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Commit 39a842e2 authored by Alan Tull's avatar Alan Tull Committed by Greg Kroah-Hartman
Browse files

of/overlay: add of overlay notifications 



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: default avatarAlan Tull <atull@opensource.altera.com>
Acked-by: default avatarRob Herring <robh@kernel.org>
Acked-by: default avatarMoritz Fischer <moritz.fischer@ettus.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c1eac0d0

drivers/of/overlay.c

+46 −1
Original line number Diff line number Diff line
@@ -58,6 +58,41 @@ 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)

{
@@ -368,6 +403,13 @@ 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)
@@ -382,6 +424,8 @@ 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;
@@ -498,9 +542,10 @@ 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);

include/linux/of.h

+25 −0
Original line number Diff line number Diff line
@@ -1266,6 +1266,18 @@ 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 */
@@ -1273,6 +1285,9 @@ 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)
@@ -1290,6 +1305,16 @@ 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 */