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Subject[PATCH v6 08/13] firmware: arm_scmi: Enable notification core
Initialize and enable SCMI Notifications core support during bus/driver
probe phase, so that protocols can start registering their supported
events during their initialization.

Reviewed-by: Jonathan Cameron <>
Signed-off-by: Cristian Marussi <>
V3 --> V4
- simplified core initialization: protocols events' registrations is now
disjoint from users' callback registrations, so that events' generation
can be enabled earlier for registered events and delayed for pending
ones in order to support deferred (or missing) protocol initialization
V2 --> V3
- reviewed core initialization: all implemented protocols must complete
their protocol-events registration phases before notifications can be
enabled as a whole; in the meantime any user's callback registration
requests possibly issued while the notifications were not enabled
remain pending: a dedicated worker completes the handlers registration
once all protocols have been initialized.
NOTE THAT this can lead to ISSUES with late inserted or missing SCMI
modules (i.e. for protocols defined in the DT and implemented by the
platform but lazily loaded or not loaded at all.), since in these
scenarios notifications dispatching will be enabled later or never.
- reviewed core exit: protocol users (devices) are accounted on probe/
remove, and protocols' events are unregisteredonce last user go
(can happen only at shutdown)
V1 --> V2
- added timestamping
- moved notification init/exit and using devres
drivers/firmware/arm_scmi/driver.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 868cc36a07c9..5c43d82e3260 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -26,6 +26,7 @@
#include <linux/slab.h>

#include "common.h"
+#include "notify.h"

#include <trace/events/scmi.h>
@@ -204,11 +205,13 @@ __scmi_xfer_put(struct scmi_xfers_info *minfo, struct scmi_xfer *xfer)

static void scmi_handle_notification(struct scmi_chan_info *cinfo, u32 msg_hdr)
+ u64 ts;
struct scmi_xfer *xfer;
struct device *dev = cinfo->dev;
struct scmi_info *info = handle_to_scmi_info(cinfo->handle);
struct scmi_xfers_info *minfo = &info->rx_minfo;

+ ts = ktime_get_boottime_ns();
xfer = scmi_xfer_get(cinfo->handle, minfo);
if (IS_ERR(xfer)) {
dev_err(dev, "failed to get free message slot (%ld)\n",
@@ -221,6 +224,8 @@ static void scmi_handle_notification(struct scmi_chan_info *cinfo, u32 msg_hdr)
scmi_dump_header_dbg(dev, &xfer->hdr);
info->desc->ops->fetch_notification(cinfo, info->desc->max_msg_size,
+ scmi_notify(cinfo->handle, xfer->hdr.protocol_id,
+ xfer->, xfer->rx.buf, xfer->rx.len, ts);

trace_scmi_rx_done(xfer->transfer_id, xfer->,
xfer->hdr.protocol_id, xfer->hdr.seq,
@@ -771,6 +776,9 @@ static int scmi_probe(struct platform_device *pdev)
if (ret)
return ret;

+ if (scmi_notification_init(handle))
+ dev_err(dev, "SCMI Notifications NOT available.\n");
ret = scmi_base_protocol_init(handle);
if (ret) {
dev_err(dev, "unable to communicate with SCMI(%d)\n", ret);
@@ -813,6 +821,8 @@ static int scmi_remove(struct platform_device *pdev)
struct scmi_info *info = platform_get_drvdata(pdev);
struct idr *idr = &info->tx_idr;

+ scmi_notification_exit(&info->handle);
if (info->users)
ret = -EBUSY;
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