linux-kernel - Re: [PATCH v2 1/4] rpmsg: Introduce rpmsg_create_default

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Message-ID: <20210630203821.GA1290178@p14s>
Date:   Wed, 30 Jun 2021 14:38:21 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com, julien.massot@....bzh
Subject: Re: [PATCH v2 1/4] rpmsg: Introduce rpmsg_create_default_ept function

On Wed, Jun 23, 2021 at 05:05:01PM +0200, Arnaud Pouliquen wrote:
> By providing a callback in the rpmsg_driver structure, the rpmsg devices
> can be probed with a default endpoint created.
> 
> In this case, it is not possible to associated to this endpoint private data
> that could allow the driver to retrieve the context.
> 
> This helper function allows rpmsg drivers to create a default endpoint
> on runtime with an associated private context.
> 
> For example, a driver might create a context structure on the probe and
> want to provide that context as private data for the default rpmsg
> callback.
> 
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
> ---
> 
> update from V1:
> - Minor: alignement of the function parameter to have homogenous function declaration.
> ---
> 
>  drivers/rpmsg/rpmsg_core.c | 51 ++++++++++++++++++++++++++++++++++++++
>  include/linux/rpmsg.h      | 13 ++++++++++
>  2 files changed, 64 insertions(+)
> 
> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> index e5daee4f9373..07b680bda61f 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -115,6 +115,57 @@ struct rpmsg_endpoint *rpmsg_create_ept(struct rpmsg_device *rpdev,
>  }
>  EXPORT_SYMBOL(rpmsg_create_ept);
>  
> +/**
> + * rpmsg_create_default_ept() - create a default rpmsg_endpoint for a rpmsg device
> + * @rpdev: rpmsg channel device
> + * @cb: rx callback handler
> + * @priv: private data for the driver's use
> + * @chinfo: channel_info with the local rpmsg address to bind with @cb
> + *
> + * On register_rpmsg_driver if no callback is provided in the rpmsg_driver structure,
> + * no endpoint is created when the device is probed by the rpmsg bus.
> + *
> + * This function returns a pointer to the default endpoint if already created or creates
> + * a endpoint and assign it as the default endpoint of the rpmsg device.

s/"a endpoint"/"an endpoint"

> + *
> + * Drivers should provide their @rpdev channel (so the new endpoint would belong
> + * to the same remote processor their channel belongs to), an rx callback
> + * function, an optional private data (which is provided back when the
> + * rx callback is invoked), and an address they want to bind with the
> + * callback. If @addr is RPMSG_ADDR_ANY, then rpmsg_create_ept will
> + * dynamically assign them an available rpmsg address (drivers should have
> + * a very good reason why not to always use RPMSG_ADDR_ANY here).
> + *
> + * Returns a pointer to the endpoint on success, or NULL on error.
> + */
> +struct rpmsg_endpoint *rpmsg_create_default_ept(struct rpmsg_device *rpdev,
> +						rpmsg_rx_cb_t cb, void *priv,
> +						struct rpmsg_channel_info chinfo)
> +{
> +	struct rpmsg_endpoint *ept;
> +
> +	if (WARN_ON(!rpdev))
> +		return NULL;
> +
> +	/* It does not make sense to create a default  endpoint without a callback. */

s/"default  endppoint"/"default endpoint"

Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>

> +	if (!cb)
> +		return NULL;
> +
> +	if (rpdev->ept)
> +		return rpdev->ept;
> +
> +	ept = rpdev->ops->create_ept(rpdev, cb, priv, chinfo);
> +	if (!ept)
> +		return NULL;
> +
> +	/* Assign the new endpoint as default endpoint */
> +	rpdev->ept = ept;
> +	rpdev->src = ept->addr;
> +
> +	return ept;
> +}
> +EXPORT_SYMBOL(rpmsg_create_default_ept);
> +
>  /**
>   * rpmsg_destroy_ept() - destroy an existing rpmsg endpoint
>   * @ept: endpoing to destroy
> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
> index d97dcd049f18..11f473834e86 100644
> --- a/include/linux/rpmsg.h
> +++ b/include/linux/rpmsg.h
> @@ -172,6 +172,9 @@ void rpmsg_destroy_ept(struct rpmsg_endpoint *);
>  struct rpmsg_endpoint *rpmsg_create_ept(struct rpmsg_device *,
>  					rpmsg_rx_cb_t cb, void *priv,
>  					struct rpmsg_channel_info chinfo);
> +struct rpmsg_endpoint *rpmsg_create_default_ept(struct rpmsg_device *rpdev,
> +						rpmsg_rx_cb_t cb, void *priv,
> +						struct rpmsg_channel_info chinfo);
>  
>  int rpmsg_send(struct rpmsg_endpoint *ept, void *data, int len);
>  int rpmsg_sendto(struct rpmsg_endpoint *ept, void *data, int len, u32 dst);
> @@ -234,6 +237,16 @@ static inline struct rpmsg_endpoint *rpmsg_create_ept(struct rpmsg_device *rpdev
>  	return ERR_PTR(-ENXIO);
>  }
>  
> +static inline struct rpmsg_endpoint *rpmsg_create_default_ept(struct rpmsg_device *rpdev,
> +							      rpmsg_rx_cb_t cb, void *priv,
> +							      struct rpmsg_channel_info chinfo)
> +{
> +	/* This shouldn't be possible */
> +	WARN_ON(1);
> +
> +	return NULL;
> +}
> +
>  static inline int rpmsg_send(struct rpmsg_endpoint *ept, void *data, int len)
>  {
>  	/* This shouldn't be possible */
> -- 
> 2.17.1
>