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path: root/drivers/rpmsg/rpmsg_char.c
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2022-03-13rpmsg: char: Introduce the "rpmsg-raw" channelArnaud Pouliquen
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
2022-03-13rpmsg: char: Add possibility to use default endpoint of the rpmsg deviceArnaud Pouliquen
Current implementation create/destroy a new endpoint on each rpmsg_eptdev_open/rpmsg_eptdev_release calls. For a rpmsg device created by the NS announcement a default endpoint is created. In this case we have to reuse the default rpmsg device endpoint associated to the channel instead of creating a new one. This patch prepares the introduction of a rpmsg channel device for the char device. The rpmsg channel device will require a default endpoint to communicate to the remote processor. Add the default_ept field in rpmsg_eptdev structure.This pointer determines the behavior on rpmsg_eptdev_open and rpmsg_eptdev_release call. - If default_ept == NULL: Use the legacy behavior by creating a new endpoint each time rpmsg_eptdev_open is called and release it when rpmsg_eptdev_release is called on /dev/rpmsgX device open/close. - If default_ept is set: use the rpmsg device default endpoint for the communication. Add protection in rpmsg_eptdev_ioctl to prevent to destroy a default endpoint. 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/20220124102524.295783-10-arnaud.pouliquen@foss.st.com
2022-03-13rpmsg: char: Refactor rpmsg_chrdev_eptdev_create functionArnaud Pouliquen
Introduce the rpmsg_chrdev_eptdev_alloc and rpmsg_chrdev_eptdev_add internal function to split the allocation part from the device add. This patch prepares the introduction of a rpmsg channel device for the char device. An default endpoint will be created, referenced in the rpmsg_eptdev structure before adding the devices. 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/20220124102524.295783-9-arnaud.pouliquen@foss.st.com
2022-03-13rpmsg: Move the rpmsg control device from rpmsg_char to rpmsg_ctrlArnaud Pouliquen
Create the rpmsg_ctrl.c module and move the code related to the rpmsg_ctrldev device in this new module. Add the dependency between rpmsg_char and rpmsg_ctrl in the kconfig file: 1) RPMSG_CTRL can set as module or built-in if RPMSG=y || RPMSG_CHAR=y || RPMSG_CHAR=n 2) RPMSG_CTRL can not be set as built-in if RPMSG=m || RPMSG_CHAR=m Note that RPMGH_CHAR and RPMSG_CTRL can be activated separately. Therefore, the RPMSG_CTRL configuration must be set for backwards compatibility. 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/20220124102524.295783-4-arnaud.pouliquen@foss.st.com
2022-03-13rpmsg: Create the rpmsg class in core instead of in rpmsg charArnaud Pouliquen
Migrate the creation of the rpmsg class from the rpmsg_char to the core that the class is usable by the rpmsg_char and the future rpmsg_ctrl module. Suggested-by: Bjorn Andersson <bjorn.andersson@linaro.org> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> Link: https://lore.kernel.org/r/20220124102524.295783-3-arnaud.pouliquen@foss.st.com
2022-03-13rpmsg: char: Export eptdev create and destroy functionsArnaud Pouliquen
To prepare the split of the code related to the control (ctrldev) and the endpoint (eptdev) devices in 2 separate files: - Rename and export the functions in rpmsg_char.h. - Suppress the dependency with the rpmsg_ctrldev struct in the rpmsg_eptdev_create function. Suggested-by: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> Link: https://lore.kernel.org/r/20220124102524.295783-2-arnaud.pouliquen@foss.st.com
2022-03-13rpmsg: char: treat rpmsg_trysend() ENOMEM as EAGAINTim Blechmann
rpmsg_trysend() returns -ENOMEM when no rpmsg buffer can be allocated. this causes write to fail with this error as opposed to -EAGAIN. this is what user space applications (and libraries like boost.asio) would expect when using normal character devices. Signed-off-by: Tim Blechmann <tim@klingt.org> Cc: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> Link: https://lore.kernel.org/r/20220313024541.1579848-2-tim@klingt.org
2022-01-17rpmsg: char: Fix race between the release of rpmsg_eptdev and cdevMatthias Kaehlcke
