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Message-ID: <20230614155453.dywcrntfjddxojfv@ripper>
Date: Wed, 14 Jun 2023 08:54:53 -0700
From: Bjorn Andersson <andersson@...nel.org>
To: Sarannya S <quic_sarannya@...cinc.com>
Cc: quic_bjorande@...cinc.com, arnaud.pouliquen@...s.st.com,
swboyd@...omium.org, quic_clew@...cinc.com,
mathieu.poirier@...aro.org, linux-kernel@...r.kernel.org,
linux-arm-msm@...r.kernel.org, linux-remoteproc@...r.kernel.org,
Deepak Kumar Singh <quic_deesin@...cinc.com>
Subject: Re: [PATCH V7 1/3] rpmsg: core: Add signal API support
On Sat, Apr 22, 2023 at 04:12:05PM +0530, Sarannya S wrote:
> From: Deepak Kumar Singh <quic_deesin@...cinc.com>
>
> Some transports like Glink support the state notifications between
> clients using flow control signals similar to serial protocol signals.
> Local glink client drivers can send and receive flow control status
> to glink clients running on remote processors.
>
> Add APIs to support sending and receiving of flow control status by
> rpmsg clients.
>
> Signed-off-by: Deepak Kumar Singh <quic_deesin@...cinc.com>
> Signed-off-by: Sarannya S <quic_sarannya@...cinc.com>
> ---
> drivers/rpmsg/rpmsg_core.c | 21 +++++++++++++++++++++
> drivers/rpmsg/rpmsg_internal.h | 2 ++
> include/linux/rpmsg.h | 15 +++++++++++++++
> 3 files changed, 38 insertions(+)
>
> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> index a2207c0..e8bbe05 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -331,6 +331,25 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
> EXPORT_SYMBOL(rpmsg_trysend_offchannel);
>
> /**
> + * rpmsg_set_flow_control() - sets/clears serial flow control signals
> + * @ept: the rpmsg endpoint
> + * @enable: pause/resume incoming data flow
As shown in the discussion, it's still not clear what true/false means.
Also, let's try to clarify that it's a request for the other side to do
something:
* rpmsg_set_flow_control() - request remote to pause/resume transmission
* ...
* @enable: flow restricted
* ...
PS. There's a stray space at the end of the line.
> + * @dst: destination address of the endpoint
> + *
> + * Return: 0 on success and an appropriate error value on failure.
> + */
> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
> +{
> + if (WARN_ON(!ept))
> + return -EINVAL;
> + if (!ept->ops->set_flow_control)
> + return -ENXIO;
> +
> + return ept->ops->set_flow_control(ept, enable, dst);
> +}
> +EXPORT_SYMBOL_GPL(rpmsg_set_flow_control);
> +
> +/**
> * rpmsg_get_mtu() - get maximum transmission buffer size for sending message.
> * @ept: the rpmsg endpoint
> *
> @@ -539,6 +558,8 @@ static int rpmsg_dev_probe(struct device *dev)
>
> rpdev->ept = ept;
> rpdev->src = ept->addr;
> +
> + ept->flow_cb = rpdrv->flowcontrol;
> }
>
> err = rpdrv->probe(rpdev);
> diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
> index 39b646d..b6efd3e 100644
> --- a/drivers/rpmsg/rpmsg_internal.h
> +++ b/drivers/rpmsg/rpmsg_internal.h
> @@ -55,6 +55,7 @@ struct rpmsg_device_ops {
> * @trysendto: see @rpmsg_trysendto(), optional
> * @trysend_offchannel: see @rpmsg_trysend_offchannel(), optional
> * @poll: see @rpmsg_poll(), optional
> + * @set_flow_control: see @rpmsg_set_flow_control(), optional
> * @get_mtu: see @rpmsg_get_mtu(), optional
> *
> * Indirection table for the operations that a rpmsg backend should implement.
> @@ -75,6 +76,7 @@ struct rpmsg_endpoint_ops {
> void *data, int len);
> __poll_t (*poll)(struct rpmsg_endpoint *ept, struct file *filp,
> poll_table *wait);
> + int (*set_flow_control)(struct rpmsg_endpoint *ept, bool enable, u32 dst);
> ssize_t (*get_mtu)(struct rpmsg_endpoint *ept);
> };
>
> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
> index 523c98b..a0e9d38 100644
> --- a/include/linux/rpmsg.h
> +++ b/include/linux/rpmsg.h
> @@ -64,12 +64,14 @@ struct rpmsg_device {
> };
>
> typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32);
> +typedef int (*rpmsg_flowcontrol_cb_t)(struct rpmsg_device *, void *, bool);
>
> /**
> * struct rpmsg_endpoint - binds a local rpmsg address to its user
> * @rpdev: rpmsg channel device
> * @refcount: when this drops to zero, the ept is deallocated
> * @cb: rx callback handler
> + * @flow_cb: remote flow control callback handler
> * @cb_lock: must be taken before accessing/changing @cb
> * @addr: local rpmsg address
> * @priv: private data for the driver's use
> @@ -92,6 +94,7 @@ struct rpmsg_endpoint {
> struct rpmsg_device *rpdev;
> struct kref refcount;
> rpmsg_rx_cb_t cb;
> + rpmsg_flowcontrol_cb_t flow_cb;
> struct mutex cb_lock;
> u32 addr;
> void *priv;
> @@ -106,6 +109,7 @@ struct rpmsg_endpoint {
> * @probe: invoked when a matching rpmsg channel (i.e. device) is found
> * @remove: invoked when the rpmsg channel is removed
> * @callback: invoked when an inbound message is received on the channel
> + * @flowcontrol: invoked when remote side flow control status is received
s/status/request/
Regards,
Bjorn
> */
> struct rpmsg_driver {
> struct device_driver drv;
> @@ -113,6 +117,7 @@ struct rpmsg_driver {
> int (*probe)(struct rpmsg_device *dev);
> void (*remove)(struct rpmsg_device *dev);
> int (*callback)(struct rpmsg_device *, void *, int, void *, u32);
> + int (*flowcontrol)(struct rpmsg_device *, void *, bool);
> };
>
> static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val)
> @@ -192,6 +197,8 @@ __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
>
> ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept);
>
> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst);
> +
> #else
>
> static inline int rpmsg_register_device_override(struct rpmsg_device *rpdev,
> @@ -316,6 +323,14 @@ static inline ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept)
> return -ENXIO;
> }
>
> +static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable, u32 dst)
> +{
> + /* This shouldn't be possible */
> + WARN_ON(1);
> +
> + return -ENXIO;
> +}
> +
> #endif /* IS_ENABLED(CONFIG_RPMSG) */
>
> /* use a macro to avoid include chaining to get THIS_MODULE */
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
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