linux-surface/patches/5.13/0006-surface-sam.patch

From 52b09d02fc983b42affcb726c94401739e45a2e5 Mon Sep 17 00:00:00 2001
From: Maximilian Luz <luzmaximilian@gmail.com>
Date: Sun, 23 May 2021 14:09:42 +0200
Subject: [PATCH] platform/surface: aggregator_registry: Consolidate node
 groups for 5th- and 6th-gen devices

5th- and 6th-generation Surface devices have all SAM clients defined in
ACPI, except for the platform profile/performance mode which his handled
via the WSID (Windows Surface Integration Device). Thus, the node groups
for those devices are the same and we can just use a single one instead
of re-defining the same one over and over again.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Patchset: surface-sam
---
 .../surface/surface_aggregator_registry.c     | 47 +++++--------------
 1 file changed, 12 insertions(+), 35 deletions(-)

diff --git a/drivers/platform/surface/surface_aggregator_registry.c b/drivers/platform/surface/surface_aggregator_registry.c
index ef83461fa536..4428c4330229 100644
--- a/drivers/platform/surface/surface_aggregator_registry.c
+++ b/drivers/platform/surface/surface_aggregator_registry.c
@@ -119,8 +119,13 @@ static const struct software_node ssam_node_hid_base_iid6 = {
 	.parent = &ssam_node_hub_base,
 };
 
-/* Devices for Surface Book 2. */
-static const struct software_node *ssam_node_group_sb2[] = {
+/*
+ * Devices for 5th- and 6th-generations models:
+ * - Surface Book 2,
+ * - Surface Laptop 1 and 2,
+ * - Surface Pro 5 and 6.
+ */
+static const struct software_node *ssam_node_group_gen5[] = {
 	&ssam_node_root,
 	&ssam_node_tmp_pprof,
 	NULL,
@@ -142,20 +147,6 @@ static const struct software_node *ssam_node_group_sb3[] = {
 	NULL,
 };
 
-/* Devices for Surface Laptop 1. */
-static const struct software_node *ssam_node_group_sl1[] = {
-	&ssam_node_root,
-	&ssam_node_tmp_pprof,
-	NULL,
-};
-
-/* Devices for Surface Laptop 2. */
-static const struct software_node *ssam_node_group_sl2[] = {
-	&ssam_node_root,
-	&ssam_node_tmp_pprof,
-	NULL,
-};
-
 /* Devices for Surface Laptop 3 and 4. */
 static const struct software_node *ssam_node_group_sl3[] = {
 	&ssam_node_root,
@@ -177,20 +168,6 @@ static const struct software_node *ssam_node_group_slg1[] = {
 	NULL,
 };
 
-/* Devices for Surface Pro 5. */
-static const struct software_node *ssam_node_group_sp5[] = {
-	&ssam_node_root,
-	&ssam_node_tmp_pprof,
-	NULL,
-};
-
-/* Devices for Surface Pro 6. */
-static const struct software_node *ssam_node_group_sp6[] = {
-	&ssam_node_root,
-	&ssam_node_tmp_pprof,
-	NULL,
-};
-
 /* Devices for Surface Pro 7 and Surface Pro 7+. */
 static const struct software_node *ssam_node_group_sp7[] = {
 	&ssam_node_root,
@@ -495,10 +472,10 @@ static struct ssam_device_driver ssam_base_hub_driver = {
 
 static const struct acpi_device_id ssam_platform_hub_match[] = {
 	/* Surface Pro 4, 5, and 6 (OMBR < 0x10) */
-	{ "MSHW0081", (unsigned long)ssam_node_group_sp5 },
+	{ "MSHW0081", (unsigned long)ssam_node_group_gen5 },
 
 	/* Surface Pro 6 (OMBR >= 0x10) */
-	{ "MSHW0111", (unsigned long)ssam_node_group_sp6 },
+	{ "MSHW0111", (unsigned long)ssam_node_group_gen5 },
 
 	/* Surface Pro 7 */
 	{ "MSHW0116", (unsigned long)ssam_node_group_sp7 },
@@ -507,16 +484,16 @@ static const struct acpi_device_id ssam_platform_hub_match[] = {
 	{ "MSHW0119", (unsigned long)ssam_node_group_sp7 },
 
 	/* Surface Book 2 */
-	{ "MSHW0107", (unsigned long)ssam_node_group_sb2 },
+	{ "MSHW0107", (unsigned long)ssam_node_group_gen5 },
 
 	/* Surface Book 3 */
 	{ "MSHW0117", (unsigned long)ssam_node_group_sb3 },
 
 	/* Surface Laptop 1 */
-	{ "MSHW0086", (unsigned long)ssam_node_group_sl1 },
+	{ "MSHW0086", (unsigned long)ssam_node_group_gen5 },
 
 	/* Surface Laptop 2 */
-	{ "MSHW0112", (unsigned long)ssam_node_group_sl2 },
+	{ "MSHW0112", (unsigned long)ssam_node_group_gen5 },
 
 	/* Surface Laptop 3 (13", Intel) */
 	{ "MSHW0114", (unsigned long)ssam_node_group_sl3 },
-- 
2.33.0

From db138a7cd760f2b0ca210dbfb44affb3df07337f Mon Sep 17 00:00:00 2001
From: Maximilian Luz <luzmaximilian@gmail.com>
Date: Fri, 4 Jun 2021 15:47:49 +0200
Subject: [PATCH] platform/surface: aggregator: Allow registering notifiers
 without enabling events

Currently, each SSAM event notifier is directly tied to one group of
events. This makes sense as registering a notifier will automatically
take care of enabling the corresponding event group and normally drivers
only need notifications for a very limited number of events, associated
with different callbacks for each group.

However, there are rare cases, especially for debugging, when we want to
get notifications for a whole event target category instead of just a
single group of events in that category. Registering multiple notifiers,
i.e. one per group, may be infeasible due to two issues: a) we might not
know every event enable/disable specification as some events are
auto-enabled by the EC and b) forwarding this to the same callback will
lead to duplicate events as we might not know the full event
specification to perform the appropriate filtering.

This commit introduces observer-notifiers, which are notifiers that are
not tied to a specific event group and do not attempt to manage any
events. In other words, they can be registered without enabling any
event group or incrementing the corresponding reference count and just
act as silent observers, listening to all currently/previously enabled
events based on their match-specification.

Essentially, this allows us to register one single notifier for a full
event target category, meaning that we can process all events of that
target category in a single callback without duplication. Specifically,
this will be used in the cdev debug interface to forward events to
user-space via a device file from which the events can be read.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210604134755.535590-2-luzmaximilian@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Patchset: surface-sam
---
 .../platform/surface/aggregator/controller.c  | 69 +++++++++++--------
 include/linux/surface_aggregator/controller.h | 17 +++++
 2 files changed, 58 insertions(+), 28 deletions(-)

diff --git a/drivers/platform/surface/aggregator/controller.c b/drivers/platform/surface/aggregator/controller.c
index a06964aa96e7..cd3a6b77f48d 100644
--- a/drivers/platform/surface/aggregator/controller.c
+++ b/drivers/platform/surface/aggregator/controller.c
@@ -2127,9 +2127,15 @@ int ssam_ctrl_notif_d0_entry(struct ssam_controller *ctrl)
  * @ctrl: The controller to register the notifier on.
  * @n:    The event notifier to register.
  *
- * Register an event notifier and increment the usage counter of the
- * associated SAM event. If the event was previously not enabled, it will be
- * enabled during this call.
+ * Register an event notifier. Increment the usage counter of the associated
+ * SAM event if the notifier is not marked as an observer. If the event is not
+ * marked as an observer and is currently not enabled, it will be enabled
+ * during this call. If the notifier is marked as an observer, no attempt will
+ * be made at enabling any event and no reference count will be modified.
+ *
+ * Notifiers marked as observers do not need to be associated with one specific
+ * event, i.e. as long as no event matching is performed, only the event target
+ * category needs to be set.
  *
  * Return: Returns zero on success, %-ENOSPC if there have already been
  * %INT_MAX notifiers for the event ID/type associated with the notifier block
@@ -2138,11 +2144,10 @@ int ssam_ctrl_notif_d0_entry(struct ssam_controller *ctrl)
  * for the specific associated event, returns the status of the event-enable
  * EC-command.
  */
-int ssam_notifier_register(struct ssam_controller *ctrl,
-			   struct ssam_event_notifier *n)
+int ssam_notifier_register(struct ssam_controller *ctrl, struct ssam_event_notifier *n)
 {
 	u16 rqid = ssh_tc_to_rqid(n->event.id.target_category);
-	struct ssam_nf_refcount_entry *entry;
+	struct ssam_nf_refcount_entry *entry = NULL;
 	struct ssam_nf_head *nf_head;
 	struct ssam_nf *nf;
 	int status;
@@ -2155,29 +2160,32 @@ int ssam_notifier_register(struct ssam_controller *ctrl,
 
 	mutex_lock(&nf->lock);
 
-	entry = ssam_nf_refcount_inc(nf, n->event.reg, n->event.id);
-	if (IS_ERR(entry)) {
-		mutex_unlock(&nf->lock);
-		return PTR_ERR(entry);
-	}
+	if (!(n->flags & SSAM_EVENT_NOTIFIER_OBSERVER)) {
+		entry = ssam_nf_refcount_inc(nf, n->event.reg, n->event.id);
+		if (IS_ERR(entry)) {
+			mutex_unlock(&nf->lock);
+			return PTR_ERR(entry);
+		}
 
-	ssam_dbg(ctrl, "enabling event (reg: %#04x, tc: %#04x, iid: %#04x, rc: %d)\n",
-		 n->event.reg.target_category, n->event.id.target_category,
-		 n->event.id.instance, entry->refcount);
+		ssam_dbg(ctrl, "enabling event (reg: %#04x, tc: %#04x, iid: %#04x, rc: %d)\n",
+			 n->event.reg.target_category, n->event.id.target_category,
+			 n->event.id.instance, entry->refcount);
+	}
 
 	status = ssam_nfblk_insert(nf_head, &n->base);
 	if (status) {
-		entry = ssam_nf_refcount_dec(nf, n->event.reg, n->event.id);
-		if (entry->refcount == 0)
-			kfree(entry);
+		if (entry) {
+			entry = ssam_nf_refcount_dec(nf, n->event.reg, n->event.id);
+			if (entry->refcount == 0)
+				kfree(entry);
+		}
 
 		mutex_unlock(&nf->lock);
 		return status;
 	}
 
-	if (entry->refcount == 1) {
-		status = ssam_ssh_event_enable(ctrl, n->event.reg, n->event.id,
-					       n->event.flags);
+	if (entry && entry->refcount == 1) {
+		status = ssam_ssh_event_enable(ctrl, n->event.reg, n->event.id, n->event.flags);
 		if (status) {
 			ssam_nfblk_remove(&n->base);
 			kfree(ssam_nf_refcount_dec(nf, n->event.reg, n->event.id));
@@ -2188,7 +2196,7 @@ int ssam_notifier_register(struct ssam_controller *ctrl,
 
 		entry->flags = n->event.flags;
 
