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7c0408d8 AP |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* | |
3 | * Copyright (C) 2021 STMicroelectronics - All Rights Reserved | |
4 | * | |
5 | * The rpmsg tty driver implements serial communication on the RPMsg bus to makes | |
6 | * possible for user-space programs to send and receive rpmsg messages as a standard | |
7 | * tty protocol. | |
8 | * | |
9 | * The remote processor can instantiate a new tty by requesting a "rpmsg-tty" RPMsg service. | |
10 | * The "rpmsg-tty" service is directly used for data exchange. No flow control is implemented yet. | |
11 | */ | |
12 | ||
88af70be AS |
13 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
14 | ||
7c0408d8 AP |
15 | #include <linux/module.h> |
16 | #include <linux/rpmsg.h> | |
17 | #include <linux/slab.h> | |
18 | #include <linux/tty.h> | |
19 | #include <linux/tty_flip.h> | |
20 | ||
73a3d4f4 | 21 | #define RPMSG_TTY_NAME "ttyRPMSG" |
7c0408d8 AP |
22 | #define MAX_TTY_RPMSG 32 |
23 | ||
24 | static DEFINE_IDR(tty_idr); /* tty instance id */ | |
25 | static DEFINE_MUTEX(idr_lock); /* protects tty_idr */ | |
26 | ||
27 | static struct tty_driver *rpmsg_tty_driver; | |
28 | ||
29 | struct rpmsg_tty_port { | |
30 | struct tty_port port; /* TTY port data */ | |
31 | int id; /* TTY rpmsg index */ | |
32 | struct rpmsg_device *rpdev; /* rpmsg device */ | |
33 | }; | |
34 | ||
35 | static int rpmsg_tty_cb(struct rpmsg_device *rpdev, void *data, int len, void *priv, u32 src) | |
36 | { | |
37 | struct rpmsg_tty_port *cport = dev_get_drvdata(&rpdev->dev); | |
38 | int copied; | |
39 | ||
40 | if (!len) | |
41 | return -EINVAL; | |
42 | copied = tty_insert_flip_string(&cport->port, data, len); | |
43 | if (copied != len) | |
44 | dev_err_ratelimited(&rpdev->dev, "Trunc buffer: available space is %d\n", copied); | |
45 | tty_flip_buffer_push(&cport->port); | |
46 | ||
47 | return 0; | |
48 | } | |
49 | ||
50 | static int rpmsg_tty_install(struct tty_driver *driver, struct tty_struct *tty) | |
51 | { | |
52 | struct rpmsg_tty_port *cport = idr_find(&tty_idr, tty->index); | |
db7f19c0 | 53 | struct tty_port *port; |
7c0408d8 AP |
54 | |
55 | tty->driver_data = cport; | |
56 | ||
db7f19c0 AP |
57 | port = tty_port_get(&cport->port); |
58 | return tty_port_install(port, driver, tty); | |
59 | } | |
60 | ||
61 | static void rpmsg_tty_cleanup(struct tty_struct *tty) | |
62 | { | |
63 | tty_port_put(tty->port); | |
7c0408d8 AP |
64 | } |
65 | ||
66 | static int rpmsg_tty_open(struct tty_struct *tty, struct file *filp) | |
67 | { | |
68 | return tty_port_open(tty->port, tty, filp); | |
69 | } | |
70 | ||
71 | static void rpmsg_tty_close(struct tty_struct *tty, struct file *filp) | |
72 | { | |
73 | return tty_port_close(tty->port, tty, filp); | |
74 | } | |
75 | ||
95713967 JSS |
76 | static ssize_t rpmsg_tty_write(struct tty_struct *tty, const u8 *buf, |
77 | size_t len) | |
7c0408d8 AP |
78 | { |
79 | struct rpmsg_tty_port *cport = tty->driver_data; | |
80 | struct rpmsg_device *rpdev; | |
81 | int msg_max_size, msg_size; | |
82 | int ret; | |
83 | ||
84 | rpdev = cport->rpdev; | |
85 | ||
86 | msg_max_size = rpmsg_get_mtu(rpdev->ept); | |
87 | if (msg_max_size < 0) | |
88 | return msg_max_size; | |
89 | ||
95713967 | 90 | msg_size = min_t(unsigned int, len, msg_max_size); |
7c0408d8 AP |
91 | |
92 | /* | |
