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- // SPDX-License-Identifier: GPL-2.0
- /*
- * Copyright (C) 2021 STMicroelectronics - All Rights Reserved
- *
- * The rpmsg tty driver implements serial communication on the RPMsg bus to makes
- * possible for user-space programs to send and receive rpmsg messages as a standard
- * tty protocol.
- *
- * The remote processor can instantiate a new tty by requesting a "rpmsg-tty" RPMsg service.
- * The "rpmsg-tty" service is directly used for data exchange. No flow control is implemented yet.
- */
- #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
- #include <linux/module.h>
- #include <linux/rpmsg.h>
- #include <linux/slab.h>
- #include <linux/tty.h>
- #include <linux/tty_flip.h>
- #define RPMSG_TTY_NAME "ttyRPMSG"
- #define MAX_TTY_RPMSG 32
- static DEFINE_IDR(tty_idr); /* tty instance id */
- static DEFINE_MUTEX(idr_lock); /* protects tty_idr */
- static struct tty_driver *rpmsg_tty_driver;
- struct rpmsg_tty_port {
- struct tty_port port; /* TTY port data */
- int id; /* TTY rpmsg index */
- struct rpmsg_device *rpdev; /* rpmsg device */
- };
- static int rpmsg_tty_cb(struct rpmsg_device *rpdev, void *data, int len, void *priv, u32 src)
- {
- struct rpmsg_tty_port *cport = dev_get_drvdata(&rpdev->dev);
- int copied;
- if (!len)
- return -EINVAL;
- copied = tty_insert_flip_string(&cport->port, data, len);
- if (copied != len)
- dev_err_ratelimited(&rpdev->dev, "Trunc buffer: available space is %d\n", copied);
- tty_flip_buffer_push(&cport->port);
- return 0;
- }
- static int rpmsg_tty_install(struct tty_driver *driver, struct tty_struct *tty)
- {
- struct rpmsg_tty_port *cport = idr_find(&tty_idr, tty->index);
- struct tty_port *port;
- tty->driver_data = cport;
- port = tty_port_get(&cport->port);
- return tty_port_install(port, driver, tty);
- }
- static void rpmsg_tty_cleanup(struct tty_struct *tty)
- {
- tty_port_put(tty->port);
- }
- static int rpmsg_tty_open(struct tty_struct *tty, struct file *filp)
- {
- return tty_port_open(tty->port, tty, filp);
- }
- static void rpmsg_tty_close(struct tty_struct *tty, struct file *filp)
- {
- return tty_port_close(tty->port, tty, filp);
- }
- static int rpmsg_tty_write(struct tty_struct *tty, const u8 *buf, int len)
- {
- struct rpmsg_tty_port *cport = tty->driver_data;
- struct rpmsg_device *rpdev;
- int msg_max_size, msg_size;
- int ret;
- rpdev = cport->rpdev;
- msg_max_size = rpmsg_get_mtu(rpdev->ept);
- if (msg_max_size < 0)
- return msg_max_size;
- msg_size = min(len, msg_max_size);
- /*
- * Use rpmsg_trysend instead of rpmsg_send to send the message so the caller is not
- * hung until a rpmsg buffer is available. In such case rpmsg_trysend returns -ENOMEM.
- */
- ret = rpmsg_trysend(rpdev->ept, (void *)buf, msg_size);
- if (ret) {
- dev_dbg_ratelimited(&rpdev->dev, "rpmsg_send failed: %d\n", ret);
- return ret;
- }
- return msg_size;
- }
- static unsigned int rpmsg_tty_write_room(struct tty_struct *tty)
- {
- struct rpmsg_tty_port *cport = tty->driver_data;
- int size;
- size = rpmsg_get_mtu(cport->rpdev->ept);
- if (size < 0)
- return 0;
- return size;
- }
- static void rpmsg_tty_hangup(struct tty_struct *tty)
- {
- tty_port_hangup(tty->port);
- }
- static const struct tty_operations rpmsg_tty_ops = {
- .install = rpmsg_tty_install,
- .open = rpmsg_tty_open,
- .close = rpmsg_tty_close,
- .write = rpmsg_tty_write,
- .write_room = rpmsg_tty_write_room,
- .hangup = rpmsg_tty_hangup,
- .cleanup = rpmsg_tty_cleanup,
- };
- static struct rpmsg_tty_port *rpmsg_tty_alloc_cport(void)
- {
- struct rpmsg_tty_port *cport;
- int ret;
- cport = kzalloc(sizeof(*cport), GFP_KERNEL);
- if (!cport)
- return ERR_PTR(-ENOMEM);