-	} else if (entry->flags != n->event.flags) {
+	} else if (entry && entry->flags != n->event.flags) {
 		ssam_warn(ctrl,
 			  "inconsistent flags when enabling event: got %#04x, expected %#04x (reg: %#04x, tc: %#04x, iid: %#04x)\n",
 			  n->event.flags, entry->flags, n->event.reg.target_category,
@@ -2205,17 +2213,16 @@ EXPORT_SYMBOL_GPL(ssam_notifier_register);
  * @ctrl: The controller the notifier has been registered on.
  * @n:    The event notifier to unregister.
  *
- * Unregister an event notifier and decrement the usage counter of the
- * associated SAM event. If the usage counter reaches zero, the event will be
- * disabled.
+ * Unregister an event notifier. Decrement the usage counter of the associated
+ * SAM event if the notifier is not marked as an observer. If the usage counter
+ * reaches zero, the event will be disabled.
  *
  * Return: Returns zero on success, %-ENOENT if the given notifier block has
  * not been registered on the controller. If the given notifier block was the
  * last one associated with its specific event, returns the status of the
  * event-disable EC-command.
  */
-int ssam_notifier_unregister(struct ssam_controller *ctrl,
-			     struct ssam_event_notifier *n)
+int ssam_notifier_unregister(struct ssam_controller *ctrl, struct ssam_event_notifier *n)
 {
 	u16 rqid = ssh_tc_to_rqid(n->event.id.target_category);
 	struct ssam_nf_refcount_entry *entry;
@@ -2236,6 +2243,13 @@ int ssam_notifier_unregister(struct ssam_controller *ctrl,
 		return -ENOENT;
 	}
 
+	/*
+	 * If this is an observer notifier, do not attempt to disable the
+	 * event, just remove it.
+	 */
+	if (n->flags & SSAM_EVENT_NOTIFIER_OBSERVER)
+		goto remove;
+
 	entry = ssam_nf_refcount_dec(nf, n->event.reg, n->event.id);
 	if (WARN_ON(!entry)) {
 		/*
@@ -2260,8 +2274,7 @@ int ssam_notifier_unregister(struct ssam_controller *ctrl,
 	}
 
 	if (entry->refcount == 0) {
-		status = ssam_ssh_event_disable(ctrl, n->event.reg, n->event.id,
-						n->event.flags);
+		status = ssam_ssh_event_disable(ctrl, n->event.reg, n->event.id, n->event.flags);
 		kfree(entry);
 	}
 
diff --git a/include/linux/surface_aggregator/controller.h b/include/linux/surface_aggregator/controller.h
index 0806796eabcb..cf4bb48a850e 100644
--- a/include/linux/surface_aggregator/controller.h
+++ b/include/linux/surface_aggregator/controller.h
@@ -795,6 +795,20 @@ enum ssam_event_mask {
 #define SSAM_EVENT_REGISTRY_REG \
 	SSAM_EVENT_REGISTRY(SSAM_SSH_TC_REG, 0x02, 0x01, 0x02)
 
+/**
+ * enum ssam_event_notifier_flags - Flags for event notifiers.
+ * @SSAM_EVENT_NOTIFIER_OBSERVER:
+ *	The corresponding notifier acts as observer. Registering a notifier
+ *	with this flag set will not attempt to enable any event. Equally,
+ *	unregistering will not attempt to disable any event. Note that a
+ *	notifier with this flag may not even correspond to a certain event at
+ *	all, only to a specific event target category. Event matching will not
+ *	be influenced by this flag.
+ */
+enum ssam_event_notifier_flags {
+	SSAM_EVENT_NOTIFIER_OBSERVER = BIT(0),
+};
+
 /**
  * struct ssam_event_notifier - Notifier block for SSAM events.
  * @base:        The base notifier block with callback function and priority.
@@ -803,6 +817,7 @@ enum ssam_event_mask {
  * @event.id:    ID specifying the event.
  * @event.mask:  Flags determining how events are matched to the notifier.
  * @event.flags: Flags used for enabling the event.
+ * @flags:       Notifier flags (see &enum ssam_event_notifier_flags).
  */
 struct ssam_event_notifier {
 	struct ssam_notifier_block base;
@@ -813,6 +828,8 @@ struct ssam_event_notifier {
 		enum ssam_event_mask mask;
 		u8 flags;
 	} event;
+
+	unsigned long flags;
 };
 
 int ssam_notifier_register(struct ssam_controller *ctrl,
-- 
2.33.0

From 049febaf3465c6543d4483293e7b23fa8a79453f Mon Sep 17 00:00:00 2001
From: Maximilian Luz <luzmaximilian@gmail.com>
Date: Fri, 4 Jun 2021 15:47:50 +0200
Subject: [PATCH] platform/surface: aggregator: Allow enabling of events
 without notifiers

We can already enable and disable SAM events via one of two ways: either
via a (non-observer) notifier tied to a specific event group, or a
generic event enable/disable request. In some instances, however,
neither method may be desirable.

The first method will tie the event enable request to a specific
notifier, however, when we want to receive notifications for multiple
event groups of the same target category and forward this to the same
notifier callback, we may receive duplicate events, i.e. one event per
registered notifier. The second method will bypass the internal
reference counting mechanism, meaning that a disable request will
disable the event regardless of any other client driver using it, which
may break the functionality of that driver.

To address this problem, add new functions that allow enabling and
disabling of events via the event reference counting mechanism built
into the controller, without needing to register a notifier.

This can then be used in combination with observer notifiers to process
multiple events of the same target category without duplication in the
same callback function.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Link: https://lore.kernel.org/r/20210604134755.535590-3-luzmaximilian@gmail.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Patchset: surface-sam
---
 .../platform/surface/aggregator/controller.c  | 293 +++++++++++++++---
 include/linux/surface_aggregator/controller.h |   8 +
 2 files changed, 253 insertions(+), 48 deletions(-)

diff --git a/drivers/platform/surface/aggregator/controller.c b/drivers/platform/surface/aggregator/controller.c
index cd3a6b77f48d..cedd0f779f7a 100644
--- a/drivers/platform/surface/aggregator/controller.c
+++ b/drivers/platform/surface/aggregator/controller.c
@@ -407,6 +407,31 @@ ssam_nf_refcount_dec(struct ssam_nf *nf, struct ssam_event_registry reg,
 	return NULL;
 }
 
+/**
+ * ssam_nf_refcount_dec_free() - Decrement reference-/activation-count of the
+ * given event and free its entry if the reference count reaches zero.
+ * @nf:  The notifier system reference.
+ * @reg: The registry used to enable/disable the event.
+ * @id:  The event ID.
+ *
+ * Decrements the reference-/activation-count of the specified event, freeing
+ * its entry if it reaches zero.
+ *
+ * Note: ``nf->lock`` must be held when calling this function.
+ */
+static void ssam_nf_refcount_dec_free(struct ssam_nf *nf,
+				      struct ssam_event_registry reg,
+				      struct ssam_event_id id)
+{
+	struct ssam_nf_refcount_entry *entry;
+
+	lockdep_assert_held(&nf->lock);
+
+	entry = ssam_nf_refcount_dec(nf, reg, id);
+	if (entry && entry->refcount == 0)
+		kfree(entry);
+}
+
 /**
  * ssam_nf_refcount_empty() - Test if the notification system has any
  * enabled/active events.
@@ -2122,6 +2147,109 @@ int ssam_ctrl_notif_d0_entry(struct ssam_controller *ctrl)
 
 /* -- Top-level event registry interface. ----------------------------------- */
 
+/**
+ * ssam_nf_refcount_enable() - Enable event for reference count entry if it has
+ * not already been enabled.
+ * @ctrl:  The controller to enable the event on.
+ * @entry: The reference count entry for the event to be enabled.
+ * @flags: The flags used for enabling the event on the EC.
+ *
+ * Enable the event associated with the given reference count entry if the
+ * reference count equals one, i.e. the event has not previously been enabled.
+ * If the event has already been enabled (i.e. reference count not equal to
+ * one), check that the flags used for enabling match and warn about this if
+ * they do not.
+ *
+ * This does not modify the reference count itself, which is done with
+ * ssam_nf_refcount_inc() / ssam_nf_refcount_dec().
+ *
+ * Note: ``nf->lock`` must be held when calling this function.
+ *
+ * Return: Returns zero on success. If the event is enabled by this call,
+ * returns the status of the event-enable EC command.
+ */
+static int ssam_nf_refcount_enable(struct ssam_controller *ctrl,
+				   struct ssam_nf_refcount_entry *entry, u8 flags)
+{
+	const struct ssam_event_registry reg = entry->key.reg;
+	const struct ssam_event_id id = entry->key.id;
+	struct ssam_nf *nf = &ctrl->cplt.event.notif;
+	int status;
+
+	lockdep_assert_held(&nf->lock);
+
+	ssam_dbg(ctrl, "enabling event (reg: %#04x, tc: %#04x, iid: %#04x, rc: %d)\n",
+		 reg.target_category, id.target_category, id.instance, entry->refcount);
+
+	if (entry->refcount == 1) {
+		status = ssam_ssh_event_enable(ctrl, reg, id, flags);
+		if (status)
+			return status;
+
+		entry->flags = flags;
+
+	} else if (entry->flags != flags) {
+		ssam_warn(ctrl,
+			  "inconsistent flags when enabling event: got %#04x, expected %#04x (reg: %#04x, tc: %#04x, iid: %#04x)\n",
+			  flags, entry->flags, reg.target_category, id.target_category,
+			  id.instance);
+	}
+
+	return 0;
+}
+
+/**
+ * ssam_nf_refcount_disable_free() - Disable event for reference count entry if it is
+ * no longer in use and free the corresponding entry.
+ * @ctrl:  The controller to disable the event on.
+ * @entry: The reference count entry for the event to be disabled.
+ * @flags: The flags used for enabling the event on the EC.
+ *
+ * If the reference count equals zero, i.e. the event is no longer requested by
+ * any client, the event will be disabled and the corresponding reference count
+ * entry freed. The reference count entry must not be used any more after a
+ * call to this function.
+ *
+ * Also checks if the flags used for disabling the event match the flags used
+ * for enabling the event and warns if they do not (regardless of reference
+ * count).
+ *
+ * This does not modify the reference count itself, which is done with
+ * ssam_nf_refcount_inc() / ssam_nf_refcount_dec().
+ *
+ * Note: ``nf->lock`` must be held when calling this function.
+ *
+ * Return: Returns zero on success. If the event is disabled by this call,
+ * returns the status of the event-enable EC command.
+ */
+static int ssam_nf_refcount_disable_free(struct ssam_controller *ctrl,
+					 struct ssam_nf_refcount_entry *entry, u8 flags)
+{
+	const struct ssam_event_registry reg = entry->key.reg;
+	const struct ssam_event_id id = entry->key.id;
+	struct ssam_nf *nf = &ctrl->cplt.event.notif;
+	int status;
+
+	lockdep_assert_held(&nf->lock);
+
+	ssam_dbg(ctrl, "disabling event (reg: %#04x, tc: %#04x, iid: %#04x, rc: %d)\n",
+		 reg.target_category, id.target_category, id.instance, entry->refcount);
+
+	if (entry->flags != flags) {
+		ssam_warn(ctrl,
+			  "inconsistent flags when disabling event: got %#04x, expected %#04x (reg: %#04x, tc: %#04x, iid: %#04x)\n",
+			  flags, entry->flags, reg.target_category, id.target_category,
+			  id.instance);
+	}
+
+	if (entry->refcount == 0) {
+		status = ssam_ssh_event_disable(ctrl, reg, id, flags);
+		kfree(entry);
+	}
+
+	return status;
+}
+
 /**
  * ssam_notifier_register() - Register an event notifier.
  * @ctrl: The controller to register the notifier on.
@@ -2166,41 +2294,26 @@ int ssam_notifier_register(struct ssam_controller *ctrl, struct ssam_event_notif
 			mutex_unlock(&nf->lock);
 			return PTR_ERR(entry);
 		}
-
-		ssam_dbg(ctrl, "enabling event (reg: %#04x, tc: %#04x, iid: %#04x, rc: %d)\n",
-			 n->event.reg.target_category, n->event.id.target_category,
-			 n->event.id.instance, entry->refcount);
 	}
 
