17c0408d8SArnaud Pouliquen // SPDX-License-Identifier: GPL-2.0
27c0408d8SArnaud Pouliquen /*
37c0408d8SArnaud Pouliquen * Copyright (C) 2021 STMicroelectronics - All Rights Reserved
47c0408d8SArnaud Pouliquen *
57c0408d8SArnaud Pouliquen * The rpmsg tty driver implements serial communication on the RPMsg bus to makes
67c0408d8SArnaud Pouliquen * possible for user-space programs to send and receive rpmsg messages as a standard
77c0408d8SArnaud Pouliquen * tty protocol.
87c0408d8SArnaud Pouliquen *
97c0408d8SArnaud Pouliquen * The remote processor can instantiate a new tty by requesting a "rpmsg-tty" RPMsg service.
107c0408d8SArnaud Pouliquen * The "rpmsg-tty" service is directly used for data exchange. No flow control is implemented yet.
117c0408d8SArnaud Pouliquen */
127c0408d8SArnaud Pouliquen
1388af70beSAndy Shevchenko #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
1488af70beSAndy Shevchenko
157c0408d8SArnaud Pouliquen #include <linux/module.h>
167c0408d8SArnaud Pouliquen #include <linux/rpmsg.h>
177c0408d8SArnaud Pouliquen #include <linux/slab.h>
187c0408d8SArnaud Pouliquen #include <linux/tty.h>
197c0408d8SArnaud Pouliquen #include <linux/tty_flip.h>
207c0408d8SArnaud Pouliquen
2173a3d4f4SAndy Shevchenko #define RPMSG_TTY_NAME "ttyRPMSG"
227c0408d8SArnaud Pouliquen #define MAX_TTY_RPMSG 32
237c0408d8SArnaud Pouliquen
247c0408d8SArnaud Pouliquen static DEFINE_IDR(tty_idr); /* tty instance id */
257c0408d8SArnaud Pouliquen static DEFINE_MUTEX(idr_lock); /* protects tty_idr */
267c0408d8SArnaud Pouliquen
277c0408d8SArnaud Pouliquen static struct tty_driver *rpmsg_tty_driver;
287c0408d8SArnaud Pouliquen
297c0408d8SArnaud Pouliquen struct rpmsg_tty_port {
307c0408d8SArnaud Pouliquen struct tty_port port; /* TTY port data */
317c0408d8SArnaud Pouliquen int id; /* TTY rpmsg index */
327c0408d8SArnaud Pouliquen struct rpmsg_device *rpdev; /* rpmsg device */
337c0408d8SArnaud Pouliquen };
347c0408d8SArnaud Pouliquen
rpmsg_tty_cb(struct rpmsg_device * rpdev,void * data,int len,void * priv,u32 src)357c0408d8SArnaud Pouliquen static int rpmsg_tty_cb(struct rpmsg_device *rpdev, void *data, int len, void *priv, u32 src)
367c0408d8SArnaud Pouliquen {
377c0408d8SArnaud Pouliquen struct rpmsg_tty_port *cport = dev_get_drvdata(&rpdev->dev);
387c0408d8SArnaud Pouliquen int copied;
397c0408d8SArnaud Pouliquen
407c0408d8SArnaud Pouliquen if (!len)
417c0408d8SArnaud Pouliquen return -EINVAL;
427c0408d8SArnaud Pouliquen copied = tty_insert_flip_string(&cport->port, data, len);
437c0408d8SArnaud Pouliquen if (copied != len)
447c0408d8SArnaud Pouliquen dev_err_ratelimited(&rpdev->dev, "Trunc buffer: available space is %d\n", copied);
457c0408d8SArnaud Pouliquen tty_flip_buffer_push(&cport->port);
467c0408d8SArnaud Pouliquen
477c0408d8SArnaud Pouliquen return 0;
487c0408d8SArnaud Pouliquen }
497c0408d8SArnaud Pouliquen
rpmsg_tty_install(struct tty_driver * driver,struct tty_struct * tty)507c0408d8SArnaud Pouliquen static int rpmsg_tty_install(struct tty_driver *driver, struct tty_struct *tty)
517c0408d8SArnaud Pouliquen {
527c0408d8SArnaud Pouliquen struct rpmsg_tty_port *cport = idr_find(&tty_idr, tty->index);
