162306a36Sopenharmony_ci// SPDX-License-Identifier: GPL-2.0 262306a36Sopenharmony_ci/* 362306a36Sopenharmony_ci * Copyright (C) 2021 STMicroelectronics - All Rights Reserved 462306a36Sopenharmony_ci * 562306a36Sopenharmony_ci * The rpmsg tty driver implements serial communication on the RPMsg bus to makes 662306a36Sopenharmony_ci * possible for user-space programs to send and receive rpmsg messages as a standard 762306a36Sopenharmony_ci * tty protocol. 862306a36Sopenharmony_ci * 962306a36Sopenharmony_ci * The remote processor can instantiate a new tty by requesting a "rpmsg-tty" RPMsg service. 1062306a36Sopenharmony_ci * The "rpmsg-tty" service is directly used for data exchange. No flow control is implemented yet. 1162306a36Sopenharmony_ci */ 1262306a36Sopenharmony_ci 1362306a36Sopenharmony_ci#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 1462306a36Sopenharmony_ci 1562306a36Sopenharmony_ci#include <linux/module.h> 1662306a36Sopenharmony_ci#include <linux/rpmsg.h> 1762306a36Sopenharmony_ci#include <linux/slab.h> 1862306a36Sopenharmony_ci#include <linux/tty.h> 1962306a36Sopenharmony_ci#include <linux/tty_flip.h> 2062306a36Sopenharmony_ci 2162306a36Sopenharmony_ci#define RPMSG_TTY_NAME "ttyRPMSG" 2262306a36Sopenharmony_ci#define MAX_TTY_RPMSG 32 2362306a36Sopenharmony_ci 2462306a36Sopenharmony_cistatic DEFINE_IDR(tty_idr); /* tty instance id */ 2562306a36Sopenharmony_cistatic DEFINE_MUTEX(idr_lock); /* protects tty_idr */ 2662306a36Sopenharmony_ci 2762306a36Sopenharmony_cistatic struct tty_driver *rpmsg_tty_driver; 2862306a36Sopenharmony_ci 2962306a36Sopenharmony_cistruct rpmsg_tty_port { 3062306a36Sopenharmony_ci struct tty_port port; /* TTY port data */ 3162306a36Sopenharmony_ci int id; /* TTY rpmsg index */ 3262306a36Sopenharmony_ci struct rpmsg_device *rpdev; /* rpmsg device */ 3362306a36Sopenharmony_ci}; 3462306a36Sopenharmony_ci 3562306a36Sopenharmony_cistatic int rpmsg_tty_cb(struct rpmsg_device *rpdev, void *data, int len, void *priv, u32 src) 3662306a36Sopenharmony_ci{ 3762306a36Sopenharmony_ci struct rpmsg_tty_port *cport = dev_get_drvdata(&rpdev->dev); 3862306a36Sopenharmony_ci int copied; 3962306a36Sopenharmony_ci 4062306a36Sopenharmony_ci if (!len) 4162306a36Sopenharmony_ci return -EINVAL; 4262306a36Sopenharmony_ci copied = tty_insert_flip_string(&cport->port, data, len); 4362306a36Sopenharmony_ci if (copied != len) 4462306a36Sopenharmony_ci dev_err_ratelimited(&rpdev->dev, "Trunc buffer: available space is %d\n", copied); 4562306a36Sopenharmony_ci tty_flip_buffer_push(&cport->port); 4662306a36Sopenharmony_ci 4762306a36Sopenharmony_ci return 0; 4862306a36Sopenharmony_ci} 4962306a36Sopenharmony_ci 5062306a36Sopenharmony_cistatic int rpmsg_tty_install(struct tty_driver *driver, struct tty_struct *tty) 5162306a36Sopenharmony_ci{ 5262306a36Sopenharmony_ci struct rpmsg_tty_port *cport = idr_find(&tty_idr, tty->index); 