93 | * Use rpmsg_trysend instead of rpmsg_send to send the message so the caller is not | |
94 | * hung until a rpmsg buffer is available. In such case rpmsg_trysend returns -ENOMEM. | |
95 | */ | |
96 | ret = rpmsg_trysend(rpdev->ept, (void *)buf, msg_size); | |
97 | if (ret) { | |
98 | dev_dbg_ratelimited(&rpdev->dev, "rpmsg_send failed: %d\n", ret); | |
99 | return ret; | |
100 | } | |
101 | ||
102 | return msg_size; | |
103 | } | |
104 | ||
105 | static unsigned int rpmsg_tty_write_room(struct tty_struct *tty) | |
106 | { | |
107 | struct rpmsg_tty_port *cport = tty->driver_data; | |
108 | int size; | |
109 | ||
110 | size = rpmsg_get_mtu(cport->rpdev->ept); | |
111 | if (size < 0) | |
112 | return 0; | |
113 | ||
114 | return size; | |
115 | } | |
116 | ||
db7f19c0 AP |
117 | static void rpmsg_tty_hangup(struct tty_struct *tty) |
118 | { | |
119 | tty_port_hangup(tty->port); | |
120 | } | |
121 | ||
7c0408d8 AP |
122 | static const struct tty_operations rpmsg_tty_ops = { |
123 | .install = rpmsg_tty_install, | |
124 | .open = rpmsg_tty_open, | |
125 | .close = rpmsg_tty_close, | |
126 | .write = rpmsg_tty_write, | |
127 | .write_room = rpmsg_tty_write_room, | |
db7f19c0 AP |
128 | .hangup = rpmsg_tty_hangup, |
129 | .cleanup = rpmsg_tty_cleanup, | |
7c0408d8 AP |
130 | }; |
131 | ||
132 | static struct rpmsg_tty_port *rpmsg_tty_alloc_cport(void) | |
133 | { | |
134 | struct rpmsg_tty_port *cport; | |
408a5079 | 135 | int ret; |
7c0408d8 AP |
136 | |
137 | cport = kzalloc(sizeof(*cport), GFP_KERNEL); | |
138 | if (!cport) | |
139 | return ERR_PTR(-ENOMEM); | |
140 | ||
141 | mutex_lock(&idr_lock); | |
408a5079 | 142 | ret = idr_alloc(&tty_idr, cport, 0, MAX_TTY_RPMSG, GFP_KERNEL); |
7c0408d8 AP |
143 | mutex_unlock(&idr_lock); |
144 | ||
408a5079 | 145 | if (ret < 0) { |
7c0408d8 | 146 | kfree(cport); |
408a5079 | 147 | return ERR_PTR(ret); |
7c0408d8 AP |
148 | } |
149 | ||
408a5079 | 150 | cport->id = ret; |
0572da28 | 151 | |
7c0408d8 AP |
152 | return cport; |
153 | } | |
154 | ||
db7f19c0 | 155 | static void rpmsg_tty_destruct_port(struct tty_port *port) |
7c0408d8 | 156 | { |
db7f19c0 AP |
157 | struct rpmsg_tty_port *cport = container_of(port, struct rpmsg_tty_port, port); |
158 | ||
7c0408d8 AP |
159 | mutex_lock(&idr_lock); |
160 | idr_remove(&tty_idr, cport->id); | |
161 | mutex_unlock(&idr_lock); | |
162 | ||
163 | kfree(cport); | |
164 | } | |
165 | ||
db7f19c0 AP |
166 | static const struct tty_port_operations rpmsg_tty_port_ops = { |
167 | .destruct = rpmsg_tty_destruct_port, | |
168 | }; | |
169 | ||
7c0408d8 AP |
170 | |
171 | static int rpmsg_tty_probe(struct rpmsg_device *rpdev) | |
172 | { | |
173 | struct rpmsg_tty_port *cport; | |
174 | struct device *dev = &rpdev->dev; | |
175 | struct device *tty_dev; | |
176 | int ret; | |
177 | ||
178 | cport = rpmsg_tty_alloc_cport(); | |
8673ef7b AS |
179 | if (IS_ERR(cport)) |
180 | return dev_err_probe(dev, PTR_ERR(cport), "Failed to alloc tty port\n"); | |
7c0408d8 AP |
181 | |
182 | tty_port_init(&cport->port); | |
183 | cport->port.ops = &rpmsg_tty_port_ops; | |
184 | ||
185 | tty_dev = tty_port_register_device(&cport->port, rpmsg_tty_driver, | |
186 | cport->id, dev); | |
187 | if (IS_ERR(tty_dev)) { | |
8673ef7b | 188 | ret = dev_err_probe(dev, PTR_ERR(tty_dev), "Failed to register tty port\n"); |
db7f19c0 AP |
189 | tty_port_put(&cport->port); |
190 | return ret; | |
7c0408d8 AP |
191 | } |
192 | ||
193 | cport->rpdev = rpdev; | |
