Date:   Tue, 11 Oct 2016 09:46:40 +0200
From:   loic pallardy <loic.pallardy@...com>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Ohad Ben-Cohen <ohad@...ery.com>
CC:     Jonathan Corbet <corbet@....net>,
        Linus Walleij <linus.walleij@...aro.org>,
        Marek Novak <marek.novak@....com>,
        Matteo Sartori <matteo.sartori@...ab.it>,
        Michal Simek <monstr@...str.eu>, <linux-doc@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-remoteproc@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH 4/5] rpmsg: Driver for user space endpoint interface



On 10/08/2016 06:23 AM, Bjorn Andersson wrote:
> This driver allows rpmsg instances to expose access to rpmsg endpoints
> to user space processes. It provides a control interface, allowing
> userspace to export endpoints and an endpoint interface for each exposed
> endpoint.
>
> The implementation is based on prior art by Texas Instrument, Google,
> PetaLogix and was derived from a FreeRTOS performance statistics driver
> written by Michal Simek.
>
> The control interface provides a "create endpoint" ioctl, which is fed a
> name, source and destination address. The three values are used to
> create the endpoint, in a backend-specific way, and a rpmsg endpoint
> device is created - with the three parameters are available in sysfs for
> udev usage.
>
> E.g. to create an endpoint device for one of the Qualcomm SMD channel
> related to DIAG one would issue:
>
>   struct rpmsg_endpoint_info info = { "DIAG_CNTL", 0, 0 };
>   int fd = open("/dev/rpmsg_ctrl0", O_RDWR);
>   ioctl(fd, RPMSG_CREATE_EPT_IOCTL, &info);
>
> Each created endpoint device shows up as an individual character device
> in /dev, allowing permission to be controlled on a per-endpoint basis.
> The rpmsg endpoint will be created and destroyed following the opening
> and closing of the endpoint device, allowing rpmsg backends to open and
> close the physical channel, if supported by the wire protocol.
>
> Cc: Marek Novak <marek.novak@....com>
> Cc: Matteo Sartori <matteo.sartori@...ab.it>
> Cc: Michal Simek <monstr@...str.eu>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
>  Documentation/ioctl/ioctl-number.txt |   1 +
>  drivers/rpmsg/Makefile               |   2 +-
>  drivers/rpmsg/rpmsg_char.c           | 576 +++++++++++++++++++++++++++++++++++
>  drivers/rpmsg/rpmsg_internal.h       |   2 +
>  include/uapi/linux/rpmsg.h           |  35 +++
>  5 files changed, 615 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/rpmsg/rpmsg_char.c
>  create mode 100644 include/uapi/linux/rpmsg.h
>
> diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt
> index 81c7f2bb7daf..08244bea5048 100644
> --- a/Documentation/ioctl/ioctl-number.txt
> +++ b/Documentation/ioctl/ioctl-number.txt
> @@ -321,6 +321,7 @@ Code  Seq#(hex)	Include File		Comments
>  0xB1	00-1F	PPPoX			<mailto:mostrows@...x.uwaterloo.ca>
>  0xB3	00	linux/mmc/ioctl.h
>  0xB4	00-0F	linux/gpio.h		<mailto:linux-gpio@...r.kernel.org>
> +0xB5	00-0F	uapi/linux/rpmsg.h	<mailto:linux-remoteproc@...r.kernel.org>
>  0xC0	00-0F	linux/usb/iowarrior.h
>  0xCA	00-0F	uapi/misc/cxl.h
>  0xCA	80-8F	uapi/scsi/cxlflash_ioctl.h
> diff --git a/drivers/rpmsg/Makefile b/drivers/rpmsg/Makefile
> index ae9c9132cf76..5daf1209b77d 100644
> --- a/drivers/rpmsg/Makefile
> +++ b/drivers/rpmsg/Makefile
> @@ -1,3 +1,3 @@
> -obj-$(CONFIG_RPMSG)		+= rpmsg_core.o
> +obj-$(CONFIG_RPMSG)		+= rpmsg_core.o rpmsg_char.o
Hi Bjorn,

Could you please create a dedicated Kconfig entry for this new interface?
