Re: [PATCH 1/3] PM: wakeup: Add routine to help fetch wakeup source object.

[Rafael J. Wysocki]

On Tue, Oct 22, 2019 at 9:51 AM Ran Wang <ran.wang_1@xxxxxxx> wrote:
>
> Some user might want to go through all registered wakeup sources
> and doing things accordingly. For example, SoC PM driver might need to
> do HW programming to prevent powering down specific IP which wakeup
> source depending on. So add this API to help walk through all registered
> wakeup source objects on that list and return them one by one.
>
> Signed-off-by: Ran Wang <ran.wang_1@xxxxxxx>
> Tested-by: Leonard Crestez <leonard.crestez@xxxxxxx>
> ---
> Change in v8
>         - Rename wakeup_source_get_next() to wakeup_sources_walk_next().
>         - Add wakeup_sources_read_lock() to take over locking job of
>           wakeup_source_get_star().
>         - Rename wakeup_source_get_start() to wakeup_sources_walk_start().
>         - Replace wakeup_source_get_stop() with wakeup_sources_read_unlock().
>         - Define macro for_each_wakeup_source(ws).
>
> Change in v7:
>         - Remove define of member *dev in wake_irq to fix conflict with commit
>         c8377adfa781 ("PM / wakeup: Show wakeup sources stats in sysfs"), user
>         will use ws->dev->parent instead.
>         - Remove '#include <linux/of_device.h>' because it is not used.
>
> Change in v6:
>         - Add wakeup_source_get_star() and wakeup_source_get_stop() to aligned
>         with wakeup_sources_stats_seq_start/nex/stop.
>
> Change in v5:
>         - Update commit message, add decription of walk through all wakeup
>         source objects.
>         - Add SCU protection in function wakeup_source_get_next().
>         - Rename wakeup_source member 'attached_dev' to 'dev' and move it up
>         (before wakeirq).
>
> Change in v4:
>         - None.
>
> Change in v3:
>         - Adjust indentation of *attached_dev;.
>
> Change in v2:
>         - None.
>
>  drivers/base/power/wakeup.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/pm_wakeup.h   |  9 +++++++++
>  2 files changed, 51 insertions(+)
>
> diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
> index 5817b51..8c7a5f9 100644
> --- a/drivers/base/power/wakeup.c
> +++ b/drivers/base/power/wakeup.c
> @@ -248,6 +248,48 @@ void wakeup_source_unregister(struct wakeup_source *ws)
>  EXPORT_SYMBOL_GPL(wakeup_source_unregister);
>
>  /**
> + * wakeup_sources_read_lock - Lock wakeup source list for read.

Please document the return value.

> + */
> +int wakeup_sources_read_lock(void)
> +{
> +       return srcu_read_lock(&wakeup_srcu);
> +}
> +EXPORT_SYMBOL_GPL(wakeup_sources_read_lock);
> +
> +/**
> + * wakeup_sources_read_unlock - Unlock wakeup source list.

Please document the argument.

> + */
> +void wakeup_sources_read_unlock(int idx)
> +{
> +       srcu_read_unlock(&wakeup_srcu, idx);
> +}
> +EXPORT_SYMBOL_GPL(wakeup_sources_read_unlock);
> +
> +/**
> + * wakeup_sources_walk_start - Begin a walk on wakeup source list

Please document the return value and add a note that the wakeup
sources list needs to be locked for reading for this to be safe.

> + */
> +struct wakeup_source *wakeup_sources_walk_start(void)
> +{
> +       struct list_head *ws_head = &wakeup_sources;
> +
> +       return list_entry_rcu(ws_head->next, struct wakeup_source, entry);
> +}
> +EXPORT_SYMBOL_GPL(wakeup_sources_walk_start);
> +
> +/**
> + * wakeup_sources_walk_next - Get next wakeup source from the list
> + * @ws: Previous wakeup source object

Please add a note that the wakeup sources list needs to be locked for
reading for this to be safe.

> + */
> +struct wakeup_source *wakeup_sources_walk_next(struct wakeup_source *ws)
> +{
> +       struct list_head *ws_head = &wakeup_sources;
> +
> +       return list_next_or_null_rcu(ws_head, &ws->entry,
> +                               struct wakeup_source, entry);
> +}
> +EXPORT_SYMBOL_GPL(wakeup_sources_walk_next);
> +
> +/**
>   * device_wakeup_attach - Attach a wakeup source object to a device object.
>   * @dev: Device to handle.
>   * @ws: Wakeup source object to attach to @dev.
> diff --git a/include/linux/pm_wakeup.h b/include/linux/pm_wakeup.h
> index 661efa0..aa3da66 100644
> --- a/include/linux/pm_wakeup.h
> +++ b/include/linux/pm_wakeup.h
> @@ -63,6 +63,11 @@ struct wakeup_source {
>         bool                    autosleep_enabled:1;
>  };
>
> +#define for_each_wakeup_source(ws) \
> +       for ((ws) = wakeup_sources_walk_start();        \
> +            (ws);                                      \
> +            (ws) = wakeup_sources_walk_next((ws)))
> +
>  #ifdef CONFIG_PM_SLEEP
>
>  /*
> @@ -92,6 +97,10 @@ extern void wakeup_source_remove(struct wakeup_source *ws);
>  extern struct wakeup_source *wakeup_source_register(struct device *dev,
>                                                     const char *name);
>  extern void wakeup_source_unregister(struct wakeup_source *ws);
> +extern int wakeup_sources_read_lock(void);
> +extern void wakeup_sources_read_unlock(int idx);
> +extern struct wakeup_source *wakeup_sources_walk_start(void);
> +extern struct wakeup_source *wakeup_sources_walk_next(struct wakeup_source *ws);
>  extern int device_wakeup_enable(struct device *dev);
>  extern int device_wakeup_disable(struct device *dev);
>  extern void device_set_wakeup_capable(struct device *dev, bool capable);
> --
> 2.7.4
>