53db7f19c0SArnaud Pouliquen struct tty_port *port;
547c0408d8SArnaud Pouliquen
557c0408d8SArnaud Pouliquen tty->driver_data = cport;
567c0408d8SArnaud Pouliquen
57db7f19c0SArnaud Pouliquen port = tty_port_get(&cport->port);
58db7f19c0SArnaud Pouliquen return tty_port_install(port, driver, tty);
59db7f19c0SArnaud Pouliquen }
60db7f19c0SArnaud Pouliquen
rpmsg_tty_cleanup(struct tty_struct * tty)61db7f19c0SArnaud Pouliquen static void rpmsg_tty_cleanup(struct tty_struct *tty)
62db7f19c0SArnaud Pouliquen {
63db7f19c0SArnaud Pouliquen tty_port_put(tty->port);
647c0408d8SArnaud Pouliquen }
657c0408d8SArnaud Pouliquen
rpmsg_tty_open(struct tty_struct * tty,struct file * filp)667c0408d8SArnaud Pouliquen static int rpmsg_tty_open(struct tty_struct *tty, struct file *filp)
677c0408d8SArnaud Pouliquen {
687c0408d8SArnaud Pouliquen return tty_port_open(tty->port, tty, filp);
697c0408d8SArnaud Pouliquen }
707c0408d8SArnaud Pouliquen
rpmsg_tty_close(struct tty_struct * tty,struct file * filp)717c0408d8SArnaud Pouliquen static void rpmsg_tty_close(struct tty_struct *tty, struct file *filp)
727c0408d8SArnaud Pouliquen {
737c0408d8SArnaud Pouliquen return tty_port_close(tty->port, tty, filp);
747c0408d8SArnaud Pouliquen }
757c0408d8SArnaud Pouliquen
rpmsg_tty_write(struct tty_struct * tty,const u8 * buf,size_t len)76*95713967SJiri Slaby (SUSE) static ssize_t rpmsg_tty_write(struct tty_struct *tty, const u8 *buf,
77*95713967SJiri Slaby (SUSE) size_t len)
787c0408d8SArnaud Pouliquen {
797c0408d8SArnaud Pouliquen struct rpmsg_tty_port *cport = tty->driver_data;
807c0408d8SArnaud Pouliquen struct rpmsg_device *rpdev;
817c0408d8SArnaud Pouliquen int msg_max_size, msg_size;
827c0408d8SArnaud Pouliquen int ret;
837c0408d8SArnaud Pouliquen
847c0408d8SArnaud Pouliquen rpdev = cport->rpdev;
857c0408d8SArnaud Pouliquen
867c0408d8SArnaud Pouliquen msg_max_size = rpmsg_get_mtu(rpdev->ept);
877c0408d8SArnaud Pouliquen if (msg_max_size < 0)
887c0408d8SArnaud Pouliquen return msg_max_size;
897c0408d8SArnaud Pouliquen
90*95713967SJiri Slaby (SUSE) msg_size = min_t(unsigned int, len, msg_max_size);
917c0408d8SArnaud Pouliquen
927c0408d8SArnaud Pouliquen /*
937c0408d8SArnaud Pouliquen * Use rpmsg_trysend instead of rpmsg_send to send the message so the caller is not
947c0408d8SArnaud Pouliquen * hung until a rpmsg buffer is available. In such case rpmsg_trysend returns -ENOMEM.
957c0408d8SArnaud Pouliquen */
967c0408d8SArnaud Pouliquen ret = rpmsg_trysend(rpdev->ept, (void *)buf, msg_size);
977c0408d8SArnaud Pouliquen if (ret) {
987c0408d8SArnaud Pouliquen dev_dbg_ratelimited(&rpdev->dev, "rpmsg_send failed: %d\n", ret);
997c0408d8SArnaud Pouliquen return ret;
1007c0408d8SArnaud Pouliquen }
1017c0408d8SArnaud Pouliquen
1027c0408d8SArnaud Pouliquen return msg_size;
1037c0408d8SArnaud Pouliquen }
1047c0408d8SArnaud Pouliquen
rpmsg_tty_write_room(struct tty_struct * tty)1057c0408d8SArnaud Pouliquen static unsigned int rpmsg_tty_write_room(struct tty_struct *tty)
1067c0408d8SArnaud Pouliquen {
1077c0408d8SArnaud Pouliquen struct rpmsg_tty_port *cport = tty->driver_data;
1087c0408d8SArnaud Pouliquen int size;