This should be an option like i2C_dev.

Regards,
Loic


>  obj-$(CONFIG_RPMSG_QCOM_SMD)	+= qcom_smd.o
>  obj-$(CONFIG_RPMSG_VIRTIO)	+= virtio_rpmsg_bus.o
> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
> new file mode 100644
> index 000000000000..a398a63e8d44
> --- /dev/null
> +++ b/drivers/rpmsg/rpmsg_char.c
> @@ -0,0 +1,576 @@
> +/*
> + * Copyright (c) 2016, Linaro Ltd.
> + * Copyright (c) 2012, Michal Simek <monstr@...str.eu>
> + * Copyright (c) 2012, PetaLogix
> + * Copyright (c) 2011, Texas Instruments, Inc.
> + * Copyright (c) 2011, Google, Inc.
> + *
> + * Based on rpmsg performance statistics driver by Michal Simek, which in turn
> + * was based on TI & Google OMX rpmsg driver.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 and
> + * only version 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +#include <linux/cdev.h>
> +#include <linux/device.h>
> +#include <linux/fs.h>
> +#include <linux/idr.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/rpmsg.h>
> +#include <linux/skbuff.h>
> +#include <linux/slab.h>
> +#include <linux/uaccess.h>
> +#include <uapi/linux/rpmsg.h>
> +
> +#include "rpmsg_internal.h"
> +
> +#define RPMSG_DEV_MAX	256
> +
> +static dev_t rpmsg_major;
> +static struct class *rpmsg_class;
> +
> +static DEFINE_IDA(rpmsg_ctrl_ida);
> +static DEFINE_IDA(rpmsg_ept_ida);
> +static DEFINE_IDA(rpmsg_minor_ida);
> +
> +#define dev_to_eptdev(dev) container_of(dev, struct rpmsg_eptdev, dev)
> +#define cdev_to_eptdev(i_cdev) container_of(i_cdev, struct rpmsg_eptdev, cdev)
> +
> +#define dev_to_ctrldev(dev) container_of(dev, struct rpmsg_ctrldev, dev)
> +#define cdev_to_ctrldev(i_cdev) container_of(i_cdev, struct rpmsg_ctrldev, cdev)
> +
> +struct rpmsg_ctrldev {
> +	struct rpmsg_device *rpdev;
> +	struct cdev cdev;
> +	struct device dev;
> +};
> +
> +struct rpmsg_eptdev {
> +	struct device dev;
> +	struct cdev cdev;
> +
> +	struct rpmsg_device *rpdev;
> +	struct rpmsg_channel_info chinfo;
> +
> +	struct mutex ept_lock;
> +	struct rpmsg_endpoint *ept;
> +
> +	spinlock_t queue_lock;
> +	struct sk_buff_head queue;
> +	wait_queue_head_t readq;
> +};
> +
> +static int rpmsg_eptdev_destroy(struct rpmsg_eptdev *eptdev);
> +
> +
> +static int rpmsg_cdev_register(struct device *dev,
> +			       struct cdev *cdev,
> +			       const struct file_operations *fops,
> +			       dev_t *assigned_devt)
> +{
> +	dev_t devt;
> +	int ret;
> +
> +	ret = ida_simple_get(&rpmsg_minor_ida, 0, 0, GFP_KERNEL);
> +	if (ret < 0)
> +		return ret;
> +
> +	devt = MKDEV(MAJOR(rpmsg_major), ret);
> +
> +	cdev_init(cdev, fops);
> +	cdev->owner = THIS_MODULE;
> +	ret = cdev_add(cdev, devt, 1);
> +	if (ret < 0) {
> +		dev_err(dev, "cdev_add failed: %d\n", ret);