- mutex_lock(&idr_lock);
- ret = idr_alloc(&tty_idr, cport, 0, MAX_TTY_RPMSG, GFP_KERNEL);
- mutex_unlock(&idr_lock);
- if (ret < 0) {
- kfree(cport);
- return ERR_PTR(ret);
- }
- cport->id = ret;
- return cport;
- }
- static void rpmsg_tty_destruct_port(struct tty_port *port)
- {
- struct rpmsg_tty_port *cport = container_of(port, struct rpmsg_tty_port, port);
- mutex_lock(&idr_lock);
- idr_remove(&tty_idr, cport->id);
- mutex_unlock(&idr_lock);
- kfree(cport);
- }
- static const struct tty_port_operations rpmsg_tty_port_ops = {
- .destruct = rpmsg_tty_destruct_port,
- };
- static int rpmsg_tty_probe(struct rpmsg_device *rpdev)
- {
- struct rpmsg_tty_port *cport;
- struct device *dev = &rpdev->dev;
- struct device *tty_dev;
- int ret;
- cport = rpmsg_tty_alloc_cport();
- if (IS_ERR(cport))
- return dev_err_probe(dev, PTR_ERR(cport), "Failed to alloc tty port\n");
- tty_port_init(&cport->port);
- cport->port.ops = &rpmsg_tty_port_ops;
- tty_dev = tty_port_register_device(&cport->port, rpmsg_tty_driver,
- cport->id, dev);
- if (IS_ERR(tty_dev)) {
- ret = dev_err_probe(dev, PTR_ERR(tty_dev), "Failed to register tty port\n");
- tty_port_put(&cport->port);
- return ret;
- }
- cport->rpdev = rpdev;
- dev_set_drvdata(dev, cport);
- dev_dbg(dev, "New channel: 0x%x -> 0x%x: " RPMSG_TTY_NAME "%d\n",
- rpdev->src, rpdev->dst, cport->id);
- return 0;
- }
- static void rpmsg_tty_remove(struct rpmsg_device *rpdev)
- {
- struct rpmsg_tty_port *cport = dev_get_drvdata(&rpdev->dev);
- dev_dbg(&rpdev->dev, "Removing rpmsg tty device %d\n", cport->id);
- /* User hang up to release the tty */
- tty_port_tty_hangup(&cport->port, false);
- tty_unregister_device(rpmsg_tty_driver, cport->id);
- tty_port_put(&cport->port);
- }
- static struct rpmsg_device_id rpmsg_driver_tty_id_table[] = {
- { .name = "rpmsg-tty" },
- { },
- };
- MODULE_DEVICE_TABLE(rpmsg, rpmsg_driver_tty_id_table);
- static struct rpmsg_driver rpmsg_tty_rpmsg_drv = {
- .drv.name = KBUILD_MODNAME,
- .id_table = rpmsg_driver_tty_id_table,
- .probe = rpmsg_tty_probe,
- .callback = rpmsg_tty_cb,
- .remove = rpmsg_tty_remove,
- };
- static int __init rpmsg_tty_init(void)
- {
- int ret;
- rpmsg_tty_driver = tty_alloc_driver(MAX_TTY_RPMSG, TTY_DRIVER_REAL_RAW |
- TTY_DRIVER_DYNAMIC_DEV);
- if (IS_ERR(rpmsg_tty_driver))
- return PTR_ERR(rpmsg_tty_driver);
- rpmsg_tty_driver->driver_name = "rpmsg_tty";
- rpmsg_tty_driver->name = RPMSG_TTY_NAME;
- rpmsg_tty_driver->major = 0;
- rpmsg_tty_driver->type = TTY_DRIVER_TYPE_CONSOLE;
- /* Disable unused mode by default */
- rpmsg_tty_driver->init_termios = tty_std_termios;
- rpmsg_tty_driver->init_termios.c_lflag &= ~(ECHO | ICANON);
- rpmsg_tty_driver->init_termios.c_oflag &= ~(OPOST | ONLCR);
- tty_set_operations(rpmsg_tty_driver, &rpmsg_tty_ops);
- ret = tty_register_driver(rpmsg_tty_driver);
- if (ret < 0) {
- pr_err("Couldn't install driver: %d\n", ret);
- goto error_put;
- }
- ret = register_rpmsg_driver(&rpmsg_tty_rpmsg_drv);
- if (ret < 0) {
- pr_err("Couldn't register driver: %d\n", ret);
- goto error_unregister;
- }
- return 0;
- error_unregister:
- tty_unregister_driver(rpmsg_tty_driver);
- error_put:
- tty_driver_kref_put(rpmsg_tty_driver);
- return ret;
- }
- static void __exit rpmsg_tty_exit(void)
- {
- unregister_rpmsg_driver(&rpmsg_tty_rpmsg_drv);
- tty_unregister_driver(rpmsg_tty_driver);
- tty_driver_kref_put(rpmsg_tty_driver);
- idr_destroy(&tty_idr);
- }
- module_init(rpmsg_tty_init);
- module_exit(rpmsg_tty_exit);
- MODULE_AUTHOR("Arnaud Pouliquen <[email protected]>");
- MODULE_DESCRIPTION("remote processor messaging tty driver");
- MODULE_LICENSE("GPL v2");
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