[PATCH v3] of/overlay: add of overlay notifications
From: Alan Tull <hidden>
Date: 2016-03-03 15:13:15
This patch add of overlay notifications.
When DT overlays are being added, some drivers/subsystems
need to see device tree overlays before the changes go into
the live tree.
This is distinct from reconfig notifiers that are
post-apply or post-remove and which issue very granular
notifications without providing access to the context
of a whole overlay.
The following 4 notificatons are issued:
OF_OVERLAY_PRE_APPLY
OF_OVERLAY_POST_APPLY
OF_OVERLAY_PRE_REMOVE
OF_OVERLAY_POST_REMOVE
In the case of pre-apply notification, if the notifier
returns error, the overlay will be rejected.
This patch exports two functions for registering/unregistering
notifications:
of_overlay_notifier_register(struct notifier_block *nb)
of_overlay_notifier_unregister(struct notifier_block *nb)
The of_mutex is held during these notifications. The
notification data includes pointers to the overlay target
and the overlay:
struct of_overlay_notify_data {
struct device_node *overlay;
struct device_node *target;
};
Signed-off-by: Alan Tull <redacted>
---
v2: add missing 'static inline' in of.h
v3: fix build for !OF_OVERLAY in of.h
add a note in the header that the of_mutex is held
---
drivers/of/overlay.c | 47 ++++++++++++++++++++++++++++++++++++++++++++++-
include/linux/of.h | 25 +++++++++++++++++++++++++
2 files changed, 71 insertions(+), 1 deletion(-)
diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 8225081..a26f0ed 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c@@ -56,6 +56,41 @@ struct of_overlay { static int of_overlay_apply_one(struct of_overlay *ov, struct device_node *target, const struct device_node *overlay); +static BLOCKING_NOTIFIER_HEAD(of_overlay_chain); + +int of_overlay_notifier_register(struct notifier_block *nb) +{ + return blocking_notifier_chain_register(&of_overlay_chain, nb); +} +EXPORT_SYMBOL_GPL(of_overlay_notifier_register); + +int of_overlay_notifier_unregister(struct notifier_block *nb) +{ + return blocking_notifier_chain_unregister(&of_overlay_chain, nb); +} +EXPORT_SYMBOL_GPL(of_overlay_notifier_unregister); + +static int of_overlay_notify(struct of_overlay *ov, + enum of_overlay_notify_action action) +{ + struct of_overlay_notify_data nd; + int i, ret; + + for (i = 0; i < ov->count; i++) { + struct of_overlay_info *ovinfo = &ov->ovinfo_tab[i]; + + nd.target = ovinfo->target; + nd.overlay = ovinfo->overlay; + + ret = blocking_notifier_call_chain(&of_overlay_chain, + action, &nd); + if (ret) + return notifier_to_errno(ret); + } + + return 0; +} + static int of_overlay_apply_single_property(struct of_overlay *ov, struct device_node *target, struct property *prop) {
@@ -370,6 +405,13 @@ int of_overlay_create(struct device_node *tree) goto err_free_idr; } + err = of_overlay_notify(ov, OF_OVERLAY_PRE_APPLY); + if (err < 0) { + pr_err("%s: Pre-apply notifier failed (err=%d)\n", + __func__, err); + goto err_free_idr; + } + /* apply the overlay */ err = of_overlay_apply(ov); if (err) {
@@ -389,6 +431,8 @@ int of_overlay_create(struct device_node *tree) /* add to the tail of the overlay list */ list_add_tail(&ov->node, &ov_list); + of_overlay_notify(ov, OF_OVERLAY_POST_APPLY); + mutex_unlock(&of_mutex); return id;
@@ -509,9 +553,10 @@ int of_overlay_destroy(int id) goto out; } - + of_overlay_notify(ov, OF_OVERLAY_PRE_REMOVE); list_del(&ov->node); __of_changeset_revert(&ov->cset); + of_overlay_notify(ov, OF_OVERLAY_POST_REMOVE); of_free_overlay_info(ov); idr_remove(&ov_idr, id); of_changeset_destroy(&ov->cset);
diff --git a/include/linux/of.h b/include/linux/of.h
index dc6e396..33832a9 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h@@ -1076,6 +1076,18 @@ static inline bool of_device_is_system_power_controller(const struct device_node * Overlay support */ +enum of_overlay_notify_action { + OF_OVERLAY_PRE_APPLY, + OF_OVERLAY_POST_APPLY, + OF_OVERLAY_PRE_REMOVE, + OF_OVERLAY_POST_REMOVE, +}; + +struct of_overlay_notify_data { + struct device_node *overlay; + struct device_node *target; +}; + #ifdef CONFIG_OF_OVERLAY /* ID based overlays; the API for external users */
@@ -1083,6 +1095,9 @@ int of_overlay_create(struct device_node *tree); int of_overlay_destroy(int id); int of_overlay_destroy_all(void); +int of_overlay_notifier_register(struct notifier_block *nb); +int of_overlay_notifier_unregister(struct notifier_block *nb); + #else static inline int of_overlay_create(struct device_node *tree)
@@ -1100,6 +1115,16 @@ static inline int of_overlay_destroy_all(void) return -ENOTSUPP; } +static inline int of_overlay_notifier_register(struct notifier_block *nb) +{ + return 0; +} + +static inline int of_overlay_notifier_unregister(struct notifier_block *nb) +{ + return 0; +} + #endif #endif /* _LINUX_OF_H */
--
1.7.9.5
--
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