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 | |
13 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
14 | |
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 | |
21 | #define RPMSG_TTY_NAME "ttyRPMSG" |
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(dev: &rpdev->dev); |
38 | int copied; |
39 | |
40 | if (!len) |
41 | return -EINVAL; |
42 | copied = tty_insert_flip_string(port: &cport->port, chars: data, size: len); |
43 | if (copied != len) |
44 | dev_err_ratelimited(&rpdev->dev, "Trunc buffer: available space is %d\n" , copied); |
45 | tty_flip_buffer_push(port: &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, id: tty->index); |
53 | struct tty_port *port; |
54 | |
55 | tty->driver_data = cport; |
56 | |
57 | port = tty_port_get(port: &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(port: tty->port); |
64 | } |
65 | |
66 | static int rpmsg_tty_open(struct tty_struct *tty, struct file *filp) |
67 | { |
68 | return tty_port_open(port: 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(port: tty->port, tty, filp); |
74 | } |
75 | |
76 | static ssize_t rpmsg_tty_write(struct tty_struct *tty, const u8 *buf, |
77 | size_t len) |
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(ept: rpdev->ept); |
87 | if (msg_max_size < 0) |
88 | return msg_max_size; |
89 | |
90 | msg_size = min_t(unsigned int, len, msg_max_size); |
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(ept: rpdev->ept, data: (void *)buf, len: 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(ept: cport->rpdev->ept); |
111 | if (size < 0) |
112 | return 0; |
113 | |
114 | return size; |
115 | } |
116 | |
117 | static void rpmsg_tty_hangup(struct tty_struct *tty) |
118 | { |
119 | tty_port_hangup(port: tty->port); |
120 | } |
121 | |
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, |
128 | .hangup = rpmsg_tty_hangup, |
129 | .cleanup = rpmsg_tty_cleanup, |
130 | }; |
131 | |
132 | static struct rpmsg_tty_port *rpmsg_tty_alloc_cport(void) |
133 | { |
134 | struct rpmsg_tty_port *cport; |
135 | int ret; |
136 | |
137 | cport = kzalloc(size: sizeof(*cport), GFP_KERNEL); |
138 | if (!cport) |
139 | return ERR_PTR(error: -ENOMEM); |
140 | |
141 | mutex_lock(&idr_lock); |
142 | ret = idr_alloc(&tty_idr, ptr: cport, start: 0, MAX_TTY_RPMSG, GFP_KERNEL); |
143 | mutex_unlock(lock: &idr_lock); |
144 | |
145 | if (ret < 0) { |
146 | kfree(objp: cport); |
147 | return ERR_PTR(error: ret); |
148 | } |
149 | |
150 | cport->id = ret; |
151 | |
152 | return cport; |
153 | } |
154 | |
155 | static void rpmsg_tty_destruct_port(struct tty_port *port) |
156 | { |
157 | struct rpmsg_tty_port *cport = container_of(port, struct rpmsg_tty_port, port); |
158 | |
159 | mutex_lock(&idr_lock); |
160 | idr_remove(&tty_idr, id: cport->id); |
161 | mutex_unlock(lock: &idr_lock); |
162 | |
163 | kfree(objp: cport); |
164 | } |
165 | |
166 | static const struct tty_port_operations rpmsg_tty_port_ops = { |
167 | .destruct = rpmsg_tty_destruct_port, |
168 | }; |
169 | |
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(); |
179 | if (IS_ERR(ptr: cport)) |
180 | return dev_err_probe(dev, err: PTR_ERR(ptr: cport), fmt: "Failed to alloc tty port\n" ); |
181 | |
182 | tty_port_init(port: &cport->port); |
183 | cport->port.ops = &rpmsg_tty_port_ops; |
184 | |
185 | tty_dev = tty_port_register_device(port: &cport->port, driver: rpmsg_tty_driver, |
186 | index: cport->id, device: dev); |
187 | if (IS_ERR(ptr: tty_dev)) { |
188 | ret = dev_err_probe(dev, err: PTR_ERR(ptr: tty_dev), fmt: "Failed to register tty port\n" ); |
189 | tty_port_put(port: &cport->port); |
190 | return ret; |
191 | } |
192 | |
193 | cport->rpdev = rpdev; |
194 | |
195 | dev_set_drvdata(dev, data: cport); |
196 | |
197 | dev_dbg(dev, "New channel: 0x%x -> 0x%x: " RPMSG_TTY_NAME "%d\n" , |
198 | rpdev->src, rpdev->dst, cport->id); |
199 | |
200 | return 0; |
201 | } |
202 | |
203 | static void rpmsg_tty_remove(struct rpmsg_device *rpdev) |
204 | { |
205 | struct rpmsg_tty_port *cport = dev_get_drvdata(dev: &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 */ |
210 | tty_port_tty_hangup(port: &cport->port, check_clocal: false); |
211 | |
212 | tty_unregister_device(driver: rpmsg_tty_driver, index: cport->id); |
213 | |
214 | tty_port_put(port: &cport->port); |
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 | { |
233 | int ret; |
234 | |
235 | rpmsg_tty_driver = tty_alloc_driver(MAX_TTY_RPMSG, TTY_DRIVER_REAL_RAW | |
236 | TTY_DRIVER_DYNAMIC_DEV); |
237 | if (IS_ERR(ptr: rpmsg_tty_driver)) |
238 | return PTR_ERR(ptr: rpmsg_tty_driver); |
239 | |
240 | rpmsg_tty_driver->driver_name = "rpmsg_tty" ; |
241 | rpmsg_tty_driver->name = RPMSG_TTY_NAME; |
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(driver: rpmsg_tty_driver, op: &rpmsg_tty_ops); |
251 | |
252 | ret = tty_register_driver(driver: rpmsg_tty_driver); |
253 | if (ret < 0) { |
254 | pr_err("Couldn't install driver: %d\n" , ret); |
255 | goto error_put; |
256 | } |
257 | |
258 | ret = register_rpmsg_driver(&rpmsg_tty_rpmsg_drv); |
259 | if (ret < 0) { |
260 | pr_err("Couldn't register driver: %d\n" , ret); |
261 | goto error_unregister; |
262 | } |
263 | |
264 | return 0; |
265 | |
266 | error_unregister: |
267 | tty_unregister_driver(driver: rpmsg_tty_driver); |
268 | |
269 | error_put: |
270 | tty_driver_kref_put(driver: rpmsg_tty_driver); |
271 | |
272 | return ret; |
273 | } |
274 | |
275 | static void __exit rpmsg_tty_exit(void) |
276 | { |
277 | unregister_rpmsg_driver(drv: &rpmsg_tty_rpmsg_drv); |
278 | tty_unregister_driver(driver: rpmsg_tty_driver); |
279 | tty_driver_kref_put(driver: 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" ); |
289 | |