> +		ida_simple_remove(&rpmsg_minor_ida, MINOR(devt));
> +		return ret;
> +	}
> +
> +	*assigned_devt = devt;
> +	return 0;
> +}
> +
> +static int rpmsg_ept_cb(struct rpmsg_device *rpdev, void *buf, int len,
> +			void *priv, u32 addr)
> +{
> +	struct rpmsg_eptdev *eptdev = priv;
> +	struct sk_buff *skb;
> +
> +	skb = alloc_skb(len, GFP_ATOMIC);
> +	if (!skb)
> +		return -ENOMEM;
> +
> +	memcpy(skb_put(skb, len), buf, len);
> +
> +	spin_lock(&eptdev->queue_lock);
> +	skb_queue_tail(&eptdev->queue, skb);
> +	spin_unlock(&eptdev->queue_lock);
> +
> +	/* wake up any blocking processes, waiting for new data */
> +	wake_up_interruptible(&eptdev->readq);
> +
> +	return 0;
> +}
> +
> +static int rpmsg_eptdev_open(struct inode *inode, struct file *filp)
> +{
> +	struct rpmsg_eptdev *eptdev = cdev_to_eptdev(inode->i_cdev);
> +	struct rpmsg_endpoint *ept;
> +	struct rpmsg_device *rpdev = eptdev->rpdev;
> +	struct device *dev = &eptdev->dev;
> +
> +	get_device(dev);
> +
> +	ept = rpmsg_create_ept(rpdev, rpmsg_ept_cb, eptdev, eptdev->chinfo);
> +	if (!ept) {
> +		dev_err(dev, "failed to open %s\n", eptdev->chinfo.name);
> +		put_device(dev);
> +		return -EINVAL;
> +	}
> +
> +	eptdev->ept = ept;
> +	filp->private_data = eptdev;
> +
> +	return 0;
> +}
> +
> +static int rpmsg_eptdev_release(struct inode *inode, struct file *filp)
> +{
> +	struct rpmsg_eptdev *eptdev = cdev_to_eptdev(inode->i_cdev);
> +	struct device *dev = &eptdev->dev;
> +	struct sk_buff *skb;
> +
> +	/* Close the endpoint, if it's not already destroyed by the parent */
> +	if (eptdev->ept)
> +		rpmsg_destroy_ept(eptdev->ept);
> +
> +	/* Discard all SKBs */
> +	while (!skb_queue_empty(&eptdev->queue)) {
> +		skb = skb_dequeue(&eptdev->queue);
> +		kfree_skb(skb);
> +	}
> +
> +	put_device(dev);
> +
> +	return 0;
> +}
> +
> +static long rpmsg_eptdev_ioctl(struct file *fp, unsigned int cmd,
> +			       unsigned long arg)
> +{
> +	struct rpmsg_eptdev *eptdev = fp->private_data;
> +
> +	if (cmd != RPMSG_DESTROY_EPT_IOCTL)
> +		return -EINVAL;
> +
> +	return rpmsg_eptdev_destroy(eptdev);
> +}
> +
> +static ssize_t rpmsg_eptdev_read(struct file *filp, char __user *buf,
> +				 size_t count, loff_t *f_pos)
> +{
> +	struct rpmsg_eptdev *eptdev = filp->private_data;
> +	unsigned long flags;
> +	struct sk_buff *skb;
> +	int use;
> +
> +	spin_lock_irqsave(&eptdev->queue_lock, flags);
> +
> +	/* Wait for data in the queue */
> +	if (skb_queue_empty(&eptdev->queue)) {
> +		spin_unlock_irqrestore(&eptdev->queue_lock, flags);
> +
> +		if (filp->f_flags & O_NONBLOCK)
> +			return -EAGAIN;
> +
> +		/* Wait until we get data or the endpoint goes away */
> +		if (wait_event_interruptible(eptdev->readq,
> +					     !skb_queue_empty(&eptdev->queue) ||
> +					     !eptdev->ept))
