eternalwrt-mt798x/target/linux/rockchip/patches-6.18/121-28-phy-core-add-notifier-infrastructure.patch

From git@z Thu Jan  1 00:00:00 1970
Subject: [PATCH v13 28/35] phy: core: add notifier infrastructure
From: Sebastian Reichel <sebastian.reichel@collabora.com>
Date: Tue, 14 Jul 2026 21:26:29 +0200
Message-Id: <20260714-rockchip-usbdp-cleanup-v13-28-6cb3e769d4c5@collabora.com>
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Some PHY devices with multiple ports (e.g. USB3 and DP) require a reset
if the configuration changes or cable orientation changes. This is a
problem, as the consumer device will run into undefined behavior.

With the new PHY notifier API introduced in this patch, the consumer
driver can hook into reset events coming from a PHY device to handle the
PHY going down gracefully.

Note that this uses -ENOSYS instead of the more sensible -ENOTSUP for
the stub functions when GENERIC_PHY is disabled to stay consistent with
the existing ones.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
---
 drivers/phy/phy-core.c  | 65 +++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/phy/phy.h | 40 ++++++++++++++++++++++++++++++
 2 files changed, 105 insertions(+)

--- a/drivers/phy/phy-core.c
+++ b/drivers/phy/phy-core.c
@@ -521,6 +521,70 @@ int phy_notify_disconnect(struct phy *ph
 EXPORT_SYMBOL_GPL(phy_notify_disconnect);
 
 /**
+ * phy_register_notifier() - register a notifier for PHY events
+ * @phy: the phy returned by phy_get()
+ * @nb: notifier block to register
+ *
+ * Allows PHY consumers to receive notifications about PHY reset events.
+ * PHY providers can signal these events using phy_notify_reset().
+ *
+ * Returns: %0 if successful, a negative error code otherwise
+ */
+int phy_register_notifier(struct phy *phy, struct notifier_block *nb)
+{
+	if (!phy)
+		return 0;
+
+	return blocking_notifier_chain_register(&phy->notifier, nb);
+}
+EXPORT_SYMBOL_GPL(phy_register_notifier);
+
+/**
+ * phy_unregister_notifier() - unregister a notifier for PHY events
+ * @phy: the phy returned by phy_get()
+ * @nb: notifier block to unregister
+ *
+ * Returns: %0 if successful, a negative error code otherwise
+ */
+int phy_unregister_notifier(struct phy *phy, struct notifier_block *nb)
+{
+	if (!phy)
+		return 0;
+
+	return blocking_notifier_chain_unregister(&phy->notifier, nb);
+}
+EXPORT_SYMBOL_GPL(phy_unregister_notifier);
+
+/**
+ * phy_notify_reset() - notify consumers of a PHY reset event
+ * @phy: the phy that is being reset
+ * @event: the notification event (PRE_RESET or POST_RESET)
+ *
+ * Called by PHY providers to notify consumers that the PHY is about to
+ * be reset or has completed a reset. This allows consumers to quiesce
+ * hardware before the PHY becomes unavailable.
+ *
+ * This may be called from within PHY provider callbacks (e.g. set_mode,
+ * power_on) where phy->mutex is held. Consumer notification handlers must
+ * therefore NOT call back into the PHY framework (e.g. phy_power_off,
+ * phy_exit) on the same PHY, as this would result in a deadlock.
+ *
+ * Returns: %0 if successful or no notifiers registered, a negative error
+ * code if a notifier returns an error (for PRE_RESET only)
+ */
+int phy_notify_reset(struct phy *phy, enum phy_notification event)
+{
+	int ret;
+
+	if (!phy)
+		return 0;
+
+	ret = blocking_notifier_call_chain(&phy->notifier, event, phy);
+	return notifier_to_errno(ret);
+}
+EXPORT_SYMBOL_GPL(phy_notify_reset);
+
+/**
  * phy_configure() - Changes the phy parameters
  * @phy: the phy returned by phy_get()
  * @opts: New configuration to apply
@@ -996,6 +1060,7 @@ struct phy *phy_create(struct device *de
 	device_initialize(&phy->dev);
 	lockdep_register_key(&phy->lockdep_key);
 	mutex_init_with_key(&phy->mutex, &phy->lockdep_key);
+	BLOCKING_INIT_NOTIFIER_HEAD(&phy->notifier);
 
 	phy->dev.class = &phy_class;
 	phy->dev.parent = dev;
--- a/include/linux/phy/phy.h
+++ b/include/linux/phy/phy.h
@@ -11,6 +11,7 @@
 #define __DRIVERS_PHY_H
 
 #include <linux/err.h>
+#include <linux/notifier.h>
 #include <linux/of.h>
 #include <linux/device.h>
 #include <linux/pm_runtime.h>
@@ -54,6 +55,16 @@ enum phy_media {
 };
 
 /**
+ * enum phy_notification - PHY notification events
+ * @PHY_NOTIFY_PRE_RESET: PHY is about to be reset, consumers should quiesce
+ * @PHY_NOTIFY_POST_RESET: PHY reset is complete, consumers may resume
+ */
+enum phy_notification {
+	PHY_NOTIFY_PRE_RESET,
+	PHY_NOTIFY_POST_RESET,
+};
+
+/**
  * union phy_configure_opts - Opaque generic phy configuration
  *
  * @mipi_dphy:	Configuration set applicable for phys supporting
@@ -159,6 +170,7 @@ struct phy_attrs {
  * @power_count: used to protect when the PHY is used by multiple consumers
  * @attrs: used to specify PHY specific attributes
  * @pwr: power regulator associated with the phy
+ * @notifier: notifier head for PHY reset events
  * @debugfs: debugfs directory
  */
 struct phy {
@@ -171,6 +183,7 @@ struct phy {
 	int			power_count;
 	struct phy_attrs	attrs;
 	struct regulator	*pwr;
+	struct blocking_notifier_head notifier;
 	struct dentry		*debugfs;
 };
 
@@ -255,6 +268,9 @@ int phy_reset(struct phy *phy);
 int phy_calibrate(struct phy *phy);
 int phy_notify_connect(struct phy *phy, int port);
 int phy_notify_disconnect(struct phy *phy, int port);
+int phy_register_notifier(struct phy *phy, struct notifier_block *nb);
+int phy_unregister_notifier(struct phy *phy, struct notifier_block *nb);
+int phy_notify_reset(struct phy *phy, enum phy_notification event);
 static inline int phy_get_bus_width(struct phy *phy)
 {
 	return phy->attrs.bus_width;
@@ -409,6 +425,30 @@ static inline int phy_notify_disconnect(
 {
 	if (!phy)
 		return 0;
+	return -ENOSYS;
+}
+
+static inline int phy_register_notifier(struct phy *phy,
+					struct notifier_block *nb)
+{
+	if (!phy)
+		return 0;
+	return -ENOSYS;
+}
+
+static inline int phy_unregister_notifier(struct phy *phy,
+					  struct notifier_block *nb)
+{
+	if (!phy)
+		return 0;
+	return -ENOSYS;
+}
+
+static inline int phy_notify_reset(struct phy *phy,
+				   enum phy_notification event)
+{
+	if (!phy)
+		return 0;
 	return -ENOSYS;
 }