| Message ID | 1633015924-881-2-git-send-email-deesin@codeaurora.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | rpmsg and glink signaling api support | expand |
Quoting Deepak Kumar Singh (2021-09-30 08:32:01) > Some transports like Glink support the state notifications between > clients using signals similar to serial protocol signals. > Local glink client drivers can send and receive signals to glink > clients running on remote processors. > > Add apis to support sending and receiving of signals by rpmsg clients. s/apis/APIs/ > > Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org> [...] > diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c > index 9151836..5cae50c 100644 > --- a/drivers/rpmsg/rpmsg_core.c > +++ b/drivers/rpmsg/rpmsg_core.c > @@ -327,6 +327,24 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, > } > EXPORT_SYMBOL(rpmsg_trysend_offchannel); > > +/** > + * rpmsg_set_flow_control() - sets/clears searial flow control signals s/searial/serial/ > + * @ept: the rpmsg endpoint > + * @enable: enable or disable serial flow control > + * > + * Returns 0 on success and an appropriate error value on failure. Use 'Return:' instead of Returns. > + */ > +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable) > +{ > + if (WARN_ON(!ept)) > + return -EINVAL; > + if (!ept->ops->set_flow_control) > + return -ENXIO; > + > + return ept->ops->set_flow_control(ept, enable); > +} > +EXPORT_SYMBOL(rpmsg_set_flow_control); > + > /* > * match a rpmsg channel with a channel info struct. > * this is used to make sure we're not creating rpmsg devices for channels
Good day Deepak, On Thu, Sep 30, 2021 at 09:02:01PM +0530, Deepak Kumar Singh wrote: > Some transports like Glink support the state notifications between > clients using signals similar to serial protocol signals. > Local glink client drivers can send and receive signals to glink > clients running on remote processors. > > Add apis to support sending and receiving of signals by rpmsg clients. > > Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org> > --- > 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 9151836..5cae50c 100644 > --- a/drivers/rpmsg/rpmsg_core.c > +++ b/drivers/rpmsg/rpmsg_core.c > @@ -327,6 +327,24 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, > } > EXPORT_SYMBOL(rpmsg_trysend_offchannel); > > +/** > + * rpmsg_set_flow_control() - sets/clears searial flow control signals > + * @ept: the rpmsg endpoint > + * @enable: enable or disable serial flow control > + * > + * Returns 0 on success and an appropriate error value on failure. > + */ > +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable) > +{ > + if (WARN_ON(!ept)) > + return -EINVAL; > + if (!ept->ops->set_flow_control) > + return -ENXIO; > + > + return ept->ops->set_flow_control(ept, enable); > +} > +EXPORT_SYMBOL(rpmsg_set_flow_control); > + I'm looking at this patchset as the introduction of an out-of-bound control interface. But looking at the implementation of the GLINK's set_flow_control() the data is sent in-band, making me perplexed about introducing a new rpmsg_endpoint_ops for something that could be done from user space. Especially when user space is triggering the message with an ioctl in patch 3. Moreover this interface is case specific and doesn't reflect the generic nature found in ept->sig_cb. > /* > * match a rpmsg channel with a channel info struct. > * this is used to make sure we're not creating rpmsg devices for channels > @@ -514,6 +532,9 @@ static int rpmsg_dev_probe(struct device *dev) > > rpdev->ept = ept; > rpdev->src = ept->addr; > + > + if (rpdrv->signals) > + ept->sig_cb = rpdrv->signals; > } > > err = rpdrv->probe(rpdev); > diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h > index a76c344..dcb2ec1 100644 > --- a/drivers/rpmsg/rpmsg_internal.h > +++ b/drivers/rpmsg/rpmsg_internal.h > @@ -53,6 +53,7 @@ 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 > * > * Indirection table for the operations that a rpmsg backend should implement. > * In addition to @destroy_ept, the backend must at least implement @send and > @@ -72,6 +73,7 @@ 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); > }; > > struct device *rpmsg_find_device(struct device *parent, > diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h > index d97dcd0..b805c70 100644 > --- a/include/linux/rpmsg.h > +++ b/include/linux/rpmsg.h > @@ -62,12 +62,14 @@ struct rpmsg_device { > }; > > typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32); > +typedef int (*rpmsg_rx_sig_t)(struct rpmsg_device *, void *, u32); > > /** > * 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 > + * @sig_cb: rx serial signal handler > * @cb_lock: must be taken before accessing/changing @cb > * @addr: local rpmsg address > * @priv: private data for the driver's use > @@ -90,6 +92,7 @@ struct rpmsg_endpoint { > struct rpmsg_device *rpdev; > struct kref refcount; > rpmsg_rx_cb_t cb; > + rpmsg_rx_sig_t sig_cb; > struct mutex cb_lock; > u32 addr; > void *priv; > @@ -104,6 +107,7 @@ 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 > + * @signals: invoked when a serial signal change is received on the channel > */ > struct rpmsg_driver { > struct device_driver drv; > @@ -111,6 +115,7 @@ 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 (*signals)(struct rpmsg_device *rpdev, void *priv, u32); > }; > > static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val) > @@ -186,6 +191,8 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, > __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp, > poll_table *wait); > > +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); > + > #else > > static inline int rpmsg_register_device(struct rpmsg_device *rpdev) > @@ -296,6 +303,14 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, > return 0; > } > > +static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); > +{ > + /* 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 >
On Mon 11 Oct 13:02 CDT 2021, Mathieu Poirier wrote: > Good day Deepak, > > On Thu, Sep 30, 2021 at 09:02:01PM +0530, Deepak Kumar Singh wrote: > > Some transports like Glink support the state notifications between > > clients using signals similar to serial protocol signals. > > Local glink client drivers can send and receive signals to glink > > clients running on remote processors. > > > > Add apis to support sending and receiving of signals by rpmsg clients. > > > > Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org> > > --- > > 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 9151836..5cae50c 100644 > > --- a/drivers/rpmsg/rpmsg_core.c > > +++ b/drivers/rpmsg/rpmsg_core.c > > @@ -327,6 +327,24 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, > > } > > EXPORT_SYMBOL(rpmsg_trysend_offchannel); > > > > +/** > > + * rpmsg_set_flow_control() - sets/clears searial flow control signals > > + * @ept: the rpmsg endpoint > > + * @enable: enable or disable serial flow control > > + * > > + * Returns 0 on success and an appropriate error value on failure. > > + */ > > +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable) > > +{ > > + if (WARN_ON(!ept)) > > + return -EINVAL; > > + if (!ept->ops->set_flow_control) > > + return -ENXIO; > > + > > + return ept->ops->set_flow_control(ept, enable); > > +} > > +EXPORT_SYMBOL(rpmsg_set_flow_control); > > + > > I'm looking at this patchset as the introduction of an out-of-bound > control interface. But looking at the implementation of the GLINK's > set_flow_control() the data is sent in-band, making me perplexed about > introducing a new rpmsg_endpoint_ops for something that could be done > from user space. Especially when user space is triggering the message > with an ioctl in patch 3. > GLINK