5362306a36Sopenharmony_ci struct tty_port *port; 5462306a36Sopenharmony_ci 5562306a36Sopenharmony_ci tty->driver_data = cport; 5662306a36Sopenharmony_ci 5762306a36Sopenharmony_ci port = tty_port_get(&cport->port); 5862306a36Sopenharmony_ci return tty_port_install(port, driver, tty); 5962306a36Sopenharmony_ci} 6062306a36Sopenharmony_ci 6162306a36Sopenharmony_cistatic void rpmsg_tty_cleanup(struct tty_struct *tty) 6262306a36Sopenharmony_ci{ 6362306a36Sopenharmony_ci tty_port_put(tty->port); 6462306a36Sopenharmony_ci} 6562306a36Sopenharmony_ci 6662306a36Sopenharmony_cistatic int rpmsg_tty_open(struct tty_struct *tty, struct file *filp) 6762306a36Sopenharmony_ci{ 6862306a36Sopenharmony_ci return tty_port_open(tty->port, tty, filp); 6962306a36Sopenharmony_ci} 7062306a36Sopenharmony_ci 7162306a36Sopenharmony_cistatic void rpmsg_tty_close(struct tty_struct *tty, struct file *filp) 7262306a36Sopenharmony_ci{ 7362306a36Sopenharmony_ci return tty_port_close(tty->port, tty, filp); 7462306a36Sopenharmony_ci} 7562306a36Sopenharmony_ci 7662306a36Sopenharmony_cistatic ssize_t rpmsg_tty_write(struct tty_struct *tty, const u8 *buf, 7762306a36Sopenharmony_ci size_t len) 7862306a36Sopenharmony_ci{ 7962306a36Sopenharmony_ci struct rpmsg_tty_port *cport = tty->driver_data; 8062306a36Sopenharmony_ci struct rpmsg_device *rpdev; 8162306a36Sopenharmony_ci int msg_max_size, msg_size; 8262306a36Sopenharmony_ci int ret; 8362306a36Sopenharmony_ci 8462306a36Sopenharmony_ci rpdev = cport->rpdev; 8562306a36Sopenharmony_ci 8662306a36Sopenharmony_ci msg_max_size = rpmsg_get_mtu(rpdev->ept); 8762306a36Sopenharmony_ci if (msg_max_size < 0) 8862306a36Sopenharmony_ci return msg_max_size; 8962306a36Sopenharmony_ci 9062306a36Sopenharmony_ci msg_size = min_t(unsigned int, len, msg_max_size); 9162306a36Sopenharmony_ci 9262306a36Sopenharmony_ci /* 9362306a36Sopenharmony_ci * Use rpmsg_trysend instead of rpmsg_send to send the message so the caller is not 9462306a36Sopenharmony_ci * hung until a rpmsg buffer is available. In such case rpmsg_trysend returns -ENOMEM. 9562306a36Sopenharmony_ci */ 9662306a36Sopenharmony_ci ret = rpmsg_trysend(rpdev->ept, (void *)buf, msg_size); 9762306a36Sopenharmony_ci if (ret) { 9862306a36Sopenharmony_ci dev_dbg_ratelimited(&rpdev->dev, "rpmsg_send failed: %d\n", ret); 9962306a36Sopenharmony_ci return ret; 10062306a36Sopenharmony_ci } 10162306a36Sopenharmony_ci 10262306a36Sopenharmony_ci return msg_size; 10362306a36Sopenharmony_ci} 10462306a36Sopenharmony_ci 10562306a36Sopenharmony_cistatic unsigned int rpmsg_tty_write_room(struct tty_struct *tty) 10662306a36Sopenharmony_ci{ 10762306a36Sopenharmony_ci struct rpmsg_tty_port *cport = tty->driver_data; 10862306a36Sopenharmony_ci int size; 10962306a36Sopenharmony_ci 11062306a36Sopenharmony_ci size = rpmsg_get_mtu(cport->rpdev->ept); 11162306a36Sopenharmony_ci if (size < 0) 11262306a36Sopenharmony_ci return 