194 | ||
195 | dev_set_drvdata(dev, cport); | |
196 | ||
73a3d4f4 | 197 | dev_dbg(dev, "New channel: 0x%x -> 0x%x: " RPMSG_TTY_NAME "%d\n", |
7c0408d8 AP |
198 | rpdev->src, rpdev->dst, cport->id); |
199 | ||
200 | return 0; | |
7c0408d8 AP |
201 | } |
202 | ||
203 | static void rpmsg_tty_remove(struct rpmsg_device *rpdev) | |
204 | { | |
205 | struct rpmsg_tty_port *cport = dev_get_drvdata(&rpdev->dev); | |
206 | ||
207 | dev_dbg(&rpdev->dev, "Removing rpmsg tty device %d\n", cport->id); | |
208 | ||
209 | /* User hang up to release the tty */ | |
db7f19c0 | 210 | tty_port_tty_hangup(&cport->port, false); |
7c0408d8 AP |
211 | |
212 | tty_unregister_device(rpmsg_tty_driver, cport->id); | |
213 | ||
db7f19c0 | 214 | tty_port_put(&cport->port); |
7c0408d8 AP |
215 | } |
216 | ||
217 | static struct rpmsg_device_id rpmsg_driver_tty_id_table[] = { | |
218 | { .name = "rpmsg-tty" }, | |
219 | { }, | |
220 | }; | |
221 | MODULE_DEVICE_TABLE(rpmsg, rpmsg_driver_tty_id_table); | |
222 | ||
223 | static struct rpmsg_driver rpmsg_tty_rpmsg_drv = { | |
224 | .drv.name = KBUILD_MODNAME, | |
225 | .id_table = rpmsg_driver_tty_id_table, | |
226 | .probe = rpmsg_tty_probe, | |
227 | .callback = rpmsg_tty_cb, | |
228 | .remove = rpmsg_tty_remove, | |
229 | }; | |
230 | ||
231 | static int __init rpmsg_tty_init(void) | |
232 | { | |
408a5079 | 233 | int ret; |
7c0408d8 AP |
234 | |
235 | rpmsg_tty_driver = tty_alloc_driver(MAX_TTY_RPMSG, TTY_DRIVER_REAL_RAW | | |
236 | TTY_DRIVER_DYNAMIC_DEV); | |
237 | if (IS_ERR(rpmsg_tty_driver)) | |
238 | return PTR_ERR(rpmsg_tty_driver); | |
239 | ||
240 | rpmsg_tty_driver->driver_name = "rpmsg_tty"; | |
73a3d4f4 | 241 | rpmsg_tty_driver->name = RPMSG_TTY_NAME; |
7c0408d8 AP |
242 | rpmsg_tty_driver->major = 0; |
243 | rpmsg_tty_driver->type = TTY_DRIVER_TYPE_CONSOLE; | |
244 | ||
245 | /* Disable unused mode by default */ | |
246 | rpmsg_tty_driver->init_termios = tty_std_termios; | |
247 | rpmsg_tty_driver->init_termios.c_lflag &= ~(ECHO | ICANON); | |
248 | rpmsg_tty_driver->init_termios.c_oflag &= ~(OPOST | ONLCR); | |
249 | ||
250 | tty_set_operations(rpmsg_tty_driver, &rpmsg_tty_ops); | |
251 | ||
408a5079 AS |
252 | ret = tty_register_driver(rpmsg_tty_driver); |
253 | if (ret < 0) { | |
88af70be | 254 | pr_err("Couldn't install driver: %d\n", ret); |
7c0408d8 AP |
255 | goto error_put; |
256 | } | |
257 | ||
408a5079 AS |
258 | ret = register_rpmsg_driver(&rpmsg_tty_rpmsg_drv); |
259 | if (ret < 0) { | |
88af70be | 260 | pr_err("Couldn't register driver: %d\n", ret); |
7c0408d8 AP |
261 | goto error_unregister; |
262 | } | |
263 | ||
264 | return 0; | |
265 | ||
266 | error_unregister: | |
267 | tty_unregister_driver(rpmsg_tty_driver); | |
268 | ||
269 | error_put: | |
270 | tty_driver_kref_put(rpmsg_tty_driver); | |
271 | ||
408a5079 | 272 | return ret; |
7c0408d8 AP |
273 | } |
274 | ||
275 | static void __exit rpmsg_tty_exit(void) | |
276 | { | |
277 | unregister_rpmsg_driver(&rpmsg_tty_rpmsg_drv); | |
278 | tty_unregister_driver(rpmsg_tty_driver); | |
279 | tty_driver_kref_put(rpmsg_tty_driver); | |
280 | idr_destroy(&tty_idr); | |
281 | } | |
282 | ||
283 | module_init(rpmsg_tty_init); | |
284 | module_exit(rpmsg_tty_exit); | |
285 | ||
286 | MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>"); | |
287 | MODULE_DESCRIPTION("remote processor messaging tty driver"); | |
288 | MODULE_LICENSE("GPL v2"); |