is built around one fifo per processor pair, similar to a virtqueue. So the signal request is muxed in the same pipe as data requests, but the signal goes alongside data request, not within them. > Moreover this interface is case specific and doesn't reflect the > generic nature found in ept->sig_cb. > The previous proposal from Deepak was to essentially expose the normal tty flags all the way down to the rpmsg driver. But I wasn't sure how those various flags should be interpreted in the typical rpmsg driver. I therefor 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. Unfortunately I don't have any good suggestion for how we could implement this in the virtio backend at this time, but with the muxing of all the different channels in the same virtqueue it would be good for a driver to able to pause the inflow on a specific endpoint, to avoid stalling other communication when a driver can't receive more messages. Regards, Bjorn > > /* > > * match a rpmsg channel with a channel info struct. > > * this is used to make sure we're not creating rpmsg devices for channels > > @@ -514,6 +532,9 @@ static int rpmsg_dev_probe(struct device *dev) > > > > rpdev->ept = ept; > > rpdev->src = ept->addr; > > + > > + if (rpdrv->signals) > > + ept->sig_cb = rpdrv->signals; > > } > > > > err = rpdrv->probe(rpdev); > > diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h > > index a76c344..dcb2ec1 100644 > > --- a/drivers/rpmsg/rpmsg_internal.h > > +++ b/drivers/rpmsg/rpmsg_internal.h > > @@ -53,6 +53,7 @@ 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 > > * > > * Indirection table for the operations that a rpmsg backend should implement. > > * In addition to @destroy_ept, the backend must at least implement @send and > > @@ -72,6 +73,7 @@ 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); > > }; > > > > struct device *rpmsg_find_device(struct device *parent, > > diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h > > index d97dcd0..b805c70 100644 > > --- a/include/linux/rpmsg.h > > +++ b/include/linux/rpmsg.h > > @@ -62,12 +62,14 @@ struct rpmsg_device { > > }; > > > > typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32); > > +typedef int (*rpmsg_rx_sig_t)(struct rpmsg_device *, void *, u32); > > > > /** > > * 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 > > + * @sig_cb: rx serial signal handler > > * @cb_lock: must be taken before accessing/changing @cb > > * @addr: local rpmsg address > > * @priv: private data for the driver's use > > @@ -90,6 +92,7 @@ struct rpmsg_endpoint { > > struct rpmsg_device *rpdev; > > struct kref refcount; > > rpmsg_rx_cb_t cb; > > + rpmsg_rx_sig_t sig_cb; > > struct mutex cb_lock; > > u32 addr; > > void *priv; > > @@ -104,6 +107,7 @@ 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 > > + * @signals: invoked when a serial signal change is received on the channel > > */ > > struct rpmsg_driver { > > struct device_driver drv; > > @@ -111,6 +115,7 @@ 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 (*signals)(struct rpmsg_device *rpdev, void *priv, u32); > > }; > > > > static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val) > > @@ -186,6 +191,8 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, > > __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp, > > poll_table *wait); > > > > +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); > > + > > #else > > > > static inline int rpmsg_register_device(struct rpmsg_device *rpdev) > > @@ -296,6 +303,14 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, > > return 0; > > } > > > > +static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); > > +{ > > + /* 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 > >
Hello, On 10/16/21 7:01 AM, Bjorn Andersson wrote: > On Mon 11 Oct 13:02 CDT 2021, Mathieu Poirier wrote: > >> Good day Deepak, >> >> On Thu, Sep 30, 2021 at 09:02:01PM +0530, Deepak Kumar Singh wrote: >>> Some transports like Glink support the state notifications between >>> clients using signals similar to serial protocol signals. >>> Local glink client drivers can send and receive signals to glink >>> clients running on remote processors. >>> >>> Add apis to support sending and receiving of signals by rpmsg clients. >>> >>> Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org> >>> --- >>> 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 9151836..5cae50c 100644 >>> --- a/drivers/rpmsg/rpmsg_core.c >>> +++ b/drivers/rpmsg/rpmsg_core.c >>> @@ -327,6 +327,24 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, >>> } >>> EXPORT_SYMBOL(rpmsg_trysend_offchannel); >>> >>> +/** >>> + * rpmsg_set_flow_control() - sets/clears searial flow control signals >>> + * @ept: the rpmsg endpoint >>> + * @enable: enable or disable serial flow control >>> + * >>> + * Returns 0 on success and an appropriate error value on failure. >>> + */ >>> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable) >>> +{ >>> + if (WARN_ON(!ept)) >>> + return -EINVAL; >>> + if (!ept->ops->set_flow_control) >>> + return -ENXIO; >>> + >>> + return ept->ops->set_flow_control(ept, enable); >>> +} >>> +EXPORT_SYMBOL(rpmsg_set_flow_control); >>> + >> >> I'm looking at this patchset as the introduction of an out-of-bound >> control interface. But looking at the implementation of the GLINK's >> set_flow_control() the data is sent in-band, making me perplexed about >> introducing a new rpmsg_endpoint_ops for something that could be done >> from user space. Especially when user space is triggering the message >> with an ioctl in patch 3. >> > > GLINK is built around one fifo per processor pair, similar to a > virtqueue. So the signal request is muxed in the same pipe as data > requests, but the signal goes alongside data request, not within them. That would be the equivalent of 2 additional virtqueues in virtio RPmsg backend - two virtqueues for the stream, - two virtqueues for the control Right? > >> Moreover this interface is case specific and doesn't reflect the >> generic nature found in ept->sig_cb. >> > > The previous proposal from Deepak was to essentially expose the normal > tty flags all the way down to the rpmsg driver. But I wasn't sure how > those various flags should be interpreted in the typical rpmsg driver. > > I therefor 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. > > > Unfortunately I don't have any good suggestion for how we could > implement this in the virtio backend at this time, but with the muxing > of all the different channels in the same virtqueue it would be good for > a driver to able to pause the inflow on a specific endpoint, to avoid > stalling other communication when a driver can't receive more messages. yes this feature is something that would improve the rpmsg protocol.this could also be interesting to pause some services on suspend. If I well remember we also spoke about QOS, with possibility to define allocated bandwidth per service. In proposed implementation the signaling is managed in RPMsg backend. This means that the backend has to be aware about the signaling defined in a service. In some other term the signaling is fixed by the backend, and this patchset would fix the signaling for all the backend, right? In this case shouldn't it be part of the rpmsg core? Then to be able to transfer signaling to the remote processor based on RPMsg protocol I suppose that the signaling has to be encapsulated in a RPMsg sent by an endpoint to a remote endpoint. How to do you keep compatibility with the legacy (no flow control)? What about associating a control endpoint with a channel? A channel could contain: - a default data ept (the exiting one) - a default control endpoint (the new one). We could extend the ns announcement mechanism to notify