On Mon 12 Jul 06:19 PDT 2021, Arnaud Pouliquen wrote:
> Allows to probe the endpoint device on a remote name service announcement,
> by registering a rpmsg_driverfor the "rpmsg-raw" channel.
>
> With this patch the /dev/rpmsgX interface can be instantiated by the remote
> firmware.
>
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@xxxxxxxxxxx>
> Reviewed-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> Tested-by: Julien Massot <julien.massot@xxxxxxx>
> ---
> drivers/rpmsg/rpmsg_char.c | 75 +++++++++++++++++++++++++++++++++++++-
> 1 file changed, 73 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
> index bd728d90ba4c..1b7b610e113d 100644
> --- a/drivers/rpmsg/rpmsg_char.c
> +++ b/drivers/rpmsg/rpmsg_char.c
> @@ -25,6 +25,8 @@
>
> #include "rpmsg_char.h"
>
> +#define RPMSG_CHAR_DEVNAME "rpmsg-raw"
> +
> static dev_t rpmsg_major;
> static struct class *rpmsg_class;
>
> @@ -421,6 +423,61 @@ int rpmsg_chrdev_eptdev_create(struct rpmsg_device *rpdev, struct device *parent
> }
> 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 rpmsg_endpoint *ept;
> +
> + memcpy(chinfo.name, RPMSG_CHAR_DEVNAME, sizeof(RPMSG_CHAR_DEVNAME));
The length should relate to the size of the destination buffer.
This looks like an excellent job for strscpy_pad()
> + chinfo.src = rpdev->src;
> + chinfo.dst = rpdev->dst;
> +
> + eptdev = __rpmsg_chrdev_eptdev_create(rpdev, &rpdev->dev, chinfo);
Note that this creates a new endpoint device as a child of the rpdev,
while new endpoints created by RPMSG_CREATE_EPT_IOCTL are parented by
the rpmsg_ctrl device.
So it is possible to create two /dev/rpmsgN nodes for the same endpoint,
I believe with the outcome that this one will be open but
__rpmsg_create_ept() in virtio_rpmsg_bus should return NULL if the user
tries to open the other one.
> + if (IS_ERR(eptdev))
> + return PTR_ERR(eptdev);
> +
> + /*
> + * Create the default endpoint associated to the rpmsg device and provide rpmsg_eptdev
> + * structure as callback private data.
> + */
> + ept = rpmsg_create_default_ept(rpdev, rpmsg_ept_cb, eptdev, eptdev->chinfo);
Why don't you just set rpdev->priv to eptdev and make rpmsg_ept_cb the
callback of your rpmsg_driver?
> + if (!ept) {
> + dev_err(&rpdev->dev, "failed to create %s\n", eptdev->chinfo.name);
> + put_device(&eptdev->dev);
> + return -EINVAL;
> + }
> +
> + /*
> + * Do not allow the creation and release of an endpoint on /dev/rpmsgX open and close,
> + * reuse the default endpoint instead
> + */
What happens when __rpmsg_chrdev_eptdev_create() delivers a uevent and
user space quickly calls open() on the newly created /dev/rpmsgN, before
the next line?
> + eptdev->static_ept = true;
> +
> + return 0;
> +}
> +
> +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_CHAR_DEVNAME },
I would expect that this list would grow, but you hard coded
RPMSG_CHAR_DEVNAME in probe, so that won't work.
Regards,
Bjorn
> + { },
> +};
> +
> +static struct rpmsg_driver rpmsg_chrdev_driver = {
> + .probe = rpmsg_chrdev_probe,
> + .remove = rpmsg_chrdev_remove,
> + .id_table = rpmsg_chrdev_id_table,
> + .drv.name = "rpmsg_chrdev",
> +};
> +
> static int rpmsg_chrdev_init(void)
> {
> int ret;
> @@ -434,16 +491,30 @@ static int rpmsg_chrdev_init(void)
> rpmsg_class = class_create(THIS_MODULE, "rpmsg");
> if (IS_ERR(rpmsg_class)) {
> pr_err("failed to create rpmsg class\n");
> - unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
> - return PTR_ERR(rpmsg_class);
> + ret = PTR_ERR(rpmsg_class);
> + goto free_region;
> + }
> +
> + ret = register_rpmsg_driver(&rpmsg_chrdev_driver);
> + if (ret < 0) {
> + pr_err("rpmsg: failed to register rpmsg raw driver\n");
> + goto free_class;
> }
>
> return 0;
> +
> +free_class:
> + class_destroy(rpmsg_class);
> +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);
> class_destroy(rpmsg_class);
> unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
> }
> --
> 2.17.1
>