struct rpmsg_eptdev contains a struct cdev. The current code frees the rpmsg_eptdev struct in rpmsg_eptdev_destroy(), but the cdev is a managed object, therefore its release is not predictable and the rpmsg_eptdev could be freed before the cdev is entirely released. The cdev_device_add/del() API was created to address this issue (see commit '233ed09d7fda ("chardev: add helper function to register char devs with a struct device")'), use it instead of cdev add/del(). Fixes: c0cdc19f84a4 ("rpmsg: Driver for user space endpoint interface") Suggested-by: Bjorn Andersson <bjorn.andersson@linaro.org> Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> Reviewed-by: Stephen Boyd <swboyd@chromium.org> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> Link: https://lore.kernel.org/r/20220110104706.v6.2.Idde68b05b88d4a2e6e54766c653f3a6d9e419ce6@changeid
2022-01-17rpmsg: char: Fix race between the release of rpmsg_ctrldev and cdevSujit Kautkar
struct rpmsg_ctrldev contains a struct cdev. The current code frees the rpmsg_ctrldev struct in rpmsg_ctrldev_release_device(), but the cdev is a managed object, therefore its release is not predictable and the rpmsg_ctrldev could be freed before the cdev is entirely released, as in the backtrace below. [ 93.625603] ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x7c [ 93.636115] WARNING: CPU: 0 PID: 12 at lib/debugobjects.c:488 debug_print_object+0x13c/0x1b0 [ 93.644799] Modules linked in: veth xt_cgroup xt_MASQUERADE rfcomm algif_hash algif_skcipher af_alg uinput ip6table_nat fuse uvcvideo videobuf2_vmalloc venus_enc venus_dec videobuf2_dma_contig hci_uart btandroid btqca snd_soc_rt5682_i2c bluetooth qcom_spmi_temp_alarm snd_soc_rt5682v [ 93.715175] CPU: 0 PID: 12 Comm: kworker/0:1 Tainted: G B 5.4.163-lockdep #26 [ 93.723855] Hardware name: Google Lazor (rev3 - 8) with LTE (DT) [ 93.730055] Workqueue: events kobject_delayed_cleanup [ 93.735271] pstate: 60c00009 (nZCv daif +PAN +UAO) [ 93.740216] pc : debug_print_object+0x13c/0x1b0 [ 93.744890] lr : debug_print_object+0x13c/0x1b0 [ 93.749555] sp : ffffffacf5bc7940 [ 93.752978] x29: ffffffacf5bc7940 x28: dfffffd000000000 [ 93.758448] x27: ffffffacdb11a800 x26: dfffffd000000000 [ 93.763916] x25: ffffffd0734f856c x24: dfffffd000000000 [ 93.769389] x23: 0000000000000000 x22: ffffffd0733c35b0 [ 93.774860] x21: ffffffd0751994a0 x20: ffffffd075ec27c0 [ 93.780338] x19: ffffffd075199100 x18: 00000000000276e0 [ 93.785814] x17: 0000000000000000 x16: dfffffd000000000 [ 93.791291] x15: ffffffffffffffff x14: 6e6968207473696c [ 93.796768] x13: 0000000000000000 x12: ffffffd075e2b000 [ 93.802244] x11: 0000000000000001 x10: 0000000000000000 [ 93.807723] x9 : d13400dff1921900 x8 : d13400dff1921900 [ 93.813200] x7 : 0000000000000000 x6 : 0000000000000000 [ 93.818676] x5 : 0000000000000080 x4 : 0000000000000000 [ 93.824152] x3 : ffffffd0732a0fa4 x2 : 0000000000000001 [ 93.829628] x1 : ffffffacf5bc7580 x0 : 0000000000000061 [ 93.835104] Call trace: [ 93.837644] debug_print_object+0x13c/0x1b0 [ 93.841963] __debug_check_no_obj_freed+0x25c/0x3c0 [ 93.846987] debug_check_no_obj_freed+0x18/0x20 [ 93.851669] slab_free_freelist_hook+0xbc/0x1e4 [ 93.856346] kfree+0xfc/0x2f4 [ 93.859416] rpmsg_ctrldev_release_device+0x78/0xb8 [ 93.864445] device_release+0x84/0x168 [ 93.868310] kobject_cleanup+0x12c/0x298 [ 93.872356] kobject_delayed_cleanup+0x10/0x18 [ 93.876948] process_one_work+0x578/0x92c [ 93.881086] worker_thread+0x804/0xcf8 [ 93.884963] kthread+0x2a8/0x314 [ 93.888303] ret_from_fork+0x10/0x18 The cdev_device_add/del() API was created to address this issue (see commit '233ed09d7fda ("chardev: add helper function to register char devs with a struct device")'), use it instead of cdev add/del(). Fixes: c0cdc19f84a4 ("rpmsg: Driver for user space endpoint interface") Signed-off-by: Sujit Kautkar <sujitka@chromium.org> Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Reviewed-by: Stephen Boyd <swboyd@chromium.org> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> Link: https://lore.kernel.org/r/20220110104706.v6.1.Iaac908f3e3149a89190ce006ba166e2d3fd247a3@changeid
2021-11-18rpmsg: char: Add pr_fmt() to prefix messagesArnaud Pouliquen
Make all messages to be prefixed in a unified way. Add pr_fmt() to achieve this. Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com> Link: https://lore.kernel.org/r/20211108135945.3364-1-arnaud.pouliquen@foss.st.com Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
2021-10-08rpmsg: char: Remove useless includeArnaud Pouliquen
No facility requests the include of rpmsg_internal.h header file. Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> Link: https://lore.kernel.org/r/20210712123752.10449-2-arnaud.pouliquen@foss.st.com
2021-03-17rpmsg: char: Return an error if device already openArnaud Pouliquen