 	status = ssam_nfblk_insert(nf_head, &n->base);
 	if (status) {
-		if (entry) {
-			entry = ssam_nf_refcount_dec(nf, n->event.reg, n->event.id);
-			if (entry->refcount == 0)
-				kfree(entry);
-		}
+		if (entry)
+			ssam_nf_refcount_dec_free(nf, n->event.reg, n->event.id);
 
 		mutex_unlock(&nf->lock);
 		return status;
 	}
 
-	if (entry && entry->refcount == 1) {
-		status = ssam_ssh_event_enable(ctrl, n->event.reg, n->event.id, n->event.flags);
+	if (entry) {
+		status = ssam_nf_refcount_enable(ctrl, entry, n->event.flags);
 		if (status) {
 			ssam_nfblk_remove(&n->base);
-			kfree(ssam_nf_refcount_dec(nf, n->event.reg, n->event.id));
+			ssam_nf_refcount_dec_free(nf, n->event.reg, n->event.id);
 			mutex_unlock(&nf->lock);
 			synchronize_srcu(&nf_head->srcu);
 			return status;
 		}
-
-		entry->flags = n->event.flags;
-
-	} else if (entry && entry->flags != n->event.flags) {
-		ssam_warn(ctrl,
-			  "inconsistent flags when enabling event: got %#04x, expected %#04x (reg: %#04x, tc: %#04x, iid: %#04x)\n",
-			  n->event.flags, entry->flags, n->event.reg.target_category,
-			  n->event.id.target_category, n->event.id.instance);
 	}
 
 	mutex_unlock(&nf->lock);
@@ -2247,35 +2360,20 @@ int ssam_notifier_unregister(struct ssam_controller *ctrl, struct ssam_event_not
 	 * If this is an observer notifier, do not attempt to disable the
 	 * event, just remove it.
 	 */
-	if (n->flags & SSAM_EVENT_NOTIFIER_OBSERVER)
-		goto remove;
-
-	entry = ssam_nf_refcount_dec(nf, n->event.reg, n->event.id);
-	if (WARN_ON(!entry)) {
-		/*
-		 * If this does not return an entry, there's a logic error
-		 * somewhere: The notifier block is registered, but the event
-		 * refcount entry is not there. Remove the notifier block
-		 * anyways.
-		 */
-		status = -ENOENT;
-		goto remove;
-	}
-
-	ssam_dbg(ctrl, "disabling event (reg: %#04x, tc: %#04x, iid: %#04x, rc: %d)\n",
-		 n->event.reg.target_category, n->event.id.target_category,
-		 n->event.id.instance, entry->refcount);
-
-	if (entry->flags != n->event.flags) {
-		ssam_warn(ctrl,
-			  "inconsistent flags when disabling event: got %#04x, expected %#04x (reg: %#04x, tc: %#04x, iid: %#04x)\n",
-			  n->event.flags, entry->flags, n->event.reg.target_category,
-			  n->event.id.target_category, n->event.id.instance);
-	}
+	if (!(n->flags & SSAM_EVENT_NOTIFIER_OBSERVER)) {
+		entry = ssam_nf_refcount_dec(nf, n->event.reg, n->event.id);
+		if (WARN_ON(!entry)) {
+			/*
+			 * If this does not return an entry, there's a logic
+			 * error somewhere: The notifier block is registered,
+			 * but the event refcount entry is not there. Remove
+			 * the notifier block anyways.
+			 */
+			status = -ENOENT;
+			goto remove;
+		}
 
-	if (entry->refcount == 0) {
-		status = ssam_ssh_event_disable(ctrl, n->event.reg, n->event.id, n->event.flags);
-		kfree(entry);
+		status = ssam_nf_refcount_disable_free(ctrl, entry, n->event.flags);
 	}
 
 remove:
@@ -2287,6 +2385,105 @@ int ssam_notifier_unregister(struct ssam_controller *ctrl, struct ssam_event_not
 }
 EXPORT_SYMBOL_GPL(ssam_notifier_unregister);
 
+/**
+ * ssam_controller_event_enable() - Enable the specified event.
+ * @ctrl:  The controller to enable the event for.
+ * @reg:   The event registry to use for enabling the event.
+ * @id:    The event ID specifying the event to be enabled.
+ * @flags: The SAM event flags used for enabling the event.
+ *
+ * Increment the event reference count of the specified event. If the event has
+ * not been enabled previously, it will be enabled by this call.
+ *
+ * Note: In general, ssam_notifier_register() with a non-observer notifier
+ * should be preferred for enabling/disabling events, as this will guarantee
+ * proper ordering and event forwarding in case of errors during event
+ * enabling/disabling.
+ *
+ * Return: Returns zero on success, %-ENOSPC if the reference count for the
+ * specified event has reached its maximum, %-ENOMEM if the corresponding event
+ * entry could not be allocated. If this is the first time that this event has
+ * been enabled (i.e. the reference count was incremented from zero to one by
+ * this call), returns the status of the event-enable EC-command.
+ */
+int ssam_controller_event_enable(struct ssam_controller *ctrl,
+				 struct ssam_event_registry reg,
+				 struct ssam_event_id id, u8 flags)
+{
+	u16 rqid = ssh_tc_to_rqid(id.target_category);
+	struct ssam_nf *nf = &ctrl->cplt.event.notif;
+	struct ssam_nf_refcount_entry *entry;
+	int status;
+
+	if (!ssh_rqid_is_event(rqid))
+		return -EINVAL;
+
+	mutex_lock(&nf->lock);
+
+	entry = ssam_nf_refcount_inc(nf, reg, id);
+	if (IS_ERR(entry)) {
+		mutex_unlock(&nf->lock);
+		return PTR_ERR(entry);
+	}
+
+	status = ssam_nf_refcount_enable(ctrl, entry, flags);
+	if (status) {
+		ssam_nf_refcount_dec_free(nf, reg, id);
+		mutex_unlock(&nf->lock);
+		return status;
+	}
+
+	mutex_unlock(&nf->lock);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ssam_controller_event_enable);
+
+/**
+ * ssam_controller_event_disable() - Disable the specified event.
+ * @ctrl:  The controller to disable the event for.
+ * @reg:   The event registry to use for disabling the event.
+ * @id:    The event ID specifying the event to be disabled.
+ * @flags: The flags used when enabling the event.
+ *
+ * Decrement the reference count of the specified event. If the reference count
+ * reaches zero, the event will be disabled.
+ *
+ * Note: In general, ssam_notifier_register()/ssam_notifier_unregister() with a
+ * non-observer notifier should be preferred for enabling/disabling events, as
+ * this will guarantee proper ordering and event forwarding in case of errors
+ * during event enabling/disabling.
+ *
+ * Return: Returns zero on success, %-ENOENT if the given event has not been
+ * enabled on the controller. If the reference count of the event reaches zero
+ * during this call, returns the status of the event-disable EC-command.
+ */
+int ssam_controller_event_disable(struct ssam_controller *ctrl,
+				  struct ssam_event_registry reg,
+				  struct ssam_event_id id, u8 flags)
+{
+	u16 rqid = ssh_tc_to_rqid(id.target_category);
+	struct ssam_nf *nf = &ctrl->cplt.event.notif;
+	struct ssam_nf_refcount_entry *entry;
+	int status = 0;
+
+	if (!ssh_rqid_is_event(rqid))
+		return -EINVAL;
+
+	mutex_lock(&nf->lock);
+
+	entry = ssam_nf_refcount_dec(nf, reg, id);
+	if (!entry) {
+		mutex_unlock(&nf->lock);
+		return -ENOENT;
+	}
+
+	status = ssam_nf_refcount_disable_free(ctrl, entry, flags);
+
+	mutex_unlock(&nf->lock);
+	return status;
+}
+EXPORT_SYMBOL_GPL(ssam_controller_event_disable);
+
 /**
  * ssam_notifier_disable_registered() - Disable events for all registered
  * notifiers.
diff --git a/include/linux/surface_aggregator/controller.h b/include/linux/surface_aggregator/controller.h
index cf4bb48a850e..7965bdc669c5 100644
--- a/include/linux/surface_aggregator/controller.h
+++ b/include/linux/surface_aggregator/controller.h
@@ -838,4 +838,12 @@ int ssam_notifier_register(struct ssam_controller *ctrl,
 int ssam_notifier_unregister(struct ssam_controller *ctrl,
 			     struct ssam_event_notifier *n);
 
+int ssam_controller_event_enable(struct ssam_controller *ctrl,
+				 struct ssam_event_registry reg,
+				 struct ssam_event_id id, u8 flags);
+
+int ssam_controller_event_disable(struct ssam_controller *ctrl,
+				  struct ssam_event_registry reg,
+				  struct ssam_event_id id, u8 flags);
+
 #endif /* _LINUX_SURFACE_AGGREGATOR_CONTROLLER_H */
-- 
2.33.0

From 90fcb577e9e9f42b56b5449e3ba90c02deb39928 Mon Sep 17 00:00:00 2001
From: Maximilian Luz <luzmaximilian@gmail.com>
Date: Fri, 4 Jun 2021 15:47:51 +0200
Subject: [PATCH] platform/surface: aggregator: Update copyright

It's 2021, update the copyright accordingly.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210604134755.535590-4-luzmaximilian@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Patchset: surface-sam
---
 drivers/platform/surface/aggregator/Kconfig             | 2 +-
 drivers/platform/surface/aggregator/Makefile            | 2 +-
 drivers/platform/surface/aggregator/bus.c               | 2 +-
 drivers/platform/surface/aggregator/bus.h               | 2 +-
 drivers/platform/surface/aggregator/controller.c        | 2 +-
 drivers/platform/surface/aggregator/controller.h        | 2 +-
 drivers/platform/surface/aggregator/core.c              | 2 +-
 drivers/platform/surface/aggregator/ssh_msgb.h          | 2 +-
 drivers/platform/surface/aggregator/ssh_packet_layer.c  | 2 +-
 drivers/platform/surface/aggregator/ssh_packet_layer.h  | 2 +-
 drivers/platform/surface/aggregator/ssh_parser.c        | 2 +-
 drivers/platform/surface/aggregator/ssh_parser.h        | 2 +-
 drivers/platform/surface/aggregator/ssh_request_layer.c | 2 +-
 drivers/platform/surface/aggregator/ssh_request_layer.h | 2 +-
 drivers/platform/surface/aggregator/trace.h             | 2 +-
 include/linux/surface_aggregator/controller.h           | 2 +-
 include/linux/surface_aggregator/device.h               | 2 +-
 include/linux/surface_aggregator/serial_hub.h           | 2 +-
 18 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/drivers/platform/surface/aggregator/Kconfig b/drivers/platform/surface/aggregator/Kconfig
index 3aaeea9f0433..fd6dc452f3e8 100644
--- a/drivers/platform/surface/aggregator/Kconfig
+++ b/drivers/platform/surface/aggregator/Kconfig
@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0+
-# Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+# Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
 
 menuconfig SURFACE_AGGREGATOR
 	tristate "Microsoft Surface System Aggregator Module Subsystem and Drivers"
diff --git a/drivers/platform/surface/aggregator/Makefile b/drivers/platform/surface/aggregator/Makefile
index c112e2c7112b..c8498c41e758 100644
--- a/drivers/platform/surface/aggregator/Makefile
+++ b/drivers/platform/surface/aggregator/Makefile
@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0+
-# Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+# Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
 