0; 11362306a36Sopenharmony_ci 11462306a36Sopenharmony_ci return size; 11562306a36Sopenharmony_ci} 11662306a36Sopenharmony_ci 11762306a36Sopenharmony_cistatic void rpmsg_tty_hangup(struct tty_struct *tty) 11862306a36Sopenharmony_ci{ 11962306a36Sopenharmony_ci tty_port_hangup(tty->port); 12062306a36Sopenharmony_ci} 12162306a36Sopenharmony_ci 12262306a36Sopenharmony_cistatic const struct tty_operations rpmsg_tty_ops = { 12362306a36Sopenharmony_ci .install = rpmsg_tty_install, 12462306a36Sopenharmony_ci .open = rpmsg_tty_open, 12562306a36Sopenharmony_ci .close = rpmsg_tty_close, 12662306a36Sopenharmony_ci .write = rpmsg_tty_write, 12762306a36Sopenharmony_ci .write_room = rpmsg_tty_write_room, 12862306a36Sopenharmony_ci .hangup = rpmsg_tty_hangup, 12962306a36Sopenharmony_ci .cleanup = rpmsg_tty_cleanup, 13062306a36Sopenharmony_ci}; 13162306a36Sopenharmony_ci 13262306a36Sopenharmony_cistatic struct rpmsg_tty_port *rpmsg_tty_alloc_cport(void) 13362306a36Sopenharmony_ci{ 13462306a36Sopenharmony_ci struct rpmsg_tty_port *cport; 13562306a36Sopenharmony_ci int ret; 13662306a36Sopenharmony_ci 13762306a36Sopenharmony_ci cport = kzalloc(sizeof(*cport), GFP_KERNEL); 13862306a36Sopenharmony_ci if (!cport) 13962306a36Sopenharmony_ci return ERR_PTR(-ENOMEM); 14062306a36Sopenharmony_ci 14162306a36Sopenharmony_ci mutex_lock(&idr_lock); 14262306a36Sopenharmony_ci ret = idr_alloc(&tty_idr, cport, 0, MAX_TTY_RPMSG, GFP_KERNEL); 14362306a36Sopenharmony_ci mutex_unlock(&idr_lock); 14462306a36Sopenharmony_ci 14562306a36Sopenharmony_ci if (ret < 0) { 14662306a36Sopenharmony_ci kfree(cport); 14762306a36Sopenharmony_ci return ERR_PTR(ret); 14862306a36Sopenharmony_ci } 14962306a36Sopenharmony_ci 15062306a36Sopenharmony_ci cport->id = ret; 15162306a36Sopenharmony_ci 15262306a36Sopenharmony_ci return cport; 15362306a36Sopenharmony_ci} 15462306a36Sopenharmony_ci 15562306a36Sopenharmony_cistatic void rpmsg_tty_destruct_port(struct tty_port *port) 15662306a36Sopenharmony_ci{ 15762306a36Sopenharmony_ci struct rpmsg_tty_port *cport = container_of(port, struct rpmsg_tty_port, port); 15862306a36Sopenharmony_ci 15962306a36Sopenharmony_ci mutex_lock(&idr_lock); 16062306a36Sopenharmony_ci idr_remove(&tty_idr, cport->id); 16162306a36Sopenharmony_ci mutex_unlock(&idr_lock); 16262306a36Sopenharmony_ci 16362306a36Sopenharmony_ci kfree(cport); 16462306a36Sopenharmony_ci} 16562306a36Sopenharmony_ci 16662306a36Sopenharmony_cistatic const struct tty_port_operations rpmsg_tty_port_ops = { 16762306a36Sopenharmony_ci .destruct = rpmsg_tty_destruct_port, 16862306a36Sopenharmony_ci}; 16962306a36Sopenharmony_ci 17062306a36Sopenharmony_ci 17162306a36Sopenharmony_cistatic int rpmsg_tty_probe(struct rpmsg_device *rpdev) 17262306a36Sopenharmony_ci{ 17362306a36Sopenharmony_ci struct rpmsg_tty_port *cport; 17462306a36Sopenharmony_ci struct device *dev = &rpdev->dev; 17562306a36Sopenharmony_ci struct