> +			return -ERESTARTSYS;
> +
> +		/* We lost the endpoint while waiting */
> +		if (!eptdev->ept)
> +			return -EPIPE;
> +
> +		spin_lock_irqsave(&eptdev->queue_lock, flags);
> +	}
> +
> +	skb = skb_dequeue(&eptdev->queue);
> +	if (!skb)
> +		return -EFAULT;
> +
> +	spin_unlock_irqrestore(&eptdev->queue_lock, flags);
> +
> +	use = min_t(size_t, count, skb->len);
> +	if (copy_to_user(buf, skb->data, use))
> +		use = -EFAULT;
> +
> +	kfree_skb(skb);
> +
> +	return use;
> +}
> +
> +static ssize_t rpmsg_eptdev_write(struct file *filp, const char __user *buf,
> +				  size_t count, loff_t *f_pos)
> +{
> +	struct rpmsg_eptdev *eptdev = filp->private_data;
> +	void *kbuf;
> +	int ret;
> +
> +	kbuf = kzalloc(count, GFP_KERNEL);
> +	if (!kbuf)
> +		return -ENOMEM;
> +
> +	if (copy_from_user(kbuf, buf, count)) {
> +		ret = -EFAULT;
> +		goto free_kbuf;
> +	}
> +
> +	if (mutex_lock_interruptible(&eptdev->ept_lock)) {
> +		ret = -ERESTARTSYS;
> +		goto free_kbuf;
> +	}
> +
> +	if (!eptdev->ept) {
> +		ret = -EPIPE;
> +		goto unlock_eptdev;
> +	}
> +
> +	if (filp->f_flags & O_NONBLOCK)
> +		ret = rpmsg_trysend(eptdev->ept, kbuf, count);
> +	else
> +		ret = rpmsg_send(eptdev->ept, kbuf, count);
> +
> +unlock_eptdev:
> +	mutex_unlock(&eptdev->ept_lock);
> +
> +free_kbuf:
> +	kfree(kbuf);
> +	return ret;
> +}
> +
> +static const struct file_operations rpmsg_eptdev_fops = {
> +	.owner = THIS_MODULE,
> +	.open = rpmsg_eptdev_open,
> +	.release = rpmsg_eptdev_release,
> +	.read = rpmsg_eptdev_read,
> +	.write = rpmsg_eptdev_write,
> +	.unlocked_ioctl = rpmsg_eptdev_ioctl,
> +};
> +
> +static ssize_t name_show(struct device *dev, struct device_attribute *attr,
> +			 char *buf)
> +{
> +	struct rpmsg_eptdev *eptdev = dev_get_drvdata(dev);
> +
> +	return sprintf(buf, "%s\n", eptdev->chinfo.name);
> +}
> +static DEVICE_ATTR_RO(name);
> +
> +static ssize_t src_show(struct device *dev, struct device_attribute *attr,
> +			 char *buf)
> +{
> +	struct rpmsg_eptdev *eptdev = dev_get_drvdata(dev);
> +
> +	return sprintf(buf, "%d\n", eptdev->chinfo.src);
> +}
> +static DEVICE_ATTR_RO(src);
> +
> +static ssize_t dst_show(struct device *dev, struct device_attribute *attr,
> +			 char *buf)
> +{
> +	struct rpmsg_eptdev *eptdev = dev_get_drvdata(dev);
> +
> +	return sprintf(buf, "%d\n", eptdev->chinfo.dst);
> +}
> +static DEVICE_ATTR_RO(dst);
> +
> +static struct attribute *rpmsg_eptdev_attrs[] = {
> +	&dev_attr_name.attr,
> +	&dev_attr_src.attr,
> +	&dev_attr_dst.attr,
> +	NULL
> +};
> +ATTRIBUTE_GROUPS(rpmsg_eptdev);
> +
> +static void rpmsg_eptdev_release_device(struct device *dev)
> +{
> +	struct rpmsg_eptdev *eptdev = dev_to_eptdev(dev);
> +
> +	ida_simple_remove(&rpmsg_minor_ida, MINOR(eptdev->dev.devt));