 # For include/trace/define_trace.h to include trace.h
 CFLAGS_core.o = -I$(src)
diff --git a/drivers/platform/surface/aggregator/bus.c b/drivers/platform/surface/aggregator/bus.c
index a9b660af0917..0169677c243e 100644
--- a/drivers/platform/surface/aggregator/bus.c
+++ b/drivers/platform/surface/aggregator/bus.c
@@ -2,7 +2,7 @@
 /*
  * Surface System Aggregator Module bus and device integration.
  *
- * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #include <linux/device.h>
diff --git a/drivers/platform/surface/aggregator/bus.h b/drivers/platform/surface/aggregator/bus.h
index 7712baaed6a5..ed032c2cbdb2 100644
--- a/drivers/platform/surface/aggregator/bus.h
+++ b/drivers/platform/surface/aggregator/bus.h
@@ -2,7 +2,7 @@
 /*
  * Surface System Aggregator Module bus and device integration.
  *
- * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #ifndef _SURFACE_AGGREGATOR_BUS_H
diff --git a/drivers/platform/surface/aggregator/controller.c b/drivers/platform/surface/aggregator/controller.c
index cedd0f779f7a..6646f4d6e10d 100644
--- a/drivers/platform/surface/aggregator/controller.c
+++ b/drivers/platform/surface/aggregator/controller.c
@@ -2,7 +2,7 @@
 /*
  * Main SSAM/SSH controller structure and functionality.
  *
- * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #include <linux/acpi.h>
diff --git a/drivers/platform/surface/aggregator/controller.h b/drivers/platform/surface/aggregator/controller.h
index 8297d34e7489..a0963c3562ff 100644
--- a/drivers/platform/surface/aggregator/controller.h
+++ b/drivers/platform/surface/aggregator/controller.h
@@ -2,7 +2,7 @@
 /*
  * Main SSAM/SSH controller structure and functionality.
  *
- * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #ifndef _SURFACE_AGGREGATOR_CONTROLLER_H
diff --git a/drivers/platform/surface/aggregator/core.c b/drivers/platform/surface/aggregator/core.c
index 8dc2c267bcd6..5d780e55f4a1 100644
--- a/drivers/platform/surface/aggregator/core.c
+++ b/drivers/platform/surface/aggregator/core.c
@@ -7,7 +7,7 @@
  * Handles communication via requests as well as enabling, disabling, and
  * relaying of events.
  *
- * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #include <linux/acpi.h>
diff --git a/drivers/platform/surface/aggregator/ssh_msgb.h b/drivers/platform/surface/aggregator/ssh_msgb.h
index 1221f642dda1..e562958ffdf0 100644
--- a/drivers/platform/surface/aggregator/ssh_msgb.h
+++ b/drivers/platform/surface/aggregator/ssh_msgb.h
@@ -2,7 +2,7 @@
 /*
  * SSH message builder functions.
  *
- * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #ifndef _SURFACE_AGGREGATOR_SSH_MSGB_H
diff --git a/drivers/platform/surface/aggregator/ssh_packet_layer.c b/drivers/platform/surface/aggregator/ssh_packet_layer.c
index 15d96eac6811..5e08049fc3ac 100644
--- a/drivers/platform/surface/aggregator/ssh_packet_layer.c
+++ b/drivers/platform/surface/aggregator/ssh_packet_layer.c
@@ -2,7 +2,7 @@
 /*
  * SSH packet transport layer.
  *
- * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #include <asm/unaligned.h>
diff --git a/drivers/platform/surface/aggregator/ssh_packet_layer.h b/drivers/platform/surface/aggregator/ssh_packet_layer.h
index e8757d03f279..2eb329f0b91a 100644
--- a/drivers/platform/surface/aggregator/ssh_packet_layer.h
+++ b/drivers/platform/surface/aggregator/ssh_packet_layer.h
@@ -2,7 +2,7 @@
 /*
  * SSH packet transport layer.
  *
- * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #ifndef _SURFACE_AGGREGATOR_SSH_PACKET_LAYER_H
diff --git a/drivers/platform/surface/aggregator/ssh_parser.c b/drivers/platform/surface/aggregator/ssh_parser.c
index e2dead8de94a..b77912f8f13b 100644
--- a/drivers/platform/surface/aggregator/ssh_parser.c
+++ b/drivers/platform/surface/aggregator/ssh_parser.c
@@ -2,7 +2,7 @@
 /*
  * SSH message parser.
  *
- * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #include <asm/unaligned.h>
diff --git a/drivers/platform/surface/aggregator/ssh_parser.h b/drivers/platform/surface/aggregator/ssh_parser.h
index 63c38d350988..3bd6e180fd16 100644
--- a/drivers/platform/surface/aggregator/ssh_parser.h
+++ b/drivers/platform/surface/aggregator/ssh_parser.h
@@ -2,7 +2,7 @@
 /*
  * SSH message parser.
  *
- * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #ifndef _SURFACE_AGGREGATOR_SSH_PARSER_H
diff --git a/drivers/platform/surface/aggregator/ssh_request_layer.c b/drivers/platform/surface/aggregator/ssh_request_layer.c
index 52a83a8fcf82..bfe1aaf38065 100644
--- a/drivers/platform/surface/aggregator/ssh_request_layer.c
+++ b/drivers/platform/surface/aggregator/ssh_request_layer.c
@@ -2,7 +2,7 @@
 /*
  * SSH request transport layer.
  *
- * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #include <asm/unaligned.h>
diff --git a/drivers/platform/surface/aggregator/ssh_request_layer.h b/drivers/platform/surface/aggregator/ssh_request_layer.h
index cb35815858d1..9c3cbae2d4bd 100644
--- a/drivers/platform/surface/aggregator/ssh_request_layer.h
+++ b/drivers/platform/surface/aggregator/ssh_request_layer.h
@@ -2,7 +2,7 @@
 /*
  * SSH request transport layer.
  *
- * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #ifndef _SURFACE_AGGREGATOR_SSH_REQUEST_LAYER_H
diff --git a/drivers/platform/surface/aggregator/trace.h b/drivers/platform/surface/aggregator/trace.h
index eb332bb53ae4..de64cf169060 100644
--- a/drivers/platform/surface/aggregator/trace.h
+++ b/drivers/platform/surface/aggregator/trace.h
@@ -2,7 +2,7 @@
 /*
  * Trace points for SSAM/SSH.
  *
- * Copyright (C) 2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2020-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #undef TRACE_SYSTEM
diff --git a/include/linux/surface_aggregator/controller.h b/include/linux/surface_aggregator/controller.h
index 7965bdc669c5..068e1982ad37 100644
--- a/include/linux/surface_aggregator/controller.h
+++ b/include/linux/surface_aggregator/controller.h
@@ -6,7 +6,7 @@
  * managing access and communication to and from the SSAM EC, as well as main
  * communication structures and definitions.
  *
- * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #ifndef _LINUX_SURFACE_AGGREGATOR_CONTROLLER_H
diff --git a/include/linux/surface_aggregator/device.h b/include/linux/surface_aggregator/device.h
index 6ff9c58b3e17..f636c5310321 100644
--- a/include/linux/surface_aggregator/device.h
+++ b/include/linux/surface_aggregator/device.h
@@ -7,7 +7,7 @@
  * Provides support for non-platform/non-ACPI SSAM clients via dedicated
  * subsystem.
  *
- * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #ifndef _LINUX_SURFACE_AGGREGATOR_DEVICE_H
diff --git a/include/linux/surface_aggregator/serial_hub.h b/include/linux/surface_aggregator/serial_hub.h
index 64276fbfa1d5..c3de43edcffa 100644
--- a/include/linux/surface_aggregator/serial_hub.h
+++ b/include/linux/surface_aggregator/serial_hub.h
@@ -6,7 +6,7 @@
  * Surface System Aggregator Module (SSAM). Provides the interface for basic
  * packet- and request-based communication with the SSAM EC via SSH.
  *
- * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #ifndef _LINUX_SURFACE_AGGREGATOR_SERIAL_HUB_H
-- 
2.33.0

From 9cb95e69b0fcc00f9b4889839d65c7ff41b99f7f Mon Sep 17 00:00:00 2001
From: Maximilian Luz <luzmaximilian@gmail.com>
Date: Fri, 4 Jun 2021 15:47:52 +0200
Subject: [PATCH] platform/surface: aggregator_cdev: Add support for forwarding
 events to user-space

Currently, debugging unknown events requires writing a custom driver.
This is somewhat difficult, slow to adapt, and not entirely
user-friendly for quickly trying to figure out things on devices of some
third-party user. We can do better. We already have a user-space
interface intended for debugging SAM EC requests, so let's add support
for receiving events to that.

This commit provides support for receiving events by reading from the
controller file. It additionally introduces two new IOCTLs to control
which event categories will be forwarded. Specifically, a user-space
client can specify which target categories it wants to receive events
from by registering the corresponding notifier(s) via the IOCTLs and
after that, read the received events by reading from the controller
device.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210604134755.535590-5-luzmaximilian@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Patchset: surface-sam
---
 .../userspace-api/ioctl/ioctl-number.rst      |   2 +-
 .../surface/surface_aggregator_cdev.c         | 460 +++++++++++++++++-
 include/uapi/linux/surface_aggregator/cdev.h  |  41 +-
 3 files changed, 477 insertions(+), 26 deletions(-)

diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
index 9bfc2b510c64..1409e40e6345 100644
--- a/Documentation/userspace-api/ioctl/ioctl-number.rst
+++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
@@ -325,7 +325,7 @@ Code  Seq#    Include File                                           Comments
 0xA3  90-9F  linux/dtlk.h
 0xA4  00-1F  uapi/linux/tee.h                                        Generic TEE subsystem
 0xA4  00-1F  uapi/asm/sgx.h                                          <mailto:linux-sgx@vger.kernel.org>
-0xA5  01     linux/surface_aggregator/cdev.h                         Microsoft Surface Platform System Aggregator
+0xA5  01-05  linux/surface_aggregator/cdev.h                         Microsoft Surface Platform System Aggregator
                                                                      <mailto:luzmaximilian@gmail.com>
 0xA5  20-2F  linux/surface_aggregator/dtx.h                          Microsoft Surface DTX driver
                                                                      <mailto:luzmaximilian@gmail.com>
diff --git a/drivers/platform/surface/surface_aggregator_cdev.c b/drivers/platform/surface/surface_aggregator_cdev.c
index 79e28fab7e40..dcda377896b7 100644
--- a/drivers/platform/surface/surface_aggregator_cdev.c
+++ b/drivers/platform/surface/surface_aggregator_cdev.c
@@ -3,29 +3,69 @@
  * Provides user-space access to the SSAM EC via the /dev/surface/aggregator
  * misc device. Intended for debugging and development.
  *
- * Copyright (C) 2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2020-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #include <linux/fs.h>
+#include <linux/ioctl.h>
 #include <linux/kernel.h>
+#include <linux/kfifo.h>
 #include <linux/kref.h>
 #include <linux/miscdevice.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/poll.h>
 #include <linux/rwsem.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
+#include <linux/vmalloc.h>
 
 #include <linux/surface_aggregator/cdev.h>
 #include <linux/surface_aggregator/controller.h>
+#include <linux/surface_aggregator/serial_hub.h>
 
 #define SSAM_CDEV_DEVICE_NAME	"surface_aggregator_cdev"
 