1097c0408d8SArnaud Pouliquen
1107c0408d8SArnaud Pouliquen size = rpmsg_get_mtu(cport->rpdev->ept);
1117c0408d8SArnaud Pouliquen if (size < 0)
1127c0408d8SArnaud Pouliquen return 0;
1137c0408d8SArnaud Pouliquen
1147c0408d8SArnaud Pouliquen return size;
1157c0408d8SArnaud Pouliquen }
1167c0408d8SArnaud Pouliquen
rpmsg_tty_hangup(struct tty_struct * tty)117db7f19c0SArnaud Pouliquen static void rpmsg_tty_hangup(struct tty_struct *tty)
118db7f19c0SArnaud Pouliquen {
119db7f19c0SArnaud Pouliquen tty_port_hangup(tty->port);
120db7f19c0SArnaud Pouliquen }
121db7f19c0SArnaud Pouliquen
1227c0408d8SArnaud Pouliquen static const struct tty_operations rpmsg_tty_ops = {
1237c0408d8SArnaud Pouliquen .install = rpmsg_tty_install,
1247c0408d8SArnaud Pouliquen .open = rpmsg_tty_open,
1257c0408d8SArnaud Pouliquen .close = rpmsg_tty_close,
1267c0408d8SArnaud Pouliquen .write = rpmsg_tty_write,
1277c0408d8SArnaud Pouliquen .write_room = rpmsg_tty_write_room,
128db7f19c0SArnaud Pouliquen .hangup = rpmsg_tty_hangup,
129db7f19c0SArnaud Pouliquen .cleanup = rpmsg_tty_cleanup,
1307c0408d8SArnaud Pouliquen };
1317c0408d8SArnaud Pouliquen
rpmsg_tty_alloc_cport(void)1327c0408d8SArnaud Pouliquen static struct rpmsg_tty_port *rpmsg_tty_alloc_cport(void)
1337c0408d8SArnaud Pouliquen {
1347c0408d8SArnaud Pouliquen struct rpmsg_tty_port *cport;
135408a5079SAndy Shevchenko int ret;
1367c0408d8SArnaud Pouliquen
1377c0408d8SArnaud Pouliquen cport = kzalloc(sizeof(*cport), GFP_KERNEL);
1387c0408d8SArnaud Pouliquen if (!cport)
1397c0408d8SArnaud Pouliquen return ERR_PTR(-ENOMEM);
1407c0408d8SArnaud Pouliquen
1417c0408d8SArnaud Pouliquen mutex_lock(&idr_lock);
142408a5079SAndy Shevchenko ret = idr_alloc(&tty_idr, cport, 0, MAX_TTY_RPMSG, GFP_KERNEL);
1437c0408d8SArnaud Pouliquen mutex_unlock(&idr_lock);
1447c0408d8SArnaud Pouliquen
145408a5079SAndy Shevchenko if (ret < 0) {
1467c0408d8SArnaud Pouliquen kfree(cport);
147408a5079SAndy Shevchenko return ERR_PTR(ret);
1487c0408d8SArnaud Pouliquen }
1497c0408d8SArnaud Pouliquen
150408a5079SAndy Shevchenko cport->id = ret;
1510572da28SAndy Shevchenko
1527c0408d8SArnaud Pouliquen return cport;
1537c0408d8SArnaud Pouliquen }
1547c0408d8SArnaud Pouliquen
rpmsg_tty_destruct_port(struct tty_port * port)155db7f19c0SArnaud Pouliquen static void rpmsg_tty_destruct_port(struct tty_port *port)
1567c0408d8SArnaud Pouliquen {
157db7f19c0SArnaud Pouliquen struct rpmsg_tty_port *cport = container_of(port, struct rpmsg_tty_port, port);
158db7f19c0SArnaud Pouliquen
1597c0408d8SArnaud Pouliquen mutex_lock(&idr_lock);
1607c0408d8SArnaud Pouliquen idr_remove(&tty_idr, cport->id);
1617c0408d8SArnaud Pouliquen mutex_unlock(&idr_lock);
1627c0408d8SArnaud Pouliquen
1637c0408d8SArnaud Pouliquen kfree(cport);
1647c0408d8SArnaud Pouliquen }
1657c0408d8SArnaud Pouliquen
166db7f19c0SArnaud Pouliquen static const struct tty_port_operations rpmsg_tty_port_ops = {
167db7f19c0SArnaud Pouliquen .destruct = rpmsg_tty_destruct_port,
168db7f19c0SArnaud Pouliquen };
169db7f19c0SArnaud Pouliquen
1707c0408d8SArnaud Pouliquen
rpmsg_tty_probe(struct rpmsg_device * rpdev)1717c0408d8SArnaud Pouliquen static int rpmsg_tty_probe(struct rpmsg_device *rpdev)