the control endpoint to a remote processor... Regards, Arnaud > > Regards, > Bjorn > >>> /* >>> * match a rpmsg channel with a channel info struct. >>> * this is used to make sure we're not creating rpmsg devices for channels >>> @@ -514,6 +532,9 @@ static int rpmsg_dev_probe(struct device *dev) >>> >>> rpdev->ept = ept; >>> rpdev->src = ept->addr; >>> + >>> + if (rpdrv->signals) >>> + ept->sig_cb = rpdrv->signals; >>> } >>> >>> err = rpdrv->probe(rpdev); >>> diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h >>> index a76c344..dcb2ec1 100644 >>> --- a/drivers/rpmsg/rpmsg_internal.h >>> +++ b/drivers/rpmsg/rpmsg_internal.h >>> @@ -53,6 +53,7 @@ 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 >>> * >>> * Indirection table for the operations that a rpmsg backend should implement. >>> * In addition to @destroy_ept, the backend must at least implement @send and >>> @@ -72,6 +73,7 @@ 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); >>> }; >>> >>> struct device *rpmsg_find_device(struct device *parent, >>> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h >>> index d97dcd0..b805c70 100644 >>> --- a/include/linux/rpmsg.h >>> +++ b/include/linux/rpmsg.h >>> @@ -62,12 +62,14 @@ struct rpmsg_device { >>> }; >>> >>> typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32); >>> +typedef int (*rpmsg_rx_sig_t)(struct rpmsg_device *, void *, u32); >>> >>> /** >>> * 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 >>> + * @sig_cb: rx serial signal handler >>> * @cb_lock: must be taken before accessing/changing @cb >>> * @addr: local rpmsg address >>> * @priv: private data for the driver's use >>> @@ -90,6 +92,7 @@ struct rpmsg_endpoint { >>> struct rpmsg_device *rpdev; >>> struct kref refcount; >>> rpmsg_rx_cb_t cb; >>> + rpmsg_rx_sig_t sig_cb; >>> struct mutex cb_lock; >>> u32 addr; >>> void *priv; >>> @@ -104,6 +107,7 @@ 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 >>> + * @signals: invoked when a serial signal change is received on the channel >>> */ >>> struct rpmsg_driver { >>> struct device_driver drv; >>> @@ -111,6 +115,7 @@ 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 (*signals)(struct rpmsg_device *rpdev, void *priv, u32); >>> }; >>> >>> static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val) >>> @@ -186,6 +191,8 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, >>> __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp, >>> poll_table *wait); >>> >>> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); >>> + >>> #else >>> >>> static inline int rpmsg_register_device(struct rpmsg_device *rpdev) >>> @@ -296,6 +303,14 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, >>> return 0; >>> } >>> >>> +static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); >>> +{ >>> + /* 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 >>>
On Sat, Oct 16, 2021 at 12:01:31AM -0500, Bjorn Andersson wrote: > On Mon 11 Oct 13:02 CDT 2021, Mathieu Poirier wrote: > > > Good day Deepak, > > > > On Thu, Sep 30, 2021 at 09:02:01PM +0530, Deepak Kumar Singh wrote: > > > Some transports like Glink support the state notifications between > > > clients using signals similar to serial protocol signals. > > > Local glink client drivers can send and receive signals to glink > > > clients running on remote processors. > > > > > > Add apis to support sending and receiving of signals by rpmsg clients. > > > > > > Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org> > > > --- > > > 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 9151836..5cae50c 100644 > > > --- a/drivers/rpmsg/rpmsg_core.c > > > +++ b/drivers/rpmsg/rpmsg_core.c > > > @@ -327,6 +327,24 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, > > > } > > > EXPORT_SYMBOL(rpmsg_trysend_offchannel); > > > > > > +/** > > > + * rpmsg_set_flow_control() - sets/clears searial flow control signals > > > + * @ept: the rpmsg endpoint > > > + * @enable: enable or disable serial flow control > > > + * > > > + * Returns 0 on success and an appropriate error value on failure. > > > + */ > > > +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable) > > > +{ > > > + if (WARN_ON(!ept)) > > > + return -EINVAL; > > > + if (!ept->ops->set_flow_control) > > > + return -ENXIO; > > > + > > > + return ept->ops->set_flow_control(ept, enable); > > > +} > > > +EXPORT_SYMBOL(rpmsg_set_flow_control); > > > + > > > > I'm looking at this patchset as the introduction of an out-of-bound > > control interface. But looking at the implementation of the GLINK's > > set_flow_control() the data is sent in-band, making me perplexed about > > introducing a new rpmsg_endpoint_ops for something that could be done > > from user space. Especially when user space is triggering the message > > with an ioctl in patch 3. > > > > GLINK is built around one fifo per processor pair, similar to a > virtqueue. So the signal request is muxed in the same pipe as data > requests, but the signal goes alongside data request, not within them. > I reflected more on this and I can see scenarios where sending control flow messages alongside other data packet could be the only solution. How the signal is implemented is a platform specific choice. I believe the same kind of delivery mechanism implemented by kick() functions would be the best way to go but if that isn't possible then in-band, as suggested in this patchset, is better than nothing. > > Moreover this interface is case specific and doesn't reflect the > > generic nature found in ept->sig_cb. > > > > The previous proposal from Deepak was to essentially expose the normal > tty flags all the way down to the rpmsg driver. But I wasn't sure how > those various flags should be interpreted in the typical rpmsg driver. That is interesting. I was hoping to keep the user level signal interfaces generic and let the drivers do as they please with them. I see your point though and this might be one of those cases where there isn't a right or wrong answer. > > I therefor 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. > This will work for as long as we have a single usecase for it, i.e flow control. I fear things will quickly get out of hands when more messages are needed, hence the idea of keeping things as generic as possible. > > Unfortunately I don't have any good suggestion for how we could > implement this in the virtio backend at this time, but with the muxing > of all the different channels in the same virtqueue it would be good for > a driver to able to pause the inflow on a specific endpoint, to avoid > stalling other communication when a driver can't receive more messages. Humm... For application to remote processor things would work the same as it does for GLINK, whether the communication is done from a rpmsg_driver (as in rpmsg_client_sample.c) or from user space via something like the rpmsg_char.c driver. For remote processor to application processor the interruptions would need to carry the destination address of the endpoint, which might not be possible. All this discussion proves that we really need to think about this before moving forward, especially with Arnaud's ongoing refactoring of the rpmsg_char driver. Thanks, Mathieu > > Regards, > Bjorn > > > > /* > > > * match a rpmsg channel with a channel info struct. > > > * this is used to make sure we're not creating rpmsg devices for channels > > > @@ -514,6 +532,9 @@ static int rpmsg_dev_probe(struct device *dev) > > > > > > rpdev->ept = ept; > > > rpdev->src = ept->addr; > > > + > > > + if (rpdrv->signals) > > > + ept->sig_cb = rpdrv->signals; > > > } > > > > > > err = rpdrv->probe(rpdev); > > > diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h > > > index a76c344..dcb2ec1 100644 > > > --- a/drivers/rpmsg/rpmsg_internal.h > > > +++ b/drivers/rpmsg/rpmsg_internal.h > > > @@ -53,6 +53,7 @@ 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 > > > * > > > * Indirection table for the operations that a rpmsg backend should implement. > > > * In addition to @destroy_ept, the backend must at least implement @send and > > > @@ -72,6 +73,7 @@ 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); > > > }; > > > > > > struct device *rpmsg_find_device(struct device *parent, > > > diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h > > > index d97dcd0..b805c70 100644 > > > --- a/include/linux/rpmsg.h > > > +++ b/include/linux/rpmsg.h > > > @@ -62,12 +62,14 @@ struct rpmsg_device { > > > }; > > > > > > typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32); > > > +typedef int (*rpmsg_rx_sig_t)(struct rpmsg_device *, void *, u32); > > > > > > /** > > > * 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 > > > + * @sig_cb: rx serial signal handler > > > * @cb_lock: must be taken before accessing/changing @cb > > > * @addr: local rpmsg address > > > * @priv: private data for the driver's use > > > @@ -90,6 +92,7 @@ struct rpmsg_endpoint { > > > struct rpmsg_device *rpdev; > > > struct kref refcount; > > > rpmsg_rx_cb_t cb; > > > + rpmsg_rx_sig_t sig_cb; > > > struct mutex cb_lock; > > > u32 addr; > > > void *priv; > > > @@ -104,6 +107,7 @@ 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 > > > + * @signals: invoked when a serial signal change is received on the channel > > > */ > > > struct rpmsg_driver { > > > struct device_driver drv; > > > @@ -111,6 +115,7 @@ 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 (*signals)(struct rpmsg_device *rpdev, void *priv, u32); > > > }; > > > > > > static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val) > > > @@ -186,6 +191,8 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, > > > __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp, > > > poll_table *wait); > > > > > > +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); > > > + > > > #else > > > > > > static inline int rpmsg_register_device(struct rpmsg_device *rpdev) > > > @@ -296,6 +303,14 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, > > > return 0; > > > } > > > > > > +static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); > > > +{ > > > + /* 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 > > >
On Mon 18 Oct 02:00 PDT 2021, Arnaud POULIQUEN wrote: > Hello, > > On 10/16/21 7:01 AM, Bjorn Andersson wrote: > > On Mon 11 Oct 13:02 CDT 2021, Mathieu Poirier wrote: > > > >> Good day Deepak, > >> > >> On Thu, Sep 30, 2021 at 09:02:01PM +0530, Deepak Kumar Singh wrote: > >>> Some transports like Glink support the state notifications between > >>> clients using signals similar to serial protocol signals. > >>> Local glink client drivers can send and receive signals to glink > >>> clients running on remote processors. > >>> > >>> Add apis to support sending and receiving of signals by rpmsg clients. > >>> > >>> Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org> > >>> --- > >>> 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 9151836..5cae50c 100644 > >>> --- a/drivers/rpmsg/rpmsg_core.c > >>> +++ b/drivers/rpmsg/rpmsg_core.c > >>> @@ -327,6 +327,24 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, > >>> } > >>> EXPORT_SYMBOL(rpmsg_trysend_offchannel); > >>> > >>> +/** > >>> + * rpmsg_set_flow_control() - sets/clears searial flow control signals > >>> + * @ept: the rpmsg endpoint > >>> + * @enable: enable or disable serial flow control > >>> + * > >>> + * Returns 0 on success and an appropriate error value on failure. > >>> + */ > >>> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable) > >>> +{ > >>> + if (WARN_ON(!ept)) > >>> + return -EINVAL; > >>> + if (!ept->ops->set_flow_control) > >>> + return -ENXIO; > >>> + > >>> + return ept->ops->set_flow_control(ept, enable); > >>> +} > >>> +EXPORT_SYMBOL(rpmsg_set_flow_control); > >>> + > >> > >> I'm looking at this patchset as the introduction of an out-of-bound > >> control interface. But looking at the implementation of the GLINK's > >> set_flow_control() the data is sent in-band, making me perplexed about > >> introducing a new rpmsg_endpoint_ops for something that could be done > >> from user space. Especially when user space is triggering the message > >> with an ioctl in patch 3. > >> > > > > GLINK is built around one fifo per processor pair, similar to a > > virtqueue. So the signal request is muxed in the same pipe as data > > requests, but the signal goes alongside data request, not within them. > > That would be the equivalent of 2 additional virtqueues in virtio RPmsg backend > - two virtqueues for the stream, > - two virtqueues for the control > Right? > Imagine rather the equivalent of struct rpmsg_hdr carrying a "type" field to specify if the payload is data, channel open, close, open_ack, close_ack and flow control commands. I.e. only "data" will be passed up to the client, the other types of messages are interpreted internally. > > > >> Moreover this interface is case specific and doesn't reflect the > >> generic nature found in ept->sig_cb. > >> > > > > The previous proposal from Deepak was to essentially expose the normal > > tty flags all the way down to the rpmsg driver. But I wasn't sure how > > those various flags should be interpreted in the typical rpmsg driver. > > > > I therefor 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. > > > > > > Unfortunately I don't have any good suggestion for how we could > > implement this in the virtio backend at this time, but with the muxing > > of all the different channels in the same virtqueue it would be good for > > a driver to able to pause the inflow on a specific endpoint, to avoid > > stalling other communication when a driver can't receive more messages. > > yes this feature is something that would improve the rpmsg protocol.this could > also be interesting to pause some services on suspend. > If I well remember we also spoke about QOS, with possibility to define allocated > bandwidth per service. > > In proposed implementation the signaling is managed in RPMsg backend. This means > that the backend has to be aware about the signaling defined in a service. In > some other term the signaling is fixed by the backend, and this patchset would > fix the signaling for all the backend, right? Correct, it's the responsibility of the backend to exchange the flow control signals. > In this case shouldn't it be part of the rpmsg core? > In the case of GLINK flow control is inband control messages, for SMD it's status bits in a fixed located "per-channel information struct". And when we have talked about introducing this for virtio we have toyed with the idea of creating a single control channel to exchange them. So I don't think we have the ability to push the implementation itself into the core, but I think if we define a small set of well defined operations (such as flow on/off), it should be fairly straight forward to implement these in the backend. > Then to be able to transfer signaling to the remote processor based on RPMsg > protocol > I suppose that the signaling has to be encapsulated in a RPMsg sent by an > endpoint to a remote endpoint. > > How to do you keep compatibility with the legacy (no flow control)? > In the case of the two Qualcomm protocols we simply have been ignoring them upstream and Qualcomm have carried downstream patches adding this functionality. This has worked out okay, because in addition to the explicit flow control there's above described data packets are also governed by a sliding window-like flow control. So no single channel is able to completely saturate the link. But for