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SubjectRe: [PATCH v3 16/21] nvmem: add a notifier chain
2018-09-12 9:51 GMT+02:00 Bartosz Golaszewski <brgl@bgdev.pl>:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> Add a blocking notifier chain with four events (add and remove for
> both devices and cells) so that users can get notified about the
> addition of nvmem resources they're waiting for.
>
> We'll use this instead of the at24 setup callback in the mityomapl138
> board file.
>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> ---
> drivers/nvmem/core.c | 36 ++++++++++++++++++++++++++++++++++
> include/linux/nvmem-consumer.h | 21 ++++++++++++++++++++
> 2 files changed, 57 insertions(+)
>
> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> index 9cc86d131e1e..af6f7163cb67 100644
> --- a/drivers/nvmem/core.c
> +++ b/drivers/nvmem/core.c
> @@ -65,6 +65,8 @@ static LIST_HEAD(nvmem_cell_tables);
> static DEFINE_MUTEX(nvmem_lookup_mutex);
> static LIST_HEAD(nvmem_lookup_list);
>
> +static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
> +
> #ifdef CONFIG_DEBUG_LOCK_ALLOC
> static struct lock_class_key eeprom_lock_key;
> #endif
> @@ -300,6 +302,7 @@ static struct nvmem_device *nvmem_find(const char *name)
>
> static void nvmem_cell_drop(struct nvmem_cell *cell)
> {
> + blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_REMOVE, cell);
> mutex_lock(&nvmem_mutex);
> list_del(&cell->node);
> mutex_unlock(&nvmem_mutex);
> @@ -319,6 +322,7 @@ static void nvmem_cell_add(struct nvmem_cell *cell)
> mutex_lock(&nvmem_mutex);
> list_add_tail(&cell->node, &cell->nvmem->cells);
> mutex_unlock(&nvmem_mutex);
> + blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_ADD, cell);
> }
>
> static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
> @@ -434,6 +438,32 @@ static int nvmem_setup_compat(struct nvmem_device *nvmem,
> return 0;
> }
>
> +/**
> + * nvmem_register_notifier() - Register a notifier block for nvmem events.
> + *
> + * @nb: notifier block to be called on nvmem events.
> + *
> + * Return: 0 on success, negative error number on failure.
> + */
> +int nvmem_register_notifier(struct notifier_block *nb)
> +{
> + return blocking_notifier_chain_register(&nvmem_notifier, nb);
> +}
> +EXPORT_SYMBOL_GPL(nvmem_register_notifier);
> +
> +/**
> + * nvmem_unregister_notifier() - Unregister a notifier block for nvmem events.
> + *
> + * @nb: notifier block to be unregistered.
> + *
> + * Return: 0 on success, negative error number on failure.
> + */
> +int nvmem_unregister_notifier(struct notifier_block *nb)
> +{
> + return blocking_notifier_chain_unregister(&nvmem_notifier, nb);
> +}
> +EXPORT_SYMBOL_GPL(nvmem_unregister_notifier);
> +
> static int nvmem_add_cells_from_table(struct nvmem_device *nvmem)
> {
> const struct nvmem_cell_info *info;
> @@ -647,6 +677,10 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
> if (rval)
> goto err_remove_cells;
>
> + rval = blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
> + if (rval)
> + goto err_remove_cells;
> +
> return nvmem;
>
> err_remove_cells:
> @@ -675,6 +709,8 @@ static void nvmem_device_release(struct kref *kref)
> nvmem_device_remove_all_cells(nvmem);
> device_del(&nvmem->dev);
> put_device(&nvmem->dev);
> +
> + blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);

Ugh this is wrong, it should be called before all the other code in
this function. I'll resend in the next version after reviews.

Bart

> }
>
> /**
> diff --git a/include/linux/nvmem-consumer.h b/include/linux/nvmem-consumer.h
> index 27eee3945405..0326b52e906b 100644
> --- a/include/linux/nvmem-consumer.h
> +++ b/include/linux/nvmem-consumer.h
> @@ -14,6 +14,7 @@
>
> #include <linux/err.h>
> #include <linux/errno.h>
> +#include <linux/notifier.h>
>
> struct device;
> struct device_node;
> @@ -47,6 +48,13 @@ struct nvmem_cell_lookup {
> struct list_head node;
> };
>
> +enum {
> + NVMEM_ADD = 1,
> + NVMEM_REMOVE,
> + NVMEM_CELL_ADD,
> + NVMEM_CELL_REMOVE,
> +};
> +
> #if IS_ENABLED(CONFIG_NVMEM)
>
> /* Cell based interface */
> @@ -80,6 +88,9 @@ void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries,
> void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries,
> size_t nentries);
>
> +int nvmem_register_notifier(struct notifier_block *nb);
> +int nvmem_unregister_notifier(struct notifier_block *nb);
> +
> #else
>
> static inline struct nvmem_cell *nvmem_cell_get(struct device *dev,
> @@ -179,6 +190,16 @@ nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries) {}
> static inline void
> nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries) {}
>
> +static inline int nvmem_register_notifier(struct notifier_block *nb)
> +{
> + return -ENOSYS;
> +}
> +
> +static inline int nvmem_unregister_notifier(struct notifier_block *nb)
> +{
> + return -ENOSYS;
> +}
> +
> #endif /* CONFIG_NVMEM */
>
> #if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OF)
> --
> 2.18.0
>

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