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