certain applications explicit flow control is necessary. > What about associating a control endpoint with a channel? > A channel could contain: > - a default data ept (the exiting one) > - a default control endpoint (the new one). As both GLINK and SMD has these operations defined in the protocol itself and the firmware is already written, I don't think we can come up with something completely generic. > > We could extend the ns announcement mechanism to notify the control endpoint to > a remote processor... > But I think these are good suggestions for how this functionality could be implemented in the virtio backend. Or one could borrow the design from GLINK and make use of the "reserved" filed in struct rpmsg_hdr? Regards, Bjorn > Regards, > Arnaud > > > > > Regards, > > Bjorn > > > >>> /* > >>> * match a rpmsg channel with a channel info struct. > >>> * this is used to make sure we're not creating rpmsg devices for channels > >>> @@ -514,6 +532,9 @@ static int rpmsg_dev_probe(struct device *dev) > >>> > >>> rpdev->ept = ept; > >>> rpdev->src = ept->addr; > >>> + > >>> + if (rpdrv->signals) > >>> + ept->sig_cb = rpdrv->signals; > >>> } > >>> > >>> err = rpdrv->probe(rpdev); > >>> diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h > >>> index a76c344..dcb2ec1 100644 > >>> --- a/drivers/rpmsg/rpmsg_internal.h > >>> +++ b/drivers/rpmsg/rpmsg_internal.h > >>> @@ -53,6 +53,7 @@ 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 > >>> * > >>> * Indirection table for the operations that a rpmsg backend should implement. > >>> * In addition to @destroy_ept, the backend must at least implement @send and > >>> @@ -72,6 +73,7 @@ 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); > >>> }; > >>> > >>> struct device *rpmsg_find_device(struct device *parent, > >>> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h > >>> index d97dcd0..b805c70 100644 > >>> --- a/include/linux/rpmsg.h > >>> +++ b/include/linux/rpmsg.h > >>> @@ -62,12 +62,14 @@ struct rpmsg_device { > >>> }; > >>> > >>> typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32); > >>> +typedef int (*rpmsg_rx_sig_t)(struct rpmsg_device *, void *, u32); > >>> > >>> /** > >>> * 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 > >>> + * @sig_cb: rx serial signal handler > >>> * @cb_lock: must be taken before accessing/changing @cb > >>> * @addr: local rpmsg address > >>> * @priv: private data for the driver's use > >>> @@ -90,6 +92,7 @@ struct rpmsg_endpoint { > >>> struct rpmsg_device *rpdev; > >>> struct kref refcount; > >>> rpmsg_rx_cb_t cb; > >>> + rpmsg_rx_sig_t sig_cb; > >>> struct mutex cb_lock; > >>> u32 addr; > >>> void *priv; > >>> @@ -104,6 +107,7 @@ 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 > >>> + * @signals: invoked when a serial signal change is received on the channel > >>> */ > >>> struct rpmsg_driver { > >>> struct device_driver drv; > >>> @@ -111,6 +115,7 @@ 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 (*signals)(struct rpmsg_device *rpdev, void *priv, u32); > >>> }; > >>> > >>> static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val) > >>> @@ -186,6 +191,8 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, > >>> __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp, > >>> poll_table *wait); > >>> > >>> +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); > >>> + > >>> #else > >>> > >>> static inline int rpmsg_register_device(struct rpmsg_device *rpdev) > >>> @@ -296,6 +303,14 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, > >>> return 0; > >>> } > >>> > >>> +static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); > >>> +{ > >>> + /* 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 > >>>
On Mon 18 Oct 10:52 PDT 2021, Mathieu Poirier wrote: > On Sat, Oct 16, 2021 at 12:01:31AM -0500, Bjorn Andersson wrote: > > On Mon 11 Oct 13:02 CDT 2021, Mathieu Poirier wrote: > > > > > Good day Deepak, > > > > > > On Thu, Sep 30, 2021 at 09:02:01PM +0530, Deepak Kumar Singh wrote: > > > > Some transports like Glink support the state notifications between > > > > clients using signals similar to serial protocol signals. > > > > Local glink client drivers can send and receive signals to glink > > > > clients running on remote processors. > > > > > > > > Add apis to support sending and receiving of signals by rpmsg clients. > > > > > > > > Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org> > > > > --- > > > > 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 9151836..5cae50c 100644 > > > > --- a/drivers/rpmsg/rpmsg_core.c > > > > +++ b/drivers/rpmsg/rpmsg_core.c > > > > @@ -327,6 +327,24 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, > > > > } > > > > EXPORT_SYMBOL(rpmsg_trysend_offchannel); > > > > > > > > +/** > > > > + * rpmsg_set_flow_control() - sets/clears searial flow control signals > > > > + * @ept: the rpmsg endpoint > > > > + * @enable: enable or disable serial flow control > > > > + * > > > > + * Returns 0 on success and an appropriate error value on failure. > > > > + */ > > > > +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable) > > > > +{ > > > > + if (WARN_ON(!ept)) > > > > + return -EINVAL; > > > > + if (!ept->ops->set_flow_control) > > > > + return -ENXIO; > > > > + > > > > + return ept->ops->set_flow_control(ept, enable); > > > > +} > > > > +EXPORT_SYMBOL(rpmsg_set_flow_control); > > > > + > > > > > > I'm looking at this patchset as the introduction of an out-of-bound > > > control interface. But looking at the implementation of the GLINK's > > > set_flow_control() the data is sent in-band, making me perplexed about > > > introducing a new rpmsg_endpoint_ops for something that could be done > > > from user space. Especially when user space is triggering the message > > > with an ioctl in patch 3. > > > > > > > GLINK is built around one fifo per processor pair, similar to a > > virtqueue. So the signal request is muxed in the same pipe as data > > requests, but the signal goes alongside data request, not within them. > > > > I reflected more on this and I can see scenarios where sending control flow > messages alongside other data packet could be the only solution. How the signal > is implemented is a platform specific choice. I believe the same kind of > delivery mechanism implemented by kick() functions would be the best way to go > but if that isn't possible then in-band, as suggested in this patchset, is > better than nothing. > > > > Moreover this interface is case specific and doesn't reflect the > > > generic nature found in ept->sig_cb. > > > > > > > The previous proposal from Deepak was to essentially expose the normal > > tty flags all the way down to the rpmsg driver. But I wasn't sure how > > those various flags should be interpreted in the typical rpmsg driver. > > That is interesting. I was hoping to keep the user level signal interfaces > generic and let the drivers do as they please with them. I see your point > though and this might be one of those cases where there isn't a right or wrong > answer. > I'm definitely in favor of something generic, my objection was simply to inherit the tty interface as that generic thing. If nothing else I myself have a hard time understanding the actual meaning of those bits and tend to have to look them up every time. > > > > I therefor 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. > > > > This will work for as long as we have a single usecase for it, i.e flow control. > I fear things will quickly get out of hands when more messages are needed, hence > the idea of keeping things as generic as possible. > Do you have any other types of signals in mind? > > > > Unfortunately I don't have any good suggestion for how we could > > implement this in the