> +	kfree(eptdev);
> +}
> +
> +static int rpmsg_eptdev_create(struct rpmsg_ctrldev *ctrldev,
> +			       struct rpmsg_channel_info chinfo)
> +{
> +	struct rpmsg_device *rpdev = ctrldev->rpdev;
> +	struct rpmsg_eptdev *eptdev;
> +	struct device *dev;
> +	int ret;
> +	int id;
> +
> +	eptdev = kzalloc(sizeof(*eptdev), GFP_KERNEL);
> +	if (!eptdev)
> +		return -ENOMEM;
> +
> +	eptdev->rpdev = rpdev;
> +	eptdev->chinfo = chinfo;
> +
> +	mutex_init(&eptdev->ept_lock);
> +	spin_lock_init(&eptdev->queue_lock);
> +	skb_queue_head_init(&eptdev->queue);
> +	init_waitqueue_head(&eptdev->readq);
> +
> +	id = ida_simple_get(&rpmsg_ept_ida, 0, 0, GFP_KERNEL);
> +	if (id < 0) {
> +		kfree(eptdev);
> +		return id;
> +	}
> +
> +	dev = &eptdev->dev;
> +	device_initialize(dev);
> +	dev->class = rpmsg_class;
> +	dev->id = id;
> +	dev->parent = &ctrldev->dev;
> +	dev->release = rpmsg_eptdev_release_device;
> +	dev->groups = rpmsg_eptdev_groups;
> +	dev_set_name(dev, "rpmsg%d", id);
> +	dev_set_drvdata(dev, eptdev);
> +
> +	ret = rpmsg_cdev_register(dev, &eptdev->cdev,
> +				  &rpmsg_eptdev_fops, &dev->devt);
> +	if (ret) {
> +		dev_err(dev, "cdev_add failed: %d\n", ret);
> +		goto out;
> +	}
> +
> +	ret = device_add(dev);
> +	if (ret) {
> +		dev_err(dev, "device_register failed: %d\n", ret);
> +		goto out;
> +	}
> +
> +out:
> +	if (ret < 0)
> +		put_device(dev);
> +
> +	return ret;
> +}
> +
> +static int rpmsg_eptdev_destroy(struct rpmsg_eptdev *eptdev)
> +{
> +	struct rpmsg_endpoint *ept = eptdev->ept;
> +
> +	mutex_lock(&eptdev->ept_lock);
> +	eptdev->ept = NULL;
> +	mutex_unlock(&eptdev->ept_lock);
> +
> +	rpmsg_destroy_ept(ept);
> +
> +	/* wake up any blocking processes */
> +	wake_up_interruptible(&eptdev->readq);
> +
> +	cdev_del(&eptdev->cdev);
> +	device_del(&eptdev->dev);
> +	put_device(&eptdev->dev);
> +
> +	return 0;
> +}
> +
> +static int rpmsg_ctrldev_open(struct inode *inode, struct file *filp)
> +{
> +	struct rpmsg_ctrldev *ctrldev = cdev_to_ctrldev(inode->i_cdev);
> +
> +	get_device(&ctrldev->rpdev->dev);
> +	filp->private_data = ctrldev;
> +
> +	return 0;
> +}
> +
> +static int rpmsg_ctrldev_release(struct inode *inode, struct file *filp)
> +{
> +	struct rpmsg_ctrldev *ctrldev = cdev_to_ctrldev(inode->i_cdev);
> +
> +	put_device(&ctrldev->rpdev->dev);
> +
> +	return 0;
> +}
> +
> +static long rpmsg_ctrldev_ioctl(struct file *fp, unsigned int cmd,
> +				unsigned long arg)
> +{
> +	struct rpmsg_ctrldev *ctrldev = fp->private_data;
> +	void __user *argp = (void __user *)arg;
> +	struct rpmsg_endpoint_info eptinfo;
> +	struct rpmsg_channel_info chinfo;
> +
> +	if (cmd != RPMSG_CREATE_EPT_IOCTL)
> +		return -EINVAL;
> +
> +	if (copy_from_user(&eptinfo, argp, sizeof(eptinfo)))
> +		return -EFAULT;
