linux/drivers/rpmsg/rpmsg_char.c
Arnaud Pouliquen bc69d10665 rpmsg: char: Introduce the "rpmsg-raw" channel
For the rpmsg virtio backend, the current implementation of the rpmsg char
only allows to instantiate static(i.e. prefixed source and destination
addresses) end points, and only on the Linux user space initiative.

This patch defines the "rpmsg-raw" channel and registers it to the rpmsg bus.
This registration allows:
- To create the channel at the initiative of the remote processor
  relying on the name service announcement mechanism. In other words the
  /dev/rpmsgX interface is instantiate by the remote processor.
- To use the channel object instead of the endpoint, thus preventing the
  user space from having the knowledge of the remote processor's
  endpoint addresses.
- To rely on udev to be inform when a /dev/rpmsgX is created on remote
  processor request, indicating that the remote processor is ready to
  communicate.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220124102524.295783-11-arnaud.pouliquen@foss.st.com
2022-03-13 11:49:53 -05:00

516 lines
12 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2022, STMicroelectronics
* Copyright (c) 2016, Linaro Ltd.
* Copyright (c) 2012, Michal Simek <monstr@monstr.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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#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/poll.h>
#include <linux/rpmsg.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <uapi/linux/rpmsg.h>
#include "rpmsg_char.h"
#include "rpmsg_internal.h"
#define RPMSG_DEV_MAX (MINORMASK + 1)
static dev_t rpmsg_major;
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)
/**
* struct rpmsg_eptdev - endpoint device context
* @dev: endpoint device
* @cdev: cdev for the endpoint device
* @rpdev: underlaying rpmsg device
* @chinfo: info used to open the endpoint
* @ept_lock: synchronization of @ept modifications
* @ept: rpmsg endpoint reference, when open
* @queue_lock: synchronization of @queue operations
* @queue: incoming message queue
* @readq: wait object for incoming queue
* @default_ept: set to channel default endpoint if the default endpoint should be re-used
* on device open to prevent endpoint address update.
*/
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;
struct rpmsg_endpoint *default_ept;
spinlock_t queue_lock;
struct sk_buff_head queue;
wait_queue_head_t readq;
};
int rpmsg_chrdev_eptdev_destroy(struct device *dev, void *data)
{
struct rpmsg_eptdev *eptdev = dev_to_eptdev(dev);
mutex_lock(&eptdev->ept_lock);
if (eptdev->ept) {
rpmsg_destroy_ept(eptdev->ept);
eptdev->ept = NULL;
}
mutex_unlock(&eptdev->ept_lock);
/* wake up any blocked readers */
wake_up_interruptible(&eptdev->readq);
cdev_device_del(&eptdev->cdev, &eptdev->dev);
put_device(&eptdev->dev);
return 0;
}
EXPORT_SYMBOL(rpmsg_chrdev_eptdev_destroy);
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;
skb_put_data(skb, 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;
if (eptdev->ept)
return -EBUSY;
get_device(dev);
/*
* If the default_ept is set, the rpmsg device default endpoint is used.
* Else a new endpoint is created on open that will be destroyed on release.
*/
if (eptdev->default_ept)
ept = eptdev->default_ept;
else
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;
/* Close the endpoint, if it's not already destroyed by the parent */
mutex_lock(&eptdev->ept_lock);
if (eptdev->ept) {
if (!eptdev->default_ept)
rpmsg_destroy_ept(eptdev->ept);
eptdev->ept = NULL;
}
mutex_unlock(&eptdev->ept_lock);
/* Discard all SKBs */
skb_queue_purge(&eptdev->queue);
put_device(dev);
return 0;
}
static ssize_t rpmsg_eptdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct file *filp = iocb->ki_filp;
struct rpmsg_eptdev *eptdev = filp->private_data;
unsigned long flags;
struct sk_buff *skb;
int use;
if (!eptdev->ept)
return -EPIPE;
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);
spin_unlock_irqrestore(&eptdev->queue_lock, flags);
if (!skb)
return -EFAULT;
use = min_t(size_t, iov_iter_count(to), skb->len);
if (copy_to_iter(skb->data, use, to) != use)
use = -EFAULT;
kfree_skb(skb);
return use;
}
static ssize_t rpmsg_eptdev_write_iter(struct kiocb *iocb,
struct iov_iter *from)
{
struct file *filp = iocb->ki_filp;
struct rpmsg_eptdev *eptdev = filp->private_data;
size_t len = iov_iter_count(from);
void *kbuf;
int ret;
kbuf = kzalloc(len, GFP_KERNEL);
if (!kbuf)
return -ENOMEM;
if (!copy_from_iter_full(kbuf, len, from)) {
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_trysendto(eptdev->ept, kbuf, len, eptdev->chinfo.dst);
if (ret == -ENOMEM)
ret = -EAGAIN;
} else {
ret = rpmsg_sendto(eptdev->ept, kbuf, len, eptdev->chinfo.dst);
}