The rpmsg_create_ept function is invoked when the device is opened. As only one endpoint must be created per device. It is not possible to open the same device twice. But there is nothing to prevent multi open. Return -EBUSY when device is already opened to have a generic error instead of relying on the back-end to potentially detect the error. Without this patch for instance the GLINK driver return -EBUSY while the virtio bus return -ENOSPC. Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com> Link: https://lore.kernel.org/r/20210311140413.31725-7-arnaud.pouliquen@foss.st.com Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
2021-03-17rpmsg: char: Use rpmsg_sendto to specify the message destination addressArnaud Pouliquen
When the endpoint device is created by the application, a destination address is specified in the rpmsg_channel_info structure. Since the rpmsg_endpoint structure does not store the destination address, this destination address must be specified when sending a message. Replaces rpmsg_send with rpmsg_sendto to allow to specify the destination address. This implementation is requested for compatibly with some rpmsg backends like the virtio backend. For this, the GLINK an SMD drivers have been updated to support the rpmsg_sendto, even if the destination address is ignored for these backends. For these drivers, the rpmsg_send and rpmsg_trysend ops are preserved to avoid breaking the legacy. Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> Link: https://lore.kernel.org/r/20210311140413.31725-5-arnaud.pouliquen@foss.st.com Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
2021-03-17rpmsg: char: Rename rpmsg_char_init to rpmsg_chrdev_initArnaud Pouliquen
To be coherent with the other functions which are prefixed by rpmsg_chrdev, rename the rpmsg_char_init function. Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com> Link: https://lore.kernel.org/r/20210311140413.31725-2-arnaud.pouliquen@foss.st.com Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
2019-12-01Merge tag 'rpmsg-v5.5' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/andersson/remoteproc Pull rpmsg updates from Bjorn Andersson: "This contains a number of bug fixes to the GLINK transport driver, an off-by-one in the GLINK smem driver and a memory leak fix in the rpmsg char driver" * tag 'rpmsg-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/andersson/remoteproc: rpmsg: Fix Kconfig indentation rpmsg: char: Simplify 'rpmsg_eptdev_release()' rpmsg: glink: Free pending deferred work on remove rpmsg: glink: Don't send pending rx_done during remove rpmsg: glink: Fix rpmsg_register_device err handling rpmsg: glink: Put an extra reference during cleanup rpmsg: glink: Fix use after free in open_ack TIMEOUT case rpmsg: glink: Fix reuse intents memory leak issue rpmsg: glink: Set tail pointer to 0 at end of FIFO rpmsg: char: release allocated memory
2019-11-08rpmsg: char: Simplify 'rpmsg_eptdev_release()'Christophe JAILLET
Use 'skb_queue_purge()' instead of re-implementing it. Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
2019-10-23compat_ioctl: move more drivers to compat_ptr_ioctlArnd Bergmann
The .ioctl and .compat_ioctl file operations have the same prototype so they can both point to the same function, which works great almost all the time when all the commands are compatible. One exception is the s390 architecture, where a compat pointer is only 31 bit wide, and converting it into a 64-bit pointer requires calling compat_ptr(). Most drivers here will never run in s390, but since we now have a generic helper for it, it's easy enough to use it consistently. I double-checked all these drivers to ensure that all ioctl arguments are used as pointers or are ignored, but are not interpreted as integer values. Acked-by: Jason Gunthorpe <jgg@mellanox.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: David Sterba <dsterba@suse.com> Acked-by: Darren Hart (VMware) <dvhart@infradead.org> Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org> Acked-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2019-10-04rpmsg: char: release allocated memoryNavid Emamdoost
In rpmsg_eptdev_write_iter, if copy_from_iter_full fails the allocated buffer needs to be released. Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
2018-08-27rpmsg: char: Migrate to iter versions of read and writeBjorn Andersson
In order to be able to use the aio interface for writing to a rpmsg_char the write_iter function must be implemented, so migrate to iter version for read and write functions. Regular read and write uses the iter methods if present and is as such unaffected. Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
