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Message-ID: <277171bf-5947-9d1b-6ad5-e80dc15c4cc1@foss.st.com>
Date: Mon, 11 Oct 2021 14:53:15 +0200
From: Arnaud POULIQUEN <arnaud.pouliquen@...s.st.com>
To: Bjorn Andersson <bjorn.andersson@...aro.org>
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 10/9/21 2:25 AM, Bjorn Andersson wrote:
> 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?
This as been done by steps to ease the review. Any way, these controls also
require, to be usable for the rpmsg_char, the implementation of the rpmsg-raw
channel in the rpmsg_char.
Should i squash the 3 patchsets in one and add concrete examples in cover letter?
>
>> 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?
No, if announced by the remote side the rpmsg_char dev should be automatically
probed by the virtio bus.
The RPMSG_CREATE_EPT_IOCTL is the legacy control that is used by QCOM drivers to
creates the cdev. It doesn't really make sense for the virtio backend, as virtio
is based on a rpmsg channel that is associated to a rpmsg device.
The only use case I have in mind would be to create endpoint without channel but
using fixed addresses. No concrete use case identified in ST Microelectronics
for hardcoded endpoint addresses.
>
>> 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?
Both a side effect but also a feature to remove a channel from the initiative of
the user application.
Regards,
Arnaud
>
> 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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