virtio backend at this time, but with the muxing > > of all the different channels in the same virtqueue it would be good for > > a driver to able to pause the inflow on a specific endpoint, to avoid > > stalling other communication when a driver can't receive more messages. > > Humm... > > For application to remote processor things would work the same as it does for > GLINK, whether the communication is done from a rpmsg_driver (as in > rpmsg_client_sample.c) or from user space via something like the rpmsg_char.c > driver. > > For remote processor to application processor the interruptions would need to > carry the destination address of the endpoint, which might not be possible. > > All this discussion proves that we really need to think about this before moving > forward, especially with Arnaud's ongoing refactoring of the rpmsg_char driver. > The concept of flow control comes pretty natural in both GLINK and SMD, given that an endpoint is the local representation of an established link to an entity on the other side - while in virtio rpmsg endpoints doesn't really have a state and a limited sense of there being something on the other side. So I agree that flow controlling in virtio rpmsg could have unforeseen consequences e.g. by a service being blocked forever because it's waiting for "flow resume" from an endpoint that never existed. But I believe the impact of this is that we need to accept that there will be cases where the flow control requests can't be fulfilled; such as a loose rpmsg_endpoint without a predefined dst address or when communicating with a remote that predates the protocol extensions that will be necessary. Regards, Bjorn > Thanks, > Mathieu > > > > > Regards, > > Bjorn > > > > > > /* > > > > * match a rpmsg channel with a channel info struct. > > > > * this is used to make sure we're not creating rpmsg devices for channels > > > > @@ -514,6 +532,9 @@ static int rpmsg_dev_probe(struct device *dev) > > > > > > > > rpdev->ept = ept; > > > > rpdev->src = ept->addr; > > > > + > > > > + if (rpdrv->signals) > > > > + ept->sig_cb = rpdrv->signals; > > > > } > > > > > > > > err = rpdrv->probe(rpdev); > > > > diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h > > > > index a76c344..dcb2ec1 100644 > > > > --- a/drivers/rpmsg/rpmsg_internal.h > > > > +++ b/drivers/rpmsg/rpmsg_internal.h > > > > @@ -53,6 +53,7 @@ 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 > > > > * > > > > * Indirection table for the operations that a rpmsg backend should implement. > > > > * In addition to @destroy_ept, the backend must at least implement @send and > > > > @@ -72,6 +73,7 @@ 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); > > > > }; > > > > > > > > struct device *rpmsg_find_device(struct device *parent, > > > > diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h > > > > index d97dcd0..b805c70 100644 > > > > --- a/include/linux/rpmsg.h > > > > +++ b/include/linux/rpmsg.h > > > > @@ -62,12 +62,14 @@ struct rpmsg_device { > > > > }; > > > > > > > > typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32); > > > > +typedef int (*rpmsg_rx_sig_t)(struct rpmsg_device *, void *, u32); > > > > > > > > /** > > > > * 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 > > > > + * @sig_cb: rx serial signal handler > > > > * @cb_lock: must be taken before accessing/changing @cb > > > > * @addr: local rpmsg address > > > > * @priv: private data for the driver's use > > > > @@ -90,6 +92,7 @@ struct rpmsg_endpoint { > > > > struct rpmsg_device *rpdev; > > > > struct kref refcount; > > > > rpmsg_rx_cb_t cb; > > > > + rpmsg_rx_sig_t sig_cb; > > > > struct mutex cb_lock; > > > > u32 addr; > > > > void *priv; > > > > @@ -104,6 +107,7 @@ 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 > > > > + * @signals: invoked when a serial signal change is received on the channel > > > > */ > > > > struct rpmsg_driver { > > > > struct device_driver drv; > > > > @@ -111,6 +115,7 @@ 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 (*signals)(struct rpmsg_device *rpdev, void *priv, u32); > > > > }; > > > > > > > > static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val) > > > > @@ -186,6 +191,8 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, > > > > __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp, > > > > poll_table *wait); > > > > > > > > +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); > > > > + > > > > #else > > > > > > > > static inline int rpmsg_register_device(struct rpmsg_device *rpdev) > > > > @@ -296,6 +303,14 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, > > > > return 0; > > > > } > > > > > > > > +static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); > > > > +{ > > > > + /* 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 > > > >
On Mon, Oct 18, 2021 at 08:05:00PM -0700, Bjorn Andersson wrote: > On Mon 18 Oct 10:52 PDT 2021, Mathieu Poirier wrote: > > > On Sat, Oct 16, 2021 at 12:01:31AM -0500, Bjorn Andersson wrote: > > > On Mon 11 Oct 13:02 CDT 2021, Mathieu Poirier wrote: > > > > > > > Good day Deepak, > > > > > > > > On Thu, Sep 30, 2021 at 09:02:01PM +0530, Deepak Kumar Singh wrote: > > > > > Some transports like Glink support the state notifications between > > > > > clients using signals similar to serial protocol signals. > > > > > Local glink client drivers can send and receive signals to glink > > > > > clients running on remote processors. > > > > > > > > > > Add apis to support sending and receiving of signals by rpmsg clients. > > > > > > > > > > Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org> > > > > > --- > > > > > 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 9151836..5cae50c 100644 > > > > > --- a/drivers/rpmsg/rpmsg_core.c > > > > > +++ b/drivers/rpmsg/rpmsg_core.c > > > > > @@ -327,6 +327,24 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, > > > > > } > > > > > EXPORT_SYMBOL(rpmsg_trysend_offchannel); > > > > > > > > > > +/** > > > > > + * rpmsg_set_flow_control() - sets/clears searial flow control signals > > > > > + * @ept: the rpmsg endpoint > > > > > + * @enable: enable or disable serial flow control > > > > > + * > > > > > + * Returns 0 on success and an appropriate error value on failure. > > > > > + */ > > > > > +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable) > > > > > +{ > > > > > + if (WARN_ON(!ept)) > > > > > + return -EINVAL; > > > > > + if (!ept->ops->set_flow_control) > > > > > + return -ENXIO; > > > > > + > > > > > + return ept->ops->set_flow_control(ept, enable); > > > > > +} > > > > > +EXPORT_SYMBOL(rpmsg_set_flow_control); > > > > > + > > > > > > > > I'm looking at this patchset as the introduction of an out-of-bound > > > > control interface. But looking at the implementation of the GLINK's > > > > set_flow_control() the data is sent in-band, making me perplexed about > > > > introducing a new rpmsg_endpoint_ops for something that could be done > > > > from user space. Especially when user space is triggering the message > > > > with an ioctl in patch 3. > > > > > > > > > > GLINK is built around one fifo per processor pair, similar to a > > > virtqueue. So the signal request is muxed in the same pipe as data > > > requests, but the signal goes alongside data request, not within them. > > > > > > > I reflected more on this and I can see scenarios where sending control flow > > messages alongside other data packet could be the only solution. How the signal > > is implemented is a platform specific choice. I believe the same kind of > > delivery mechanism implemented by kick() functions would be the best way to go > > but if that isn't possible then in-band, as suggested in this patchset, is > > better than nothing. > > > > > > Moreover this