2018-07-30rpmsg: Add compat ioctl for rpmsg char driverArun Kumar Neelakantam
Add compat ioctl callback to support 32bit user space applications. Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
2018-06-03rpmsg: char: Switch to SPDX license identifierSuman Anna
Use the appropriate SPDX license identifier in the rpmsg char driver source file and drop the previous boilerplate license text. The uapi header file already had the SPDX license identifier added as part of a mass update but the license text removal was deferred for later, and this patch drops the same. Signed-off-by: Suman Anna <s-anna@ti.com> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
2018-04-25rpmsg: added MODULE_ALIAS for rpmsg_charRamon Fried
Added "rpmsg:rpmsg_chrdev" MODULE_ALIAS to autoload rpmg_chrdev module automatically. Signed-off-by: Ramon Fried <rfried@codeaurora.org> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
2018-02-11vfs: do bulk POLL* -> EPOLL* replacementLinus Torvalds
This is the mindless scripted replacement of kernel use of POLL* variables as described by Al, done by this script: for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'` for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done done with de-mangling cleanups yet to come. NOTE! On almost all architectures, the EPOLL* constants have the same values as the POLL* constants do. But they keyword here is "almost". For various bad reasons they aren't the same, and epoll() doesn't actually work quite correctly in some cases due to this on Sparc et al. The next patch from Al will sort out the final differences, and we should be all done. Scripted-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-28the rest of drivers/*: annotate ->poll() instancesAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-07-06Merge tag 'rpmsg-v4.13' of git://github.com/andersson/remoteprocLinus Torvalds
Pull rpmsg updates from Bjorn Andersson: "This introduces the Qualcomm GLINK protocol driver and DeviceTree-based modalias support, as well as a number of smaller fixes" * tag 'rpmsg-v4.13' of git://github.com/andersson/remoteproc: rpmsg: Make modalias work for DeviceTree based devices rpmsg: Drop VIRTUALIZATION dependency from RPMSG_VIRTIO rpmsg: Don't overwrite release op of rpdev rpmsg: virtio_rpmsg_bus: cleanup multiple assignment to ops rpmsg: virtio_rpmsg_bus: fix nameservice address rpmsg: cleanup incorrect function in dev_err message rpmsg: virtio_rpmsg_bus: fix announce for devices without endpoint rpmsg: Introduce Qualcomm RPM glink driver soc: qcom: Add device tree binding for GLINK RPM rpmsg: Release rpmsg devices in backends
2017-06-25rpmsg: cleanup incorrect function in dev_err messageHenri Roosen
Trivial cleanup for incorrect function in dev_err message Signed-off-by: Henri Roosen <henri.roosen@ginzinger.com> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
2017-06-16networking: introduce and use skb_put_data()Johannes Berg
A common pattern with skb_put() is to just want to memcpy() some data into the new space, introduce skb_put_data() for this. An spatch similar to the one for skb_put_zero() converts many of the places using it: @@ identifier p, p2; expression len, skb, data; type t, t2; @@ ( -p = skb_put(skb, len); +p = skb_put_data(skb, data, len); | -p = (t)skb_put(skb, len); +p = skb_put_data(skb, data, len); ) ( p2 = (t2)p; -memcpy(p2, data, len); | -memcpy(p, data, len); ) @@ type t, t2; identifier p, p2; expression skb, data; @@ t *p; ... ( -p = skb_put(skb, sizeof(t)); +p = skb_put_data(skb, data, sizeof(t)); | -p = (t *)skb_put(skb, sizeof(t)); +p = skb_put_data(skb, data, sizeof(t)); ) ( p2 = (t2)p; -memcpy(p2, data, sizeof(*p)); | -memcpy(p, data, sizeof(*p)); ) @@ expression skb, len, data; @@ -memcpy(skb_put(skb, len), data, len); +skb_put_data(skb, data, len); (again, manually post-processed to retain some comments) Reviewed-by: Stephen Hemminger <stephen@networkplumber.org> Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-30rpmsg: unlock on error in rpmsg_eptdev_read()Dan Carpenter
We should unlock before returning if skb_dequeue() returns a NULL. Fixes: c0cdc19f84a4 ("rpmsg: Driver for user space endpoint interface") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
2017-01-18rpmsg: Driver for user space endpoint interfaceBjorn Andersson
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@nxp.com> Cc: Matteo Sartori <matteo.sartori@t3lab.it> Cc: Michal Simek <monstr@monstr.eu> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>