device *tty_dev; 17662306a36Sopenharmony_ci int ret; 17762306a36Sopenharmony_ci 17862306a36Sopenharmony_ci cport = rpmsg_tty_alloc_cport(); 17962306a36Sopenharmony_ci if (IS_ERR(cport)) 18062306a36Sopenharmony_ci return dev_err_probe(dev, PTR_ERR(cport), "Failed to alloc tty port\n"); 18162306a36Sopenharmony_ci 18262306a36Sopenharmony_ci tty_port_init(&cport->port); 18362306a36Sopenharmony_ci cport->port.ops = &rpmsg_tty_port_ops; 18462306a36Sopenharmony_ci 18562306a36Sopenharmony_ci tty_dev = tty_port_register_device(&cport->port, rpmsg_tty_driver, 18662306a36Sopenharmony_ci cport->id, dev); 18762306a36Sopenharmony_ci if (IS_ERR(tty_dev)) { 18862306a36Sopenharmony_ci ret = dev_err_probe(dev, PTR_ERR(tty_dev), "Failed to register tty port\n"); 18962306a36Sopenharmony_ci tty_port_put(&cport->port); 19062306a36Sopenharmony_ci return ret; 19162306a36Sopenharmony_ci } 19262306a36Sopenharmony_ci 19362306a36Sopenharmony_ci cport->rpdev = rpdev; 19462306a36Sopenharmony_ci 19562306a36Sopenharmony_ci dev_set_drvdata(dev, cport); 19662306a36Sopenharmony_ci 19762306a36Sopenharmony_ci dev_dbg(dev, "New channel: 0x%x -> 0x%x: " RPMSG_TTY_NAME "%d\n", 19862306a36Sopenharmony_ci rpdev->src, rpdev->dst, cport->id); 19962306a36Sopenharmony_ci 20062306a36Sopenharmony_ci return 0; 20162306a36Sopenharmony_ci} 20262306a36Sopenharmony_ci 20362306a36Sopenharmony_cistatic void rpmsg_tty_remove(struct rpmsg_device *rpdev) 20462306a36Sopenharmony_ci{ 20562306a36Sopenharmony_ci struct rpmsg_tty_port *cport = dev_get_drvdata(&rpdev->dev); 20662306a36Sopenharmony_ci 20762306a36Sopenharmony_ci dev_dbg(&rpdev->dev, "Removing rpmsg tty device %d\n", cport->id); 20862306a36Sopenharmony_ci 20962306a36Sopenharmony_ci /* User hang up to release the tty */ 21062306a36Sopenharmony_ci tty_port_tty_hangup(&cport->port, false); 21162306a36Sopenharmony_ci 21262306a36Sopenharmony_ci tty_unregister_device(rpmsg_tty_driver, cport->id); 21362306a36Sopenharmony_ci 21462306a36Sopenharmony_ci tty_port_put(&cport->port); 21562306a36Sopenharmony_ci} 21662306a36Sopenharmony_ci 21762306a36Sopenharmony_cistatic struct rpmsg_device_id rpmsg_driver_tty_id_table[] = { 21862306a36Sopenharmony_ci { .name = "rpmsg-tty" }, 21962306a36Sopenharmony_ci { }, 22062306a36Sopenharmony_ci}; 22162306a36Sopenharmony_ciMODULE_DEVICE_TABLE(rpmsg, rpmsg_driver_tty_id_table); 22262306a36Sopenharmony_ci 22362306a36Sopenharmony_cistatic struct rpmsg_driver rpmsg_tty_rpmsg_drv = { 22462306a36Sopenharmony_ci .drv.name = KBUILD_MODNAME, 22562306a36Sopenharmony_ci .id_table = rpmsg_driver_tty_id_table, 22662306a36Sopenharmony_ci .probe = rpmsg_tty_probe, 22762306a36Sopenharmony_ci .callback = rpmsg_tty_cb, 22862306a36Sopenharmony_ci .remove = rpmsg_tty_remove, 22962306a36Sopenharmony_ci}; 23062306a36Sopenharmony_ci 23162306a36Sopenharmony_cistatic int __init rpmsg_tty_init(void) 23262306a36Sopenharmony_ci{ 