interface is case specific and doesn't reflect the > > > > generic nature found in ept->sig_cb. > > > > > > > > > > The previous proposal from Deepak was to essentially expose the normal > > > tty flags all the way down to the rpmsg driver. But I wasn't sure how > > > those various flags should be interpreted in the typical rpmsg driver. > > > > That is interesting. I was hoping to keep the user level signal interfaces > > generic and let the drivers do as they please with them. I see your point > > though and this might be one of those cases where there isn't a right or wrong > > answer. > > > > I'm definitely in favor of something generic, my objection was simply to > inherit the tty interface as that generic thing. > > If nothing else I myself have a hard time understanding the actual > meaning of those bits and tend to have to look them up every time. > > > > > > > I therefor 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. > > > > > > > This will work for as long as we have a single usecase for it, i.e flow control. > > I fear things will quickly get out of hands when more messages are needed, hence > > the idea of keeping things as generic as possible. > > > > Do you have any other types of signals in mind? > I currently don't have anything in mind but I know it will happen at one point, hence hoping to proceed differently than having one ioctl per signal. > > > > > > Unfortunately I don't have any good suggestion for how we could > > > implement this in the virtio backend at this time, but with the muxing > > > of all the different channels in the same virtqueue it would be good for > > > a driver to able to pause the inflow on a specific endpoint, to avoid > > > stalling other communication when a driver can't receive more messages. > > > > Humm... > > > > For application to remote processor things would work the same as it does for > > GLINK, whether the communication is done from a rpmsg_driver (as in > > rpmsg_client_sample.c) or from user space via something like the rpmsg_char.c > > driver. > > > > For remote processor to application processor the interruptions would need to > > carry the destination address of the endpoint, which might not be possible. > > > > All this discussion proves that we really need to think about this before moving > > forward, especially with Arnaud's ongoing refactoring of the rpmsg_char driver. > > > > The concept of flow control comes pretty natural in both GLINK and SMD, > given that an endpoint is the local representation of an established > link to an entity on the other side - while in virtio rpmsg endpoints > doesn't really have a state and a limited sense of there being something > on the other side. > > So I agree that flow controlling in virtio rpmsg could have unforeseen > consequences e.g. by a service being blocked forever because it's > waiting for "flow resume" from an endpoint that never existed. > > But I believe the impact of this is that we need to accept that there > will be cases where the flow control requests can't be fulfilled; such > as a loose rpmsg_endpoint without a predefined dst address or when > communicating with a remote that predates the protocol extensions that > will be necessary. > > Regards, > Bjorn > > > Thanks, > > Mathieu > > > > > > > > Regards, > > > Bjorn > > > > > > > > /* > > > > > * match a rpmsg channel with a channel info struct. > > > > > * this is used to make sure we're not creating rpmsg devices for channels > > > > > @@ -514,6 +532,9 @@ static int rpmsg_dev_probe(struct device *dev) > > > > > > > > > > rpdev->ept = ept; > > > > > rpdev->src = ept->addr; > > > > > + > > > > > + if (rpdrv->signals) > > > > > + ept->sig_cb = rpdrv->signals; > > > > > } > > > > > > > > > > err = rpdrv->probe(rpdev); > > > > > diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h > > > > > index a76c344..dcb2ec1 100644 > > > > > --- a/drivers/rpmsg/rpmsg_internal.h > > > > > +++ b/drivers/rpmsg/rpmsg_internal.h > > > > > @@ -53,6 +53,7 @@ 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 > > > > > * > > > > > * Indirection table for the operations that a rpmsg backend should implement. > > > > > * In addition to @destroy_ept, the backend must at least implement @send and > > > > > @@ -72,6 +73,7 @@ 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); > > > > > }; > > > > > > > > > > struct device *rpmsg_find_device(struct device *parent, > > > > > diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h > > > > > index d97dcd0..b805c70 100644 > > > > > --- a/include/linux/rpmsg.h > > > > > +++ b/include/linux/rpmsg.h > > > > > @@ -62,12 +62,14 @@ struct rpmsg_device { > > > > > }; > > > > > > > > > > typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32); > > > > > +typedef int (*rpmsg_rx_sig_t)(struct rpmsg_device *, void *, u32); > > > > > > > > > > /** > > > > > * 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 > > > > > + * @sig_cb: rx serial signal handler > > > > > * @cb_lock: must be taken before accessing/changing @cb > > > > > * @addr: local rpmsg address > > > > > * @priv: private data for the driver's use > > > > > @@ -90,6 +92,7 @@ struct rpmsg_endpoint { > > > > > struct rpmsg_device *rpdev; > > > > > struct kref refcount; > > > > > rpmsg_rx_cb_t cb; > > > > > + rpmsg_rx_sig_t sig_cb; > > > > > struct mutex cb_lock; > > > > > u32 addr; > > > > > void *priv; > > > > > @@ -104,6 +107,7 @@ 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 > > > > > + * @signals: invoked when a serial signal change is received on the channel > > > > > */ > > > > > struct rpmsg_driver { > > > > > struct device_driver drv; > > > > > @@ -111,6 +115,7 @@ 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 (*signals)(struct rpmsg_device *rpdev, void *priv, u32); > > > > > }; > > > > > > > > > > static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val) > > > > > @@ -186,6 +191,8 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, > > > > > __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp, > > > > > poll_table *wait); > > > > > > > > > > +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); > > > > > + > > > > > #else > > > > > > > > > > static inline int rpmsg_register_device(struct rpmsg_device *rpdev) > > > > > @@ -296,6 +303,14 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, > > > > > return 0; > > > > > } > > > > > > > > > > +static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); > > > > > +{ > > > > > + /* 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 > > > > >
Hi Deepak,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on linus/master]
[also build test ERROR on v5.15]
[cannot apply to next-20211106]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Deepak-Kumar-Singh/rpmsg-core-Add-signal-API-support/20211001-003225
base: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 02d5e016800d082058b3d3b7c3ede136cdc6ddcb
config: arm-randconfig-c002-20211001 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 962e503cc8bc411f7523cc393acae8aae425b1c4)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# install arm cross compiling tool for clang build
# apt-get install binutils-arm-linux-gnueabi
# https://github.com/0day-ci/linux/commit/b1743368f111ecd56fb976dd6dea19d041e3ad4e
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Deepak-Kumar-Singh/rpmsg-core-Add-signal-API-support/20211001-003225
git checkout b1743368f111ecd56fb976dd6dea19d041e3ad4e
# save the attached .config to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash drivers/bluetooth/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
In file included from drivers/bluetooth/btqcomsmd.c:9:
>> include/linux/rpmsg.h:307:1: error: expected identifier or '('
{
^
1 error generated.