+
+/* -- Main structures. ------------------------------------------------------ */
+
+enum ssam_cdev_device_state {
+	SSAM_CDEV_DEVICE_SHUTDOWN_BIT = BIT(0),
+};
+
 struct ssam_cdev {
 	struct kref kref;
 	struct rw_semaphore lock;
+
+	struct device *dev;
 	struct ssam_controller *ctrl;
 	struct miscdevice mdev;
+	unsigned long flags;
+
+	struct rw_semaphore client_lock;  /* Guards client list. */
+	struct list_head client_list;
+};
+
+struct ssam_cdev_client;
+
+struct ssam_cdev_notifier {
+	struct ssam_cdev_client *client;
+	struct ssam_event_notifier nf;
+};
+
+struct ssam_cdev_client {
+	struct ssam_cdev *cdev;
+	struct list_head node;
+
+	struct mutex notifier_lock;	/* Guards notifier access for registration */
+	struct ssam_cdev_notifier *notifier[SSH_NUM_EVENTS];
+
+	struct mutex read_lock;		/* Guards FIFO buffer read access */
+	struct mutex write_lock;	/* Guards FIFO buffer write access */
+	DECLARE_KFIFO(buffer, u8, 4096);
+
+	wait_queue_head_t waitq;
+	struct fasync_struct *fasync;
 };
 
 static void __ssam_cdev_release(struct kref *kref)
@@ -47,24 +87,169 @@ static void ssam_cdev_put(struct ssam_cdev *cdev)
 		kref_put(&cdev->kref, __ssam_cdev_release);
 }
 
-static int ssam_cdev_device_open(struct inode *inode, struct file *filp)
+
+/* -- Notifier handling. ---------------------------------------------------- */
+
+static u32 ssam_cdev_notifier(struct ssam_event_notifier *nf, const struct ssam_event *in)
 {
-	struct miscdevice *mdev = filp->private_data;
-	struct ssam_cdev *cdev = container_of(mdev, struct ssam_cdev, mdev);
+	struct ssam_cdev_notifier *cdev_nf = container_of(nf, struct ssam_cdev_notifier, nf);
+	struct ssam_cdev_client *client = cdev_nf->client;
+	struct ssam_cdev_event event;
+	size_t n = struct_size(&event, data, in->length);
+
+	/* Translate event. */
+	event.target_category = in->target_category;
+	event.target_id = in->target_id;
+	event.command_id = in->command_id;
+	event.instance_id = in->instance_id;
+	event.length = in->length;
+
+	mutex_lock(&client->write_lock);
+
+	/* Make sure we have enough space. */
+	if (kfifo_avail(&client->buffer) < n) {
+		dev_warn(client->cdev->dev,
+			 "buffer full, dropping event (tc: %#04x, tid: %#04x, cid: %#04x, iid: %#04x)\n",
+			 in->target_category, in->target_id, in->command_id, in->instance_id);
+		mutex_unlock(&client->write_lock);
+		return 0;
+	}
 
-	filp->private_data = ssam_cdev_get(cdev);
-	return stream_open(inode, filp);
+	/* Copy event header and payload. */
+	kfifo_in(&client->buffer, (const u8 *)&event, struct_size(&event, data, 0));
+	kfifo_in(&client->buffer, &in->data[0], in->length);
+
+	mutex_unlock(&client->write_lock);
+
+	/* Notify waiting readers. */
+	kill_fasync(&client->fasync, SIGIO, POLL_IN);
+	wake_up_interruptible(&client->waitq);
+
+	/*
+	 * Don't mark events as handled, this is the job of a proper driver and
+	 * not the debugging interface.
+	 */
+	return 0;
 }
 
-static int ssam_cdev_device_release(struct inode *inode, struct file *filp)
+static int ssam_cdev_notifier_register(struct ssam_cdev_client *client, u8 tc, int priority)
 {
-	ssam_cdev_put(filp->private_data);
-	return 0;
+	const u16 rqid = ssh_tc_to_rqid(tc);
+	const u16 event = ssh_rqid_to_event(rqid);
+	struct ssam_cdev_notifier *nf;
+	int status;
+
+	/* Validate notifier target category. */
+	if (!ssh_rqid_is_event(rqid))
+		return -EINVAL;
+
+	mutex_lock(&client->notifier_lock);
+
+	/* Check if the notifier has already been registered. */
+	if (client->notifier[event]) {
+		mutex_unlock(&client->notifier_lock);
+		return -EEXIST;
+	}
+
+	/* Allocate new notifier. */
+	nf = kzalloc(sizeof(*nf), GFP_KERNEL);
+	if (!nf) {
+		mutex_unlock(&client->notifier_lock);
+		return -ENOMEM;
+	}
+
+	/*
+	 * Create a dummy notifier with the minimal required fields for
+	 * observer registration. Note that we can skip fully specifying event
+	 * and registry here as we do not need any matching and use silent
+	 * registration, which does not enable the corresponding event.
+	 */
+	nf->client = client;
+	nf->nf.base.fn = ssam_cdev_notifier;
+	nf->nf.base.priority = priority;
+	nf->nf.event.id.target_category = tc;
+	nf->nf.event.mask = 0;	/* Do not do any matching. */
+	nf->nf.flags = SSAM_EVENT_NOTIFIER_OBSERVER;
+
+	/* Register notifier. */
+	status = ssam_notifier_register(client->cdev->ctrl, &nf->nf);
+	if (status)
+		kfree(nf);
+	else
+		client->notifier[event] = nf;
+
+	mutex_unlock(&client->notifier_lock);
+	return status;
 }
 
-static long ssam_cdev_request(struct ssam_cdev *cdev, unsigned long arg)
+static int ssam_cdev_notifier_unregister(struct ssam_cdev_client *client, u8 tc)
+{
+	const u16 rqid = ssh_tc_to_rqid(tc);
+	const u16 event = ssh_rqid_to_event(rqid);
+	int status;
+
+	/* Validate notifier target category. */
+	if (!ssh_rqid_is_event(rqid))
+		return -EINVAL;
+
+	mutex_lock(&client->notifier_lock);
+
+	/* Check if the notifier is currently registered. */
+	if (!client->notifier[event]) {
+		mutex_unlock(&client->notifier_lock);
+		return -ENOENT;
+	}
+
+	/* Unregister and free notifier. */
+	status = ssam_notifier_unregister(client->cdev->ctrl, &client->notifier[event]->nf);
+	kfree(client->notifier[event]);
+	client->notifier[event] = NULL;
+
+	mutex_unlock(&client->notifier_lock);
+	return status;
+}
+
+static void ssam_cdev_notifier_unregister_all(struct ssam_cdev_client *client)
+{
+	int i;
+
+	down_read(&client->cdev->lock);
+
+	/*
+	 * This function may be used during shutdown, thus we need to test for
+	 * cdev->ctrl instead of the SSAM_CDEV_DEVICE_SHUTDOWN_BIT bit.
+	 */
+	if (client->cdev->ctrl) {
+		for (i = 0; i < SSH_NUM_EVENTS; i++)
+			ssam_cdev_notifier_unregister(client, i + 1);
+
+	} else {
+		int count = 0;
+
+		/*
+		 * Device has been shut down. Any notifier remaining is a bug,
+		 * so warn about that as this would otherwise hardly be
+		 * noticeable. Nevertheless, free them as well.
+		 */
+		mutex_lock(&client->notifier_lock);
+		for (i = 0; i < SSH_NUM_EVENTS; i++) {
+			count += !!(client->notifier[i]);
+			kfree(client->notifier[i]);
+			client->notifier[i] = NULL;
+		}
+		mutex_unlock(&client->notifier_lock);
+
+		WARN_ON(count > 0);
+	}
+
+	up_read(&client->cdev->lock);
+}
+
+
+/* -- IOCTL functions. ------------------------------------------------------ */
+
+static long ssam_cdev_request(struct ssam_cdev_client *client, struct ssam_cdev_request __user *r)
 {
-	struct ssam_cdev_request __user *r;
 	struct ssam_cdev_request rqst;
 	struct ssam_request spec = {};
 	struct ssam_response rsp = {};
@@ -72,7 +257,6 @@ static long ssam_cdev_request(struct ssam_cdev *cdev, unsigned long arg)
 	void __user *rspdata;
 	int status = 0, ret = 0, tmp;
 
-	r = (struct ssam_cdev_request __user *)arg;
 	ret = copy_struct_from_user(&rqst, sizeof(rqst), r, sizeof(*r));
 	if (ret)
 		goto out;
@@ -152,7 +336,7 @@ static long ssam_cdev_request(struct ssam_cdev *cdev, unsigned long arg)
 	}
 
 	/* Perform request. */
-	status = ssam_request_sync(cdev->ctrl, &spec, &rsp);
+	status = ssam_request_sync(client->cdev->ctrl, &spec, &rsp);
 	if (status)
 		goto out;
 
@@ -177,48 +361,247 @@ static long ssam_cdev_request(struct ssam_cdev *cdev, unsigned long arg)
 	return ret;
 }
 
-static long __ssam_cdev_device_ioctl(struct ssam_cdev *cdev, unsigned int cmd,
+static long ssam_cdev_notif_register(struct ssam_cdev_client *client,
+				     const struct ssam_cdev_notifier_desc __user *d)
+{
+	struct ssam_cdev_notifier_desc desc;
+	long ret;
+
+	ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
+	if (ret)
+		return ret;
+
+	return ssam_cdev_notifier_register(client, desc.target_category, desc.priority);
+}
+
+static long ssam_cdev_notif_unregister(struct ssam_cdev_client *client,
+				       const struct ssam_cdev_notifier_desc __user *d)
+{
+	struct ssam_cdev_notifier_desc desc;
+	long ret;
+
+	ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
+	if (ret)
+		return ret;
+
+	return ssam_cdev_notifier_unregister(client, desc.target_category);
+}
+
+
+/* -- File operations. ------------------------------------------------------ */
+
+static int ssam_cdev_device_open(struct inode *inode, struct file *filp)
+{
+	struct miscdevice *mdev = filp->private_data;
+	struct ssam_cdev_client *client;
+	struct ssam_cdev *cdev = container_of(mdev, struct ssam_cdev, mdev);
+
+	/* Initialize client */
+	client = vzalloc(sizeof(*client));
+	if (!client)
+		return -ENOMEM;
+
+	client->cdev = ssam_cdev_get(cdev);
+
+	INIT_LIST_HEAD(&client->node);
+
+	mutex_init(&client->notifier_lock);
+
+	mutex_init(&client->read_lock);
+	mutex_init(&client->write_lock);
+	INIT_KFIFO(client->buffer);
+	init_waitqueue_head(&client->waitq);
+
+	filp->private_data = client;
+
+	/* Attach client. */
+	down_write(&cdev->client_lock);
+
+	if (test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &cdev->flags)) {
+		up_write(&cdev->client_lock);
+		mutex_destroy(&client->write_lock);
+		mutex_destroy(&client->read_lock);
+		mutex_destroy(&client->notifier_lock);
+		ssam_cdev_put(client->cdev);
+		vfree(client);
+		return -ENODEV;
+	}
+	list_add_tail(&client->node, &cdev->client_list);
+
+	up_write(&cdev->client_lock);
+
+	stream_open(inode, filp);
+	return 0;
+}
+
+static int ssam_cdev_device_release(struct inode *inode, struct file *filp)
+{
+	struct ssam_cdev_client *client = filp->private_data;
+
+	/* Force-unregister all remaining notifiers of this client. */
+	ssam_cdev_notifier_unregister_all(client);
+
+	/* Detach client. */
+	down_write(&client->cdev->client_lock);
+	list_del(&client->node);
+	up_write(&client->cdev->client_lock);
+
+	/* Free client. */
+	mutex_destroy(&client->write_lock);
+	mutex_destroy(&client->read_lock);
+
+	mutex_destroy(&client->notifier_lock);
+
+	ssam_cdev_put(client->cdev);
+	vfree(client);
+
+	return 0;
+}
+
+static long __ssam_cdev_device_ioctl(struct ssam_cdev_client *client, unsigned int cmd,
 				     unsigned long arg)
 {
 	switch (cmd) {
 	case SSAM_CDEV_REQUEST:
-		return ssam_cdev_request(cdev, arg);
+		return ssam_cdev_request(client, (struct ssam_cdev_request __user *)arg);
+
+	case SSAM_CDEV_NOTIF_REGISTER:
+		return ssam_cdev_notif_register(client,
+						(struct ssam_cdev_notifier_desc __user *)arg);
+
+	case SSAM_CDEV_NOTIF_UNREGISTER:
+		return ssam_cdev_notif_unregister(client,
+						  (struct ssam_cdev_notifier_desc __user *)arg);
 
 	default:
 		return -ENOTTY;
 	}
 }
 
-static long ssam_cdev_device_ioctl(struct file *file, unsigned int cmd,
-				   unsigned long arg)
+static long ssam_cdev_device_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
-	struct ssam_cdev *cdev = file->private_data;
+	struct ssam_cdev_client *client = file->private_data;
 	long status;
 