> +
> +	memcpy(chinfo.name, eptinfo.name, RPMSG_NAME_SIZE);
> +	chinfo.name[RPMSG_NAME_SIZE-1] = '\0';
> +	chinfo.src = eptinfo.src;
> +	chinfo.dst = eptinfo.dst;
> +
> +	return rpmsg_eptdev_create(ctrldev, chinfo);
> +};
> +
> +static const struct file_operations rpmsg_ctrldev_fops = {
> +	.owner = THIS_MODULE,
> +	.open = rpmsg_ctrldev_open,
> +	.release = rpmsg_ctrldev_release,
> +	.unlocked_ioctl = rpmsg_ctrldev_ioctl,
> +};
> +
> +static void rpmsg_chrdev_release_device(struct device *dev)
> +{
> +	struct rpmsg_ctrldev *ctrldev = dev_to_ctrldev(dev);
> +
> +	ida_simple_remove(&rpmsg_ctrl_ida, MINOR(dev->devt));
> +	cdev_del(&ctrldev->cdev);
> +	kfree(ctrldev);
> +}
> +
> +static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
> +{
> +	struct rpmsg_ctrldev *ctrldev;
> +	struct device *dev;
> +	int ret;
> +	int id;
> +
> +	ctrldev = kzalloc(sizeof(*ctrldev), GFP_KERNEL);
> +	if (!ctrldev)
> +		return -ENOMEM;
> +
> +	dev = &ctrldev->dev;
> +
> +	ctrldev->rpdev = rpdev;
> +
> +	id = ida_simple_get(&rpmsg_ctrl_ida, 0, 0, GFP_KERNEL);
> +	if (id < 0) {
> +		kfree(ctrldev);
> +		return id;
> +	}
> +
> +	device_initialize(dev);
> +	dev->parent = &rpdev->dev;
> +	dev->class = rpmsg_class;
> +	dev->release = rpmsg_chrdev_release_device;
> +	dev_set_name(&ctrldev->dev, "rpmsg_ctrl%d", id);
> +
> +	ret = rpmsg_cdev_register(dev, &ctrldev->cdev,
> +				  &rpmsg_ctrldev_fops, &dev->devt);
> +	if (ret < 0) {
> +		put_device(dev);
> +		return ret;
> +	}
> +
> +	ret = device_add(dev);
> +	if (ret) {
> +		dev_err(&rpdev->dev, "device_register failed: %d\n", ret);
> +		put_device(dev);
> +	}
> +
> +	dev_set_drvdata(&rpdev->dev, ctrldev);
> +
> +	return ret;
> +}
> +
> +static int _rpmsg_eptdev_destroy(struct device *dev, void *data)
> +{
> +	struct rpmsg_eptdev *eptdev = dev_to_eptdev(dev);
> +
> +	return rpmsg_eptdev_destroy(eptdev);
> +}
> +
> +static void rpmsg_chrdev_remove(struct rpmsg_device *rpdev)
> +{
> +	struct rpmsg_ctrldev *ctrldev = dev_get_drvdata(&rpdev->dev);
> +	int ret;
> +
> +	/* Destroy all endpoints */
> +	ret = device_for_each_child(&ctrldev->dev, NULL, _rpmsg_eptdev_destroy);
> +	if (ret)
> +		dev_warn(&rpdev->dev, "failed to nuke endpoints: %d\n", ret);
> +
> +	device_del(&ctrldev->dev);
> +	put_device(&ctrldev->dev);
> +}
> +
> +static struct rpmsg_driver rpmsg_chrdev_driver = {
> +	.probe = rpmsg_chrdev_probe,
> +	.remove = rpmsg_chrdev_remove,
> +	.drv = {
> +		.name = "rpmsg_chrdev",
> +	},
> +};
> +
> +/**
> + * rpmsg_chrdev_register_device() - register chrdev device based on rpdev
> + * @rpdev:	prepared rpdev to be used for creating endpoints
> + *
> + * This function wraps rpmsg_register_device() preparing the rpdev for use as
> + * basis for the rpmsg chrdev.