1727c0408d8SArnaud Pouliquen {
1737c0408d8SArnaud Pouliquen struct rpmsg_tty_port *cport;
1747c0408d8SArnaud Pouliquen struct device *dev = &rpdev->dev;
1757c0408d8SArnaud Pouliquen struct device *tty_dev;
1767c0408d8SArnaud Pouliquen int ret;
1777c0408d8SArnaud Pouliquen
1787c0408d8SArnaud Pouliquen cport = rpmsg_tty_alloc_cport();
1798673ef7bSAndy Shevchenko if (IS_ERR(cport))
1808673ef7bSAndy Shevchenko return dev_err_probe(dev, PTR_ERR(cport), "Failed to alloc tty port\n");
1817c0408d8SArnaud Pouliquen
1827c0408d8SArnaud Pouliquen tty_port_init(&cport->port);
1837c0408d8SArnaud Pouliquen cport->port.ops = &rpmsg_tty_port_ops;
1847c0408d8SArnaud Pouliquen
1857c0408d8SArnaud Pouliquen tty_dev = tty_port_register_device(&cport->port, rpmsg_tty_driver,
1867c0408d8SArnaud Pouliquen cport->id, dev);
1877c0408d8SArnaud Pouliquen if (IS_ERR(tty_dev)) {
1888673ef7bSAndy Shevchenko ret = dev_err_probe(dev, PTR_ERR(tty_dev), "Failed to register tty port\n");
189db7f19c0SArnaud Pouliquen tty_port_put(&cport->port);
190db7f19c0SArnaud Pouliquen return ret;
1917c0408d8SArnaud Pouliquen }
1927c0408d8SArnaud Pouliquen
1937c0408d8SArnaud Pouliquen cport->rpdev = rpdev;
1947c0408d8SArnaud Pouliquen
1957c0408d8SArnaud Pouliquen dev_set_drvdata(dev, cport);
1967c0408d8SArnaud Pouliquen
19773a3d4f4SAndy Shevchenko dev_dbg(dev, "New channel: 0x%x -> 0x%x: " RPMSG_TTY_NAME "%d\n",
1987c0408d8SArnaud Pouliquen rpdev->src, rpdev->dst, cport->id);
1997c0408d8SArnaud Pouliquen
2007c0408d8SArnaud Pouliquen return 0;
2017c0408d8SArnaud Pouliquen }
2027c0408d8SArnaud Pouliquen
rpmsg_tty_remove(struct rpmsg_device * rpdev)2037c0408d8SArnaud Pouliquen static void rpmsg_tty_remove(struct rpmsg_device *rpdev)
2047c0408d8SArnaud Pouliquen {
2057c0408d8SArnaud Pouliquen struct rpmsg_tty_port *cport = dev_get_drvdata(&rpdev->dev);
2067c0408d8SArnaud Pouliquen
2077c0408d8SArnaud Pouliquen dev_dbg(&rpdev->dev, "Removing rpmsg tty device %d\n", cport->id);
2087c0408d8SArnaud Pouliquen
2097c0408d8SArnaud Pouliquen /* User hang up to release the tty */
2107c0408d8SArnaud Pouliquen tty_port_tty_hangup(&cport->port, false);
2117c0408d8SArnaud Pouliquen
2127c0408d8SArnaud Pouliquen tty_unregister_device(rpmsg_tty_driver, cport->id);
2137c0408d8SArnaud Pouliquen
214db7f19c0SArnaud Pouliquen tty_port_put(&cport->port);
2157c0408d8SArnaud Pouliquen }
2167c0408d8SArnaud Pouliquen
2177c0408d8SArnaud Pouliquen static struct rpmsg_device_id rpmsg_driver_tty_id_table[] = {
2187c0408d8SArnaud Pouliquen { .name = "rpmsg-tty" },
2197c0408d8SArnaud Pouliquen { },
2207c0408d8SArnaud Pouliquen };
2217c0408d8SArnaud Pouliquen MODULE_DEVICE_TABLE(rpmsg, rpmsg_driver_tty_id_table);
2227c0408d8SArnaud Pouliquen
2237c0408d8SArnaud Pouliquen static struct rpmsg_driver rpmsg_tty_rpmsg_drv = {
2247c0408d8SArnaud Pouliquen .drv.name = KBUILD_MODNAME,
2257c0408d8SArnaud Pouliquen .id_table = rpmsg_driver_tty_id_table,
2267c0408d8SArnaud Pouliquen .probe = rpmsg_tty_probe,
2277c0408d8SArnaud Pouliquen .callback = rpmsg_tty_cb,
2287c0408d8SArnaud Pouliquen .remove = rpmsg_tty_remove,
2297c0408d8SArnaud Pouliquen };
2307c0408d8SArnaud Pouliquen