 	/* Ensure that controller is valid for as long as we need it. */
+	if (down_read_killable(&client->cdev->lock))
+		return -ERESTARTSYS;
+
+	if (test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &client->cdev->flags)) {
+		up_read(&client->cdev->lock);
+		return -ENODEV;
+	}
+
+	status = __ssam_cdev_device_ioctl(client, cmd, arg);
+
+	up_read(&client->cdev->lock);
+	return status;
+}
+
+static ssize_t ssam_cdev_read(struct file *file, char __user *buf, size_t count, loff_t *offs)
+{
+	struct ssam_cdev_client *client = file->private_data;
+	struct ssam_cdev *cdev = client->cdev;
+	unsigned int copied;
+	int status = 0;
+
 	if (down_read_killable(&cdev->lock))
 		return -ERESTARTSYS;
 
-	if (!cdev->ctrl) {
+	/* Make sure we're not shut down. */
+	if (test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &cdev->flags)) {
 		up_read(&cdev->lock);
 		return -ENODEV;
 	}
 
-	status = __ssam_cdev_device_ioctl(cdev, cmd, arg);
+	do {
+		/* Check availability, wait if necessary. */
+		if (kfifo_is_empty(&client->buffer)) {
+			up_read(&cdev->lock);
+
+			if (file->f_flags & O_NONBLOCK)
+				return -EAGAIN;
+
+			status = wait_event_interruptible(client->waitq,
+							  !kfifo_is_empty(&client->buffer) ||
+							  test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT,
+								   &cdev->flags));
+			if (status < 0)
+				return status;
+
+			if (down_read_killable(&cdev->lock))
+				return -ERESTARTSYS;
+
+			/* Need to check that we're not shut down again. */
+			if (test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &cdev->flags)) {
+				up_read(&cdev->lock);
+				return -ENODEV;
+			}
+		}
+
+		/* Try to read from FIFO. */
+		if (mutex_lock_interruptible(&client->read_lock)) {
+			up_read(&cdev->lock);
+			return -ERESTARTSYS;
+		}
+
+		status = kfifo_to_user(&client->buffer, buf, count, &copied);
+		mutex_unlock(&client->read_lock);
+
+		if (status < 0) {
+			up_read(&cdev->lock);
+			return status;
+		}
+
+		/* We might not have gotten anything, check this here. */
+		if (copied == 0 && (file->f_flags & O_NONBLOCK)) {
+			up_read(&cdev->lock);
+			return -EAGAIN;
+		}
+	} while (copied == 0);
 
 	up_read(&cdev->lock);
-	return status;
+	return copied;
+}
+
+static __poll_t ssam_cdev_poll(struct file *file, struct poll_table_struct *pt)
+{
+	struct ssam_cdev_client *client = file->private_data;
+	__poll_t events = 0;
+
+	if (test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &client->cdev->flags))
+		return EPOLLHUP | EPOLLERR;
+
+	poll_wait(file, &client->waitq, pt);
+
+	if (!kfifo_is_empty(&client->buffer))
+		events |= EPOLLIN | EPOLLRDNORM;
+
+	return events;
+}
+
+static int ssam_cdev_fasync(int fd, struct file *file, int on)
+{
+	struct ssam_cdev_client *client = file->private_data;
+
+	return fasync_helper(fd, file, on, &client->fasync);
 }
 
 static const struct file_operations ssam_controller_fops = {
 	.owner          = THIS_MODULE,
 	.open           = ssam_cdev_device_open,
 	.release        = ssam_cdev_device_release,
+	.read           = ssam_cdev_read,
+	.poll           = ssam_cdev_poll,
+	.fasync         = ssam_cdev_fasync,
 	.unlocked_ioctl = ssam_cdev_device_ioctl,
 	.compat_ioctl   = ssam_cdev_device_ioctl,
-	.llseek         = noop_llseek,
+	.llseek         = no_llseek,
 };
 
+
+/* -- Device and driver setup ----------------------------------------------- */
+
 static int ssam_dbg_device_probe(struct platform_device *pdev)
 {
 	struct ssam_controller *ctrl;
@@ -236,6 +619,7 @@ static int ssam_dbg_device_probe(struct platform_device *pdev)
 	kref_init(&cdev->kref);
 	init_rwsem(&cdev->lock);
 	cdev->ctrl = ctrl;
+	cdev->dev = &pdev->dev;
 
 	cdev->mdev.parent   = &pdev->dev;
 	cdev->mdev.minor    = MISC_DYNAMIC_MINOR;
@@ -243,6 +627,9 @@ static int ssam_dbg_device_probe(struct platform_device *pdev)
 	cdev->mdev.nodename = "surface/aggregator";
 	cdev->mdev.fops     = &ssam_controller_fops;
 
+	init_rwsem(&cdev->client_lock);
+	INIT_LIST_HEAD(&cdev->client_list);
+
 	status = misc_register(&cdev->mdev);
 	if (status) {
 		kfree(cdev);
@@ -256,8 +643,32 @@ static int ssam_dbg_device_probe(struct platform_device *pdev)
 static int ssam_dbg_device_remove(struct platform_device *pdev)
 {
 	struct ssam_cdev *cdev = platform_get_drvdata(pdev);
+	struct ssam_cdev_client *client;
 
-	misc_deregister(&cdev->mdev);
+	/*
+	 * Mark device as shut-down. Prevent new clients from being added and
+	 * new operations from being executed.
+	 */
+	set_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &cdev->flags);
+
+	down_write(&cdev->client_lock);
+
+	/* Remove all notifiers registered by us. */
+	list_for_each_entry(client, &cdev->client_list, node) {
+		ssam_cdev_notifier_unregister_all(client);
+	}
+
+	/* Wake up async clients. */
+	list_for_each_entry(client, &cdev->client_list, node) {
+		kill_fasync(&client->fasync, SIGIO, POLL_HUP);
+	}
+
+	/* Wake up blocking clients. */
+	list_for_each_entry(client, &cdev->client_list, node) {
+		wake_up_interruptible(&client->waitq);
+	}
+
+	up_write(&cdev->client_lock);
 
 	/*
 	 * The controller is only guaranteed to be valid for as long as the
@@ -266,8 +677,11 @@ static int ssam_dbg_device_remove(struct platform_device *pdev)
 	 */
 	down_write(&cdev->lock);
 	cdev->ctrl = NULL;
+	cdev->dev = NULL;
 	up_write(&cdev->lock);
 
+	misc_deregister(&cdev->mdev);
+
 	ssam_cdev_put(cdev);
 	return 0;
 }
diff --git a/include/uapi/linux/surface_aggregator/cdev.h b/include/uapi/linux/surface_aggregator/cdev.h
index fbcce04abfe9..4f393fafc235 100644
--- a/include/uapi/linux/surface_aggregator/cdev.h
+++ b/include/uapi/linux/surface_aggregator/cdev.h
@@ -6,7 +6,7 @@
  * device. This device provides direct user-space access to the SSAM EC.
  * Intended for debugging and development.
  *
- * Copyright (C) 2020 Maximilian Luz <luzmaximilian@gmail.com>
+ * Copyright (C) 2020-2021 Maximilian Luz <luzmaximilian@gmail.com>
  */
 
 #ifndef _UAPI_LINUX_SURFACE_AGGREGATOR_CDEV_H
@@ -73,6 +73,43 @@ struct ssam_cdev_request {
 	} response;
 } __attribute__((__packed__));
 
-#define SSAM_CDEV_REQUEST	_IOWR(0xA5, 1, struct ssam_cdev_request)
+/**
+ * struct ssam_cdev_notifier_desc - Notifier descriptor.
+ * @priority:        Priority value determining the order in which notifier
+ *                   callbacks will be called. A higher value means higher
+ *                   priority, i.e. the associated callback will be executed
+ *                   earlier than other (lower priority) callbacks.
+ * @target_category: The event target category for which this notifier should
+ *                   receive events.
+ *
+ * Specifies the notifier that should be registered or unregistered,
+ * specifically with which priority and for which target category of events.
+ */
+struct ssam_cdev_notifier_desc {
+	__s32 priority;
+	__u8 target_category;
+} __attribute__((__packed__));
+
+/**
+ * struct ssam_cdev_event - SSAM event sent by the EC.
+ * @target_category: Target category of the event source. See &enum ssam_ssh_tc.
+ * @target_id:       Target ID of the event source.
+ * @command_id:      Command ID of the event.
+ * @instance_id:     Instance ID of the event source.
+ * @length:          Length of the event payload in bytes.
+ * @data:            Event payload data.
+ */
+struct ssam_cdev_event {
+	__u8 target_category;
+	__u8 target_id;
+	__u8 command_id;
+	__u8 instance_id;
+	__u16 length;
+	__u8 data[];
+} __attribute__((__packed__));
+
+#define SSAM_CDEV_REQUEST		_IOWR(0xA5, 1, struct ssam_cdev_request)
+#define SSAM_CDEV_NOTIF_REGISTER	_IOW(0xA5, 2, struct ssam_cdev_notifier_desc)
+#define SSAM_CDEV_NOTIF_UNREGISTER	_IOW(0xA5, 3, struct ssam_cdev_notifier_desc)
 
 #endif /* _UAPI_LINUX_SURFACE_AGGREGATOR_CDEV_H */
-- 
2.33.0

From 811e4033759c0b149be60b3a4f27cb409f00c62a Mon Sep 17 00:00:00 2001
From: Maximilian Luz <luzmaximilian@gmail.com>
Date: Fri, 4 Jun 2021 15:47:53 +0200
Subject: [PATCH] platform/surface: aggregator_cdev: Allow enabling of events
 from user-space

While events can already be enabled and disabled via the generic request
IOCTL, this bypasses the internal reference counting mechanism of the
controller. Due to that, disabling an event will turn it off regardless
of any other client having requested said event, which may break
functionality of that client.

