// 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 ssize_t rpmsg_tty_write(struct tty_struct *tty, const u8 *buf,			       size_t 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_t(unsigned int, 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_obj(*cport);	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 <arnaud.pouliquen@foss.st.com>");MODULE_DESCRIPTION("remote processor messaging tty driver");MODULE_LICENSE("GPL v2");