Hello, On 12/7/22 14:04, Sarannya S wrote: > 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@xxxxxxxxxxx> > Signed-off-by: Sarannya S <quic_sarannya@xxxxxxxxxxx> > --- > 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 d6dde00e..77aeba0 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: enable or disable serial flow control What does it mean "enable and disable serial flow control"? Do you speak about the flow control feature or the data flow itself? I guess it is the activation/deactivation of the data stream regarding Bjorn's comment in V1: "I therefore asked Deepak to change it so the rpmsg api would contain a single "pause incoming data"/"resume incoming data" - given that this is a wish that we've seen in a number of discussions." For me this is the software flow control: https://en.wikipedia.org/wiki/Software_flow_control I would suggest not limiting the control only to activation/deactivation but to offer more flexibility in terms of services. replace the boolean by a bitmap would allow to extend it later. For instance by introducing 2 definitions: /* RPMSG pause transmission request: * sent to the remote endpoint to request to suspend its transmission */ */ #define RPMSG_FC_PT_REQ (1 << 0) /* RPMSG resume transmission request * sent to the remote endpoint to allow to resume its transmission */ #define RPMSG_FC_RT_REQ (1 << 1) Then we could add (in a next step) some other flow controls such as /* RPMSG pause transmission information * Sent to the remote endpoint to inform that no more data will be sent * until the reception of RPMSG_FC_RT_INFO */ #define RPMSG_FC_PT_INFO (1 << 16) #define RPMSG_FC_RT_INFO (1 << 16) > + * @dst: destination address of the endpoint Thanks to have integrated this in your patch! Regards, Arnaud > + * > + * 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(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 > */ > 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 */