To solve this, add IOCTLs wrapping the ssam_controller_event_enable()
and ssam_controller_event_disable() functions, which have been
previously introduced for this specific purpose.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210604134755.535590-6-luzmaximilian@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Patchset: surface-sam
---
 .../surface/surface_aggregator_cdev.c         | 58 +++++++++++++++++++
 include/uapi/linux/surface_aggregator/cdev.h  | 32 ++++++++++
 2 files changed, 90 insertions(+)

diff --git a/drivers/platform/surface/surface_aggregator_cdev.c b/drivers/platform/surface/surface_aggregator_cdev.c
index dcda377896b7..7b86b36eaaa0 100644
--- a/drivers/platform/surface/surface_aggregator_cdev.c
+++ b/drivers/platform/surface/surface_aggregator_cdev.c
@@ -387,6 +387,58 @@ static long ssam_cdev_notif_unregister(struct ssam_cdev_client *client,
 	return ssam_cdev_notifier_unregister(client, desc.target_category);
 }
 
+static long ssam_cdev_event_enable(struct ssam_cdev_client *client,
+				   const struct ssam_cdev_event_desc __user *d)
+{
+	struct ssam_cdev_event_desc desc;
+	struct ssam_event_registry reg;
+	struct ssam_event_id id;
+	long ret;
+
+	/* Read descriptor from user-space. */
+	ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
+	if (ret)
+		return ret;
+
+	/* Translate descriptor. */
+	reg.target_category = desc.reg.target_category;
+	reg.target_id = desc.reg.target_id;
+	reg.cid_enable = desc.reg.cid_enable;
+	reg.cid_disable = desc.reg.cid_disable;
+
+	id.target_category = desc.id.target_category;
+	id.instance = desc.id.instance;
+
+	/* Disable event. */
+	return ssam_controller_event_enable(client->cdev->ctrl, reg, id, desc.flags);
+}
+
+static long ssam_cdev_event_disable(struct ssam_cdev_client *client,
+				    const struct ssam_cdev_event_desc __user *d)
+{
+	struct ssam_cdev_event_desc desc;
+	struct ssam_event_registry reg;
+	struct ssam_event_id id;
+	long ret;
+
+	/* Read descriptor from user-space. */
+	ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
+	if (ret)
+		return ret;
+
+	/* Translate descriptor. */
+	reg.target_category = desc.reg.target_category;
+	reg.target_id = desc.reg.target_id;
+	reg.cid_enable = desc.reg.cid_enable;
+	reg.cid_disable = desc.reg.cid_disable;
+
+	id.target_category = desc.id.target_category;
+	id.instance = desc.id.instance;
+
+	/* Disable event. */
+	return ssam_controller_event_disable(client->cdev->ctrl, reg, id, desc.flags);
+}
+
 
 /* -- File operations. ------------------------------------------------------ */
 
@@ -473,6 +525,12 @@ static long __ssam_cdev_device_ioctl(struct ssam_cdev_client *client, unsigned i
 		return ssam_cdev_notif_unregister(client,
 						  (struct ssam_cdev_notifier_desc __user *)arg);
 
+	case SSAM_CDEV_EVENT_ENABLE:
+		return ssam_cdev_event_enable(client, (struct ssam_cdev_event_desc __user *)arg);
+
+	case SSAM_CDEV_EVENT_DISABLE:
+		return ssam_cdev_event_disable(client, (struct ssam_cdev_event_desc __user *)arg);
+
 	default:
 		return -ENOTTY;
 	}
diff --git a/include/uapi/linux/surface_aggregator/cdev.h b/include/uapi/linux/surface_aggregator/cdev.h
index 4f393fafc235..08f46b60b151 100644
--- a/include/uapi/linux/surface_aggregator/cdev.h
+++ b/include/uapi/linux/surface_aggregator/cdev.h
@@ -90,6 +90,36 @@ struct ssam_cdev_notifier_desc {
 	__u8 target_category;
 } __attribute__((__packed__));
 
+/**
+ * struct ssam_cdev_event_desc - Event descriptor.
+ * @reg:                 Registry via which the event will be enabled/disabled.
+ * @reg.target_category: Target category for the event registry requests.
+ * @reg.target_id:       Target ID for the event registry requests.
+ * @reg.cid_enable:      Command ID for the event-enable request.
+ * @reg.cid_disable:     Command ID for the event-disable request.
+ * @id:                  ID specifying the event.
+ * @id.target_category:  Target category of the event source.
+ * @id.instance:         Instance ID of the event source.
+ * @flags:               Flags used for enabling the event.
+ *
+ * Specifies which event should be enabled/disabled and how to do that.
+ */
+struct ssam_cdev_event_desc {
+	struct {
+		__u8 target_category;
+		__u8 target_id;
+		__u8 cid_enable;
+		__u8 cid_disable;
+	} reg;
+
+	struct {
+		__u8 target_category;
+		__u8 instance;
+	} id;
+
+	__u8 flags;
+} __attribute__((__packed__));
+
 /**
  * struct ssam_cdev_event - SSAM event sent by the EC.
  * @target_category: Target category of the event source. See &enum ssam_ssh_tc.
@@ -111,5 +141,7 @@ struct ssam_cdev_event {
 #define SSAM_CDEV_REQUEST		_IOWR(0xA5, 1, struct ssam_cdev_request)
 #define SSAM_CDEV_NOTIF_REGISTER	_IOW(0xA5, 2, struct ssam_cdev_notifier_desc)
 #define SSAM_CDEV_NOTIF_UNREGISTER	_IOW(0xA5, 3, struct ssam_cdev_notifier_desc)
+#define SSAM_CDEV_EVENT_ENABLE		_IOW(0xA5, 4, struct ssam_cdev_event_desc)
+#define SSAM_CDEV_EVENT_DISABLE		_IOW(0xA5, 5, struct ssam_cdev_event_desc)
 
 #endif /* _UAPI_LINUX_SURFACE_AGGREGATOR_CDEV_H */
-- 
2.33.0

From 5ac0e06512474674cb5bf71f4805111b1768e526 Mon Sep 17 00:00:00 2001
From: Maximilian Luz <luzmaximilian@gmail.com>
Date: Fri, 4 Jun 2021 15:47:54 +0200
Subject: [PATCH] platform/surface: aggregator_cdev: Add lockdep support

Mark functions with locking requirements via the corresponding lockdep
calls for debugging and documentary purposes.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210604134755.535590-7-luzmaximilian@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Patchset: surface-sam
---
 .../platform/surface/surface_aggregator_cdev.c   | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/platform/surface/surface_aggregator_cdev.c b/drivers/platform/surface/surface_aggregator_cdev.c
index 7b86b36eaaa0..30fb50fde450 100644
--- a/drivers/platform/surface/surface_aggregator_cdev.c
+++ b/drivers/platform/surface/surface_aggregator_cdev.c
@@ -139,6 +139,8 @@ static int ssam_cdev_notifier_register(struct ssam_cdev_client *client, u8 tc, i
 	struct ssam_cdev_notifier *nf;
 	int status;
 
+	lockdep_assert_held_read(&client->cdev->lock);
+
 	/* Validate notifier target category. */
 	if (!ssh_rqid_is_event(rqid))
 		return -EINVAL;
@@ -188,6 +190,8 @@ static int ssam_cdev_notifier_unregister(struct ssam_cdev_client *client, u8 tc)
 	const u16 event = ssh_rqid_to_event(rqid);
 	int status;
 
+	lockdep_assert_held_read(&client->cdev->lock);
+
 	/* Validate notifier target category. */
 	if (!ssh_rqid_is_event(rqid))
 		return -EINVAL;
@@ -257,6 +261,8 @@ static long ssam_cdev_request(struct ssam_cdev_client *client, struct ssam_cdev_
 	void __user *rspdata;
 	int status = 0, ret = 0, tmp;
 
+	lockdep_assert_held_read(&client->cdev->lock);
+
 	ret = copy_struct_from_user(&rqst, sizeof(rqst), r, sizeof(*r));
 	if (ret)
 		goto out;
@@ -367,6 +373,8 @@ static long ssam_cdev_notif_register(struct ssam_cdev_client *client,
 	struct ssam_cdev_notifier_desc desc;
 	long ret;
 
+	lockdep_assert_held_read(&client->cdev->lock);
+
 	ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
 	if (ret)
 		return ret;
@@ -380,6 +388,8 @@ static long ssam_cdev_notif_unregister(struct ssam_cdev_client *client,
 	struct ssam_cdev_notifier_desc desc;
 	long ret;
 
+	lockdep_assert_held_read(&client->cdev->lock);
+
 	ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
 	if (ret)
 		return ret;
@@ -395,6 +405,8 @@ static long ssam_cdev_event_enable(struct ssam_cdev_client *client,
 	struct ssam_event_id id;
 	long ret;
 
+	lockdep_assert_held_read(&client->cdev->lock);
+
 	/* Read descriptor from user-space. */
 	ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
 	if (ret)
@@ -421,6 +433,8 @@ static long ssam_cdev_event_disable(struct ssam_cdev_client *client,
 	struct ssam_event_id id;
 	long ret;
 
+	lockdep_assert_held_read(&client->cdev->lock);
+
 	/* Read descriptor from user-space. */
 	ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
 	if (ret)
@@ -513,6 +527,8 @@ static int ssam_cdev_device_release(struct inode *inode, struct file *filp)
 static long __ssam_cdev_device_ioctl(struct ssam_cdev_client *client, unsigned int cmd,
 				     unsigned long arg)
 {
+	lockdep_assert_held_read(&client->cdev->lock);
+
 	switch (cmd) {
 	case SSAM_CDEV_REQUEST:
 		return ssam_cdev_request(client, (struct ssam_cdev_request __user *)arg);
-- 
2.33.0

From a9fbb1fe47b37b11b7022691dbe035ceca365bf4 Mon Sep 17 00:00:00 2001
From: Maximilian Luz <luzmaximilian@gmail.com>
Date: Wed, 2 Jun 2021 20:07:47 +0200
Subject: [PATCH] docs: driver-api: Update Surface Aggregator user-space
 interface documentation

Update the controller-device user-space interface (cdev) documentation
for the newly introduced IOCTLs and event interface.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Patchset: surface-sam
---
 .../surface_aggregator/clients/cdev.rst       | 127 +++++++++++++++++-
 1 file changed, 122 insertions(+), 5 deletions(-)

diff --git a/Documentation/driver-api/surface_aggregator/clients/cdev.rst b/Documentation/driver-api/surface_aggregator/clients/cdev.rst
index 248c1372d879..0134a841a079 100644
--- a/Documentation/driver-api/surface_aggregator/clients/cdev.rst
+++ b/Documentation/driver-api/surface_aggregator/clients/cdev.rst
@@ -1,9 +1,8 @@
 .. SPDX-License-Identifier: GPL-2.0+
 
-.. |u8| replace:: :c:type:`u8 <u8>`
-.. |u16| replace:: :c:type:`u16 <u16>`
 .. |ssam_cdev_request| replace:: :c:type:`struct ssam_cdev_request <ssam_cdev_request>`
 .. |ssam_cdev_request_flags| replace:: :c:type:`enum ssam_cdev_request_flags <ssam_cdev_request_flags>`
+.. |ssam_cdev_event| replace:: :c:type:`struct ssam_cdev_event <ssam_cdev_event>`
 
 ==============================
 User-Space EC Interface (cdev)
@@ -23,6 +22,40 @@ These IOCTLs and their respective input/output parameter structs are defined in
 A small python library and scripts for accessing this interface can be found
 at https://github.com/linux-surface/surface-aggregator-module/tree/master/scripts/ssam.
 
+.. contents::
+
+
+Receiving Events
+================
+
+Events can be received by reading from the device-file. The are represented by
+the |ssam_cdev_event| datatype.
+
+Before events are available to be read, however, the desired notifiers must be
+registered via the ``SSAM_CDEV_NOTIF_REGISTER`` IOCTL. Notifiers are, in
+essence, callbacks, called when the EC sends an event. They are, in this
+interface, associated with a specific target category and device-file-instance.
+They forward any event of this category to the buffer of the corresponding
+instance, from which it can then be read.
+
+Notifiers themselves do not enable events on the EC. Thus, it may additionally
+be necessary to enable events via the ``SSAM_CDEV_EVENT_ENABLE`` IOCTL. While
+notifiers work per-client (i.e. per-device-file-instance), events are enabled
+globally, for the EC and all of its clients (regardless of userspace or
+non-userspace). The ``SSAM_CDEV_EVENT_ENABLE`` and ``SSAM_CDEV_EVENT_DISABLE``
+IOCTLs take care of reference counting the events, such that an event is
+enabled as long as there is a client that has requested it.
+
+Note that enabled events are not automatically disabled once the client
+instance is closed. Therefore any client process (or group of processes) should
+balance their event enable calls with the corresponding event disable calls. It
+is, however, perfectly valid to enable and disable events on different client
+instances. For example, it is valid to set up notifiers and read events on
+client instance ``A``, enable those events on instance ``B`` (note that these
+will also be received by A since events are enabled/disabled globally), and
+after no more events are desired, disable the previously enabled events via
+instance ``C``.
+
 
 Controller IOCTLs
 =================
@@ -45,9 +78,33 @@ The following IOCTLs are provided:
      - ``REQUEST``
      - Perform synchronous SAM request.
 