23362306a36Sopenharmony_ci int ret; 23462306a36Sopenharmony_ci 23562306a36Sopenharmony_ci rpmsg_tty_driver = tty_alloc_driver(MAX_TTY_RPMSG, TTY_DRIVER_REAL_RAW | 23662306a36Sopenharmony_ci TTY_DRIVER_DYNAMIC_DEV); 23762306a36Sopenharmony_ci if (IS_ERR(rpmsg_tty_driver)) 23862306a36Sopenharmony_ci return PTR_ERR(rpmsg_tty_driver); 23962306a36Sopenharmony_ci 24062306a36Sopenharmony_ci rpmsg_tty_driver->driver_name = "rpmsg_tty"; 24162306a36Sopenharmony_ci rpmsg_tty_driver->name = RPMSG_TTY_NAME; 24262306a36Sopenharmony_ci rpmsg_tty_driver->major = 0; 24362306a36Sopenharmony_ci rpmsg_tty_driver->type = TTY_DRIVER_TYPE_CONSOLE; 24462306a36Sopenharmony_ci 24562306a36Sopenharmony_ci /* Disable unused mode by default */ 24662306a36Sopenharmony_ci rpmsg_tty_driver->init_termios = tty_std_termios; 24762306a36Sopenharmony_ci rpmsg_tty_driver->init_termios.c_lflag &= ~(ECHO | ICANON); 24862306a36Sopenharmony_ci rpmsg_tty_driver->init_termios.c_oflag &= ~(OPOST | ONLCR); 24962306a36Sopenharmony_ci 25062306a36Sopenharmony_ci tty_set_operations(rpmsg_tty_driver, &rpmsg_tty_ops); 25162306a36Sopenharmony_ci 25262306a36Sopenharmony_ci ret = tty_register_driver(rpmsg_tty_driver); 25362306a36Sopenharmony_ci if (ret < 0) { 25462306a36Sopenharmony_ci pr_err("Couldn't install driver: %d\n", ret); 25562306a36Sopenharmony_ci goto error_put; 25662306a36Sopenharmony_ci } 25762306a36Sopenharmony_ci 25862306a36Sopenharmony_ci ret = register_rpmsg_driver(&rpmsg_tty_rpmsg_drv); 25962306a36Sopenharmony_ci if (ret < 0) { 26062306a36Sopenharmony_ci pr_err("Couldn't register driver: %d\n", ret); 26162306a36Sopenharmony_ci goto error_unregister; 26262306a36Sopenharmony_ci } 26362306a36Sopenharmony_ci 26462306a36Sopenharmony_ci return 0; 26562306a36Sopenharmony_ci 26662306a36Sopenharmony_cierror_unregister: 26762306a36Sopenharmony_ci tty_unregister_driver(rpmsg_tty_driver); 26862306a36Sopenharmony_ci 26962306a36Sopenharmony_cierror_put: 27062306a36Sopenharmony_ci tty_driver_kref_put(rpmsg_tty_driver); 27162306a36Sopenharmony_ci 27262306a36Sopenharmony_ci return ret; 27362306a36Sopenharmony_ci} 27462306a36Sopenharmony_ci 27562306a36Sopenharmony_cistatic void __exit rpmsg_tty_exit(void) 27662306a36Sopenharmony_ci{ 27762306a36Sopenharmony_ci unregister_rpmsg_driver(&rpmsg_tty_rpmsg_drv); 27862306a36Sopenharmony_ci tty_unregister_driver(rpmsg_tty_driver); 27962306a36Sopenharmony_ci tty_driver_kref_put(rpmsg_tty_driver); 28062306a36Sopenharmony_ci idr_destroy(&tty_idr); 28162306a36Sopenharmony_ci} 28262306a36Sopenharmony_ci 28362306a36Sopenharmony_cimodule_init(rpmsg_tty_init); 28462306a36Sopenharmony_cimodule_exit(rpmsg_tty_exit); 28562306a36Sopenharmony_ci 28662306a36Sopenharmony_ciMODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>"); 28762306a36Sopenharmony_ciMODULE_DESCRIPTION("remote processor messaging tty driver"); 28862306a36Sopenharmony_ciMODULE_LICENSE("GPL v2"); 289