> + */
> +int rpmsg_chrdev_register_device(struct rpmsg_device *rpdev)
> +{
> +	strcpy(rpdev->id.name, "rpmsg_chrdev");
> +	rpdev->driver_override = "rpmsg_chrdev";
> +
> +	return rpmsg_register_device(rpdev);
> +}
> +EXPORT_SYMBOL(rpmsg_chrdev_register_device);
> +
> +static int rpmsg_char_init(void)
> +{
> +	int ret;
> +
> +	ret = alloc_chrdev_region(&rpmsg_major, 0, RPMSG_DEV_MAX, "rpmsg");
> +	if (ret < 0) {
> +		pr_err("rpmsg: failed to allocate char dev region\n");
> +		return ret;
> +	}
> +
> +	rpmsg_class = class_create(THIS_MODULE, "rpmsg");
> +	if (IS_ERR(rpmsg_class)) {
> +		pr_err("failed to create rpmsg class\n");
> +		ret = PTR_ERR(rpmsg_class);
> +		goto unregister_chrdev;
> +	}
> +
> +	ret = register_rpmsg_driver(&rpmsg_chrdev_driver);
> +	if (ret < 0) {
> +		pr_err("rpmsgchr: failed to register rpmsg driver\n");
> +		goto destroy_class;
> +	}
> +
> +	return 0;
> +
> +destroy_class:
> +	class_destroy(rpmsg_class);
> +
> +unregister_chrdev:
> +	unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
> +
> +	return ret;
> +}
> +postcore_initcall(rpmsg_char_init);
> +
> +static void rpmsg_chrdev_exit(void)
> +{
> +	unregister_rpmsg_driver(&rpmsg_chrdev_driver);
> +	unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
> +}
> +module_exit(rpmsg_chrdev_exit);
> diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
> index 8075a20f919b..53d300eacc1c 100644
> --- a/drivers/rpmsg/rpmsg_internal.h
> +++ b/drivers/rpmsg/rpmsg_internal.h
> @@ -79,4 +79,6 @@ int rpmsg_unregister_device(struct device *parent,
>  struct device *rpmsg_find_device(struct device *parent,
>  				 struct rpmsg_channel_info *chinfo);
>
> +int rpmsg_chrdev_register_device(struct rpmsg_device *rpdev);
> +
>  #endif
> diff --git a/include/uapi/linux/rpmsg.h b/include/uapi/linux/rpmsg.h
> new file mode 100644
> index 000000000000..dedc226e0d3f
> --- /dev/null
> +++ b/include/uapi/linux/rpmsg.h
> @@ -0,0 +1,35 @@
> +/*
> + * Copyright (c) 2016, Linaro Ltd.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 and
> + * only version 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef _UAPI_RPMSG_H_
> +#define _UAPI_RPMSG_H_
> +
> +#include <linux/ioctl.h>
> +#include <linux/types.h>
> +
> +/**
> + * struct rpmsg_endpoint_info - endpoint info representation
> + * @name: name of service
> + * @src: local address
> + * @dst: destination address
> + */
> +struct rpmsg_endpoint_info {
> +	char name[32];
> +	__u32 src;
> +	__u32 dst;
> +};
> +
> +#define RPMSG_CREATE_EPT_IOCTL	_IOW(0xb5, 0x1, struct rpmsg_endpoint_info)
> +#define RPMSG_DESTROY_EPT_IOCTL	_IO(0xb5, 0x2)
> +
> +#endif
>

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