unlock_eptdev:
mutex_unlock(&eptdev->ept_lock);
free_kbuf:
kfree(kbuf);
return ret < 0 ? ret : len;
}
static __poll_t rpmsg_eptdev_poll(struct file *filp, poll_table *wait)
{
struct rpmsg_eptdev *eptdev = filp->private_data;
__poll_t mask = 0;
if (!eptdev->ept)
return EPOLLERR;
poll_wait(filp, &eptdev->readq, wait);
if (!skb_queue_empty(&eptdev->queue))
mask |= EPOLLIN | EPOLLRDNORM;
mask |= rpmsg_poll(eptdev->ept, filp, wait);
return mask;
}
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;
/* Don't allow to destroy a default endpoint. */
if (eptdev->default_ept)
return -EINVAL;
return rpmsg_chrdev_eptdev_destroy(&eptdev->dev, NULL);
}
static const struct file_operations rpmsg_eptdev_fops = {
.owner = THIS_MODULE,
.open = rpmsg_eptdev_open,
.release = rpmsg_eptdev_release,
.read_iter = rpmsg_eptdev_read_iter,
.write_iter = rpmsg_eptdev_write_iter,
.poll = rpmsg_eptdev_poll,
.unlocked_ioctl = rpmsg_eptdev_ioctl,
.compat_ioctl = compat_ptr_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_ept_ida, dev->id);
ida_simple_remove(&rpmsg_minor_ida, MINOR(eptdev->dev.devt));
kfree(eptdev);
}
static struct rpmsg_eptdev *rpmsg_chrdev_eptdev_alloc(struct rpmsg_device *rpdev,
struct device *parent)
{
struct rpmsg_eptdev *eptdev;
struct device *dev;
eptdev = kzalloc(sizeof(*eptdev), GFP_KERNEL);
if (!eptdev)
return ERR_PTR(-ENOMEM);
dev = &eptdev->dev;
eptdev->rpdev = rpdev;
mutex_init(&eptdev->ept_lock);
spin_lock_init(&eptdev->queue_lock);
skb_queue_head_init(&eptdev->queue);
init_waitqueue_head(&eptdev->readq);
device_initialize(dev);
dev->class = rpmsg_class;
dev->parent = parent;
dev->groups = rpmsg_eptdev_groups;
dev_set_drvdata(dev, eptdev);
cdev_init(&eptdev->cdev, &rpmsg_eptdev_fops);
eptdev->cdev.owner = THIS_MODULE;
return eptdev;
}
static int rpmsg_chrdev_eptdev_add(struct rpmsg_eptdev *eptdev, struct rpmsg_channel_info chinfo)
{
struct device *dev = &eptdev->dev;
int ret;
eptdev->chinfo = chinfo;
ret = ida_simple_get(&rpmsg_minor_ida, 0, RPMSG_DEV_MAX, GFP_KERNEL);
if (ret < 0)
goto free_eptdev;
dev->devt = MKDEV(MAJOR(rpmsg_major), ret);
ret = ida_simple_get(&rpmsg_ept_ida, 0, 0, GFP_KERNEL);
if (ret < 0)
goto free_minor_ida;
dev->id = ret;
dev_set_name(dev, "rpmsg%d", ret);
ret = cdev_device_add(&eptdev->cdev, &eptdev->dev);
if (ret)
goto free_ept_ida;
/* We can now rely on the release function for cleanup */
dev->release = rpmsg_eptdev_release_device;
return ret;
free_ept_ida:
ida_simple_remove(&rpmsg_ept_ida, dev->id);
free_minor_ida:
ida_simple_remove(&rpmsg_minor_ida, MINOR(dev->devt));
free_eptdev:
put_device(dev);
kfree(eptdev);
return ret;
}
int rpmsg_chrdev_eptdev_create(struct rpmsg_device *rpdev, struct device *parent,
struct rpmsg_channel_info chinfo)
{
struct rpmsg_eptdev *eptdev;
int ret;
eptdev = rpmsg_chrdev_eptdev_alloc(rpdev, parent);
if (IS_ERR(eptdev))
return PTR_ERR(eptdev);
ret = rpmsg_chrdev_eptdev_add(eptdev, chinfo);
return ret;
}
EXPORT_SYMBOL(rpmsg_chrdev_eptdev_create);
static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
{
struct rpmsg_channel_info chinfo;
struct rpmsg_eptdev *eptdev;
struct device *dev = &rpdev->dev;
memcpy(chinfo.name, rpdev->id.name, RPMSG_NAME_SIZE);
chinfo.src = rpdev->src;
chinfo.dst = rpdev->dst;
eptdev = rpmsg_chrdev_eptdev_alloc(rpdev, dev);
if (IS_ERR(eptdev))
return PTR_ERR(eptdev);
/* Set the default_ept to the rpmsg device endpoint */
eptdev->default_ept = rpdev->ept;
/*
* The rpmsg_ept_cb uses *priv parameter to get its rpmsg_eptdev context.
* Storedit in default_ept *priv field.
*/
eptdev->default_ept->priv = eptdev;
return rpmsg_chrdev_eptdev_add(eptdev, chinfo);
}
static void rpmsg_chrdev_remove(struct rpmsg_device *rpdev)
{
int ret;
ret = device_for_each_child(&rpdev->dev, NULL, rpmsg_chrdev_eptdev_destroy);
if (ret)
dev_warn(&rpdev->dev, "failed to destroy endpoints: %d\n", ret);
}
static struct rpmsg_device_id rpmsg_chrdev_id_table[] = {
{ .name = "rpmsg-raw" },
{ },
};
static struct rpmsg_driver rpmsg_chrdev_driver = {
.probe = rpmsg_chrdev_probe,
.remove = rpmsg_chrdev_remove,
.callback = rpmsg_ept_cb,
.id_table = rpmsg_chrdev_id_table,
.drv.name = "rpmsg_chrdev",
};
static int rpmsg_chrdev_init(void)
{
int ret;
ret = alloc_chrdev_region(&rpmsg_major, 0, RPMSG_DEV_MAX, "rpmsg_char");
if (ret < 0) {
pr_err("failed to allocate char dev region\n");
return ret;
}
ret = register_rpmsg_driver(&rpmsg_chrdev_driver);
if (ret < 0) {
pr_err("rpmsg: failed to register rpmsg raw driver\n");
goto free_region;
}
return 0;
free_region:
unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
return ret;
}
postcore_initcall(rpmsg_chrdev_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);
MODULE_ALIAS("rpmsg:rpmsg_chrdev");
MODULE_LICENSE("GPL v2");