On Thu, 25 Feb 2016, Alan Tull wrote:
> 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 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 <atull@xxxxxxxxxxxxxxxxxxxxx>
> ---
> 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..e70a686 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -1083,6 +1083,21 @@ int of_overlay_create(struct device_node *tree);
> int of_overlay_destroy(int id);
> int of_overlay_destroy_all(void);
>
> +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;
> +};
> +
> +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;
> }
>
> +int of_overlay_notifier_register(struct notifier_block *nb)
Needs 'static inline'
> +{
> + return 0;
> +}
> +
> +int of_overlay_notifier_unregister(struct notifier_block *nb)
Needs 'static inline'
Alan
> +{
> + return 0;
> +}
> +
> #endif
>
> #endif /* _LINUX_OF_H */
> --
> 1.7.9.5
>
>
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