.drv.name	= KBUILD_MODNAME,
	.id_table	= rpmsg_driver_tty_id_table,
	.probe		= rpmsg_tty_probe,
	.callback	= rpmsg_tty_cb,
	.remove		= rpmsg_tty_remove,
};

static int __init rpmsg_tty_init(void)
{
	int ret;

	rpmsg_tty_driver = tty_alloc_driver(MAX_TTY_RPMSG, TTY_DRIVER_REAL_RAW |
					    TTY_DRIVER_DYNAMIC_DEV);
	if (IS_ERR(rpmsg_tty_driver))
		return PTR_ERR(rpmsg_tty_driver);

	rpmsg_tty_driver->driver_name = "rpmsg_tty";
	rpmsg_tty_driver->name = RPMSG_TTY_NAME;
	rpmsg_tty_driver->major = 0;
	rpmsg_tty_driver->type = TTY_DRIVER_TYPE_CONSOLE;

	/* Disable unused mode by default */
	rpmsg_tty_driver->init_termios = tty_std_termios;
	rpmsg_tty_driver->init_termios.c_lflag &= ~(ECHO | ICANON);
	rpmsg_tty_driver->init_termios.c_oflag &= ~(OPOST | ONLCR);

	tty_set_operations(rpmsg_tty_driver, &rpmsg_tty_ops);

	ret = tty_register_driver(rpmsg_tty_driver);
	if (ret < 0) {
		pr_err("Couldn't install driver: %d\n", ret);
		goto error_put;
	}

	ret = register_rpmsg_driver(&rpmsg_tty_rpmsg_drv);
	if (ret < 0) {
		pr_err("Couldn't register driver: %d\n", ret);
		goto error_unregister;
	}

	return 0;

error_unregister:
	tty_unregister_driver(rpmsg_tty_driver);

error_put:
	tty_driver_kref_put(rpmsg_tty_driver);

	return ret;
}

static void __exit rpmsg_tty_exit(void)
{
	unregister_rpmsg_driver(&rpmsg_tty_rpmsg_drv);
	tty_unregister_driver(rpmsg_tty_driver);
	tty_driver_kref_put(rpmsg_tty_driver);
	idr_destroy(&tty_idr);
}

module_init(rpmsg_tty_init);
module_exit(rpmsg_tty_exit);

MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>");
MODULE_DESCRIPTION("remote processor messaging tty driver");
MODULE_LICENSE("GPL v2");