vim +307 include/linux/rpmsg.h
305
306 static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable);
> 307 {
308 /* This shouldn't be possible */
309 WARN_ON(1);
310
311 return -ENXIO;
312 }
313
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Hi Deepak,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on linus/master]
[also build test ERROR on v5.15]
[cannot apply to next-20211109]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Deepak-Kumar-Singh/rpmsg-core-Add-signal-API-support/20211001-003225
base: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 02d5e016800d082058b3d3b7c3ede136cdc6ddcb
config: arm-randconfig-c002-20211001 (attached as .config)
compiler: arm-linux-gnueabi-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/0day-ci/linux/commit/b1743368f111ecd56fb976dd6dea19d041e3ad4e
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Deepak-Kumar-Singh/rpmsg-core-Add-signal-API-support/20211001-003225
git checkout b1743368f111ecd56fb976dd6dea19d041e3ad4e
# save the attached .config to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=arm SHELL=/bin/bash drivers/bluetooth/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
In file included from drivers/bluetooth/btqcomsmd.c:9:
>> include/linux/rpmsg.h:307:1: error: expected identifier or '(' before '{' token
307 | {
| ^
In file included from drivers/bluetooth/btqcomsmd.c:9:
include/linux/rpmsg.h:306:19: warning: 'rpmsg_set_flow_control' declared 'static' but never defined [-Wunused-function]
306 | static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable);
| ^~~~~~~~~~~~~~~~~~~~~~
vim +307 include/linux/rpmsg.h
305
306 static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable);
> 307 {
308 /* This shouldn't be possible */
309 WARN_ON(1);
310
311 return -ENXIO;
312 }
313
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c index 9151836..5cae50c 100644 --- a/drivers/rpmsg/rpmsg_core.c +++ b/drivers/rpmsg/rpmsg_core.c @@ -327,6 +327,24 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, } EXPORT_SYMBOL(rpmsg_trysend_offchannel); +/** + * rpmsg_set_flow_control() - sets/clears searial flow control signals + * @ept: the rpmsg endpoint + * @enable: enable or disable serial flow control + * + * Returns 0 on success and an appropriate error value on failure. + */ +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable) +{ + if (WARN_ON(!ept)) + return -EINVAL; + if (!ept->ops->set_flow_control) + return -ENXIO; + + return ept->ops->set_flow_control(ept, enable); +} +EXPORT_SYMBOL(rpmsg_set_flow_control); + /* * match a rpmsg channel with a channel info struct. * this is used to make sure we're not creating rpmsg devices for channels @@ -514,6 +532,9 @@ static int rpmsg_dev_probe(struct device *dev) rpdev->ept = ept; rpdev->src = ept->addr; + + if (rpdrv->signals) + ept->sig_cb = rpdrv->signals; } err = rpdrv->probe(rpdev); diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h index a76c344..dcb2ec1 100644 --- a/drivers/rpmsg/rpmsg_internal.h +++ b/drivers/rpmsg/rpmsg_internal.h @@ -53,6 +53,7 @@ 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 * * Indirection table for the operations that a rpmsg backend should implement. * In addition to @destroy_ept, the backend must at least implement @send and @@ -72,6 +73,7 @@ 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); }; struct device *rpmsg_find_device(struct device *parent, diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h index d97dcd0..b805c70 100644 --- a/include/linux/rpmsg.h +++ b/include/linux/rpmsg.h @@ -62,12 +62,14 @@ struct rpmsg_device { }; typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32); +typedef int (*rpmsg_rx_sig_t)(struct rpmsg_device *, void *, u32); /** * 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 + * @sig_cb: rx serial signal handler * @cb_lock: must be taken before accessing/changing @cb * @addr: local rpmsg address * @priv: private data for the driver's use @@ -90,6 +92,7 @@ struct rpmsg_endpoint { struct rpmsg_device *rpdev; struct kref refcount; rpmsg_rx_cb_t cb; + rpmsg_rx_sig_t sig_cb; struct mutex cb_lock; u32 addr; void *priv; @@ -104,6 +107,7 @@ 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 + * @signals: invoked when a serial signal change is received on the channel */ struct rpmsg_driver { struct device_driver drv; @@ -111,6 +115,7 @@ 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 (*signals)(struct rpmsg_device *rpdev, void *priv, u32); }; static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val) @@ -186,6 +191,8 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp, poll_table *wait); +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); + #else static inline int rpmsg_register_device(struct rpmsg_device *rpdev) @@ -296,6 +303,14 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, return 0; } +static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable); +{ + /* 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 */
Some transports like Glink support the state notifications between clients using signals similar to serial protocol signals. Local glink client drivers can send and receive signals to glink clients running on remote processors. Add apis to support sending and receiving of signals by rpmsg clients. Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org> --- drivers/rpmsg/rpmsg_core.c | 21 +++++++++++++++++++++ drivers/rpmsg/rpmsg_internal.h | 2 ++ include/linux/rpmsg.h | 15 +++++++++++++++ 3 files changed, 38 insertions(+)