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Date: Fri, 8 Oct 2021 17:25:26 -0700
From: Bjorn Andersson <bjorn.andersson@...aro.org>
To: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
Cc: Ohad Ben-Cohen <ohad@...ery.com>,
Mathieu Poirier <mathieu.poirier@...aro.org>,
linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-stm32@...md-mailman.stormreply.com
Subject: Re: [PATCH v3] rpmsg: ctrl: Introduce new
RPMSG_CREATE/RELEASE_DEV_IOCTL controls
On Mon 12 Jul 06:23 PDT 2021, Arnaud Pouliquen wrote:
> Allow the user space application to create and release an rpmsg device
> by adding RPMSG_CREATE_DEV_IOCTL and RPMSG_RELEASE_DEV_IOCTL ioctrls to
> the /dev/rpmsg_ctrl interface
>
With
https://lore.kernel.org/linux-remoteproc/CAHk-=wgea9bo-j4+LAvZF7OKPAXKqrGgiBAhXTJ3Jv5JAZgA+A@mail.gmail.com/
and
https://lore.kernel.org/linux-arm-msm/1609958656-15064-1-git-send-email-hemantk@codeaurora.org/
in mind, I would like some concrete examples of when and how this is
going to be used.
Also, as I said previously, this would have been better to put together
with the split out of rpmsg_ctrl, because afaict this is the only reason
for doing that. Or am I simply missing something?
> The RPMSG_CREATE_DEV_IOCTL Ioctl can be used to instantiate a local rpmsg
> device.
> Depending on the back-end implementation, the associated rpmsg driver is
> probed and a NS announcement can be sent to the remote processor.
>
So, does this imply that in order to spawn a new rpmsg_char from the
host side, I would use RPMSG_CREATE_DEV_IOCTL and to open a channel
announced by the remote I would use RPMSG_CREATE_EPT_IOCTL?
> The RPMSG_RELEASE_DEV_IOCTL allows the user application to release a
> rpmsg device created either by the remote processor or with the
> RPMSG_CREATE_DEV_IOCTL call.
Is this a side effect, bug or a feature?
Regards,
Bjorn
> Depending on the back-end implementation, the associated rpmsg driver is
> removed and a NS destroy rpmsg can be sent to the remote processor.
>
> Suggested-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
> Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> ---
> update from V2
> - add Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> - rebased on kernel V.14-rc1 +
> series V5 Restructure the rpmsg char to decorrelate the control part [1]
>
>
> [1] https://patchwork.kernel.org/project/linux-remoteproc/list/?series=514017
>
> ---
> drivers/rpmsg/rpmsg_ctrl.c | 37 +++++++++++++++++++++++++++++++++----
> include/uapi/linux/rpmsg.h | 10 ++++++++++
> 2 files changed, 43 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/rpmsg/rpmsg_ctrl.c b/drivers/rpmsg/rpmsg_ctrl.c
> index eeb1708548c1..cb19e32d05e1 100644
> --- a/drivers/rpmsg/rpmsg_ctrl.c
> +++ b/drivers/rpmsg/rpmsg_ctrl.c
> @@ -23,6 +23,7 @@
> #include <uapi/linux/rpmsg.h>
>
> #include "rpmsg_char.h"
> +#include "rpmsg_internal.h"
>
> static dev_t rpmsg_major;
>
> @@ -37,11 +38,13 @@ static DEFINE_IDA(rpmsg_minor_ida);
> * @rpdev: underlaying rpmsg device
> * @cdev: cdev for the ctrl device
> * @dev: device for the ctrl device
> + * @ctrl_lock: serialize the ioctrls.
> */
> struct rpmsg_ctrldev {
> struct rpmsg_device *rpdev;
> struct cdev cdev;
> struct device dev;
> + struct mutex ctrl_lock;
> };
>
> static int rpmsg_ctrldev_open(struct inode *inode, struct file *filp)
> @@ -70,9 +73,8 @@ static long rpmsg_ctrldev_ioctl(struct file *fp, unsigned int cmd,
> void __user *argp = (void __user *)arg;
> struct rpmsg_endpoint_info eptinfo;
> struct rpmsg_channel_info chinfo;
> -
> - if (cmd != RPMSG_CREATE_EPT_IOCTL)
> - return -EINVAL;
> + struct rpmsg_device *rpdev;
> + int ret = 0;
>
> if (copy_from_user(&eptinfo, argp, sizeof(eptinfo)))
> return -EFAULT;
> @@ -82,7 +84,33 @@ static long rpmsg_ctrldev_ioctl(struct file *fp, unsigned int cmd,
> chinfo.src = eptinfo.src;
> chinfo.dst = eptinfo.dst;
>
> - return rpmsg_chrdev_eptdev_create(ctrldev->rpdev, &ctrldev->dev, chinfo);
> + mutex_lock(&ctrldev->ctrl_lock);
> + switch (cmd) {
> + case RPMSG_CREATE_EPT_IOCTL:
> + ret = rpmsg_chrdev_eptdev_create(ctrldev->rpdev, &ctrldev->dev, chinfo);
> + break;
> +
> + case RPMSG_CREATE_DEV_IOCTL:
> + rpdev = rpmsg_create_channel(ctrldev->rpdev, &chinfo);
> + if (!rpdev) {
> + dev_err(&ctrldev->dev, "failed to create %s channel\n", chinfo.name);
> + ret = -ENXIO;
> + }
> + break;
> +
> + case RPMSG_RELEASE_DEV_IOCTL:
> + ret = rpmsg_release_channel(ctrldev->rpdev, &chinfo);
> + if (ret)
> + dev_err(&ctrldev->dev, "failed to release %s channel (%d)\n",
> + chinfo.name, ret);
> + break;
> +
> + default:
> + ret = -EINVAL;
> + }
> + mutex_unlock(&ctrldev->ctrl_lock);
> +
> + return ret;
> };
>
> static const struct file_operations rpmsg_ctrldev_fops = {
> @@ -119,6 +147,7 @@ static int rpmsg_ctrldev_probe(struct rpmsg_device *rpdev)
> device_initialize(dev);
> dev->parent = &rpdev->dev;
>
> + mutex_init(&ctrldev->ctrl_lock);
> cdev_init(&ctrldev->cdev, &rpmsg_ctrldev_fops);
> ctrldev->cdev.owner = THIS_MODULE;
>
> diff --git a/include/uapi/linux/rpmsg.h b/include/uapi/linux/rpmsg.h
> index f5ca8740f3fb..1637e68177d9 100644
> --- a/include/uapi/linux/rpmsg.h
> +++ b/include/uapi/linux/rpmsg.h
> @@ -33,4 +33,14 @@ struct rpmsg_endpoint_info {
> */
> #define RPMSG_DESTROY_EPT_IOCTL _IO(0xb5, 0x2)
>
> +/**
> + * Instantiate a new local rpmsg service device.
> + */
> +#define RPMSG_CREATE_DEV_IOCTL _IOW(0xb5, 0x3, struct rpmsg_endpoint_info)
> +
> +/**
> + * Release a local rpmsg device.
> + */
> +#define RPMSG_RELEASE_DEV_IOCTL _IOW(0xb5, 0x4, struct rpmsg_endpoint_info)
> +
> #endif
> --
> 2.17.1
>
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