+   * - ``0xA5``
+     - ``2``
+     - ``W``
+     - ``NOTIF_REGISTER``
+     - Register event notifier.
 
-``REQUEST``
------------
+   * - ``0xA5``
+     - ``3``
+     - ``W``
+     - ``NOTIF_UNREGISTER``
+     - Unregister event notifier.
+
+   * - ``0xA5``
+     - ``4``
+     - ``W``
+     - ``EVENT_ENABLE``
+     - Enable event source.
+
+   * - ``0xA5``
+     - ``5``
+     - ``W``
+     - ``EVENT_DISABLE``
+     - Disable event source.
+
+
+``SSAM_CDEV_REQUEST``
+---------------------
 
 Defined as ``_IOWR(0xA5, 1, struct ssam_cdev_request)``.
 
@@ -82,6 +139,66 @@ submitted, and completed (i.e. handed back to user-space) successfully from
 inside the IOCTL, but the request ``status`` member may still be negative in
 case the actual execution of the request failed after it has been submitted.
 
-A full definition of the argument struct is provided below:
+A full definition of the argument struct is provided below.
+
+``SSAM_CDEV_NOTIF_REGISTER``
+----------------------------
+
+Defined as ``_IOW(0xA5, 2, struct ssam_cdev_notifier_desc)``.
+
+Register a notifier for the event target category specified in the given
+notifier description with the specified priority. Notifiers registration is
+required to receive events, but does not enable events themselves. After a
+notifier for a specific target category has been registered, all events of that
+category will be forwarded to the userspace client and can then be read from
+the device file instance. Note that events may have to be enabled, e.g. via the
+``SSAM_CDEV_EVENT_ENABLE`` IOCTL, before the EC will send them.
+
+Only one notifier can be registered per target category and client instance. If
+a notifier has already been registered, this IOCTL will fail with ``-EEXIST``.
+
+Notifiers will automatically be removed when the device file instance is
+closed.
+
+``SSAM_CDEV_NOTIF_UNREGISTER``
+------------------------------
+
+Defined as ``_IOW(0xA5, 3, struct ssam_cdev_notifier_desc)``.
+
+Unregisters the notifier associated with the specified target category. The
+priority field will be ignored by this IOCTL. If no notifier has been
+registered for this client instance and the given category, this IOCTL will
+fail with ``-ENOENT``.
+
+``SSAM_CDEV_EVENT_ENABLE``
+--------------------------
+
+Defined as ``_IOW(0xA5, 4, struct ssam_cdev_event_desc)``.
+
+Enable the event associated with the given event descriptor.
+
+Note that this call will not register a notifier itself, it will only enable
+events on the controller. If you want to receive events by reading from the
+device file, you will need to register the corresponding notifier(s) on that
+instance.
+
+Events are not automatically disabled when the device file is closed. This must
+be done manually, via a call to the ``SSAM_CDEV_EVENT_DISABLE`` IOCTL.
+
+``SSAM_CDEV_EVENT_DISABLE``
+---------------------------
+
+Defined as ``_IOW(0xA5, 5, struct ssam_cdev_event_desc)``.
+
+Disable the event associated with the given event descriptor.
+
+Note that this will not unregister any notifiers. Events may still be received
+and forwarded to user-space after this call. The only safe way of stopping
+events from being received is unregistering all previously registered
+notifiers.
+
+
+Structures and Enums
+====================
 
 .. kernel-doc:: include/uapi/linux/surface_aggregator/cdev.h
-- 
2.33.0

From d7e63a9c9b6ab4d2bbcb2529ac75040afbb2ef57 Mon Sep 17 00:00:00 2001
From: Maximilian Luz <luzmaximilian@gmail.com>
Date: Fri, 4 Jun 2021 23:09:06 +0200
Subject: [PATCH] platform/surface: aggregator: Do not return uninitialized
 value

The status variable in ssam_nf_refcount_disable_free() is only set when
the reference count equals zero. Otherwise, it is returned
uninitialized. Fix this by always initializing status to zero.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: 640ee17199e4 ("platform/surface: aggregator: Allow enabling of events without notifiers")
Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Link: https://lore.kernel.org/r/20210604210907.25738-2-luzmaximilian@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Patchset: surface-sam
---
 drivers/platform/surface/aggregator/controller.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/platform/surface/aggregator/controller.c b/drivers/platform/surface/aggregator/controller.c
index 6646f4d6e10d..634399387d76 100644
--- a/drivers/platform/surface/aggregator/controller.c
+++ b/drivers/platform/surface/aggregator/controller.c
@@ -2228,7 +2228,7 @@ static int ssam_nf_refcount_disable_free(struct ssam_controller *ctrl,
 	const struct ssam_event_registry reg = entry->key.reg;
 	const struct ssam_event_id id = entry->key.id;
 	struct ssam_nf *nf = &ctrl->cplt.event.notif;
-	int status;
+	int status = 0;
 
 	lockdep_assert_held(&nf->lock);
 
-- 
2.33.0

From 6e3cc31d888abadbc7c077bc77f9b75a85d1fbc7 Mon Sep 17 00:00:00 2001
From: Maximilian Luz <luzmaximilian@gmail.com>
Date: Fri, 4 Jun 2021 23:09:07 +0200
Subject: [PATCH] platform/surface: aggregator: Drop unnecessary variable
 initialization

The status variable in ssam_controller_event_disable() is always set, no
need to initialize it.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Link: https://lore.kernel.org/r/20210604210907.25738-3-luzmaximilian@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Patchset: surface-sam
---
 drivers/platform/surface/aggregator/controller.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/platform/surface/aggregator/controller.c b/drivers/platform/surface/aggregator/controller.c
index 634399387d76..b8c377b3f932 100644
--- a/drivers/platform/surface/aggregator/controller.c
+++ b/drivers/platform/surface/aggregator/controller.c
@@ -2464,7 +2464,7 @@ int ssam_controller_event_disable(struct ssam_controller *ctrl,
 	u16 rqid = ssh_tc_to_rqid(id.target_category);
 	struct ssam_nf *nf = &ctrl->cplt.event.notif;
 	struct ssam_nf_refcount_entry *entry;
-	int status = 0;
+	int status;
 
 	if (!ssh_rqid_is_event(rqid))
 		return -EINVAL;
-- 
2.33.0

From 3efcf53a8fc5281a40890c35584c2f21ff37c24f Mon Sep 17 00:00:00 2001
From: Baokun Li <libaokun1@huawei.com>
Date: Wed, 9 Jun 2021 15:26:38 +0800
Subject: [PATCH] platform/surface: aggregator: Use list_move_tail instead of
 list_del/list_add_tail in ssh_request_layer.c

Using list_move_tail() instead of list_del() + list_add_tail() in ssh_request_layer.c.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Maximilian Luz <luzmaximilian@gmail.com>
Link: https://lore.kernel.org/r/20210609072638.1358174-1-libaokun1@huawei.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Patchset: surface-sam
---
 .../platform/surface/aggregator/ssh_request_layer.c    | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/platform/surface/aggregator/ssh_request_layer.c b/drivers/platform/surface/aggregator/ssh_request_layer.c
index bfe1aaf38065..790f7f0eee98 100644
--- a/drivers/platform/surface/aggregator/ssh_request_layer.c
+++ b/drivers/platform/surface/aggregator/ssh_request_layer.c
@@ -863,9 +863,7 @@ static void ssh_rtl_timeout_reap(struct work_struct *work)
 		clear_bit(SSH_REQUEST_SF_PENDING_BIT, &r->state);
 
 		atomic_dec(&rtl->pending.count);
-		list_del(&r->node);
-
-		list_add_tail(&r->node, &claimed);
+		list_move_tail(&r->node, &claimed);
 	}
 	spin_unlock(&rtl->pending.lock);
 
@@ -1204,8 +1202,7 @@ void ssh_rtl_shutdown(struct ssh_rtl *rtl)
 		smp_mb__before_atomic();
 		clear_bit(SSH_REQUEST_SF_QUEUED_BIT, &r->state);
 
-		list_del(&r->node);
-		list_add_tail(&r->node, &claimed);
+		list_move_tail(&r->node, &claimed);
 	}
 	spin_unlock(&rtl->queue.lock);
 
@@ -1238,8 +1235,7 @@ void ssh_rtl_shutdown(struct ssh_rtl *rtl)
 			smp_mb__before_atomic();
 			clear_bit(SSH_REQUEST_SF_PENDING_BIT, &r->state);
 
-			list_del(&r->node);
-			list_add_tail(&r->node, &claimed);
+			list_move_tail(&r->node, &claimed);
 		}
 		spin_unlock(&rtl->pending.lock);
 	}
-- 
2.33.0

From 0dc803d88061434dbe86713ef132d239a8adaebd Mon Sep 17 00:00:00 2001
From: Baokun Li <libaokun1@huawei.com>
Date: Wed, 9 Jun 2021 15:24:48 +0800
Subject: [PATCH] platform/surface: aggregator: Use list_move_tail instead of
 list_del/list_add_tail in ssh_packet_layer.c

Using list_move_tail() instead of list_del() + list_add_tail() in ssh_packet_layer.c.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Maximilian Luz <luzmaximilian@gmail.com>
Link: https://lore.kernel.org/r/20210609072448.1357524-1-libaokun1@huawei.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Patchset: surface-sam
---
 drivers/platform/surface/aggregator/ssh_packet_layer.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/platform/surface/aggregator/ssh_packet_layer.c b/drivers/platform/surface/aggregator/ssh_packet_layer.c
index 5e08049fc3ac..8a4451c1ffe5 100644
--- a/drivers/platform/surface/aggregator/ssh_packet_layer.c
+++ b/drivers/platform/surface/aggregator/ssh_packet_layer.c
@@ -1567,9 +1567,7 @@ static void ssh_ptl_timeout_reap(struct work_struct *work)
 		clear_bit(SSH_PACKET_SF_PENDING_BIT, &p->state);
 
 		atomic_dec(&ptl->pending.count);
-		list_del(&p->pending_node);
-
-		list_add_tail(&p->pending_node, &claimed);
+		list_move_tail(&p->pending_node, &claimed);
 	}
 
 	spin_unlock(&ptl->pending.lock);
@@ -1957,8 +1955,7 @@ void ssh_ptl_shutdown(struct ssh_ptl *ptl)
 		smp_mb__before_atomic();
 		clear_bit(SSH_PACKET_SF_QUEUED_BIT, &p->state);
 
-		list_del(&p->queue_node);
-		list_add_tail(&p->queue_node, &complete_q);
+		list_move_tail(&p->queue_node, &complete_q);
 	}
 	spin_unlock(&ptl->queue.lock);
 
@@ -1970,8 +1967,7 @@ void ssh_ptl_shutdown(struct ssh_ptl *ptl)
 		smp_mb__before_atomic();
 		clear_bit(SSH_PACKET_SF_PENDING_BIT, &p->state);
 
-		list_del(&p->pending_node);
-		list_add_tail(&p->pending_node, &complete_q);
+		list_move_tail(&p->pending_node, &complete_q);
 	}
 	atomic_set(&ptl->pending.count, 0);
 	spin_unlock(&ptl->pending.lock);
-- 
2.33.0