rpmsg_tty_init(void)2317c0408d8SArnaud Pouliquen static int __init rpmsg_tty_init(void)
2327c0408d8SArnaud Pouliquen {
233408a5079SAndy Shevchenko int ret;
2347c0408d8SArnaud Pouliquen
2357c0408d8SArnaud Pouliquen rpmsg_tty_driver = tty_alloc_driver(MAX_TTY_RPMSG, TTY_DRIVER_REAL_RAW |
2367c0408d8SArnaud Pouliquen TTY_DRIVER_DYNAMIC_DEV);
2377c0408d8SArnaud Pouliquen if (IS_ERR(rpmsg_tty_driver))
2387c0408d8SArnaud Pouliquen return PTR_ERR(rpmsg_tty_driver);
2397c0408d8SArnaud Pouliquen
2407c0408d8SArnaud Pouliquen rpmsg_tty_driver->driver_name = "rpmsg_tty";
24173a3d4f4SAndy Shevchenko rpmsg_tty_driver->name = RPMSG_TTY_NAME;
2427c0408d8SArnaud Pouliquen rpmsg_tty_driver->major = 0;
2437c0408d8SArnaud Pouliquen rpmsg_tty_driver->type = TTY_DRIVER_TYPE_CONSOLE;
2447c0408d8SArnaud Pouliquen
2457c0408d8SArnaud Pouliquen /* Disable unused mode by default */
2467c0408d8SArnaud Pouliquen rpmsg_tty_driver->init_termios = tty_std_termios;
2477c0408d8SArnaud Pouliquen rpmsg_tty_driver->init_termios.c_lflag &= ~(ECHO | ICANON);
2487c0408d8SArnaud Pouliquen rpmsg_tty_driver->init_termios.c_oflag &= ~(OPOST | ONLCR);
2497c0408d8SArnaud Pouliquen
2507c0408d8SArnaud Pouliquen tty_set_operations(rpmsg_tty_driver, &rpmsg_tty_ops);
2517c0408d8SArnaud Pouliquen
252408a5079SAndy Shevchenko ret = tty_register_driver(rpmsg_tty_driver);
253408a5079SAndy Shevchenko if (ret < 0) {
25488af70beSAndy Shevchenko pr_err("Couldn't install driver: %d\n", ret);
2557c0408d8SArnaud Pouliquen goto error_put;
2567c0408d8SArnaud Pouliquen }
2577c0408d8SArnaud Pouliquen
258408a5079SAndy Shevchenko ret = register_rpmsg_driver(&rpmsg_tty_rpmsg_drv);
259408a5079SAndy Shevchenko if (ret < 0) {
26088af70beSAndy Shevchenko pr_err("Couldn't register driver: %d\n", ret);
2617c0408d8SArnaud Pouliquen goto error_unregister;
2627c0408d8SArnaud Pouliquen }
2637c0408d8SArnaud Pouliquen
2647c0408d8SArnaud Pouliquen return 0;
2657c0408d8SArnaud Pouliquen
2667c0408d8SArnaud Pouliquen error_unregister:
2677c0408d8SArnaud Pouliquen tty_unregister_driver(rpmsg_tty_driver);
2687c0408d8SArnaud Pouliquen
2697c0408d8SArnaud Pouliquen error_put:
2707c0408d8SArnaud Pouliquen tty_driver_kref_put(rpmsg_tty_driver);
2717c0408d8SArnaud Pouliquen
272408a5079SAndy Shevchenko return ret;
2737c0408d8SArnaud Pouliquen }
2747c0408d8SArnaud Pouliquen
rpmsg_tty_exit(void)2757c0408d8SArnaud Pouliquen static void __exit rpmsg_tty_exit(void)
2767c0408d8SArnaud Pouliquen {
2777c0408d8SArnaud Pouliquen unregister_rpmsg_driver(&rpmsg_tty_rpmsg_drv);
2787c0408d8SArnaud Pouliquen tty_unregister_driver(rpmsg_tty_driver);
2797c0408d8SArnaud Pouliquen tty_driver_kref_put(rpmsg_tty_driver);
2807c0408d8SArnaud Pouliquen idr_destroy(&tty_idr);
2817c0408d8SArnaud Pouliquen }
2827c0408d8SArnaud Pouliquen
2837c0408d8SArnaud Pouliquen module_init(rpmsg_tty_init);
2847c0408d8SArnaud Pouliquen module_exit(rpmsg_tty_exit);
2857c0408d8SArnaud Pouliquen
2867c0408d8SArnaud Pouliquen MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>");
2877c0408d8SArnaud Pouliquen MODULE_DESCRIPTION("remote processor messaging tty driver");
2887c0408d8SArnaud Pouliquen MODULE_LICENSE("GPL v2");
289