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1// SPDX-License-Identifier: GPL-2.02/*3 * Copyright (C) 2021 STMicroelectronics - All Rights Reserved4 *5 * The rpmsg tty driver implements serial communication on the RPMsg bus to makes6 * possible for user-space programs to send and receive rpmsg messages as a standard7 * 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 ": " fmt14 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 3223 24static DEFINE_IDR(tty_idr); /* tty instance id */25static DEFINE_MUTEX(idr_lock); /* protects tty_idr */26 27static struct tty_driver *rpmsg_tty_driver;28 29struct 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 35static 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 50static 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);53 struct tty_port *port;54 55 tty->driver_data = cport;56 57 port = tty_port_get(&cport->port);58 return tty_port_install(port, driver, tty);59}60 61static void rpmsg_tty_cleanup(struct tty_struct *tty)62{63 tty_port_put(tty->port);64}65 66static int rpmsg_tty_open(struct tty_struct *tty, struct file *filp)67{68 return tty_port_open(tty->port, tty, filp);69}70 71static void rpmsg_tty_close(struct tty_struct *tty, struct file *filp)72{73 return tty_port_close(tty->port, tty, filp);74}75 76static 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(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 not94 * 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 105static 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 117static void rpmsg_tty_hangup(struct tty_struct *tty)118{119 tty_port_hangup(tty->port);120}121 122static 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 132static struct rpmsg_tty_port *rpmsg_tty_alloc_cport(void)133{134 struct rpmsg_tty_port *cport;135 int ret;136 137 cport = kzalloc(sizeof(*cport), GFP_KERNEL);138 if (!cport)139 return ERR_PTR(-ENOMEM);140 141 mutex_lock(&idr_lock);142 ret = idr_alloc(&tty_idr, cport, 0, MAX_TTY_RPMSG, GFP_KERNEL);143 mutex_unlock(&idr_lock);144 145 if (ret < 0) {146 kfree(cport);147 return ERR_PTR(ret);148 }149 150 cport->id = ret;151 152 return cport;153}154 155static 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, cport->id);161 mutex_unlock(&idr_lock);162 163 kfree(cport);164}165 166static const struct tty_port_operations rpmsg_tty_port_ops = {167 .destruct = rpmsg_tty_destruct_port,168};169 170 171static 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(cport))180 return dev_err_probe(dev, PTR_ERR(cport), "Failed to alloc tty port\n");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)) {188 ret = dev_err_probe(dev, PTR_ERR(tty_dev), "Failed to register tty port\n");189 tty_port_put(&cport->port);190 return ret;191 }192 193 cport->rpdev = rpdev;194 195 dev_set_drvdata(dev, 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 203static 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 */210 tty_port_tty_hangup(&cport->port, false);211 212 tty_unregister_device(rpmsg_tty_driver, cport->id);213 214 tty_port_put(&cport->port);215}216 217static struct rpmsg_device_id rpmsg_driver_tty_id_table[] = {218 { .name = "rpmsg-tty" },219 { },220};221MODULE_DEVICE_TABLE(rpmsg, rpmsg_driver_tty_id_table);222 223static 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 231static 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(rpmsg_tty_driver))238 return PTR_ERR(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(rpmsg_tty_driver, &rpmsg_tty_ops);251 252 ret = tty_register_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 266error_unregister:267 tty_unregister_driver(rpmsg_tty_driver);268 269error_put:270 tty_driver_kref_put(rpmsg_tty_driver);271 272 return ret;273}274 275static 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 283module_init(rpmsg_tty_init);284module_exit(rpmsg_tty_exit);285 286MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>");287MODULE_DESCRIPTION("remote processor messaging tty driver");288MODULE_LICENSE("GPL v2");289